Corrosion and Chemical Resistant Masonry Mtls Hbk (PARTIAL) - W. Sheppard (Noyes, 1986) WW

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CORROSION AND

CHEMICAL RESISTANT

MASONRY MATERIALS

HANDBOOK

Edited by

Walter Lee Sheppard, Jr.

C.C.R.M., Inc.

Havertown, Pennsylvania

NOYES PUBLICATIONS

Park Ridge, New Jersey, U.S.A.



Copyright @ 1986 by Noyes Publications

No part of this book may be reproduced in any form

without permission in writing from the Publisher.

Library of Congress Catalog Card Number: 8525929

ISBN: O-8155-1053-5

Printed in the United States

Published in the United States of America by

Noyes Publications

Mill Road, Park Ridge, New Jersey 07656

10987654321

Library of Congress Cataloging-in-Publication Data

Main entry under title:

Corrosion and chemical resistant masonry.

Bibliography: p.

Includes index.

1. Corrosion and anti-corrosives--Handbooks,

manuals, etc. 2. Masonry--Materials--Corrosion--

Handbooks, manuals, etc. I. Sheppard, Walter Lee,

1911-

TA418.74.C5926 1986 620.1’304223 85-25929

ISBN O-8155-1053-5



It seems appropriate to dedicate this volume tothose friends and experts who had agreed to pro-

vide sections for this book, but who died before

their sections could be written. There are four of

them: lgnatius Metil, Walter Szymansky, David W.

McDowell, and Stanley Morrow, each an author-

ity in his field, and a wonderful person who will

ever remain in the respect and affection of his

associates as well as those of his family.



ACKNOWLEDGMENTS

Those who have rendered assistance to the authors

and editor in putting this volume together are far

too numerous to mention individually. Those who

have given permission for the use of previously

published material, and those who have permitted

our use of their drawings and illustrations are

acknowledged individually at the appropriate

spots. However there is one person who by dedi-

cation and selfless work has merited special men-

tion, and that is Sylvia Levy, who has been of in-

estimable assistance to the editor in rearranging

and retyping corrected material for publication.

x i i



Contributors

William H. Bauer

Department of Ceramics

College of Engineering

Rutgers University

Piscataway, New Jersey

James P. Bennett

United States Department

of Interior

Bureau of MinesTuscaloosa Research Center

University of Alabama

University, Alabama

John A. Bonar

Refractories Division

Sohio Engineered Materials Co.

Niagara Falls, New York

A.A. Boova

Atlas Minerals and Chemicals, Inc.

Mertztown, Pennsylvania

Brian L. Cooley

Peabody Continental-Heine Corp.

Des Plaines, Illinois

Thomas F. Degnan

Wilmington, Delaware

William M. Eckert

Dow Chemical Corporation, U.S.A.

Freeport, Texas

W.O. Eisenhut

Adhesive Engineering Company

San Carlos, California

Harold L. Fike

The Sulphur InstituteWashington, D.C.

David W. Fowler

Department of Civil Engineering

University of Texas

Austin, Texas

Kurt Goltz

Pennwalt Corporation

King of Prussia, Pennsylvania

Eugene C. Heilhecker I I I

Garlock, Incorporated

Sodus, New York

Al Hendricks

Wisconsin Protective Coatings

Green Bay, Wisconsin

.XIII



x i v Contributors

Hans J. Hoffmann

Abresist Corporation

Urbana, Indiana

Edmond W. Jarret

Con/Chem Incorporated

Furlong, Pennsylvania

Harlan H. Kline

Ameron-Protective Coatings

Division

Brea, California

Donald J. Kossler


Orange, California

William C. McBee

Albany Research Center

Bureau of Mines

United States Departmentof the Interior

Albany, Oregon

Henry G. Midgley

llminster Cement Research

Iiminster, United Kingdom

Robert E. Moore

United Engineers and

Constructors, Incorporated

Philadelphia, Pennsylvania

Edward G. Nawy

Department of Civil and

Environmental Engineering

Rutgers University

New Brunswick, New Jersey

Keith R. Pierce

Department of Mathematical

Sciences

University of Minnesota

Duluth, Minnesota

Sandor PopovicsDepartment of Civil Engineering

Drexel University


Kenneth A. Poss

Ashland Chemical Company

Columbus, Ohio

Milton H. Potter


Dorothy A. Richter

G EOSS

Salem, New Hampshire

Paul E. Schlett

Exxon Research and

Engineering Company

Florham Park, New Jersey

Mary Lou Schmidt



Wesley SeveranceThe Ceilcote Company

Berea, Ohio


C.C.R.M., Incorporated


Oliver W. Siebert

Monsanto Corporation

St. Louis, Missouri

William R. Slama

The Ceilcote Company

Berea, Ohio

Richard J. Smith

Patterson-Kelley Company

Harsco Corporation

East Stroudsburg, Pennsylvania

Joseph J. Spisak


Pittsburgh, Pennsylvania

Larry C. StephansRochester, New York



Contributors xv

Anthony J. Stump0

Burmah-Castro1 Incorporated

Hackensack, New Jersey

Thomas A. Sullivan (Retired)

Boulder City Engineering

Laboratory

Bureau of Mines

United States Department

of the Interior

Boulder City, Nevada

Robert L. Trinklein

Horseshoe Bend, Arkansas

Joseph M. WaltersJ.M. Waiters Company

Chester Springs, Pennsylvania

C.V. Wittenwyler

Shell Development Company

Westhollow Research Center

Houston, Texas



Contents

PREFACE.............................................vi i

CONTRIBUTORS ....................................... xiii

SECTION IINTRODUCTION

1. AN ENGINEER LOOKS AT CHEMICALLY RESISTANT MASONRY. .. .2

Robert E. Moore

Introduction. ..................................... .2

Definition and Types of Chemically Resistant Masonry. ......... .3

Chemically Resistant Masonry Components and Materials. ....... .5

Membranes. .................................... .6

Masonry Units .................................. .7

AcidBrick ................................. ...7

Carbon Brick ................................. .8

Foamed Borosilicate Glass Block .................... .9

High Alumina and Insulating Brick, Silica Brick, and

Specialty Brick and Block ........................ .9

Tile........................................1 0

Mortars and Grouts for Brick and Tile. .................. 10

Silicate Mortars.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1

Silica Mortars. ............................... .I1

Sulfur Mortars ............................... .I1

Resin Mortars. ............................... .I1

Hydraulic Mortars ............................. .I2

Chemically Resistant Masonry Applications ................. 13

Power Industry-Flue Gas Desulfurization Systems .......... 14

Specific Power Plant FGD System Experience. ............. 15

Conclusion. ..................................... .I8

Bibliography. .................................... .I8

xvii



.x VIII Contents

2. AN ARCHITECTURAL SPECIFIER LOOKS AT CORROSION

RESISTANT MASONRY ................................ .20

Milton H. Potter

Preview. ....................................... .20

Basic Data ...................................... .21

Materials and Methods of Construction-Masonry System ....... .22

Substrate. .................................... .22

Membrane.....................................2 2

Masonry Units ................................. .23

Liner Plate and Tile. ........................... .23

Quarry Tile ................................. .24

Ceramic Tile. ................................ .24

Corrosion Resistant Cements and Mortars ............... .24Sulfur Cements. .............................. .24

Resin Mortars. ............................... .25

Expansion Joints. ............................... .25

Required Details. ............................... .25

SECTION II

STRUCTURAL MATERIALS SUPPORTING

CORROSION RESISTANT MASONRY

3. METALLIC SHELLS. .................................. .28

Thomas F. Degnan

Introduction. .................................... .28

Materials Selection. ................................ .28

General Considerations. ........................... .28

Brittle Fracture. ................................ .29

Low Temperature Service .......................... .31

High Temperature Service. ......................... .34Corrosion Resistant Shells. ......................... .35

Other Corrosion Considerations ...................... .37

Economics of Steel Selection. ....................... .37

Design Considerations .............................. .39

Thickness of Shell ............................... .39

Tolerances. ................................... .40

Vertical Cylindrical Vessels ......................... .43

Dished or Conical Bottoms ....................... .43Flat Bottoms ................................ .43

Horizontal Cylindrical Vessels ....................... .44

Rectangular or Square Vessels ....................... .44

Flooring.. .................................. ..4 6

Construction Details ............................. .47

Nozzles, Inlets and Outlets ....................... .47

Internals ................................... .48

Welds......................................4 8

Surface Preparation ............................ .48

Pressure Testing ................................ .48



Contents xix

Model Specification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

Appendix: Guideline Specification for the Design and Fabrication

of Metallic Vessels Which Are to Receive Chemical-Resistant

Masonry Linings for Chemical Immersion Service. . . . . . . . . . . . .49References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

4.CONCRETE..........................................5 7

Edward G. Nawy

Introduction. .................................... .57

Concrete-Producing Materials. ......................... .57

Portland Cement. ............................... .57

Manufacture. ................................ .57

Strength ................................... .58Influence of Voids and Type of Cement on the Durability

of Concrete ................................ .59

Water and Air. ................................. .59

Water......................................5 9

Entrained Air. ............................... .60

Water/Cement Ratio ........................... .60

Aggregates. ................................... .60

Introduction. ................................ .60Coarse Aggregate. ............................. .60

Fine Aggregate. .............................. .61

Admixtures ................................... .61

Criteria for Quality Concrete. ......................... .62

Compactness .................................. .62

Strength.. .................................. ..6 2

Water/Cement Ratio ............................. .62

Texture. ..................................... .62

Mix Designs for Nuclear-Shielding Concrete .............. .63

Quality Tests on Concrete. ........................... .63

Workability or Consistency. ........................ .63

Air Content ................................... .63

Compressive Strength of Hardened Concrete. ............. .63

Flexural Strength of Plain Concrete Beams. .............. .66

Tensile Splitting Tests ............................ .66

Placing and Curing of Concrete ........................ .67

Placing.. ................................... ..6 7

Curing........................................6 7

Properties of Hardened Concrete ....................... .67

Compressive Strength. ............................ .68

Tensile Strength ................................ .68

Stress-Strain Curve. .............................. .69

Shrinkage. .................................... .70

Creep........................................7 1

Reinforcement ................................... .71Summary........................................7 2

References. ..................................... .73



xx Contents

5. TIMBER AS A STRUCTURAL MATERIAL TO SUPPORT

CHEMICAL RESISTANT MASONRY. ....................... .74


Selection of Wood Structure .......................... .80DesignNotes.. ................................. ..8 0

Possible Sizes and Shapes ............................ .83

Bibliography. .................................... .84

6. SOME NOTES ON PLASTICS AS THE SUPPORTING STRUCTURE. . . .85


SECTION III

MEMBRANES

7. SHEET LININGS ..................................... .88


History.........................................8 8

Types of Sheet ................................... .89

Loose Liners. .................................... .91

Substrate Requirements ............................. .92

Testing the Completed Lining ......................... .92Curing..........................................g 3

Manufacturer .................................... .93

Diffusion and Absorption ............................ .94

Chemical and Thermal Resistance. ...................... .94

Damage or Degradation ............................. .95

Repairs.. ..................................... ..9 6

Sources of Data on Chemical Resistance .................. .96

Bibliography. .................................... .97

Addendum.......................................9 7

8. FLUID-APPLIED MEMBRANES. .


Introduction. . . . . . . . . . . . .

Methods of Application . . . . .

Fillers. . . . . . . . . . . . . . . . . .

References. . . . . . . . . . . . . .

. . . . . . . 98

....... 98

....... 99

...... 1 0 0

. . . . . . 107

9. RIGID NONMETALLIC MEMBRANES . . . . . . . . . . . . . 109


10. HOT ASPHALT .............


Suitable Substrates .......

Application ............

Gauging Thickness. .......

Inspection and Repair .....

Limitations ............

. . . . . . . . . . . . . . . . . . 1 1 1

........ 113

........ 113

........ 115

........ 116

........ 117



Contents xxi

Reinforcing .................................... 117

Other Applications of Hot Asphalt ..................... 117

Cold Asphalt Applications. .......................... 118

Additional Notes. ................................ 119

Reinforcing Fabrics for Asphalt Membranes ............... 121

11. FIRED GLASS AND PORCELAIN AS MEMBRANES. . . . . . . . . . . . 123


References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .I26

Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

12. LEAD AS A MEMBRANE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127Oliver W. Siebert and Walter Lee Sheppard, Jr.

13. GLASS FABRIC REINFORCED FURAN MEMBRANES .......... 134


Installation. .................................... 137

References. .................................... 138

14. EPOXY/PHENOLICS. ......................

Al Hendricks

Properties ..........................

Resistance ..........................

Water Resistance. ...................

Solvents. .........................

Alkalies. .........................

Acids ...........................

Temperature Resistance ...............

Abrasion Resistance. .................Weathering. .......................

Toxicity ...........................

Surface Preparation ....................

Application .........................

Usage .............................

Bake Systems. .....................

Air Dry Systems ....................

. . . . . . . . . . 1 3 9

.......... 1 3 9

. . . . . . . . . . 140

.......... 140

.......... 140

.......... 140

.......... 140

.......... 140

.......... 140

.......... 140

.......... 141

.......... 141

.......... 141

.......... 141

.......... 141

.......... 141

SECTION IV

MASONRY UNITS

15. ACID BRICK AND SILICA BRICK ........................ 144

James P. Bennett and William M. Eckert

Acid Brick (Red Shale and Fireclay Bricks) ............... 144

Properties ................................... 144

Applications. ................................. 147

Chemical Resistance. .......................... 149

Temperature Limit ........................... 149

Pressure Effect .............................. 149



xxii Contents

irreversible Growth ........................... 150

Dimensions ................................ 150

Silica Brick. .................................... 150

Properties ................................... 150

Applications. ................................. 152

Chemical Resistance. .......................... 152

Temperature Limit ........................... 153

Thermal Expansion and Thermal Shock Resistance ...... 153

Strength and Abrasion Resistance. ................. 154

Pressure Effects. ............................. 154

Irreversible Growth ........................... 154

cost.....................................15 4

References. .................................... 154

16. CARBON BRICK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155


Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

17. CLOSED CELL FOAMED BOROSILICATE GLASS BLOCK

LlNlNGSYSTEM....................................16 0

Mary Lou Schmidt

Installation Methods .............................. 162

Bonding Systems. .............................. 163

Urethane Asphalt Adhesive/Membrane .............. 163

Inorganic Silica-Based Mortar. .................... 164

Combination Linings Incorporating Glass Block ........ 164

Flue Gas Desulfurization Systems. ................... 166

Waste Incineration. ............................. 166

Smelting Operations. ............................ 167

Baghouses ................................... 167

Tall Stacks. .................................. 167

Pickle Tanks. ................................. 168

Vessel Covers ................................. 168

Bibliography. ................................... 168

18. REFRACTORY AND INSULATING FIREBRICK . . . . . . . . . . . . . 170

Paul E. Schlett

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170Design Parameters Which Affect Refractory Lining Selection. . . . 170

Temperature.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

Atmospheric Composition. . . . . . . . . . . . . . . . . . . . . . . . . 174

Optimized Thermal Gradient Design Through a Refractory

Lining.......................................177

Brick Shapes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

References. . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179

19. SPECIALTIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180

Part A: Porcelain Brick . . . . . . . . . . . . . . . . . . . . . . . . . . . 180




Contents ..’XIII

Part B: Basalt Bricks. ............................. 183

Hans J. Hoffmann

What is Raw Basalt?. .......................... 183

Manufacture of Fused Cast Basalt. ................. 183Chemical Analysis ............................ 183

The Use of Fused Cast Basalt. .................... 184

Properties of Fused Cast Basalt ................... 184

Chemical Resistance of Fused Cast Basalt. ............ 184

Choice of Setting Material. .................... 184

Type of Tile Construction. .................... 185

Resistance of Fused Cast Basalt to Bases ............. 185

Resistance of Fused Cast Basalt to Acids ............. 185

Conclusion. ................................ 186

Part C: Corrosion of Silicon Carbide Products ............. 187

John A. Bonar

Introduction ............................... 187

Bond Systems. .............................. 187

Corrosion Mechanisms ......................... 189

Acidic Solutions ............................. 189

Basic Solutions .............................. 191

Diffusion Reactions Control Corrosion .............. 191Choosing Silicon Carbides for Corrosive Service. ........ 191

Design. ................................... 192

References. ................................ 192

Part D: Granite as Chemically Resistant Masonry ........... 192

Dorothy A. Richter

Introduction. ............................... 192

Definition of Granite .......................... 193

Industrial Uses of Granite ....................... 193

Granite Surface Plates ....................... 193

Granite Press Rolls. .......................... 193

Granite Skid Caps and Tank Liners in Steel Pickling

Lines. ................................. 194

Properties of Granite .......................... 194

Granite Fabrication and Limitations ................ 195

References. ................................ 196

Part E: Portland Cement/Aggregate Brick ................ 196

Larry C. Stephans

20. CERAMICTILE. .................................... 198

William H. Bauer

Glazed Wall Tile ................................. 198

Mosaic Tile. .................................... 199

Quarry Tile .................................... 199

Paver Tile. .................................... .200

Tile Standards. .................................. 203Ceramic Tile Definitions. .......................... .206



xxiv Contents

SECTION V

MORTARS AND GROUTS (FOR TILE)

21. SILICATE MORTARS AND GROUTS (FOR TILE) ............ .212

Robert L. Trinklein

Sodium and Potassium Silicates ....................... 212

Silicate Cements ................................ .214

Chemical Resistant Mortars and Grouts .................. 214

Silicate Mortars and Grouts-Air Drying. ............... 215

Sodium Silicate Mortars and Grouts-Chemical Setting ...... 215

Potassium Silicate-Chemical Resistant Mortars and Grouts ... 215

Modified Silicate Mortars and Grouts ................. 216

22. SILICA MORTARS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .218

Joseph J. Spisak

Bibliography. . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221

23. SULFUR MORTARS. ................................ .222


Characteristics and Use. ............................ 225

Handling ......................................226

Specifications and Standards for Sulfur Mortars ............ 228

References. ................................... .228

24. PHENOLIC RESINS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,230

Kurt Goltz

Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,238

25. FURAN RESINS. ................................... .240

Joseph M. Walters

Introduction to Furan Resin Materials. .................. 240

Furan Resin Formulations. .......................... 242

Chemical and Heat Resistance ........................ 244

Installation of Mortars and Grouts ..................... 245

Mortars.....................................24 5

Grouts......................................24 6

Mixing Mortars and Grouts ....................... .246

Cleaning Brick and Tile After Installation. .............. 247Furan Resin Membranes ............................ 248

Furan Monolithic Surfacings ......................... 249

Standards. .................................... .250

Specifications. ............................... .250

Test Methods ................................ .251

Practices ................................... .251

References. ................................... .251

26. EPOXY RESIN CHEMICALLY RESISTANT MORTARS. . . . . . . . .252

C. V. Witten wyler

Epoxy Resins. . . . . . . . . . . . , . . . . . . . . . . . . . . . . . .252



Contents xxv

Chemistry of Epoxies. .....................

Physical Properties of Cured Epoxy Resins. .......

Cure of Epoxies .........................

Epoxy Mortars ..........................

Self-Leveling Epoxies. .....................

Trowellable Epoxy Floorings. ................

Fillers for Epoxy Materials ..................

Wear Resistance of Epoxy Floorings ............

Chemical Resistance of Epoxy Floorings .........

Substrate Preparation. .....................

Handling of Epoxy Monolithics and Mortars. ......

References. ............................

....... 252

....... 253

....... 255

....... 255

....... 257

....... 258

....... 261

....... 262

....... 263

....... 263

....... 266

....... 266

27. POLYESTER AND VINYL ESTER RESINS ................. .267

Kenneth A. Poss

Introduction. ................................... 267

ResinTypes.................................... 8

Uses.........................................26 8

Properties .................................... .270

Chemical Resistance Properties ....................... 270

Formula Components. ............................ .271Resins. .................................... .271

Catalysts ................................... .272

Promoters and Cure Systems. ...................... 272

Inhibitors. .................................. .273

Fillers. .................................... .273

Additives. .................................. .273

Formulations .................................. .274

Grout......................................27 5

Cement.....................................27 5

Mortar. .................................... .275

Substrate Preparation. ............................. 275

Usefulness .................................... .276

Limitations ................................... .277

Raw Material Suppliers. ............................ 277

Additives-Wetting, Air Release and Adhesion Promoters .... 277

Catalysts (Initiators) ............................ 278

Fillers. .................................... .278Inhibitors. .................................. .278

Pigments....................................27 8

Promoters (Accelerators) ......................... 278

Resins. .................................... .279

28. ACRYLIC POLYMER MORTARS AND CONCRETES .......... .280

W.O. Eisenhut

General ...................................... .280

Definitions. ................................... .282

Filler Design. .................................. .283



xx vi Contents

Binder Composition. .............................. 284

Cure.........................................28 5

Physical Properties. ............................... 286

Chemical Resistance. ............................. .289

Substrates and Substrate Preparation. ................... 289

Application ................................... .291

Performance. .................................. .291

References. ................................... .292

29. HYDRAULICS. .................................... .293

Part A: Chemical Resistance of Portland Cement Mortar and

Concrete ...................................... .293

Sandor Popovics

Introduction. ................................. 293

Composition of Portland Cement Clinker. .............. 294

Oxide Composition ........................... 294

Major Constituents of Portland Cement. ............. 295

Minor Constituents ........................... 296

Various Types of Portland Cement. .................. 296

Blended Cements. .............................. 298

Latent Hydraulic Materials ........................ 300Hydration: Reactions Between Cement and Water. ........ 302

General Aspects of Concrete Deterioration. ............. 303

Materials Which Attack Concrete .................... 305

Sulfate Attack ............................. .327

Attack by Seawater on Concrete .................. 330

Attack by Seawater on Reinforced Concrete. .......... 332

Attack by Salts Other Than Sulfates ................ 334

Acid Attack. .............................. .334

Other Attacks. ............................. .335Efflorescence ................................. 336

Polymer Modified Concrete. ...................... .337

Concluding Remarks ............................ 337

References. ................................. .338

Part B: The Use of High Alumina Cement in Chemical and Civil

Engineering .................................... .340

Henry G. Midgley

Introduction. ................................. 340Manufacture of Cement .......................... 341

Hydration of High Alumina Cement .................. 344

Strength Development in High Alumina Cement .......... 345

Permeability in High Alumina Cement Concrete .......... 347

Physical Properties of High Alumina Cement Concrete and

Mortar.....................................34 7

The Structural Use of High Alumina Cement Concrete ...... 348

Chemical Resistance of High Alumina Cement Concrete ..... 350

Alkaline Hydrolysis. ............................ 354

High Alumina Cement Concrete for Chemical Resistance .... 356



Contents xxvii

Examination of High Alumina Cement Concretes and

Mortars in the Field ............................ 356

Practical Hints on the Use of High Alumina Cement. ....... 358

References. ................................. .362Part C: Latex-Modified Mortars and Monolithics. ............. 363

David W. Fowler

Introduction. ................................ .363

Acrylic Latex. ............................... .363

Mix Design. ............................... .364

Properties ................................ .365

Applications. .............................. .367

Styrene-Butadiene. ............................ .368

Properties ................................ .368

Applications. .............................. .369

References. ................................. .369

Part D: “RHA” and “Fumed Silica”. .................... .369


References. ................................. .37 1

SECTION VI

CASTABLES, MACHINE GROUTS AND POLYMER CONCRETE

30. SILICATE CASTABLES, GROUTS, AND POLYMER CONCRETES . .374

Robert L. Trinklein

31. POLYMER PORTLAND CEMENT CONCRETE. .............. .376

David W. Fowler

Latex-Modified Concrete .......................... .377

Epoxy-Modified Concrete. ......................... .377Properties .................................... .378

Applications. .................................. .379

Mixing and Placement .......................... .380

Finishing. .................................. .380

Curing. .................................... .380

References. ................................... .381

32. POLYMER-IMPREGNATED CONCRETE. .................. .383

David W. Fowler

Introduction. .................................. .383

Monomer Systems. .............................. .383

Polymerization ................................. .384

Impregnation Procedures ........................... 384

Full Impregnation ............................. .384

Partial-Depth Impregnation. ....................... 385

Properties .................................... .387

Applications. .................................. .389

References. ................................... .390



.xx VIII Contents

33. POLYMER CONCRETES. ............................. .392

Part A: Corrosion-Resistant Sulfur Concretes. ............... 392

William C. &Bee, Thomas A. Sullivan and Harold F. Fike

Introduction. ................................. 392

Historical. ................................ .393

Current Technology. .......................... 393

Sulfur Cements. .............................. .395

Modifiers (Plasticizers) ......................... 395

Mixture Design ............................... .399

Aggregate Gradation .......................... 399

Binder Requirements. ........................ .401

Properties of Sulfur Concrete. ..................... .401

Mechanical Properties. ........................ .401Load Deflection in Compression. .................. 403

Moisture Absorption ......................... .404

Specific Gravity and Air Voids. ................... 405

Thermal Expansion of Modified-Sulfur Concrete. ....... 406

Freeze-Thaw Durability ........................ 407

Resistance to Acid and Salt Corrosion. .............. 407

Manufacturing Process ........................... 409

Equipment. ............................... .409Preparation, Casting, and Finishing. ................ 409

Quality Control. ............................ .412

Sampling and Analysis ...................... .412

Safety....................................41 3

Advantages and Disadvantages in Using Sulfur Concrete ..... 414

Summary. .................................. .415

References. ................................. .415

Part B: Epoxy and Vinyl Ester Grouts and Polymer Concretes .... 417

William Slama

History. ................................... .417

Scope......................................41 8

Function of Grout. ............................ ,419

Uses.....................................42 0

Composition. ................................ .420

Resin Component ........................... .420

Curing Agent .............................. .420

Aggregate or Filler. ........................... 420

Types of Grout. .............................. .422

Aggregate-Filled-Flowable ..................... .422

Aggregate-Filled-Dry-Pack ..................... .422

Low-Viscosity, Crack-Repair Grouts. .............. .422

Underwater Grouts .......................... .423

Polyester/Vinyl Ester Grouts. .................... 423

Properties and Tests. ........................... .423

Compressive Strength. ........................ .423Tensile Strength ............................ .425

Bond Strength ............................. .425



Contents xxix

Shrinkage. ................................ .425

Coefficient of Expansion ...................... .426

Temperature Resistance ....................... .427

Resistance to Creep. ......................... .428Density. ................................. .428

Fill Ratio. ................................ .428

Radiation Resistance ......................... .428

Electrical Resistivity .......................... 428

Installation. ................................. .429

Safety....................................42 9

Foundation ............................... .429

Anchor-Bolt Grouting ........................ .429

Equipment Base or Plates ...................... .430

Forms....................................43 0

Mixing. .................................. .432

Installation Temperature Conditions. .............. .432

Placement ................................ .433

Curing. .................................. .433

Bibliography. ................................ .433

Part C: Furan Polymer Concretes. ...................... .434

Joseph M. Walters

References. .................................. 435

Part D: Superplasticized Portland Cement Concrete for Special

Purposes ...................................... .436

Anthony J. Stump0

Background ................................. .436

The Admixture. .............................. .437

Observations. ................................ .437

Discussion ...................................438

Testing .................................... ,438

Reference .................................. .438

SECTION VII

MONOLITHICS

34. TROWELLED EPOXY, POLYESTER, VINYL ESTER MONOLITHIC

LININGS..........................................44 0

Wesley A. Severance

Introduction. .................................. ,440

Definition .................................. .440

History .................................... .440

Theory of Thermosetting-Resin, Monolithic Linings ......... 441

Resinous Materials Used in Monolithic Linings ............. 442

Epoxy Resins. ............................... .442

Polyester Resins .............................. .442

Vinyl Ester Resins. .............................443

Types of Linings. ............................... .443

Epoxy %-Inch (3.2 mm) Silica or Carbon-Filled Lining. ..... 443



xxx Contents

Unreinforced X-Inch (6.4 mm) Lining. ................ 443

Fabric-Reinforced %-Inch (3.2 mm) Lining ............. 444

Mat-Reinforced Epoxy, Polyester or Vinyl Ester-Based

Linings ................................... ,444

Glass-Flake-Filled Lining-Polyester or Vinyl Ester. ........ 444

Service Limitations of Linings ........................ 444

Temperature Limits in Immersion. ................... 445

Selecting the Lining. .............................. 445

Designing for Monolithic Linings ...................... 447

Vessels-Steel or Alloys. .......................... 447

Rigidity. ................................. .447

Accessibility. ............................... 447

Joints....................................44 7

Structural Reinforcement Members (Stiffeners). ........ 448

Appurtenances Inside Structures ................. .448

Welds .................................. ..44 8

Shell Penetrations ........................... .449

Concrete Vessels. ............................. .449

Surface Quality. ............................ .449

Exterior Waterproofing. ........................ 450

Wall Penetrations. ........................... .450Concrete and Steel Vessels ........................ 450

Floors....................................45 0

Surface Preparation. .......................... 452

Practical Considerations During Installation ............... 453

Ventilation. ................................. .453

Temperature. ................................ .453

Humidity. .................................. .453

Inspection-Linings on Steel ....................... 454

Inspection-Linings on Concrete. .................... 454

Troubleshooting .............................. .455

Maintenance. ................................ .455

References. ................................... .456

35. SPRAY APPLIED EPOXY SURFACING. ................... .458

Harlan H. Kline

History of Epoxy Surfacing Materials ................... 458

Application Equipment ........................... .459Controlling Surface Finish. .......................... 461

Application Temperature Range. ...................... 461

Trowel and Spray Applications ...................... .461

Chemical Resistance. ............................. .461

Performance of Epoxy Surfacers ..................... .467

Epoxy Surfacers on Concrete. ....................... .468

Situations Where Epoxy Surfacers Are Not Used. ......... 468

Situations Where Epoxy Surfacers May Be Conditionally

Used......................................46 8

Typical Uses of Epoxy Surfacers ..................... .469



Contents xxxi

Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .472

36. A NOTE ON OTHER MONOLITHICS: EPOXY-PHENOLICS AND

URETHANES.......................................473Walter Lee Sheppard, Jr.

37. GUNNED LININGS. ................................. ,478

Part A: Gunned Linings-Hydraulics. .................... .478

Richard J. Smith

Advantages. ................................. .479

Compressive, Flexural, and Tensile Strength. ............ 480

Manufacturers of Guniting Equipment. ............... .480

Dry Guns..................................48 0

Wet Guns. ................................ .481

Terms of Reference. ........................... .481

Components. ................................ .481

Cementing Matrix ........................... .482

Aggregates. ............................... .482

Additives. ................................ .483

Application Over a Steel Surface .................... 484

Mixing Water ................................ .487Summary....................................48 7

References. ................................. .489

Part B: Silicate Monolithics, Gunned Sodium Silicates. ......... 489

Robert L. Trinklein

Part C: Gunned Potassium Silicate. ...................... 491


History and Limitations .......................... 491

Composition and Properties. ....................... 492

Curing. .................................... .493

Application ................................. .493

Anchors, Reinforcing and Membranes ................ .494

Rebound. .................................. .494

Hardening or Curing Agent ........................ 495

Chemical Resistance. ........................... .495

Bibliography. ................................ .496

SECTION VIII

EXPANSION JOINT COMPONENTS AND REINFORCEMENTS

38. EXPANSION JOINT COMPONENTS . .

Donald J. Kossler

Sealants-Flexible and Deformable

Epoxies. . . . . . . . . . . . . . .

Urethanes . . . . . . . . . . . . .

Polysulfide. . . . . . . . . . . . . .Silicones . . . . . . . . . . . . . . .

Mastics and Thermoplastics. . .

. . . . . .

. . . . .

. . . . . .

. . . . . .

. . . . . . . . 498

. . . . . . .

. . . . . .

. . . . . .

. . . 498

. . . 498

. . . 499

. . .499

. . . 500

. . . 500



xxxii Contents

Other Types of Sealants ........... .............. 501

Design and Uses ................ .............. 501

Sponges. ....................... .............. 501

Sliding Joints .................... .............. 503

39. CERAMIC FIBERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .505


40. ORGANIC FIBERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .508


41. CARBON FIBERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .511

Eugene C. Heilhecker Ill

42. USE OF FLUOROCARBONS IN EXPANSION JOINTS. . . . . . . . . . .514


43. PREFABRICATED EXPANSION JOINTS. . . . . . . . . . . . . . . . . . . .516


SECTION IXRIGID THERMOPLASTIC FABRICATIONS

44. RIGID THERMOPLASTIC FABRICATIONS. ...

A.A. Boova

Introduction. .....................

Discussion .......................

Chemical Resistance. ..............

Fabrication ....................

Polyethylene ..................Polypropylene .................

Polyvinyl Chloride (PVC) ..........

Other Nonolefinics (Aliphatic Polymers)

Aromatic Polymers ..............

Fluoroplastics. .................

Conclusion. .....................

References. .....................

. . . . . . . . . . . . 520

........ . . . 520

........ . . . . 520

........ . . . . 521

........ . . . . 523

........ . . . 525

........ . . . . 528

........ . . . . 533

........ . . . . 538

........ . . . . 538

........ . . . 539

........ . . . . 539

........ . . . 540

SECTION X

DESIGNING CHEMICALLY-RESISTANT MASONRY CONSTRUCTIONS

45. DESIGNING WITH CHEMICALLY-RESISTANT MASONRY. ..... .542


The Basic Principles. .............................. 543

Designing Brickwork Without Reinforcing-Contouring ....... 545

Stability ..................................... .548

Expansion Joints-General .......................... 550

Thrust Blocks. ................................. .555

Trenches ..................................... .558



Contents “’XXlll

Weirs and Overflows. .............................. 564

Vessels ...................................... .565

Bottoms ..................................... ,566

Capping. ..................................... .572

Covers. ...................................... .572

Prestressing .................................... 574

Expansion Joints in Vessels. ......................... 575

More About Floors .............................. .576

Monolithics ................................. .576

Differences Between Expansion Joints in Bonded Brick and

Brick Over a Membrane. ......................... 579

Determining Floor Thicknesses ..................... 580

Curbs ..................................... .581Walls Subject to Spray or Splash. .................... 582

Tile........................................58 2

Substrate. .................................... .583

Side Effects ................................... .584

Galvanic Corrosion of Lead and Stainless Steel Due to Prox-

imity to Carbon and Carbon-Filled Mortars and Grouts. .... 584

Bibliography. ............................... 586

Brick Growth. ............................... .586Bibliography. ............................... 587

Swelling of Brick. .......................... 587

Other Related Articles ....................... 588

SECTION XI

USES OF NONMETALLIC CHEMICALLY RESISTANT MATERIALS

IN WASTE HANDLING

46. USES OF NONMETALLIC CHEMICALLY RESISTANT

MATERIALS IN WASTE HANDLING ...............


Piping .................................

Support and Backfill .......................

Manholes. ..............................

Trenches ...............................

Holding, “Equalizing,” or Neutralizing Tanks .......

Scrubbers and Ancillary Equipment .............Inspection and Repairs of Manholes and Clay Pipe. ...

Armoring. ............................

Internal Repair. ........................

Bibliography. ............................

SECTION XII

PRESTRESSED BRICKWORK

47. PRESTRESSED BRICKWORK . . . . . . . . . . . . . . . . . . . .Keith R. Pierce

...... 614

Introduction. . . . . . . . . . . . . . . . . . . . ...... 614

. . . . . . 594

...... 594

...... 601

...... 602

...... 604

...... 607

...... 608

...... 608

...... 609

...... 610

...... 610



xxxiv Contents

Brick Linings-A General Discussion, and the Problem of

Tensile Stresses. ................................ 614

A Solution-Prestressing ............................ 614

Description of the Prestressing Process. .................. 615

Mathematical Analysis ............................. 615

Methods of Analysis. ................................ 616

Composite Properties of Brick/Mortar Layers .............. 616

Thermal Gradient Calculation ........................ 616

Stress and Strain Calculations ........................ 617

Stresses During and After Cure. ....................... 618

Stresses at Operating and Shutdown Conditions ............ 619

Sample Calculation ................................ .619

Summary and Conclusions ........................... .622References. ..................................... .623

SECTION XIII

SPECIAL SUBJECTS

48. CHIMNEYS........................................62 6

Brian Coole y

Introduction. .................................. .626Concept. ................................... .626

Past Design Considerations .......................... 627

Corbel Supported Brick ......................... .627

Independent Brick. ............................ ,628

Shell Supported Steel. ........................... 629

Present Conditions. .............................. .630

Overall System Design-The Outer Shell. ................. 631

Steel Shells. ................................. ,631

Brick Shells ................................. .631

Reinforced Concrete Shells. ....................... 632

Dynamic Wind ............................. ,634

Seismic Loads. ............................. .635

Overall System Design-The Liner. ..................... 635

Acid Resistant Masonry .......................... 636

Steel and FRP Liners. ........................... 637

Refractory Liners (Gunite or Cast) ................... 638

Unlined Independent Concrete Liners. ................ 641Specific Design Recommendations-Brick Liner ............ 641

Banding System .............................. ,641

Breeching Ductwork ............................ 643

Annulus Pressurization. .......................... 644

Present and Future Aspects. ......................... 645

Recent Problems Due to Wet Gas Conditions ............ 645

Preconditioning of Brick. ......................... 648

Moisture/Heat Shielding. ......................... 648Flow Diversion Arrangements ...................... 648



Contents xxx v

49. COATINGS FOR NUCLEAR POWER GENERATING STATIONS ... .650

Edmond W. Jarret

Operating Conditions. ............................ .650

Qualification Requirements..........................

653

Coating Varieties and Application. ..................... 654

Inspection .................................... .656

References. ................................... .658

50. SULFUR SPRAY COATINGS. .......................... .659

William C. McBee, Thomas A. Sullivan and Harold L. Fike

Introduction. ................... .’ .............. .659

Sulfur Spray Coatings. ............................ .661

Mixture Design ............................... .661Sulfur Modifiers .............................. .661

Fillers and Fibers. ............................. .662

Uses.......................................66 2

Manufacture and Application. ........................ 662

Preparation and Spraying Equipment ................. 662

Manufacture and Applications. ..................... 662

Quality Control. .............................. .664

Safety......................................66 4Properties of Sulfur Spray Coatings. .................... 664

Physical and Mechanical Properties. .................. 664

Chemical Resistance. ........................... .665

Durability .................................. .666

Advantages and Disadvantages ....................... .667

Summary......................................66 7

References. ................................... .667

51. PULP AND PAPER INDUSTRY USE OF CORROSION RESISTANT

MASONRY CONSTRUCTION. .......................... .669

Larry C. Stephans

Materials of Construction ........................... 669

History of Brick and Tile Construction in the Pulp and Paper

Industry. .................................... .670

Acid Sulfite Digesters. ............................. 672

Peripheral Equipment in the Digester Area. ............... 674

Kraft and Neutral Sulfite Digesters ..................... 674

Kraft Liquor Systems. ............................ .674

Pulp Storage Vessels. .............................. 675

Chlorine Dioxide Vessels. ........................... 675

Chlorination, Hypochlorite, Peroxide, and Caustic Extraction

Towers .................................... ..67 6

Washers and Seal Pits ............................. .676

Paper Mill .................................... .676

Tall Oil Reactors. ................................ 677Tall Oil Spent Acid Tanks. ......................... .677

Floors. ...................................... .677



xxx vi Contents

Summary. ........................

References. .......................

. . . . .

. . . .

SECTION XIVINSPECTION AND FAILURE ANALYSIS

52. INSPECTION AND FAILURE ANALYSIS ......


Inspection ........................

Preliminaries. ....................

Concrete .......................

Brick. .........................

Mortars ........................Membranes and Expansion Joint Materials

Installation. .......................

Membrane ......................

Monolithics .....................

Brickwork and Expansion Joint. .......

Final Inspection ..................

Failure Analysis ....................

Bibliography. ......................

. . .

. . . .

.

. . . .

. . . .

. . . .

. . .

. .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . . . 678

. . . . . 678

. . . . 680

. . . . 682

. . . . 682

. . . . . 685

. . . . . 687

. . . . . 688

. . . . 689

. 689

. . 690

. . . 691

. . 692

. . . . . 694

. . . . . 694

. . . . 715

INDEX..............................................716



Preface

The public is accustomed to thinking of “corrosion” as the rusting of iron

(and of some other metals). The engineer usually considers it to include damage

to concrete that results from the rusting of the reinforcing bars, and the pitting

and eventual wasting away of various metals and alloys.

The public generally thinks of the rusting (or corrosion) of iron and steel as

a result of weathering-the action of air, rain, and contaminants that are air-

borne such as salt spray from the ocean. The engineer recognizes that the sources

also include chemicals contained in tanks, and spilled or splashed on floors, walls

and other equipment. But few other than chemists and chemical engineers iden-

tify “corrosion” as chemical degradation or destruction of a material, and there-

fore, something that can happen to nonmetals (concrete, plastics, brick, timber,

etc.) as well as to metals. The National Association of Corrosion Engineers so de-

fined “corrosion” over thirty years ago but this fact has still not attained publicrecognition, nor even that of a large number of that Society’s membership. The

subject of the “corrosion” of nonmetals has never been adequately studied be-

cause it is so vast-there are so many different kinds of “nonmetals.”

The university trained engineer usually thinks first of metal (steel, alloy,

etc.) when designing chemical equipment-something easily shaped and erected,

not occupying more space than is needed. Both architects and engineers think

of concrete first when they think of floors, dykes, trenches, sumps, pits, etc.,

because they are easily formed and poured.

The designer of equipment, whether it be a storage vessel, or process vessel,

looks for a metal that will be suitable-without “corrosion” (or chemical dam-

age) from his process or chemicals. He often forgets to check what differences

there may be in the suitability of the metal if the order of adding the chemicals

to the process is changed, the temperature range of the process is increased, or

if certain types of cleaners are used on the equipment. The civil engineer who

designs the floor may have worked out all his structural details correctly, and

specified the correct mix of sand, cement and aggregate, but still not considered

v i i



.VIII Preface

what chemicals may be spilled on the floor and how to protect it from “corro-

sion” (chemical damage), or that the additives put in the concrete mix by the

bulk plant or contractor may have an adverse effect on the concrete under the

conditions that will prevail.

Metal or steel reinforced concrete structures which are not in themselves in-

ert to chemical attack (corrosion) from the environment in which they are de-

signed to serve can very rarely be protected by a metallic surfacing. The normal

protection under such conditions will be supplied by a nonmetal, often a coat-

ing. Each nonmetal so used has its own limitations-chemical or thermal-which

must be considered. Therefore, in many cases, a combination of two or more

nonmetals is required to provide the necessary ultimate protection to the steel

or concrete.

Among the chemicals known to the ancients was sulfuric acid-or “oil of

vitriol” as they called it. Two millenia ago “alchemists” found that cold sulfuric

acid had little effect on granite and on hard burned fireclay. The acid was there-

fore manufactured in areas where the floor could be made of granite blocks

cemented together with either hot-poured sulfur joints or a slow setting mortar

made of “water-glass” (sodium silicate) mixed with clean silica sand. Containers

for the acid could be hard burned clay pots or lead, the latter being much more

expensive. The acid could be carried in clay pipe with either sulfur or lead joints,

or in lead pipe. Natural asphalts were used as coatings and as membranes to pre-vent leakage. A putty made of litharge (lead oxide) and glycerin was often used

to seal clay sections or tops. This was the inception of chemically resistant

masonry, a discipline that has evolved over two millenia without ever being codi-

fied, and rarely recognized for its importance to the engineer or the architect.

Chemically resistant masonry structures are composed of three independent

parts: supporting structure, membrane fluid stop, and inner lining to protect

the membrane from thermal and mechanical abuse. These three parts are essen-

tial to any economically satisfactory chemically resistant structure. This does

not mean that the three functions may always require three distinct materials.

The three functions may be accomplished by two materials, or even a single one.

A storage vessel for 93% sulfuric acid, for instance, may be constructed en-

tirely out of carbon steel, providing that the acid concentration is kept high, the

temperature ambient, and that there is no objection to some iron pick-up (con-

tamination) in the acid. However, if the sulfuric acid is to be used to “pickle”

steel (to clean off mill scale), it is diluted to 12 to 15% and will then destroy

the storage tank, unless the tank is lined with sheet rubber or another material

that is unaffected by that acid concentration and can act as a true (barrier) mem-brane. In the pickling of steel, the temperature of the acid is raised to approxi-

mately 200°F. This temperature is too high for natural rubber (and for many

such membrane materials) which will age rapidly and fail unless the rubber is

inner lined with an insulating layer such as “acid” brick with an acid resistant

mortar joint, which lining can itself accept the higher temperature while reduc-

ing the temperature on the face of the rubber to an acceptable level. It also

acts as a mechanical protection to keep the pickled steel from damaging the

rubber lining. The brick lining may not serve by itself-without the rubber mem-

brane-because structures composed of brick and mortar joints can not be made

liquid and gas tight. Some liquid will always pass through this lining and get to



Preface ix

the steel, causing the steel to be “corroded” and eventually destroyed.

An all plastic tank may be used for a chemical process such as the reconsti-

tuting of spent hydrochloric acid. However, at higher temperatures, the acid will

attack the plastic sufficiently rapidly to make its use uneconomical unless a ma-

sonry lining is placed inside the plastic to insulate the interior-to bring the tem-

perature on the face of the plastic down to an acceptable level. The plastic, then,

functions as supporting structure and membrane, and the three necessary func-

tions are supplied by two materials.

Brick and mortar materials should only be used alone where the fact that

gas and liquid can penetrate, though slowly, through them is not important,

but where their considerable compressive strength (load bearing ability), com-

bined with their resistance to chemical attack can be useful. Examples of these

types of structures are: self-supporting chimney liners (some of them 800+ feet

tall), foundations set in acid contaminated soil, and supports for chemical equip-

ment subject to splash or spill.

From what has been said above, the following rules can be outlined for the

design, construction and use of chemically resistant masonry:

(I) All chemically resistant construction must be composed of com-

ponents to provide three functions: (I) a supporting structure,

(2) an impervious membrane to keep the supporting structure

from being reached and attacked by the chemicals or other cor-

roding medium, and (3) a chemically resistant masonry lining to

protect the membrane.

(II) The chemically resistant masonry liner (which may be a mono-

lithic material or a laid up lining composed of individual units

and mortar joints) supplies protection to membrane and/or sub-

strate by: (I) providing a hard, strong layer to prevent mechani-

cal abuse or abrasion, (2) providing thermal protection by insu-

lating the membrane from the unacceptably high temperatures

of the contained liquid, (3) by altering the environment on the

surface of the membrane-preventing movement of chemicals

over the surface-creating a stagnant condition.

This third item may puzzle some. Think of it this way. If the

masonry were not present, the contained fluid would be in

direct contact with the membrane. As the fluids moved over the

interior surface, any reaction products created by the attack of

the contained fluids on the membrane would be washed off and

fresh surfaces exposed. With the brick in place, the only ap-

proach of the liquids through the brickwork is linear-through

tiny capillaries in the brick, terminating at the membrane surface.

The reaction products, then, remain in place and slow down

further approach of the fluids to the surface of the membrane.

Thus a membrane lining material that is unacceptable when ex-

posed directly to the fluids may become acceptable by the in-

terposition of a brick lining. A large chemical company has for

years been able to protect rubber lined steel tanks from damage



X Preface

by a solution of hydrochloric acid containing some mineral oils,

by installing brick linings in the tanks. Without the brick, the oils

swell the rubber and the acid penetrates to the steel in a few days.

With the brick in place, the oils penetrate into the rubber, which

soon swells to fill all the tiny pores in the brickwork. But then it

can swell no further, being restrained by the brick. The swelling

stops, and the acid can not get through to the steel.

(II I) Chemically resistant masonry, unlike concrete, is not usually rein-

forced. Where it is composed of structural units and mortar, rein-

forcement is usually impossible. (In the section on paper mills to-

ward the end of this book is the exception that proves this rule.)

Where the masonry is cast-a monolithic silicate, a sulfur concrete

or a polymer concrete-the same rule holds. Where it is gunned, it

is most often reinforced by anchoring it to the substrate. There-

fore, chemically resistant masonry (except for polymer concretes)

are: (1) Excellent in compression, but normally weak in tension

and shear (since they rely on bond strength of mortar to con-

struction unit). (2) They are, in many cases, somewhat brittle.

They will, in thick sections, absorb blows, but not (in most cases)

vibration and regular pounding. (3) They all have some measur-

able degree of absorption. They can not contain pressurized gases

nor restrain a liquid head. In other words, they can not be ex-

pected to be in themselves liquid tight.

This volume is directed to those engineers and architects who are charged

with designing buildings and equipment which may require chemical resistant

masonry materials. It contains the information necessary to select the most ap-

propriate materials, write the specifications and instructions and draw the de-

tails covering them and necessary for their proper installation. We have at-tempted to select those authors best informed on each topic to discuss its ad-

vantages and limitations. In areas where there is disagreement as many view-

points as possible have been given.

The volume is divided into fourteen sections. The introductory section gives

the views of a practicing engineer and an experienced architect on the impor-

tance of these materials. Section II discusses the various materials that may be

used to provide the physical strength, the supporting structure and the consid-

erations involved in its selection and design.

The third section provides data on the various membrane systems most fre-

quently employed, together with data on a great many other types.

The fourth section covers the various types of construction units: brick,

block, etc., and the limitations and advantages of each. The fifth section pro-

vides similar information for mortars for brick and grouts for tile. Section VI

covers castables, grouts for large voids and machinery, and polymer concretes;

the seventh-monolithics-includes gunned linings together with application

data, and the eighth section covers expansion joint materials.

Next is a short section covering the fabrication of rigid plastics, followed bysections on design fundamentals, waste handling (piping and manholes), and



Preface xi

“prestressing’‘-the system employed to prevent a supporting structure from

expanding away from an inner lining leaving the inner lining in unacceptable

tension.

The penultimate section covers special subjects: chimneys, uses of chemicalresistant masonry materials in the nuclear power field, a short discussion of the

uses and limitations of hot sprayed sulfur coatings, and the use of chemically

resistant materials in the pulp and paper industry. The final section is devoted

to the related subjects of inspection and failure analysis.


January 1986




Section I

Introduction



1

An Engineer Looks at

Chemically Resistant Masonry

Robert E. Moore

United Engineers and Constructors, Incorporated


INTRODUCTION

Chemically resistant masonry (CRM) is at once one of the oldest and most

widely used groups of engineering materials, components and structures cur-

rently available to the Materials/Corrosion Engineer. CRM construction includes

many diverse non-metallic inorganic and organic materials which can be utilized

as independent, self-supporting structures or as protective linings for steel, con-

crete, wood and other substrates. These versatile composites are often the most

cost-effective construction for various industrial applications and, when properly

designed and installed, have given reliable, extended service under adverse condi-

tions that are damaging to other major types of corrosion resistant materials (al-

loys, plastics, coatings).

In general, CRM is characterized by excellent resistance to a broad range of

corrosive chemical environments including acids (dilute and concentrated), ex-

treme temperatures (beyond the limits of most common materials), and very

good strength in compression (but not in tension). It is mainly this unique com-bination of superior chemical resistance and high thermal stability that makes

CRM so useful throughout the power, steel and metalworking, chemical, pulp

and paper, pharmaceutical, food processing and beverage, waste treatment and

other industries. In severe environments, such as strong acids, solvents or alka-

lies at elevated temperatures, CRM may be the only practical solution to these

aggressive conditions. Even very exotic, costly and scarce metals and alloys can-

not always withstand such exposures, at least not at an affordable price. Some

typical industrial CRM applications are floors, trenches, sumps, reaction vessels,

2



An Engineer Looks at Chemically Resistant Masonry 3

tanks (storage, plating, pickling), scrubbers, ducts, stacks, chimneys and other

air pollution control equipment.

Since a prime objective is to select and use the optimum (cost-effective) ma-

terial, component or system for each application, CRM should be carefully eval-uated and compared with other corrosion resistant materials to best achieve

this long-term economic goal. While the total installed cost of any industrial

plant construction is important, the acceptance criterion for a successful ma-

terials composite such as CRM should be trouble-free performance and protec-

tion with minimum maintenance for a prolonged duration. That is, the optimum

engineering structure (e.g., CRM) is the one that best meets the design require-

ments at the least overall cost. For plants such as nuclear and fossil fuel power

stations, the design life ranges 30-40 years; and the daily lost or purchased

power cost of a forced (unscheduled) outage due to a critical component failure

is astronomical. Accordingly, materials reliability far overshadows its initial capi-

tal cost, and the cheapest material often proves to be the most expensive to the

plant owner. A similar precaution is necessary when considering low bid installa-

tion contractors, unless they are previously qualified based upon a long track re-

cord of successful case histories involving the same generic materials and prod-

ucts specified for the application.

DEFINITION AND TYPES OF CHEMICALLY RESISTANT MASONRY

To quote the editor’ CRM may be defined as “a structure composed of non-

metallic, chemically inert masonry units such as brick, stone, block or other ag-

gregate bonded together with a mortar or mortars of adequate adhesion to the

units and possessing suitable chemical and thermal resistance for the anticipated

exposure. Such a structure may be assembled from units and mortars of a single

type or from a combination of several different types of such units and mortars

in order to achieve optimum and most economically satisfactory results.” CRM

structures as such comprise three components: (1) Masonry units such as brick

or tile; (2) Mortars to bond them together, and (3) Membranes to attain a liquid-

tight, fully resistant system. All of these components are available in various

forms and are produced from many different materials. All three components

must be chosen to meet both the environmental conditions and the design re-

quirements of each application.

There are two general categories of CRM construction:

(1) Load bearing structures with suitable physical, mechanical and chemical

resistance properties to withstand corrosive service conditions. One example of

a load bearing CRM structure is an independent, free standing chimney liner

made of acid resistant brick and mortar. The tallest known acid brick chimney

lining in the United States is a 900-foot high fireclay brick liner in a l,OOO-foot

high reinforced concrete chimney (Figure 1-I). This two unit coal-fired power

station operates on high sulfur coal and emits hot corrosive flue gases from a wet

lime flue gas desulfurization (FGD) system incorporating both particulate and

sulfur dioxide (SO,) scrubbing. Moreover, acid brick chimney liners greater than1,000 feet in height are designed and used successfully in Europe and other parts

of the world.



4 Corrosion and Chemical Resistant Masonry Materials Handbook

(2) Linings to protect floors, vessels and other equipment subjected to cor-

rosion, erosion, abrasion and/or thermal attack from chemical environments.

The most common substrates for CRM linings are carbon steel and concrete, but

other structural materials such as wood and plastics may also be effectively pro-tected. CRM linings can provide any one or all of the following protection modes:

(1) Barrier to control physical or mechanical damage such as abrasion or wear;

(2) Thermal insulation effects by limiting the substrate and membrane tempera-

ture to prevent thermal damage; and (3) Reduce permeation of corrosive fluid to

the substrate, thus minimizing its corrosion rate. CRM linings, such as acid brick

and monolithic cements, also prevent “wash”, which is the removal of the mem-

brane or substrate corrosion products by the circulating medium. Even when the

fluid eventually reaches the membrane or substrate surface, the amount is rela-

tively small, thus limiting chemical attack, and any corrosion products are trapped

beneath the masonry shield.

By analogy, carbon steel immersed in stagnant seawater corrodes at an av-

erage rate of only about 5 mils/year (mpy), discounting pitting, because its un-

disturbed corrosion products are semi-protective. However, when subjected to

f/owing seawater, mild steel corrodes at a much higher rate because the water

velocity and attendant turbulence erodes away the hydrated rust layer and at-

tacks the freshly exposed steel surface. Hence, bare steel piping cannot economi-

cally handle seawater at normal pipe design velocities. Either a protective pipe

lining must be used or a more erosion-corrosion resistant alloy or fiberglass re-

inforced plastic (FRP) pipe employed for a reasonable service life. Likewise, thr6

CRM sheathing enables the barrier membrane to perform its primary function of

protecting the substrate from chemical corrosion while blocking removal of cor-

rosion products.

CRM structures as installed consist of three component parts: (1) External

structural support (e.g., steel, concrete, wood, plastic); (2) Fluid-tight mem-

brane; (3) Non-metallic masonry unit and bonding mortar shielding the mem-brane. The choice of the materials used in each of the components depends upon

the following factors and conditions: (1) Chemicals and their concentrations, en-

compassing all major constituents and any trace impurities and cleaning agents;

(2) Ranges of pH and total acidity or alkalinity; (3) Temperature ranges, includ-

ing transient thermal cycles and excursions; and (4) Physical effects such as im-

pact, wear, abrasion and positive or negative (vacuum) pressure. The rate of

change of pressure or temperature (e.g., thermal shock) must also be considered

in evaluating materials for CRM structures. Rapid fluctuations in any of these

variables can significantly affect the selection, design and performance of the

CRM components. In some cases, operational shocks could be the controlling

element in determining the useful life of a CRM structure. To avoid a premature

failure, the CRM structure must be capable of resisting any or all of the stresses,

strains, static or dynamic loads and other service conditions imposed on it.

To illustrate, in a fossil fuel power plant the loss of boiler air preheater(s)

can create a sudden increase in flue gas temperature from G3OO’F up to 500°-

7OO’F for a brief (e.g., 20-30 minute) period. (Air preheaters are energy conserv-

ing heat exchangers that heat incoming boiler combustion air with hot boilerflue gas which is thereby cooled prior to particulate scrubbing. If an air pre-

heater fails, the hot flue gas will not be cooled by the heat transfer to the in-




coming boiler combustion air, and will enter the scrubbing system at the higher

temperature.) Should this rare accidental event occur, materials and linings in

the FGD system ducts and chimney liner must be able to survive this rapid tran-

sition (thermal shock) without substantial structural damage-i.e., preserve plant

integrity. For this and many other reasons, CRM structures and linings offer in-herent advantages over less thermally stable materials such as coatings and FRP.

With very few exceptions, notably the fluoropolymers (Teflon@, Kynar@,

Viton@), even the best protective coatings and FRP have upper thermal limits of

250°-350°F, while some CRM materials can endure temperatures up to 1000°-

2000°F, well above the worst-case single or double air preheater failure scenario.

Before reviewing the basic CRM materials, these four design limitations for

CRM construction must be recognized and addressed by the specifier and end

user: (1) CRM structures, like concrete, have excellent compressive strength and

thus have good load bearing properties; (2) Conversely, CRM structures are weak

in tension, shear and torsion, requiring that they be reinforced or supported by

suitable substrates (e.g., steel) to withstand such loads; (3) CRM structures are

relatively rigid and brittle and tend to break, rather than flex, when bent; and

(4) A structure composed of such units cannot restrain a fluid head. For such a

container to be liquid tight and function properly, it must be supported by an

outer shell to take the thrust and a liquid tight barrier or membrane behind the

brick. For example, a circular duct or cylindrical (or spherical) tank would be

the optimum design for a CRM lining as it would keep the masonry lining incompression. All of these design characteristics of CRM structures will be de-

tailed later in a separate chapter. Suffice it to say for now, these fundamental

guidelines must be faithfully observed to realize the manifold benefits of CRM

construction.

CHEMICALLY RESISTANT MASONRY COMPONENTS AND MATERIALS

The major CRM components and materials will be generally described, fol-

lowed by some industrial applications of CRM structures and protective linings.

Each generic type of CRM component and related materials will be discussed in

detail elsewhere by leading specialists in the CRM field. Hence, this section will

briefly review the three basic building blocks of the composite CRM structures

and linings. As stated, CRM construction incorporates three major components:

(1) Primary membrane applied to a structural substrate; (2) Chemical resistant

brick or tile to protect the membrane chemically, thermally, and mechanically;

and (3) Chemical resistant mortar or grout for bedding and jointing the brick or

tile.

The general categories of CRM components detailed in this handbook are:

(I) Membranes; (2) Masonry units; (3) Mortars and grouts (for tile); (4) Cast-

ables, grouts and polymer concretes; (5) Monolithics; and (6) Expansion joint

compounds. (A monolithic lining applied over a membrane coated substrate

would also constitute CRM.) Only the first three of these CRM component

classes will be discussed below-namely, membranes, masonry units and mor-

tars. Each of these components is available in a variety of forms, shapes, sizesand materials including both inorganic and organic compounds, even metallic




(e.g., lead). Most of the organic materials are high molecular weight polymers or

resins with excellent resistance to a wide range of chemicals within their specific

thermal limits. By contrast, the inorganic alkali silicates used as mortars and

monoliths offer outstanding high temperature resistance in virtually all media

except acid fluorides (HF) and strong alkalies (NaOH). For these exposures car-

bon brick joined with carbon filled furan mortar is effective. Chemically almost

any environmental condition can be handled by suitably designed and installed

CRM components. It is essential that the above four design guidelines or limita-

tions of CRM materials and components be closely followed for a successful

application. The principal CRM components and materials will now be reviewed

along with their functions in forming the CRM structures and linings.

Membranes

A membrane is a key material that serves as fluid-tight barrier between the

somewhat permeable CRM lining and the substrate or supporting structure. The

selection of a good membrane depends upon these major facors; (1) Chemical

composition and temperature of the environment, (2) Substrate rigidity, (3)

Maximum economic brick thickness that can be installed, (4) Internal pressure,

and (5) Unprotected corrosion rate of the substrate in the chemical. A CRM

membrane applied to a properly cleaned (often primed) steel or concrete sub-

strate is the “last line of defense” in protecting that substrate from accelerated

chemical attack and premature failure. Hence, effective membranes must have

both high chemical resistance to corrosive fluids and low permeability to the

same media, along with good adhesion to the substrate. Therefore, an elasto-

meric membrane used under an acid brick lining to control acid corrosion of a

carbon steel tank must not only resist attack by the corrosive but be a complete

barrier to any of the corrodent that has migrated through the brick and mortar.

It is necessary but insufficient that the membrane remain intact and unaffected;

it must also prevent the corrosive from reaching the substrate or at least limit its

diffusion to a tolerable rate. While the masonry units (brick or tile) protect themembrane against excessive temperature and physical abuse,the membrane in turn

guards the substrate against environmental damage. This is a classic example of

synergism in which the properties of complementary materials are effectively

combined into a very useful composite.

Membranes, which include both liquid applied and solid sheet linings, can

be classified as: (I) True membranes that are completely impermeable barriers to

specific corrosives, or (2) Semi-membranes which allow a low but acceptable

amount of the chemical to reach the substrate. Further, these membrane types

may be divided into rigid and non-rigid materials. The rigid membranes include

epoxy, phenolic, polyester and furan resin coatings, glass linings, unplasticized

polyvinyl chloride (PVC) sheet, and both flake glass filled and fiberglass cloth

or mat reinforced epoxy, polyester and vinyl ester resin linings. Non-rigid mem-

branes include hot applied asphalt, the most widely used membrane on concrete

substrates (but not on steel); asphalt mastic and bitumastic epoxies; plasticized

PVC; and a wide variety of sheet (and some liquid) elastomers including natural

rubber, neoprene, butyl, chlorobutyl, Hypalon@, ethylene-propylene, Viton@

and polyurethane. Natural and synthetic rubbers are the most common mem-brane materials for steel substrates. Fluorocarbon (e.g., Teflon@, Kynar@) sheet




linings and baked coatings are employed as membranes for very corrosive pro-

cesses. These fluoropolymers are almost chemically inert and are the most heat

resistant of the organic membranes but have high thermal expansion coefficients

and require chemical etching for good adhesion to overcome their anti-stick

properties. When flexible membranes with superior chemical and heat (to 4OO’F)

resistance are needed, fluoroelastomers such as Viton@ and Fluorel@ should be

considered. Liquid applied coatings based upon Viton@ are now available in ad-

dition to sheet membranes. Metallic sheet membranes are also utilized including

lead, chromium-nickel (austenitic) stainless steels and other corrosion resistant

alloys. All of these and other membrane materials (e.g., porcelain enamel, glass

lining) and their selection for CRM applications are detailed in subsequent

chapters.

Masonry Units

Masonry or construction units, like membranes, are vital components in

CRM construction. ASTM defines a chemical resistant construction unit as “a

modular non-metallic material, either vitreous or nonvitreous, used in industrial

processes primarily for applications where chemical, thermal and mechanical re-

sistance is required.” Masonry units are used both in CRM structures such as free

standing acid brick stack liners and in CRM linings such as acid brick or tile lin-

ings for floors and process vessels. If fluid (liquid or gas) barriers are required,

masonry units should be used in conjunction with membranes applied directly to

properly prepared substrates. Most masonry units are installed by laying the

brick or tile with a suitable chemically resistant mortar or grout chosen to resist

the environmental conditions. There is a great variety of masonry units available

for various industrial applications requiring superior resistance to chemical cor-

rosion, erosion, abrasion, wear and/or elevated temperatures. Practically, no

other generic class of engineering materials can withstand such a broad array of

adverse conditions as well as the right combination of CRM units, mortars andmembranes. These CRM composites are effective against corrosive acids, alkalies,

salts and solvents over the wide range of pH, concentrations and temperatures

found in industry.

Masonry units used in CRM construction encompass the following basic

types: (I) Acid brick (red shale, fireclay); (2) Carbon brick; (3) Foamed boro-

silicate glass block; (4) High alumina and insulating brick; (5) Silica brick; (6)

Special composition brick and block (porcelain, basalt, silicon carbide, granite,

press-molded hydraulic); and (7) Tile (quarry, ceramic, glazed porcelain). Each

of these masonry units has its particular area of utility in CRM construction.

Among these diverse CRM units, industry can combat virtually all chemical and

thermal exposures within the design limitations of CRM linings and structures.

In chemical services that are also abrasive, these CRM bricks would rank in abra-

sion resistance as follows: high alumina (best), silicon carbide, hard burned fire-

clay, and red shale.

Acid Brick: Acid brick, also called acid resistant or acid proof brick (cov-

ered by ASTM C279), are of two major types: (I) Red shale, the predominant

brick in CRM construction; and (2) Fireclay, another common brick in CRM ap-plications. These two acid brick are the most widely used masonry units in CRM

structures and linings, including floors, trenches, sumps, vessels and chimney




liners. Both types of acid brick are made from selected clays or shale containing

little acid-soluble constituents and are fired in kilns at higher temperatures and

for longer times than ordinary face brick. This produces a much stronger, den-

ser brick with far lower water absorption and superb resistance to most acidsexcept hydrofluoric (HF), which requires carbon brick. Red shale brick is higher

in silica and iron content, while fireclay brick contains more alumina. The gen-

erally denser shale brick normally shows lower water absorption and better sul-

furic acid resistance than fireclay brick, which has somewhat greater thermal

shock resistance (less brittle) than red shale brick. Because of the low (<I%) ab-

sorption of Type L (usually red shale brick), these bricks are more often used in

process vessels and other applications demanding maximum acid resistance and

minimum absorption. However, fireclay brick can also be manufactured to meet

the 1% absorption and 8% acid solubility limits of Type L shale brick. The

lower iron content of the buff-colored fireclay brick is beneficial in certain

industrial processes. For example, one sulfuric acid plant producing 98% sulfuric

acid guarantees a maximum iron content of 25 ppm, in which fireclay brick and

potassium silicate mortar are employed as a fully resistant, non-contaminating

CRM construction.

In sulfuric acid production, acid brick lining of membrane coated mild steel

tanks and reaction vessels is considered the most durable and versatile construc-

tion material for the sulfuric acid plant. Such linings will reduce the steel shelltemperature and prevent erosion of the normally protective iron sulfate film that

forms in stagnant, concentrated (oxidizing) sulfuric acid. Dilute (reducing) sul-

furic acid solutions are very corrosive to carbon steel, which must be protected

by impermeable (e.g., elastomeric) membranes and acid brick lining systems.

Such acid brick linings often employ membranes comprising a thin film of Tef-

lon@ or Kynar@ sandwiched between layers of asphalt mastic.

In phosphoric acid production plants, both red shale and fireclay brick have

excellent resistance to all concentrations of phosphoric acid at temperatures up

to 250°F, provided the acid contains no HF. If HF is present in the phosphoric

acid, carbon brick construction must be used. As a rough rule-of-thumb, HF

levels above 50 ppm in phosphoric acid require tank linings of carbon brick

bonded and jointed with a carbon (or barytes) filled furan mortar over a suitable

membrane to match the steel or concrete substrate structure.

ASTM specifications on acid brick include: (I) C279, Chemical-Resistant

Masonry Units, which covers Types H and L brick; (2) C410, Industrial Floor

Brick, covering Types H, L, M and T brick; and (3) C980, Industrial Chimney

Lining Brick, which concerns solid kiln-fired brick made from clay and/or shale

suitable for use in masonry construction in contact with the chemicals present

in the flue gases found in industrial chimneys. All of these brick types will be

fully described in later chapters. The newer ASTM C980 specification covers

three acid bricks: (1) Type I (old H), for use where low absorption and high acid

resistance are not major factors; (2) Type I I, for use where lower absorption and

higher acid resistance are required; and (3) Type II I (old L), for use where lowest

absorption and highest acid resistance are required. ASTM C279 has been re-

vised to adopt these three acid brick types.Carbon Brick: Carbon brick, though costing much more than acid brick, is

required in some CRM applications because of its high resistance to HF and con-




centrated alkalies such as caustic soda (NaOH). Red shale and fireclay bricks are

not compatible with strong alkalies and are attacked by acidic fluorides above

certain threshold concentrations. Currently economically allowable acid fluoride

(HF) levels are judged to be under 50 ppm in immersion service and 1,500 ppm

in wetdry conditions. However, recent long-term HF test programs of various

CRM materials indicate they might tolerate slightly higher acid fluoride limits

without significant damage. This greater tolerance of HF has been observed in

power plant chimney liners made of acid brick and potassium silicate mortar

handling flue gases from coals containing fluorides. Despite acidic fluoride con-

centrations well above the 50/l ,500 ppm range in some FGD systems, the acid

brick chimney liners are performing well with little or no HF attack. Neverthe-

less, carbon brick offers excellent resistance to the two media, HF and NaOH,

detrimental to acid brick, silicate mortars and monolithics, and silica filled resins.

Carbon brick differs from acid brick in other respects: much higher absorp-

tion, generally lower thermal expansion coefficient, superior shock resistance

(less dense), and much higher thermal conductivity (K factor). Because carbon

brick is more conductive than acid brick, thicker carbon brick tank linings fre-

quently must be used for equivalent thermal insulation over the membrane/sub-

strate. This greater lining thickness further increases the higher price of carbon

versus acid brick linings, but in some environments only carbon brick will work.

Carbon brick is often used with carbon filled furan resin mortar for floors or ves-sels exposed to hot aggressive chemicals such as HF and NaOH. Another differ-

ence in the two CRM bricks is the much lower thermal limit (“75O’F in the

presence of oxygen) of carbon brick due to its susceptibility to strong oxidizing

conditions in combination with heat (e.g., nitric acid, concentrated sulfuric

acid). By contrast, acid brick can readily handle service temperatures well above

1000°F, even to 2000°F, whether in oxidizing or reducing acid environments.

Foamed Borosilicate Glass Block: This thermally insulating closed cell

foamed glass block lining, commercially introduced in recent years, has found

increasing usage in many industries because of several unique properties: out-

standing chemical resistance (except to HF and NaOH), thermal resistance up to

960°F, very low K factor (excellent insulator), impermeability, good thermal

shock resistance and very light weight. The foamed glass block comes in many

standard sizes (common lining thickness is IX”) and is bonded to itself and the

substrate by an asphalt-urethane adhesive/membrane or an acid resistant mortar.

Since this glass block lining is such an efficient thermal insulator, it provides very

effective internal insulation to a steel tank or duct. Its light weight, only 12 pcf

(8-12% the density of cementitious linings), is another design benefit in reducing

dead loads on lined structures. The installed weight of only 2-3 psf is similar to

flyash design loadings and permits retrofits to existing plant ductwork and stack

liners with little or no structural modifications. Two major advantages of the

borosilicate glass block versus gunned monolithic silicate linings are its lower per-

meability and virtual immunity to cracking. This block lining has performed

well for several years in the outlet ducts and chimneys of a number of air pollu-

tion control facilities including electric utility FGD systems, pulp and paper

mills and municipal and industrial incinerators.High Alumina and Insulating Brick, Silica Brick, and Specialty Brick and

Block: These special composition brick and block are employed for specific ap-

plications as outlined below:




High Alumina Brick: This 90-99% Al,Oa brick is used as refractory brick to

resist extreme temperatures ranging 2000’-3OOO’F. Insulating firebrick is gener-

ally light weight and somewhat porous with the higher alumina than silica con-

tent used for the highest temperature ranges to 3000°F. and the higher silicathan alumina compositions used below 2000°F.

Silica Brick: Brick containing about 99% silica is favored over acid brick for

very high acid concentrations, especially phosphoric acid.

Specialty Masonry Units: These include: (I) Porcelain, an 85% alumina,

very hard and dense brick, good to 15OO’F, very cleanable with nil absorption;

(2) Basalt, an extremely dense and costly cast block, having outstanding abra-

sion resistance, used for bottom ash slurry linings, coal/ash hoppers, bunkers and

chutes; (3) Silicon carbide brick, noted for its excellent resistance to abrasion

and elevated temperatures; (4) Granite block, one of the oldest but now seldom

used natural stone units-its high density makes bonding at joints difficult; and

(5) Press-molded hydraulic bonded brick, a special brick designed for caustic and

alkaline bleach solutions and bonded with a hydraulic mortar meeting ASTM

C398 requirements.

Tile: The three types of chemical resistant tile are quarry, ceramic and glazed

porcelain. Tile is chemically similar to, but thinner than, acid brick and is dis-

tinguished from it as follows: (I) Tiles are masonry units <IX” thickness, while

(2) Bricks are masonry units >11/4” thickness. (This is roughly analogous to thedistinction between metallic sheet (or strip) at <3/16” and plate >%6” thickness.)

Packing house or dairy tile (pavers), usually made from red shale clay with a higher

(5-6%) absorption than red shale brick, is set on a bed of CRM grout over a

membrane and the open joints filled by grouting. Quarry and ceramic tiles fired

from the same clays and shale as acid brick are widely used to protect all types

of concrete floors and walls in various industries from corrosive chemicals, with

the same media restrictions (to HF & NaOH) as acid brick. Quarry, glazed tile

and ceramic tile (all units under 1” thick) must be bonded directly to the sub-

strate with an adhesive that also serves as the membrane. Units thinner than 1 ‘I,

when laid over a soft membrane such as asphalt, tend to break up under traffic,

even foot traffic.

Mortars and Grouts for Brick and Tile

Chemical resistant mortars for acid or carbon brick and grouts for tile are

the third important component and complete the three part CRM composite.

The most durable CRM structures and linings utilize impervious membranes

against a substrate sheathed with masonry units bonded with mortars or grouts.

Depending upon the service conditions, the brick or tile may be applied directly

onto the primary membrane or over a bedding layer of mortar or grout troweled

onto the membrane surface. The CRM mortars and grouts used with masonry

units fall into three generic classes: siliceous, resinous, and sulfur. Resinous mor-

tars used in CRM construction include phenolic, furan, epoxy, polyester and

vinyl ester resins. The proper selection of these chemical resistant bonding agents

with the appropriate brick or tile will resist any hot corrosive environment en-

countered in industry. When the optimum CRM materials are installed by askilled, experienced contractor, the net result is the most cost-effective anti-

corrosion system currently available.



An Engineer Looks at Chemically Resistant Masonry I I

Silicate Mortars: The major inorganic silicate (“water glass”) mortars are

based upon sodium or potassium silicates cured with various organic or inorganic

acidic catalysts (hardeners, setting agents). Perhaps the best of these products

are those containing no fluorides, employing other types of hardeners. All ofthese alkali silicate mortars are very heat resistant, some up to about 175O’F and

are fully acid resistant below pH 7 except to HF and acid fluoride salts above

certain threshold concentrations. Some silicate mortars are considered resistant

to mild, dilute organic bases to pH 8, possibly pH 9, depending upon the specific

base. Sodium silicates are susceptible to sulfation-hydration reactions when con-

tacting hot sulfuric acid and thus are the least suitable mortars for acid brick

stack liners handling wet sulfur oxide-laden flue gases and acid condensates from

utility boilers. Since potassium silicate mortars are not subject to this growth

type reaction, they are more commonly used in hot, strong sulfurous and sul-

furic acids and are the standard mortars for acid brick in power plant chimney

liners. However, potassium silicates are subject to the formation of other growth

salts, particularly alums, in the presence of sulfuric acid and iron, aluminum or

magnesium. In such combinations, a silica, rather than silicate mortar may be

considered. The best potassium silicate mortars are free of sodium, calcium and

fluorides. Both single and two component systems are available to industry. Sili-

cate mortars are the most absorbent and thus the most permeable of all acid re-

sistant mortars. Only hydraulic mortars have higher absorptions than silicates.Silica Mortars: Silica mortar is a strictly acid and heat resistant material,

handling all acids except HF and acidic fluorides at pH O-7 and thermally stable

up to 2000°F. A relatively recent self-curing silica mortar contains only borosili-

cate glass powder, silica sol and crushed silica with no metallic constituents. This

avoids both the sulfation-hydration reaction of the sodium silicates and the alum

formation problems of the potassium silicates. Like the silicate mortars, silica

mortars also resist organic chemicals.

Sulfur Mortars: Hot melt-and-pour sulfur mortars are ancient, doubtless

one of the oldest of all chemical resistant materials still used today. They are

very resistant to non-oxidizing acids and weak alkalies below 200°F over a pH

range of O-12. Three types of sulfur mortars are typically employed: (I) One

containing an all-silica filler with minimum plasticizer, used to bond acid brick;

(2) A mortar with an all-carbon filler and minimum plasticizer, used primarily to

lay carbon brick for nitric-hydrofluoric acid pickling tanks (to clean stainless

steels) and the underlying floors; and (3) A much more flexible all-silica filled

product with double the amount of plasticizer of the other two mortars, used to

join vitrified clay (terra cotta) pipe conveying waste acids and other effluent

chemicals, and to assemble “pole line hardware” for the power industry.

Resin Mortars: The following organic/polymeric mortars are used in CRM

construction, all being usable in HF exposures if non-silica fillers such as carbon

or barytes are employed:

Phenolic Mortars: Phenolics are the oldest resinous mortars used with acid

brickwork. The original phenol-formaldehyde materials have an effective pH

range of about O-IO. They are very resistant to dilute and concentrated nonoxi-

dizing acids, solvents and dilute alkalies. Modified phenolics further increase thispH range. Such mortars raise the maximum pH well above the normal pH O-12

range, and are the only resin-based mortars resistant to aniline. Phenolics are use-

ful up to an upper service temperature of 36O’F.




Furan Mortars: Furans have the broadest range of resistance to both acid

and alkali (pH O-14) and temperatures of all the resin mortars. Furan mortars

can accept temperatures up to 350°-36O’F. Modified furans are available that

can withstand continuous temperatures of up to 425’F and intermittent tempera-

tures to 475OF. Unlike the other mortar materials, furans have excellent resis-

tance to strong alkalies as well as non-oxidizing acids and many organic chemi-

cals. However, furan mortars are attacked by some organic solvents such as

aniline. Furans are available with silica, carbon or barytes fillers, the filler choice

depending upon the environmental conditions.

Epoxy Mortars: Epoxies are the strongest resin mortars, have the best bond

strength to other CRM materials, and resist many solvents, mild to moderate

acids, non-oxidizing and alkaline media. Their useful pH range is about 2-14,

and their thermal limit is approximately 230°F. Besides their excellent alkali and

dilute acid resistance, epoxy mortars handle many organic chemicals and sodium

hypochlorite at low temperatures. Epoxies should not be exposed to acetic acid

and its esters. Epoxy mortars have the best physical and mechanical properties

of all the resin mortars.

Polyester and Vinyl Ester Mortars: These two mortars, of which there are

many types, are suitable for a pH range of about O-l 1 and a continuous service

temperature of 225’-23O’F. The two related resins, which complement the

epoxy resins, resist dilute and concentrated acids and weak alkalies. Their re-sistance to acid bleaches such as chlorine dioxide and to oxidizing acids such as

nitric and chromic is superior to that of other resinous mortars, and they are ex-

cellent in acetic acid and related esters. However, polyester and vinyl ester mor-

tars are the poorest resin mortars in other organic chemical exposures including

solvents in general. Such mortars are widely used in paper mills and are suitable

with acid brick or ceramic tile in the lower temperature zones of mildly acidic

utility FGD systems.

Hydraulic Mortars: The two common types of hydraulic (water cured) ce-

ments or mortars are portland cement, the basic limederived cement used in

structural concrete (five types per ASTM C150), and calcium aluminate (e.g.,

Lumnite). Portland cement normally contains <5% alumina, while Lumnite has

>30% alumina. Chemically, portland cement mortar or concrete is not resistant

to acids, being limited to pH 26.0, whereas Lumnite resists dilute acids to about

pH 4.5, below which it is attacked too rapidly for practical use. Various latex

modified or augmented portland cement concretes have been developed to im-

prove its neutral and alkaline corrosion resistance, either by densifying the con-

crete or by coating the reactive components. For example, latex impregnated

concretes have been used on northern bridge decks to better resist deicing

salt/chloride corrosion of the steel rebars and attendant spalling of the rein-

forced concrete decks. (Elastomeric membranes, epoxy coated and galvanized

rebar, calcium nitrite corrosion inhibitive admixture and cathodic protection

have also been effective in concrete bridge deck protection.)

Another version of portland cement mortar or concrete is the replacement

of some of the portland cement with rice hull ash. This ash additive markedly

improves the resistance of the mortar or concrete to food acids and similarchemicals. Flyash (pozzolanic admixture) meeting ASTM C618 has also been

widely used to improve the properties and sulfate resistance of portland cement




concrete. It should be noted that ASTM Cl 50 Types I I and V portland cements,

while much more sulfate resistant, are no more acid resistant than ordinary Type

I portland cement. Although Type II and V based concretes and mortars are sub-

stantially better in neutral or alkaline sulfate solutions, they would be destroyedby sulfuric acid and its acid salts. Mortars based upon Lumnite, aluminum sili-

cate and calcium silicate extend economic sulfuric acid resistance down to ap-

proximately pH 45 (fairly dilute mineral acids). For stronger acids below about

pH 4,’ the mortar selection would involve one of the acid resistant inorganic or

organic materials described above, depending upon the acid type, concentration

and temperature.

All of these materials-brick, mortars and membranes-will be fully discussed

in later chapters along with (I) Castables, grouts, and polymer concretes; (2)

Monolithics (troweled, sprayed and gunned linings); and (3) Expansion joint

compounds, plus rigid plastic fabrications such as polyethylene, polypropylene

and PVC. These components made from a whole host of materials are effectively

used in a wide variety of industrial applications requiring superior chemical and

thermal resistance.

In closing this section, the energy conservation aspects of CRM construction

should be cited as a principal benefit. Because all CRM linings are internally in-

sulating to varying degrees, CRM lined equipment will operate cooler and more

efficiently while the costs and maintenance of external insulation are saved. Withthe thermal insulation (CRM lining) inside the duct or vessel, it is subject to less

damage than external insulation. When closed cell borosilicate glass block lining

is employed, no external thermal insulation is needed for the lined steel struc-

ture, simply a suitable thin film exterior coating such as an epoxy, vinyl or ali-

phatic urethane. In addition, plant personnel are safeguarded by the moderate

outer steel surface temperature resulting from the insulative CRM lining. The

energy and materials savings realized from this internal CRM design merit serious

consideration.

CHEMICALLY RESISTANT MASONRY APPLICATIONS

The industrial applications of CRM linings and structures are both numerous

and varied. This handbook could be filled with countless CRM case histories

from around the world. There are a number of excellent publications available to

the interested reader (see Bibliography at end of this chapter). In general, any

industry requiring reliable, long-term chemical and thermal resistance does or

should use one or more types of CRM construction. Cheaper, less durable engi-

neering materials and components have been used but are seldom as cost-effec-

tive as CRM systems. In some severe environments at elevated temperatures,

CRM construction is the only viable or practical solution. Since the author’s

chief experience with CRM structures and linings has been in the fossil fuel

power generation industry, especially in air pollution control systems, the fol-

lowing discussion will emphasize these CRM application areas. Certainly, the

many CRM uses in other industries are no less important and are detailed else-where in this handbook as well as in the open literature.




Power Industry-Flue Gas Desulfurization Systems

Electric utility FGD systems pose many difficult operating and maintenance

problems to the owner and his architect/engineer and constructor, not the least

of which are corrosion, erosion and abrasion effects from high velocity flyash-laden flue gas, scrubber and flyash slurries, chlorides, fluorides, sulfurous (SO*),

and sulfuric (SOS) acids over a wide range of temperatures. Though the process

slurry in the SO* scrubber (absorber, spray tower) is controlled at a normal pH

5.5-6.5 at moderate temperatures of 120°-1350F, the wet scrubbed gases leaving

the mist eliminators still contain up to 10% of the inlet flue gas SOZ content plus

some SOs, halides (Cl, F) and flyash at an uncontrolled pH. When this gas mix-

ture enters the outlet ducting and is reheated with hot (300”? 25’F) bypass flue

gas to temperatures ranging 150’-200°F or higher in the duct mixing zone re-

gion, a very corrosive mixed gas/condensate condition below the acid dew point

develops in the outlet ducts and full chimney height. It has been well established

that the postscrubber portion of the FGD system-i.e., outlet ducts and chim-

ney liner-are the most severe environmental zones and the highest maintenance

areas. A wide variety of materials (alloys, FRP, organic linings) have been used

with mixed success downstream of the mist eliminators and outlet dampers,

CRM construction has generally performed the best in this extremely hostile

region of the FGD system. This is especially true of power plant chimney liners,

where acid brick linings with pressurized annuli have proved more reliable than

coated steel or FRP liners in FGD systems employing hot bypass reheat opera-

tion.

In addition, non-metallic inorganic materials have been used in FGD system

prescrubbers, spray nozzles and slurry pumps. The favored CRM materials in-

clude acid brick, chemical resistant mortars and chemically bonded (cast or

gunned) cements, used as monolithic linings for their high chemical, thermal

and/or abrasion resistance. Hard, dense pre-fired shapes of alumina and silicon

carbide are employed for abrasive/erosive slurry spray nozzles and slurry pumpcomponents. Acid brick bonded with potassium silicate mortar is the preferred

construction for chimney liners or flues. Venturi throats of SO* scrubbers have

been lined with high alumina or silicon carbide bricks, which resist hot sulfuric

acid and are more abrasion resistant than acid brick. Hydraulic cement linings

are sometimes used to protect steel prescrubbers (quench zones) in FGD sys-

tems. These typically contain calcium aluminate or aluminum silicate cements

that are rapidly attacked by sulfuric and other acids below pH 4.5. Because of

the controlled, mildly acidic pH in the SOZ scrubbers, gunited hydraulic cements

are often used in the prescrubber area. However, chemically bonded cement

linings based upon sodium or potassium silicate are much more acid and heat re-

sistant and thus would better handle system upsets in pH and temperature. Some

completely non-metallic SOs scrubbers are now built of concrete lined with

chemical resistant ceramic tile. For any of these gunned cementious linings or

the tile lined concrete to work properly, the gunned or tile lining must be ap-

plied over impervious membranes well bonded to a suitably prepared, preferably

blast cleaned, steel (or concrete) substrate. Even the best potassium silicate-

based lining is permeable and may crack from thermal and vibrational stresses,thus exposing the steel substrate to rapid attack by acid condensates unless pro-




tected with an impermeable, acid-resistant membrane. Such cracking can be min-

imized by using properly spaced corrosion resistant alloy stud anchors, which

distribute the stresses

Specific Power Plant FGD System Experience

The extensive in-plant testing, evaluation and use of CAM linings and struc-

tures at a high sulfur coal-fired power station amply demonstrate the utility and

effectiveness of many types of CAM components, which are successfully used in

most utility FGD systems and other air pollution control facilities!'4,14,22 This

large steam electric generating station features twin units located in a river val-

ley, requiring two 1,000 foot high chimneys to adequately disperse the scrubbed

flue gasses (Figure 1-1) .The power boiler flue gases are cleaned by a highly ef-

ficient FGD system comprising: (1) Electrostatic precipitators to remove essen-

tially all of the particulates (flyash), followed by (2) Lime slurry-based S02

scrubbers to remove over 90% of the S02 from the flue gas. The wet scrubbed

flue gases containing various levels of S02, S03, CI, F and fiyash then pass through

Fi~re 1-1: Large coal-fired power station with FGD system and two 1 ,000 foothigh chimneys, one containing the tallest acid brick liner in the United States.




FRP mist eliminators, enter lined steel ducts which join a scrubber bypass reheat

duct, through turning vanes (mixing zone region), into the chimney breeching

(100 foot elevation), and up the 900 foot high chimney liner to the atmosphere.

All lined rectangular ductwork and the internal bracing werefabricated

of weldedASTM A36 carbon steel plate or pipe, while each 1,000 foot high chimney was

constructed of reinforced concrete with an independent protective liner. [The

preferred design for CRM linings is cylindrical ducting with external (no inter-

nal) stiffeners.]

I21 POTASSIUM SILICA TE C EMENT OVER YINILESTER.

Figure 1-2: Stack and duct linings. All eight modules are SO* scrubber modules.

Figure l-2 shows the plan view of Units 1 and 2 ducts and chimneys with

the various generic CRM lining materials used in different sections of the FGD

system. The SO2 scrubber modules (four/unit) were initially lined with soft nat-

ural rubber sheet, which was later upgraded to a slightly thicker, more im-

permeable and heat resistant chlorobutyl rubber lining. (Chlorobutyl, neoprene

and triply (soft/hard/soft) sheet rubber linings are the most commonly used

elastomeric linings in wet SO* absorbers.) The 1,000 foot Unit 2 chimney was

protected with a self-supporting 900 foot acid brick lining. This tallest Americanacid brick liner was built of modified Type H (or Type II) fireclay brick bonded

with a chemically cured potassium silicate mortar containing a silica sand aggre-

gate. This is the preferred CRM materials combination used in such free standing

structures. The annulus between the acid brick lining and the outer concrete

shell was pressurized by fans to maintain a positive pressure in the annular space

greater than the outlet flue gas pressure. Pressurization is standard industrial

practice to prevent acid vapors from penetrating through cracks and permeabil-

ity in the brick/mortar liner and condensing on the non-acid resistant concrete

column. In some chimneys, the concrete shell interior is lined with an acid resis-

tant mastic or other protective coating to further retard acid attack of the sus-




The most acid resistant CRM linings and acid brick structures are providing

cost-effective protection to the major problem areas of this and many other coal

fueled power plant FGD systems.

CONCLUSION

In concluding this overview of CRM, it is recommended that the technical

sources listed in the Bibliography be reviewed. In addition, the reader is referred

to the following organizations:

(I) The American Society for Testing and Materials (ASTM), Phila-

delphia, Pennsylvania, with particular emphasis on these ASTMcommittees:

(a) ASTM C-3, Chemical Resistant Non-Metallic Materials

(b) ASTM C-15, Manufactured Masonry Units

These two ASTM committees have prepared and issued the stan-

dard specifications and test methods on CRM materials and com-

ponents that are used throughout industry.

(2) The National Association of Corrosion Engineers (NACE), Hous-

ton, Texas with emphasis on NACE Technical Committees such as

Unit Committee T-6K on Corrosion Resistant Construction With

Masonry and Allied Materials. The first two reports issued by NACE

T-6K were: (I) Acidproof Vessel Construction With Membrane

and Brick Linings, and (2) Acidproof Floor Construction With

Membrane and Brick.

BIBLIOGRAPHY

1. Sheppard, W.L., Jr., A Handbook of Chemically Resistant Masonry, C.C.R.M., Inc.,

923 Old Manoa Rd., Havertown, PA, 2nd edition (1982).

2. Haffner, R.F. and Ebner, A.M., Materials Behavior in the Ducts and Chimneys of the

Pleasants Power Station, pres. at 3rd NACE/APCA/IGCI Seminar, Solving Corro-

sion Problems in Air Pollution Control Equipment, Denver, CO (Aug. II-13,198l).

3. Sheppard, W.L., Jr., Applications of Chemical Resistant Masonry in Liquid Waste

Handling, pres. at NACE CORROSION/80, Chicago, IL (Mar. 3-7,198O).

4. Sheppard, W.L., Jr., Using Chemical-Resistant Masonry in Air Pollution Control Equip-

ment, Chem. Engr.,203-210 (Nov. 20,1978).

5. Sheppard, W.L., Jr., Membranes Behind Brick-Parts I & ll,Chem. Engr. (5/15/72 and

6112172).

6. Sheppard, W.L., Jr., Materials of Construction of Pickling Tanks, Blast Furnace and

Steel Plant (Nov., 19681.

7. Sheppard, W.L., Jr., Obtaining Sound Chemically Resistant Masonry Construction, The

Construction Specifier, 20-26 (Dec., 1981).

8. Sheppard, W.L., Jr., Spotting and Avoiding Problems with Acid-Resistant Brick, Chem.

Eng. (May 3,1982).

9. Sheppard, W.L., Jr., Inspecting Chemically Resistant Masonry-Parts I & II, Plant Eng.

(3119181 & 4/16/81).



An Engineer Looks at Chemical/y Resistant Masonry 19

10. Sheppard, W.L., Jr., Trouble Shooting Chemically Resistant Masonry, Civil Eng.-ASCE,

68-71 (may, 1982).

11. McDowell, D., Specifications for Acidproof Brick, C/rem. Eng., loo-104 (June 10,

1974).

12. McDowell, D.W., Jr., Handling Sulfuric Acid, Chem. Eng. (Nov. 11, 1974).13. McDowell, D.W., Jr., Handling Phosphoric Acid and Phosphate Fertilizers, Chem. Eng.

(Aug. 4,1975).

14. Sheppard, W.L., Jr. and McDowell, D.W., Jr., Controlling Corrosion in Flue Gas Scrub-

bers-parts I & I I, Plant Eng. (2122179 & 318179).

15. McDowell, D.W., Jr. and Sheppard, W.L., Jr., Use of Non-Metallics in Mineral Acid

Plant Construction, Paper #57, NACE CORROSION/75, Toronto, Ontario, Canada

(April 14-18,1975).

16. McDowell, D.W., Jr. and Sheppard, W.L., Jr., Using Acid-Proof Brick and Mortar in

Masonry Construction and Picking Nonmetallic Construction Materials to Resist Min-

eral Acid Attack, Plant Eng. (2/19/76 & 3118176).

17. Hall, G.R. and Connell, P.E., Inorganic Corrosion-Resistant Cements for New Con-

structionand MaintenanceinChemical Industries,Paper#94,NACECORROSION/83,

Anaheim,CA (April 18-22.1983).

18. Carpenter, G. and Pierce, R.R., Linings for Sulfuric and Phosphoric Acid Plant Process

Vessels, Paper #95, NACE CORROSION/83, Anaheim, CA (4/18-22/83).

19. Boova, A.A., Chemical Resistant Joints for Vitrifield Clay Pipe Conveying Chemical

Wastes, Paper #229, NACE CORROSION/80, Chicago, IL (March 3-7,198O).

20. Boova, A.A., Masonry and Lining Technology and Techniques, Paper #253, NACE

CORROSION/82, Houston, TX (March 22-26,1982).

21. Boova, A.A., Furans as Chemical Construction Materials, Paper #159, NACE CORRO-

SION/77, San Francisco,CA (March 14-18.1977).

22. Boova, A.A., Chemical Resistant Masonry, Flake and Fabric Reinforced Linings for

Pollution Control Equipment, pres. at 2nd NACE/APCA/IGCI Seminar on Corrosion

Problems in Air Pollution Control Equipment,Atlanta, GA (Jan. 17-19).

23. Boova, A.A., Acid Proof Floors: Yesterday, Today and Tomorrow, pres. at 20th An-

nual Convention of the Southern Tile, Terrazzo and Marble Contractors’ Association,

Charlotte, NC (3/8/68).

24. Killam, E.H., Poor Pressurization Can Wreck Stacks, Electrical World, pp 71-73 (April

1983).

25. Rosenberg, H.S., et al., Construction Materials for Wet Scrubbers: Update, ~01s. 1 & 2,

EPRI CS-1736, prepared by Battelle Columbus Labs. (March 1981).26. Rosenberg, H.S., et al., Construction Materials for Wet Scrubbers: Update, vols. 1 &

2, EPRI CS3350, prepared by Battelle Columbus Labs. (July 1984).

27. Pierce, R .R. and Semler, C.E., Ceramic and Refractory Linings for Acid Condensation-

Parts I & I , Chem. Engr. (12/l 2183 and l/23/84).

28. Sheppard, W.L., Jr., Failure Analysis of Chemically Resistant Monolithic Surfacings,

Chem. Engr. (July 23,1984).

29. ASTM, Manual of Protective Linings for FGD Systems, STP837 (March 1984).



2

An Architectural Specifier Looks at

Corrosion Resistant Masonry

Milton H. Potter


PREVIEW

This chapter will present an overview of corrosion resistant construction,

materials and methods. It will discuss the importance of complete and accurate

information needed to establish Basic Data required for Design Development.

Material limitations not commonly known to the architectural practitioner,

which will affect design are listed. Lack of knowledge of corrosion resistant ma-

sonry construction has resulted in costly mistakes. This approach will appear

sophomoric but such errors have occurred with sufficient frequency to warrant

inclusion. The information is covered more specifically and in greater detail in

other chapters. While redundant, it is important that the less experienced be

forewarned of these limitations.

The average architect will never or very seldom encounter severe corrosive

exposures in his practice. He will more likely encounter the so called milder ex-

posures, such as food manufacturing, food preparation, food serving and dairy

product processing. Involved with these are the cleanup areas, i.e., sterilizing

processes. The correct design of an area which will not harbor contaminants is

important. The architect will also become involved in public toilets as well as

employee toilets and change facilities.

We have learned to contain corrosive media much more successfully in the

last 20 to 30 years. This can be attributed to the many-fold increase in knowhow

in metallurgy, in protective coatings and in the field of plastics. The need for

overall protection of the structure or building has evolved into a more localized.

protection and is needless to say, more sophisticated.

20




project. List all material limitations. Also note final appearance. Insist that the

owner or principal review the information, not just the “liaison” person. Then

insist on evidence that the owner has reviewed the document. This is of great im-

portance especially in work with corrosion resistant materials. You want no un-

pleasant surprises; neither does the owner. We have experienced many strange

situations, for example, the liaison person did not talk with the plant mainten-

ance superintendent, hence there was a gap in knowledge of proven plant main-

tenance procedures.

MATERIALS AND METHODS OF CONSTRUCTION-MASONRY SYSTEM

Corrosion resistant masonry is generally more commonly used in floors,

trenches, and pits or catch basins. Other applications are chimneys, basically fire

brick, and the lining of process vessels. Both are highly specialized and are cov-

ered in other chapters in detail.

The masonry system consists of an impermeable membrane, a bed joint of

corrosion resistant cement or mortar with joints between the brick filled with

corrosion resistant mortar, usually the same as the bed joint.

With the exception of the epoxies, the adhesive quality of the cements and

mortars is not high. They will develop hair cracks at interface with the masonryunits; consider these joints not watertight. The membrane is the major line of de-

fense and is the watertight element in this construction.

Substrate

While several substrates are acceptable, portland cement concrete is by far

the most common and the most satisfactory.

The finish of the concrete can be critical. A dense steel troweled finish will

not provide the porosity required for adhesion of some of the materials used asmembranes. A carpet float finish will provide just about the correct texture. Do

not use magnesium floats as this will close the surface and prevent the escape of

“bleed” water. Do not use curing compounds or those intended to prevent evap-

oration of water. These are incompatible with some bedding or membrane ma-

terials resulting in very poor adhesion.

Floor drains are generally cast into the concrete. They are furnished with a

drainage flange which is dished to the drain body, with weep holes into the

drains. The outer or top edge of this flange should be cast flush with or slightly

below the top surface of the concrete. The membrane should then extend over

and into the flange. The neck of the drain above the flange can be obtained in

different lengths to accommodate various thicknesses of the masonry units.

Membrane

The more common membrane is asphalt, hot applied. It is a different formu-

lation than that used in road or roof construction and is designed for maximum

corrosion resistance. It is impermeable to fluids. At elevated floors, all openings

in floor and at edges must be curbed, with membrane extending to the top of



An Architectural Specifier Looks at Corrosion Resistant Masonry 23

the curb behind the brick. While the asphaltic membrane is used to correct mi-

nor defects in the substrate, in no case shall the membrane be used to correct

major inequities in the substrate.

The thickness of the asphalt is critical, a minimum of l/s”, a maximum ofYs ‘I, l/4” is the optimum thickness.

Example. A contractor applied an asphaltic membrane up to 1” thick in an

attempt to corrrect an improperly installed concrete base slab. In the southwest

Texas summer sun, the asphalt softened and the brick shifted, severely damaging

the joints in the brick floor. Repair of the area ran into five figures.

Asphaltic membrane is adversely affected by solvent. A layer of fluorocar-

bon film such as Tedlar@ or Kynar @ 2 mils thick, is placed on top of the mem-

brane in such exposures.

Other membranes are sometimes used. They are usually considered thin,

compared to the asphlatic, rarely exceeding ‘/a” thick. Epoxies are commonly

used. Thin membranes should never be used to correct defects in the substrate.

Note. Asphaltic membranes will bridge minor joints or cracks in substrates.

Thin membranes are very rigid and will not absorb movement in the substrate.

Movement will telegraph through to the finished work. Expansion joints in the

finished surface must be located directly over the joints in substrate.

Masonry Units

Bricks are manufactured from deaerated shale and are very dense with low

absorption. ASTM C-279 Type H or L.

The Type L, 2l/4” thick, are most commonly used and in general meet the

needs of the user. The vertical fiber brick is preferred. Brick 13/s” thick called

packing house tile is a horizontal fiber brick.

The fiber structure of the brick is the result of the extrusion process during

manufacture. The fiber structure is in the direction of the extrusion of the clay

matrix. The texture of the sides of the extrusion can be varied to provide scored,

mat or textured patterns.

The horizontal fiber structure is extruded in a ribbon 1 3/8” x 37/8” then wire

cut to 8” lengths. The surface texture may be smooth,-diamond pattern or have

an emery grit surface. The horizontal fiber brick is more susceptible to spalling

from excessive wheel load traffic and to thermal shock. Voids or blisters may

form within the brick during the burning process. After a period of exposure,

salts tend to filter into these voids and expand, resulting in spalling. While the

exposed faces of this type of brick is more easily cleaned, the use of horizontalfiber brick is not often recommended.

Important fact. Corrosion resistant brick manufactured in the USA has an

expansive growth factor of 0.16% in any direction, 3/s” in 20 feet. This is not a

thermal expansion. Expansion joints every 10 to 15 feet should be specified.

Liner f/ate and Tile: In addition to the above mentioned brick there is also

liner tile, smooth faced with dove tailed or grooved backs. These are used to line

concrete pipe and trenches. They are set into the forms, joints filled with corro-

sion resistant mortar, then concrete of the pipe or trench walls poured. Simi-

larly, half round tile known as channel tile is available. This may be installed in




the same manner as the liner plates and used as trench bottoms with concrete

poured under and around the channel tile. Note channel tile and liner plates are

installed without a membrane. They are subject to the physical stress due to the

movement of concrete, thermal movement and the like. They are not recom-

mended in submerged or high corrosive situations.

Quarry Tile: Tile is used in much of the food process and food preparation

areas, also toilet and change areas. In general, it is installed without an asphaltic

membrane but with a thin adhesive membrane usually an epoxy type. As noted

above, the concrete substrate must be true to line without irregularities such as

humps and bumps. All such flaws will telegraph through to the finished surface.

Cleanliness is a major attribute of the quarry tile installation. For example, in a

synthetic elastomer plant the raw latex when spilled stuck tightly to the con-

crete floors. Quarry tile was used with an epoxy bed and a furan joint (very nar-row, %6”). Due to the greater density of the quarry tile the unvulcanized mate-

rial cleaned up easily.

Note. Patterned tile such as the diamond pattern will harbor grease and or-

ganic residue. It is not acceptable under some local sanitary laws. Labor safety

laws often require a non-skid surface. Emery grit embedded in the surface of the

quarry tile will meet the non-skid criteria. However, the employees may com-

plain that the emery surface wears out their shoes too quickly and is difficult

to clean. Warn the owner.

Ceramic Tile: Tile is quite commonly used in toilets and shower areas. It

is mentioned here only to note that the case of quarry tile when used in con-

nection with a corrosion resistant grout, the installation will withstand the stain

ing and discolorization so common from exposure to urine (uric acid) and the

strong cleaning solutions found in toilet areas.

The Tile Council of America publishes The Handbook for Ceramic Tile ln-

stallation which is an excellent guide for both ceramic and quarry tile. It is an

ANSI standard.

American National Standards Institute

1430 Broadway

New York, NY 10018

Do not forget expansion joints in ceramic tile and quarry tile work must be

directly over joints in the substrate but not limited to such locations.

Corrosion Resistant Cements and Mortars

These are covered in other chapters in greater depth. Again at risk of re-

dundancy here are a few things to keep in mind.

Sulfur Cements: Sulfur base cements are heated in a kettle similar to as-

phalts and joints poured hot, done in several steps to assure the joints are filled

before cement cools below flowable temperature. Sulfur cements are plasticized

using 0.6% olefin polysulfide (Thiokol@). Other plasticizers have been tried but

none have proven as effective as the polysulfide. Sulfur cements are filled with

either silica or carbon depending on exposure (carbon in the case of hydrofluoric



An Architectural Specifier Looks at Corrosion Resistant Masonry 25

acid). In the interest of reducing warehouse stocks some manufacturers stock

only the more expensive carbon sulfur. If carbon is specified you are charged for

it. If silica is ordered, you are only charged for silica but get carbon filler.

Resin Mortars: This group includes the furans, phenolics, polyesters and the

epoxies. Some of these mortars are used as thin membrane beds in lieu of as-

phaltic. Except for the epoxies and polyesters, most of these are acid catalyzed

materials. The alkalinity of the concrete will retard the catalyzing reaction.

Therefore, the concrete substrate must be neutralized before such a mortar is in-

stalled in direct contact with concrete.

Much quarry tile is installed using an epoxy bed with furan joints. This is an

excellent system particularly for moderate exposures. It overcomes the acidity

problem of the furans, is not subject to stain damage and is easy to clean. Note

this system was proprietary (patented) at one time but patents expired severalyears ago and to our knowledge were never renewed.

Sanitary Note. When laying groove backed quarry tile, it is important that

the grooves are completely filled with the bedding mortar. To accomplish this,

the back of the tile should be buttered before the tile is set. (In food preparation

areas and when organic materials are used in process, voids in grooves will serve

as host to deposits and subsequent bacterial growth.) The same applies to pack-

ing house tile and other grooved back units.

Also, note the reaction of the catalyzer in the mortars has a narrow opti-

mum temperature range. Elevated temperatures will accelerate to a point where

the mortar will set up before application. Cold will retard so mortar does not set

at all. In cold weather, the mortar should be stored in a heated room. Brick to be

used should be heated to 70°F for at least 24 hours prior to use.

The proportion of accelerator to resin in epoxies is critical. In cold condi-

tions, the accelerator will not flow well. Store the epoxy in a warm area.

Expansion Joints

There are many expansion joint materials. The general practice is to leave

the mortar out of the joint. Then partially fill with a vinyl sponge rod as a back-

up.

The so called “flexiblized” epoxy is most commonly used for filling such

joints. Sponge rod is not used in food plants due to possible subsurface contam-

ination and bacterial growth. Several years ago, a series of tests were made and it

was found that silicones are better for strong oxidizing chemical resistance, such

as nitric acid. Unfortunately they lose adhesion in wet or submerged exposures.

They require very dry clean surfaces and a silicone primer. A test installation is

recommended before you use silicone in a project.

Required Details

It is important that the installation be carefully detailed. Do not leave it to

the discretion of the contractor. Figure 2-1 is a suggested detail.




1. Acid-brick laid in acid-resisting mortar over a liquid-tight membrane.

2. Expansion joints around periphery of floor, continued through capping.

Also spaced equidistant from drain, 10' to 15' apart.

3. Drain, centered between expansion joints. Not surrounded by an expansion-joint.

4.

5.

Pipes through floor, surrounded by a skirt so pipe can be removed and

replaced. Expansion joint around skirt, set out slightly from skirt.

Gutter or trench, sloped from ends to center, drains through wall, down

floor on opposite side. Note expansion joint next to trench, 2 brick

out from trench wall. Peripheral expansion jozonadjacent floor

continues through trench and across brick capping.

6. Outlet through common wall permits trench to drain. Membrane continued

through outlet and protected by sleeve set in acid-resistant cement and

mortared to brick lining.

1

r--- ----r-----

KEY-

Figure Z-l: A typical section of the construction: curbs, expansion joint-includ-ing locations, edges, slopes-a minimum of %” per foot, floor drains, sleeves and

all penetrations.



Section II

27



3

Metallic Shells

Thomas F. Degnan


INTRODUCTION

Corrosion resistant masonry lined metallic process equipment combine three

vital components that must be designed to complement each other and function

as a whole.

First, there is a metal shell, generally made of carbon steel, which must pro-

vide a rigid leakproof elastic casing to support the ceramic lining, the possible

stresses resulting from its growth, thermal stresses, the contents of the vessel andother static and dynamic loadings that will be imposed upon the vessel when it is

placed in service.

Second, a membrane is almost always applied to the inside surface of the

shell to protect it against corrosion. The membrane can range from a few coats

of paint to an elastomer or plastic lining. The metallic vessel must be designed

and fabricated so that the I n ing can be properly appl ied .

Third, there is the masonry lining itself, which must be designed with the

necessary thickness and shape to be thermally and mechanically stable. The lowercoefficient of thermal expansion of the lining compared to that of the shell, un-

der thermal loading, for example, must be compensated for by the insulating ef-

fect of sufficient lining thickness to keep the lining in compression.

MATERIALS SELECTION

General Considerations

The vast majority of metallic shells for Corrosion Resistant Masonry (CRM)

28

lined vessels have been made of ASME,1 (American Society of Mechanical En-

gineers) SA-36 or SA-283 Grade C structural quality carbon steel, sometimes



Metallic Shells 29

(1) The vessels are not to be used to contain lethal substances, either

liquid or gas.

(2) The materials are not to be used in the construction of unfired

steam boilers.

(3) The design temperature at which the material is used is between

-20°F (-29°C) and 650°F (343°C).

(4) For shells, heads and nozzles only, the thickness of the plate on

which strength welding is applied shall not exceed S/8" (16 mm).

It is recommended that the ASME Code, Section VIII, Division 1 be used for

the construction of CAM lined metallic vessels. The use of Code construction is

only required where the operating pressure exceeds 15 psig, but it should be re-membered that a CAM lining can swell and exert high stresses.

Although SA-36 and SA-283 have been the most common shell materials, in

many cases they are not the safest or most economic steels to use.

Brittle Fracture

Over the years, a number of steel vessels, including those that have been

lined with CRM, have failed by brittle fracture. A photograph of a failure of a

brick lined tower, 60 ft. high that cracked the fulJlength of the shell is shown inan article "Brick-Lined Tanks" by R. Ladd3 in the March 14 issue of Chemical

Engineering p 192-198. The author knows of a similar experience where a

lined "dry tower" in a sulfuric acid plant failed in a similar manner on a cold day

in February. A "dry tower" drys combustion air by passing it countercurrent to

a downward flow of sulfuric acid.

During the last twenty years, there has been an increasing awareness of the

danger of brittle fracture of steel vessels at ambient temperatures, largely as a

result of the work of Pellini and Puzak4 at the Naval Research Laboratory and

their investigations of failures of World War II ships. Their" Fracture-AnalysisDiagram" (Figure 3-1) shows that a small flaw can initiate brittle fracture at tem-

called "tank steel." These are the least expensive grades of weldable steel plate.

They are similar steels. SA-36 has slightly higher strength [58,000 psi (400 MPa)

minimum tensile and 36,000 psi (248 MPa) minimum yield] than SA-283 Grade

C [55,000 psi (379 MPa) minimum tensile and 30,000 psi (207 MPa) minimumyield] .The API (American Petroleum Institute) Standard 620 II Recommended

Rules For Design and Construction of Large, Welded, Low Pressure Storage

Tanks"2 allows a slightly higher maximum allowable tensile stress for SA-36

than SA-283 Grade C [16,000 psi (110 MPa)vs 15,200 psi (104MPa)],butthe

more conservative ASME Boiler and Pressure Vessel Code, Section VIII, Division

1, Para UCS-23 shows the same maximum allowable design stress of 12,700 psi

[ -20° to +650°F (-29° to 343°C)] for both grades.

It should be noted that the ASME Code, Section VIII, Division 1, Para UCS-

6 has the following restrictions on the use of SA-36 and SA-283 (Grades A, B, Cand D) steels when used for pressure parts in pressure vessels:




peratures at or below the nilductility transition (NDT) temperature of a plate,

but that the critical flaw size increases rapidly once this temperature has been

exceeded. There has developed a science based on Plain Strain Fracture Mechan-

ics to make sophisticated analyses of structures to derive critical flaw sizes.

I (FRINlflAlION CURVES

IACTURE STRESSES

FOR SPECTRUM OF

, ’ JPLASTIC

ELASTIC

LOADS

FRACTURESDO NOT

l PROPAGATE

RMURE LIMITATION)

NOT NDT + 30-F NOT + 60-F NOT + l20.F

TEMP. -

Figure 3-1: Fracture analysis diagram. Reprinted with permission from Naval Research

Laboratory Report 5920, Fracture-Analysis Diagram Procedure For the Fracture Safe En-

gineering Design of Steel Structures, W.S. Pellini and P.P. Puzak, Figure 9,p 8 (March 15,

1963).

NDT temperatures vary from plate to plate and are dependent on manga-

nese to carbon ratio, thickness and grain size, among other things. True NDT

temperature can be determined by a drop weight test (ASTM E-208 “Standard

Method for Conducting Drop Weight Test to Determine Nil-Ductility Transition

Temperature of Ferritic Steels”) but is only applicable to plates %” (15.9 mm)

thick or thicker. NDT temperatures for thinner plates can be estimated by

Charpy V notch impact testing.

Vessels built in accordance with Section VII I, Division 1 of the ASME Code

seldom fail from brittle fracture, even when constructed of materials with high

NDT temperatures because the maximum allowable design stresses are only ‘/4 ofthe minimum tensile strength, which is generally less than % of the yield strength.

Hydrostatic testing, which is done 1% times the design pressure, is also bene-

ficial by causing plastic yielding at the tip of crack-like defects as long as the hy-

drostatic testing is carried out above the NDT temperature. The Code recom-

mends that hydrostatic testing be carried out with the metal wall temperature

above 6O’F (16’C). [Section VIII, Division 1, Para UG-99 (h)l

Nevertheless, failures have been known to occur during hydrostatic testing

because the metal temperature was below the NDT temperature of some plate

and a stress riser, such as the presence of two unreinforced nozzles near one an-

other or a large defect, was present.



Me t a l l i c h e l l s 3 1

Corrosion resistant masonry (CRM) lined steel vessels can present a special

risk of brittle fracture because high stresses can develop by:

l Swelling of the brick or mortar.

0 Swelling of the membrane.

0 Crystallization of the product handled in and behind the brick.

l Corrosion products of the shell if the membrane is penetrated.

It is recommended that carbon steel material for non-refrigerated outdoor

vessels be selected from Table 3-1, based on the design temperature. The informa-

tion in this table is taken from API Standard 620,* except that only materials

listed in Section II of the ASME Code are included. API Standard 620 lists

these and also ship and structural grades that are not included in the ASME

Code. API Standard 620 covers large storage tanks operating below 15 psig [and

200°F (93’C)I while the ASME Code covers vessels designed to operate at 15

psig or higher. The API Standard allows 20% higher allowable stress than Section

VIII, Division 1 of the ASME Code.

The design temperature for outdoor, non-refrigerated tanks according to

API Standard 620 is the lowest mean daily temperature on record for the locality

plus 15’F (8OC). Isothermal lines showing the lowest mean daily temperatures for

the United States is shown on Figure 3-2. This design criteria was established by

API after failure of a few large new oil storage tanks during hydrostatic testing

with: “a view to providing a high order of resistance to brittle fracture at the

lowest temperature to which the metal walls of the tank is expected to fall on

the coldest day of record for the locality where the tank is to be installed.“*

In practice, many vessels designed for outdoor service in moderate climate

are constructed of ASME SA-516 Grade 70, a fully killed, fine grain practice

pressure vessel quality carbon steel plate for moderate and lower temperature

service, so as to provide protection against brittle fracture.

Low Temperature Service

If a CRM lined pressure vessel is to be designed for below -20°F (-29’C) for

reasons other than seasonal atmospheric temperature, Section VIII, Division 1 of

the ASME Code requires that the materials and fabrication practices meet mini-

mum notch toughness requirements (Paragraph UG-84). Paragraphs UCS-65,66

and 67 cover the requirements for vessels operating below -2O’F. The use of

SA-36 or SA-283 is not permitted. Impact tests are required except for seasonaltemperature excursions below -2O’F (-29’C) or when exempted by paragraph

UCS-66 (c) which states that “no impact test is required for materials used for

metal temperatures below -2O’F (-29°C) when the minimum thickness is the

greater of those determined under the most severe conditions of coincident pres-

sure (external or internal) and temperature in accordance with UG-21 for tem-

peratures of (a) -2O’F (-29’C) and above and (b) below -2O’F (-29°C). in which

case the coincident pressure (internal if above atmospheric pressure and external

if below atmospheric pressure) shall be multiplied by 2X.”

Paragraph UCS-67 requires postweld heat treatment of all vessels requiring

impact testing, unless exempted in paragraph UCS 66 (c). Heat treatment shall




Table 3-1: Minimum Requirements for ASME Pressure Vessel Steels

to Be Used at Various Design Metal Temperatures in Accordance

with API Standard 620

Design Metal

Temperature*

To 65"~

and over

25' F

and over

-5°F

and over

-35°F

and over

-

To 314 inclusive

To 1 inclusive

To 4 inclusive

Note 6

SA 36

Any listed in

Note 6

To 1 inclusive

Over 1.

To 4 inclusive

Over 4

SA36Mod. 2

SA 442

SA 442

SA 442

SA 516

SA 662

SA 737

To $ inclusive SA 442

SA 516SA 537

SA 662

SA 737

To 1 inclusive SA 442

SA 516

SA 537

SA 662

SA 737

Over 1 SA 516

SA 537SA 662

SA 737

Code, (Sect. II

Grade

Specifications

Special

Requirements

--’one

none

"One

Nate 5

55, 60 Note 3

55. 60

55, 60

55.60.65.70

B, C

B

Note 1. 3

Note 3

Note 3

55, 60

55,60.65,70Class 1, 2

B, C

B

55, 60

55.60,65,70

Class 1, 2

B. C

B

Notes 1, 2

Note 2

Note 2

Note 2

Note 2

55.60,65,70 Notes 2,3,4

Class 1, 2Notes 2.3.4

B, C Notes 2.3.4

B Notes 2,334 I-

Excerpts from Table 2-1, API Standard 620, "Design and Construction of Large, Welded.

Low Pressure Storage Tanks," Seventh Edition (1982). Reprinted by courtesy of The

American Petroleum Institute, except only equivalent ASME Code grades shown.

*Design metal temperatures for unheated outdoor tanks in no" refrigerated service

shall be 15°F above the lowest one day mean ambient temperature for the locality

recorded as determined from Figure 2 or from similarly authentic metereological data.

Note 1:

Note 2:

Note 3:

Note 4:

Note 5:

Note 6:

The steel shall be made with fine grain practice.

The plates shall be normalized or quenched tempered.

All plates over 14 inches in thickness shall be normalized.

Each plate shall be impact tested and meet the Charpy V notch (ASTM A 370,

Type) requirements of Par. 2.2.5 of API Specification 620.

API Modification to ASTM A 36 requires the manganese content to have a range

of 0.80 to 1.20. The material supplied shall be other than rimed or capped

steel.

ASME SA 36, SA 283 Grades C 6 D. SA 285 Grade C, SA 442, SA 516, SA 537,

SA 662 Grades B h C. SA 737 Grade B.



aS

‘W~OSUSUOUMO&

‘dm1,‘Q




be in accordance with paragraph UW-40 (“Procedures for Post Weld Heat Treat-

ment”). Exempted vessel shall comply with the post weld heat treatment re-

quirements of UW-10 and UCS-56 (“Requirements for Post Weld Heat Treat-

ment”) that apply to all design temperatures.

The grades of steel normally specified for low temperature service and the

minimum temperature of mill Charpy V notch acceptance testing, as abstracted

from ASTM A-20431b “Standard Specification For General Requirements For

Steel Plates For Pressure Vessels” are as shown in Table 3-2.

Table 3-2: Generally Available Grade-Thickness-Minimum Test Temperature

Combinations Meeting Charpy V-Notch Requirements Indicated

(Normalized and Tempered Condition)

Acceptance Criteria Test Temperatur e OF For Plate

Charp y V Notch Thickness (unless otherwise

Specification agreed upon)

Ener gy Absorpt ion an d

Avg. for Minimum

3 specimens for 1

ft. lbs.min. specimen

ft. lbs.

Gra de 1” an d Over 1” over 2” Over 3”

un der to 2” to 3” t” 5”

15 12 A 516, Gra de 70 -50 -40 -30 -20

15 12 A 537 Class 1

(2Jg’ ma x.) -80 -75 -75 _-

20 15 A 537 Class 2

(2Y’ ma x.) -90 -90 -90 -_

15 12 A 203 Grade E -150 -150 -125 -_

Source: ASTM Stan dard Specificat ion A20-Sib, Ta ble 15.

Copyright. ASTM, 1916 Race Str eet, Ph iladelph ia, PA 19103. Reprint ed with

permission.

The design temperature should be at least IO’F (6OC) higher than the testing

temperatures shown in the table, since it will be necessary to meet Charpy V

notch test requirements in the heat affected zones of welds. Also the minimum

temperatures listed are for longitudinal tests. For transverse tests, the minimum

testing temperature may be higher. It should also be noted that plates must be

normalized or quenched and tempered to meet these requirements.If ultra low temperatures down to -32O’F (-196’C) are required, 9% nickel

steel and austenitic stainless steels can be used. Nickel steels with their lower co-

efficients of thermal expansion may be preferred, since low temperature is likely

to result in excessive compression of the CRM lining with the higher coefficient

of expansion of austenitic stainless steels.

High Temperature Service

It is unusual for CRM lined equipment to be designed with a high metal

wall temperature. However, it is possible for the walls of furnaces and incinera-



Metallic Shells 35

tots lined with refractories and insulated on the outside surfaces to develop sub-

stantial metal surface temperatures.

Although the ASME Code permits the use of certain unalloyed carbon steels

as high as 1000°F (538’C), it is desirable to limit their use to temperatures below

8OO’F (426OC) for two reasons:

0 Low strength compared to alloy steel.

0 Graphitization of the pearlite structure in the heat affected zones

of welded components upon long exposure to temperatures of 8OO’F

(426’C) and higher. At temperatures above 95O’F (51O’C) oxida-

tion of unalloyed carbon steels becomes significant.

The most popular steels for the 750°-1 IOO’F (400’-593’C) range are the lowalloy, chromium-molybdenum types such as SA 387 Grades 11 (1’1’4% Cr-%%

MO) and 12 (1% Cr-%% MO) class 2.

Corrosion Resistant Shells

Austenitic stainless steels UNS S30400 (Type 304) and UNS S31600 (Type

316) have been used for the shells of CRM lined vessels. Some examples are:

0A CRM lined S30403 (Type 304L) stainless steel vessel with sili-cate mortar joints is successfully used for boiling 30% nitric acid

containing an abrasive slurry. Stainless steel is used because there is

no economically satisfactory membrane to protect the steel shell in

such service and an unlined stainless steel shell could not withstand

the abrasive slurry.

l A special CRM lined UNS S31600 (Type 316 stainless steel) vessel

is used to manufacture chlorosulfonic acid with an iron contamina-

tion limit in parts per billion. An unlined UNS S31600 vessel wouldhave adequate chemical resistance but would contribute to unac-

ceptable iron pickup.

Austenitic stainless steels have high coefficients of thermal expansion, about

50% higher than those of carbon steels. This property can result in the require-

ment of a greater thickness of brick, to provide more insulation and reduce the

temperature of the shell, and to prevent it from expanding away from the lining.

The use of stainless steel cladding can minimize this problem as well as reduce

cost. The use of clad steel can also minimize the possibility of chloride stress

corrosion cracking, a principal cause of failure of austenitic stainless steels. It is

recommended that low carbon grades (0.030% C max.) be used for clad con-

struction in severely corrosive environment to avoid possible intergrannular cor-

rosion.

Nickel alloys such as Alloy 600 (UNS N06600) have been used to fabricate

shells of CRM lined vessels used in high temperature chlorinations. Alloy 600 has

coefficients of thermal expansion comparable to those of carbon steels. The

shells are often cooled externally with a falling film of water to reduce corrosionand also to keep the CRM lining in compression.




Table 3-3: Allowable Design Stresses

Allovable Design Srr essea (ksi) For Her a1 Tempera tu res ‘I’. Not Exceeding:

(Source: ASHE Code Section VIII. Division 1* - Para UCS-23 and WA-23)

16.3

!M)

16.3

15.7

13.416.2

13.3

7.2 7.2

6.3 6.3

2.1

0.32.5

0.0

7.2

6.3

1.2

9.51.6

9.2

0.6

9.11.0

8.6

6.5

Specifications

p_

17.2

16.3

14.1

12.014.6

11.9

L7.2

16.3

SA 537 Cl 1

(under 24”

thick)

SA 537 C1 2

(under 2Y

rhlck)

SA 20 3

Grade E

(34% Nickel)

Sh 240**

“NS 530400

“NS s30403UNS S31600

“NS 331603

=20

6::

12.:

12.:

13.1

-

1

1

1 I

i 1

I I

17.1

16.:

18.8

L3.:

L6.1

L6.:

6.8

-

16.:

-

10.:

12.t

16.:

6. : i

6.1

-~-

Ii--i--r1 1I 1050-

2.1

6.t 4.3 2.6

6.9 4.6 1.8

- -

1.4

.l

-

1.0

1.2

Carbon Steels___-

SA 36

SA 283

Grade D

SA 285

Grade C

SA 516

Grade 70

Lou Alloy

Sreels

SA 387Cradr 12 Cl 2

(12 cr. 4% na .

(N+T)

SA 387

Crrdr 11 Cl 2

(1U cr.-u no

(N + T)

Reprint ed With Pemis sion. The llmerican Society of “echanical En gineers.

*consu1r lat est issu e of Secrio” VIII. since addenda are published twice yearly.

**Tw s ets of allowable str esses ar e given for each grade in ““A-23. Laver sets of values shown sincedimeoslona l sra b‘llty critical in cera,,,ic lined equipm ent .



Steel

Specification

SA 285

SA 516

SA 36

SA 36

(API modified

SA 537Heat treated

with Long.

Impact tests

SA 516

Normalized

SA 516

Normalized

with Long.

Impact tests

SA 537

Heat treated

with Long.

Impact tests

:rade

C

70

ilass 20 2%"

ncl.

70

70

:lass 1

to

!?$I

ncl.

Table 3-4: Relative Metal Economy of Carbon Steel Plate

Minimum Minimum Max imum !linimum

Yield Tensile allowable hickness

(ksi) !kSi) (ksi) (in.1

30 55 13.8 0.575

38 70 17.5 0.454

36 58 12.7 0.625

36 58 12.7 0.625

60 a0 20.0 0.397

38

38

50

70

70

70

17.5

17.5

17.5

0.454

0.454

0.454

Base Price Extras

($/lo0 lbs: ($/lo0 lb

24.25 2.10

24.25 4.80

24.25 0.95

24.25 2.55

24.25 15.25

3se and

?xtras

j/l00 lb:

26.35

29.05

25.20

26.80

39.50

lbs/

sq.ft. s/q fl

23.48 6.19

21.93 6.37

25.50 6.43

25.50 6.83

19.19 7.58

24.25 10.75 35.00 21.93 7.68

24.25 11.75 36.00 21.93 7.89

24.25 12.70 36.95 21.93 a.10

Prices as of November 15, 1982

Source - Lukens Steel Company - "Lukens Plate Steels"

Assumptions: 20,000 pound minimum order. 96" length and 72" width

Maximum Allowable Stresses per ASMX Code Section VIII, Division 1, (1980) Para UCS-23, for -20 to +650"F except SA-537

A-36 Modified is made to fine grain practice with manganese in range 0.80 to 1.20 percent by ladle analysis.



Metallic Shells 39

this will result in a tensile strain greater than 0.067% (670 microinches per inch)

which is considered the upper limit for good design. Since the steel shell must

support in inelastic brittle lining, its movement must be limited or the lining will

crack.

Other factors that must be considered before selecting a stronger steel are

minimum thickness and stiffness requirements.

DESIGN CONSIDERATIONS

Thickness of Shell

If the CRM lined vessel operates at ambient temperature or so that there is a

nelgligible thermal difference between the inside and outside of the vessel, then

the thickness of the steel shell should be calculated by the rules of the ASME

Boiler and Pressure Vessel Code, Section VI II, Division 1 taking into account the

following stresses:

(a) Internal pressure

(b) Loadings described in Para. UG-22:

l Weight of vessel and normal contents under operating

or test conditions, including additional pressure due

to static head of liquids.

l Superimposed static reactions from the weight of at-

tached equipment such as motors, machinery, other

vessels, linings and insulation.

(c) Weight of internals including agitators and heating elements (coils)

(d) Dynamic loading

(e) The irreversible growth of shale or fireclay brick in acid or aqueous

service. The growth can be up to a maximum of 0.16% (or 3/a in. in

20 feet). The irreversible growth varies from batch to batch. There

is sometimes more growth in red shale than in fireclay brick.6 Some

mortars, such as sodium silicate mortar in sulfuric acid, may also

contribute to irreversible growth. In cylindrical shells and dished

heads, 10% can be added to the thickness. In flat bottoms and

sometimes in shells, it is necessary to incorporate squeeze joints in-

to the brickwork.6

If the operating pressure is to be 15 psig or less, consideration should be

given to designing the vessel to permit hydrostatic testing (before lining) at

twice the operating pressure. Hydrostatic testing must be done at a minimum

metal temperature of 60°F (16°C) to minimize the possibility of brittle fracture.

(Ref. 1, Div. 1, Para. UG-99h).

If a thermal difference will exist between the CRM lining and the shell and

expansion joints are not provided in the lining, then NACE Publication 6K157

“Acidproof Vessel Construction With Membrane and Brick”’ suggests using the




following formula to determine the increased thickness of the shell required to

resist this reversible stress:

&AT,,- A,AT,- $

s >

where: At, =

tb =

E, =

Eb =

s, =

A, =

Ab =

AT, =

ATb=

Increased thickness of shell-inches

Thickness of brick lining-inches

Modulus of elasticity for steel psi (Table)

Modulus of elasticity in compression for brick lining-psi

(may vary from 2 x 1 O6 to 7 x 1 06)

Allowable stress for shell-psi (Table)

Coefficient of expansion for steel-inches/inch/aF (Table)

Coefficient of expansion for brick-inches/inch/F (Table)

Average temperature rise of the steel “F

Average temperature rise of the brick “F

This calculation is based on equilibrium temperatures. Charging a cold vessel

with a hot fluid in a short time will generate much higher pressure of the bricklining against the steel shell and is not recommended.

When the term in parentheses is negative, it indicates the steel tank will ex-

pand more than the brick lining or that the stress in the steel shell caused by ex-

pansion of the brick lining is less than the maximum allowable design stress (Ss)

for the steel.

NACE Publication 6K-157 also recommends a minimum shell thickness of

l/4” (6.4 mm) for vessels four feet or more in diameter and a minimum thickness

of 3/s” (9.5 mm) for bottom plates.

If the steel tanks expand more than the CRM lining, then the lining will

crack under any internal loading or pressure, since the lining is weak in tension.

Conversely, if the lining expands excessively and the allowable compression

stress in the lining is exceeded, it will also fail.

An allowance for corrosion loss of the metal may sometimes be necessary.

An internal corrosion allowance is not necessary if a relatively impermeable lin-

ing such as a plastic or elastomeric membrane is to be installed before the vessel

is to be lined. An external corrosion allowance may, however, be required, par-

ticularly if the vessel is installed without sufficient clearances on side or bottomto permit sandblasting and maintenance painting.

Tolerances

The ASME Boiler and Pressure Vessel Code, Division VIII, Section 1, Par-

agraph UG-81 permits an out of roundness maximum of 1% variation of all di-

ameters from the nominal diameter. This is not sufficient to assure a satisfac-

tory CRM lining. A German standard DIN 28050, Section 4 (10.54 issue) spec-

ifies that the roundness shall be determined by measuring the radians and thatthe radians must not vary more than 310.4% from the average value in the cy-

lindrical part of the apparatus to be CRM lined after final erection.



Metallic Shells 4 I

Table 3-6: Mean Coefficients of Thermal Expansion of Steels and

Austenitic Stainless Steels*

i”./ilI/“F X 10-6 between 68’~ (2oY) and:

TeLllperE&“rCZs

HaterhI 212-F 392°F 572’F 600°F 752°F BOO’P 932OP 1OOO'F 11OO'F

IOO'C 2OOY 3OO'C 312-C 400°C 422-C 5oo"c 532-C 597°C

Carbon Steel 6.51 6.13 7.12 - 7.45 - 7.73 -

(SAE 1020)

Alloy Steels

l%Cr.g4Ho. 7.32 7.56 7.63

lkxCr.l%Mo. 7.65 - 7.72 -

*usteniticscain1ess Steels

(UNS)

530400 9.6 9.9 - 10.2

S316')O 8.8 9.0 - 9.7

*See References 10.11 ,12-used by permission.

Table 3-6: Tensile Moduli of Elasticity of Steel and Austenitic

Stainless Steels*

106psi

Material Temperature

70°F 200°F 400°F 600°F

21°C 92°C 202°C 312°C

Carbon Steels 29.9 29.5 28.3 26.7

Austenitic Stainless

Steels (UNS s30400 28.0 27.5 26.1 25.0

531600)

*See Reference 13-used by permission.

Table 3-7: Thermal Conductivity of Steel and Austenitic Stainless Steels*

BTlJ/sq ft/hr/"F/in.

Materials

Carbon Steel

(SAE 1025)

212'F

100°C

360

Temperature

392OF 572°F 752°F 932°F

2oo"c 300°C 400°C 500°C

340 319 296 273

Austenltic

Stainless Steels 9.4

(UNS S30400 and

S31600)

10.3 11.0 ii.8 12.4

*See References 14 and 15-used by permission




Table 3-8: Typical Properties of Brick

Carbon Fireclay Red Shale FoamedProperty Domestic Foreign Type H ASTM C-279 Type L ASTM C-279 Glass

Weight3

Lbs/ft 96.7 93 135-145 145 12

% Water

Absorption 15 17 4 0.7 nil

Modulus of

Rupture psi 2,600 1,500 3,500 3,300

compressive

Strength 8030- 10,000 7,000 Min. 10,000 200

Psi 8800

Coefficientof Thermal

Expansion

1.7-1,:

x 10

2.8-3:6

x 10

2.4-3.26

x 10

3.0-3:2 1.6 x 10 6

x 10

ill.lilIl"F

Thermal

Conductivity 36-46 11.5-20 9 8 0.6-0.8

BTU/hs/ft/"F/in.

Source- Sheppard "A Handbook of Chemically Resistant Masonry."

Reprinted With Permission.

Another method for controlling distortion, specified by a major chemical

company and included in the model specification (Appendix) is as follows:

(a)

(b)

(cl

The out of roundness of a cylindrical vessel shall not exceed 0.75%

of the difference between the maximum and minimum diameters.

A template with an arc length of three feet or five percent of the

circumference shall be made to the specified radium of the vessel.

When held tightly to the wall, the maximum gap or deviation shall

not exceed %6 inch (except at welds where the gap shall not ex-

ceed ‘1s inch).

The sidewall flatness, as determined by means of a three-foot (0.9

m) long (or 25% of the length of the vessel, whichever is greater)

straight edge, shall be held tightly against the wall parallel to the

axis of the vessel. The maximum gap between the straight edge and

the wall shall not exceed l/16nch except for welds, where the gap

shall not exceed ‘/a inch. Measurements taken at juncture of heads

and shells shall meet this criteria.

The ASME Code (Paragraph UG-81) permits a l%% out of roundness of the

flanges, but does not mention the out of roundness of the bodies of the nozzles

themselves. Where these nozzles are to be sleeved, the out of roundness must be

limited to 0.4%. (Reference 8, p 73).



Metallic Shells 43

Vertical Cylindrical Vessels

Dished or Conical Bottoms: “Supports must be so located as to support the

vessel and its extra weight uniformly and completely without distortion of the

vessel. Thus:

(a) If support legs are used, they should be centered under the brick

lining column tangentially to the vessel body.

(b) If a continuous skirt is used, the skirt should be centered directly

under the brick column and should be vented to provide adequate

ventilation under the vessel” (Reference 8, pp 73-74) so that the

temperature of the bottom will not be significantly hotter than the

shell during operation.

lf the head of the vessel is not to be brick lined, it may be necessary to in-

stall an internal thrust ring at the top of the vessel to contain the brick lining in

compression.

Flat Bottoms: Flat bottom vertical cylindrical tanks present particular

problems. The bottom must be so constructed and supported as to be com-

pletely rigid and well ventilated from the sides and underneath. This may usua-

lly be provided by I beams. The bottom shall be tack welded to the I beam so

that the bottom will not flex and crack the lining when it is installed. (Refer-ence 8, p 74). The maximum free span between I beams can be calculated on the

basis that the maximum deflection under full load conditions shall not exceed

the free span divided by 1000. However, in the case of vessels containing only

gas at atmospheric pressure and no internal spheres, then the deflection can be

as great as the distance divided by 500.9 It is good design to leave sufficient

space between I beams to allow for maintenance: perhaps enough space for a

man to crawl between them.

WRONG RIGHT

Figure 3-3: Tank head. The right way and the wrong way to weld a dome head on a cylin-

drical tank. It is next to impossible to make a tight weld in the head on the left, due to theinaccessible void. A continuous filled weld is used on the head on the right.



Metallic Shells 45

teed the compressive strengths of brick or mortar, will not require expansion

joints in construction. Such a design makes possible, in low temperature service,

the use of minimum thicknesses of acid proof masonry at considerable saving of

labor and material.

“If it is impractical on account of size to contour the bottom, it is recom-

mended that at least the sides be contoured. The bottom can be provided for

with peripheral squeeze joints and additional expansion joints. However, mini-

mum thickness of the brick walls will still be possible and except in rare occa-

sion without requiring expansion joints in them.” (Reference 8, p 64).

Rectangular or square tanks will usually require external reinforcing to pre-

vent deflection of the walls or bottom.

“A flat bottom should be supported by continuous I beams welded on close

enough centers to prevent measurable deflection.In any case deflection of the fully loaded vessel between supports shall not

exceed the distance between supports divided by 1000. “The beams should

run from one side completely to the opposite. In the case of rectangular vessels,

the recommended design is to carry them across the bottom, parallel to the short

dimension, and continued out both sides.

“To provide adequate stiffness to the walls, gusset plates or T-bars should be

welded vertically to the sides from top to the bottom, on the same center as on

the I beam support. The bottom periphery of the walls is kept from flexing by

its weld to the bottom plate. Similarly, the top should be stiffened, preferably

by a channel, or at the least, by a heavy angle, which should be continuously

welded completely around the top. The gusset or T plates should be welded to

the channel at the top and at the bottom to the centers of the I beam supports,

exactly opposite the web, to give optimum stability. A sketch (Figure 34) shows

exactly how this should be done.

B

1

- .II#;

==z=_= z=: r=- _-_

__- __ _- - -_

A-A

Figure 34: Recommended style of reinforcing for a rectangular steel tank. Note gusset (sec-

tion above, left) welded at top to channel, on side to tank wall, on bottom to extension of

I beam. I beam weld is to face exactly opposite web (see Section B-B). This type reinforcing

prevents deformation of tank walls when loaded. From Chemically Resistant Masonry, by

Walter L. Sheppard, Jr., 2nd Ed. (19821, Marcel Dekker, NYC, p 81. Used by permission.




“I beams are not welded along the bottoms of the ends of the tanks. In-

stead, I beams are welded in from the ends and continuously welded to the first

I beam inside the tank end. The short sides also require gusset or T-plates. These

are also welded to the channel at the top and continued down the sides of the

ends to be continuously welded to the short I beams running in from the end.”

(Reference 8, p 80).

These supports will not make a rectangular or square vessel suitable for pres-

sure or vacuum service. If such a vessel is to receive a masonry lining, it must be

designed as a cylinder with dished or hemispherical heads, both top and bottom

or as a sphere. (Reference 8, p 80). Such vessel must also be designed in accord-

ance with the ASME Code For Unfired Pressure Vessels, Section VIII.

Flooring

Sometimes it is necessary to apply acid-proof brick or monolithics such as

trowelled epoxies to a steel decking. This practice is not recommended for the

following reasons:

Unless the steel deck is rigidly supported, it will flex under loading,

causing the brick or monolithic lining to crack.

If the steel decking is restrained from expanding during tempera-

ture changes by support pillars or walls, it will flex and crack theflooring.

If the flooring undergoes temperature cycling, a monolithic coating

which is bonded to the steel will develop cracks because of the con-

siderable differences in coefficients of thermal expansion. This can

be prevented in the case of a brick flooring, which is not bonded

and is free to slide by providing expansion joints in the brickwork.

Steel decking transmits vibrations which have been known to crack

plastic monolithic coatings and brickwork.

If the designer decides to protect a steel deck with acid-proof brick, he

should consider the following recommendations:

l The steel decking should be sufficiently thick and be rigidly sup-

ported at frequent intervals to prevent any flexing or bulging due

to movement or thermal expansion. The design criteria should be

the same as for flat bottoms vertical tanks, as described previously.

l The design must include fixed anchorage only at a suitable mid-

point and the deck should be able to slide latterally over the other

supports as it stretches. Expansion joints, if used, must be carefully

located to prevent humping or flexing.

0 All welds must be continuous and be as thick as the plate to pre-

vent flexing.

0 In preparing the steel for application of a coating or membrane, the

steel surfaces must be free of mill scale, rust, grease or other con-

tamination. Surface preparation shall be as specified by the manu-




shell, internals, contents and other loadings uniformly and com-

pletely without distortion of the structure. If a vessel is conical

or dome-headed, and support legs are used, they are typically

centered under the brick lining column, tangentially to the ves-

sel body. If a vessel is conical or dome-headed, and supported

by a continuous skirt, the skirt is typically centered under the

brick column of the equipment, and it must be vented to pro-

vide adequate ventilation under the equipment. If the vessel is

flat-bottomed, the bottom must be constructed and supported

as to be completely rigid, and well ventilated from the sides and

underneath. This type of support is usually provided by crib-

bage or l-beams. Flat bottoms are less stable than dished bot-

toms and should be avoided, particularly if the vessel will besubject to fluctuating temperature and pressure. Dished bottoms

shall be suitably stiffened as well as the juncture between the

bottom and the sidewalls. Horizontally aligned cylindrical ves-

sels are typically supported on padded saddles. Such saddles

shall support the lower 120’ of the cylinder, and the support

pads shall be wide enough to prevent concentrated load points.

2.1.6 The design of shell thicknesses of vessels must take into account

loading created by the design operating conditions, the weightof the lining materials, residual stresses o be created if the brick

lining is to be pre-stressed, thermal stress conditions under maxi-

mum and minimum operations, shutdown conditions and vary-

ing external ambient conditions, and also, stresses created by

the irreversible growth of brick. Supports must take into ac-

count the weight of the lined vessels and contents and also any

dynamic loading they may have to resist.

2.1.7 The bottom flatness of a vessel shall be measured by means ofplacing a straight edge across the full diameter of the vessel/tank

bottom, and measuring the distance between the underside of

the straight edge and the steel. The distance measured at any

point must not exceed %” (6.3 mm) or the diameter divided by

1000, whichever is greater. If the vessel is a gas filled tower

without internal piers, the maximum deflation shall not exceed

the diameter divided by 500. l-beams shall extend across the full

diameter and chords under the vessel bottom so that the steel

walls and bottom are fully supported. The bottom steel shall be

tack-welded to the l-beams such that the bottom will not flex

and crack the brick lining when installed. The underside of the

vessel shall be allowed to ventilate, i.e., do not set directly on a

full concrete pad. The space between the supporting l-beams

must be dimensioned in such a way that sufficient space is main-

tained to allow a workman to crawl between them. With respect

to the “bending through” of the bottom construction, the fol-

lowing shall be met:



Metallic Shells 5 1

If the free span between the beams supporting the

steel floorplate is “a”, then the deflection of the steel

plate measured across this span (deviation from a

straight line) shall be no more than “a” divided by

500 under full load operational conditions.

2.1.8 The sidewall flatness of a cylindrical vessel shall be measured by

means of a straight edge having a length of 3’ (0.9 m) or 25% of

the height of the wall, whichever is greater. This straight edge

shall be placed against the wall at various locations. The distance

between the straight edge and any point on the steel shell is to

be measured. The maximum deviation from true linearity shall

not exceed %6” (1.6 mm) except at circumferential welds where

the deviation shall not exceed l/s” (3.2 mm).

2.1.9 Rectangular vesselsshould not have straight sides and preferably

not flat bottoms. The sides should be designed with an outward

curve on each wall. The depth of the curve should be a mini-

mum of 1% of the length of the vessel and 2% of the width of

the vessel. The measured differences between the cross center

dimensions and the cross end dimensions should be within the

specified range. Also a template shall be made with the specified

curve. The template shall be 3’ long (0.9 m) or 25% of the

length of the side to be measured, whichever is greater. When

the template is held against the wall, the template deviation

shall not exceed l/16” (1.6 mm). Stiffness must be provided to

keep all walls rigid and to prevent flexing.

2.1 .I0 The outof-roundness of a cylindrical vessel shall be determined

by measuring the maximum and minimum internal diameters

in the same planes. The difference shall not exceed 0.75% of

the larger diameter. Also a template shall be made representingthe calculated arc of inside cylindrical wall. The arc length

should be 3’ (0.9 m) or 5% of the circumference, whichever is

longer. When held tightly against the wall, the maximum gap

(deviation) shall not exceed %6” (1.6 mm) except at longitudi-

nal welds where the gap shall not exceed l/s” (3.2 mm). See Fig-

ure 3-5.

2.1 .I 1 The maximum out-of-plumbness (in inches) of a vessel shall not

exceed the tank height x %oo, where the tank height is ex-pressed in inches.

Note: In brick lining vessels, it is not a matter of particular con-

cern that vessels be perfectly plumb. If the vesselshave floating

heads, then the plumbness does become very important. It is

more critical for out work that we have the center line estab-

lished, and then our other criteria, namely, out-of-roundness

will tell us if the steel is acceptable for receiving a chemically-

resistant masonry lining.




Figure 3-5: Allowable outaf-roundness of cylindrical shells to be lined. A = greatest diame-ter, B = smallest diameter, A - B < 0.75%A. Template length = (0.9 m) or 5% of circumfer-

ence, whichever is greater. Maximum deviation from true arc = ‘116” (1.6 mm), except l/a”

(3.2 mm) permitted at longitudinal (not circumferential) welds.

2.1 .I2 Vessels must be tested and found to be liquid tight before being

lined. Pressure vessels must be hydrostatically tested at 1% times

design pressure as required by the ASME Boiler and Pressure

Vessel Code. Non code vessels must be tested using one or more

of the following methods:

(a) Fill with water

(b) Hydrostatic test at 1% times design pressure

(c) Vacuum-box-test welds

(d) Air/soap/water using specified internal pressure

Note: Water temperature should be a minimum of

6O’F (16OC). Air/soap test must be preceded by a higher

pressure hydrostatic test.

2.2 Accessibility

2.2.1 All surfaces of the steel vessel interior shall be readily accessiblefor welding, surface preparation and lining application.

2.2.2 The minimum manway diameter for working entrances during

application shall be 24 inches (60 cm).

2.2.2.1 In field erected vertical tanks, one manway

should be located near ground (work) level.

2.2.2.2 Large vessels should have a minimum of two

(2) manways, one in the roof and one near

ground level, preferably 18O’apart.



Metallic Shells 53

2.2.3 Additional openings should be provided as needed to facilitate

ventilation and material handling during lining work.

2.3 Fabrication

2.3.1

2.3.2

2.3.3

2.3.4

2.3.5

2.3.6

The alignment of steel plate surfaces at butt weld joints shall be

matched to within l/16” (1.6 mm) on both circumferential and

longitudinal joints on the inside surfaces of the vessel. Where

plates of different thicknesses are welded together, such as heads

and shells, the thicker plate shall be machined or ground on the

outside surface with a 4: 1 taper so as to have approximately the

same thickness as the thinner plate at their junction.

All welds that will be lined over shall be continuous. No inter-

mittent or spot welding shall be allowed.

All welds shall be ground to remove sharp edges, laps, undercuts

and other surface irregularities and projections. (See Figure 3-2).

All weld spatter shall be removed. Chipping may be utilized if

followed by grinding for finish.

Pinholes, pits, blind holes, porosity, undercutting or similar de-

pressions shall not exist in the finished surface of the weld be-

fore or after blast cleaning.

Temporary welds used for attaching alignment plates and dogs

and arc strikes shall be ground smooth.

Circumferential and longitudinal seam welds-allowable weld

height and distortion tolerance. (Weld height is defined as the

plus variation from the plane of the welded sheets of steel .)

2.3.6.1 Circumferential Seams: To check this par-

ticular concern, take a 16” (406 mm) long

straight edge, plumb it on the weld so that 8”

(203 mm) is aboveand 8” (203 mm) is below.

If the measured distance between the straight

edge and the steel shell is greater than %” (3.2

mm) anywhere, then the weld is too high, or

there has been an excessivedraw string effect,

and necessary corrections are to be made.

2.3.6.2 Longitudinal Seams: To check this particu-

lar concern, take a 3 foot (0.9 meter) long

template cut to the calculated arc of tank

wall and center it horizontally across the

weld. Hold it tight against the steel and

measure the maximum clearance between

the curvature of the template and the curva-

ture of the tank wall. If the clearance is

greater than l/s” (3.2 mm) then the weld is

too high or has caused excessive distortion,and necessary corrections are to be made.




All abrupt contours, including sharp edges,

fillet welds, inside and outside corners, etc.

to be lined over, shall be rounded off by

grinding or machining to a l/s” (3.2 mm)

minimum radius.

2.3.7 Smooth, ripple-free welds with crowns not exceeding l/16” (1.6

mm) in height that blend smoothly into adjacent surfaces need

not be ground.

2.3.8 Lap-welded joints shall be avoided wherever possible. If lap-

welded joints are used, they must be fully welded on the inside.

The lap welded edge must ground to make a smooth transition

from one plate to the next. (See Figure 3-2).

2.3.9 Riveted joints shall not be used.

2.3.10 The use of internal bolted joints in any areas to be lined is pro-

hibited.

2.4 Connections

2.4.1 All connections to the vessel shall be flanged.

2.4.2 Vessel/tank nozzles shall be of flanged design wherever possible.

Nozzles should not be under 3” IPS and never under 2” IPS in

diameter. Flanged nozzles 2” (50.8 mm) and greater shall have

maximum lengths in accordance with the following schedule:

Nozzle Diameter (IPS)

(inches) (mm)

2 56

3 76

4 1028-24 203-610

24-36 610-915

Over 36 Over 915

Maximum Length

Shell to Face of Flange

(inches) (mm1

3 76

4 102

8 20316 406

24 610

Any length

Note: The lining thickness may change the nozzle diameter and

maximum length.

2.4.3 Nozzles to be sleeved in brick-lined vessels/tanks must be limi-

ted to ?0.4% out-of-roundness.

2.4.4 Nozzles must not extend beyond the inside of the shell.

2.4.5 Nozzles to be sleeved should be placed in the center of heads

and near the bottom of vertical walls. Otherwise, relative move-

ment of the lining and shell is likely to destroy the sleeve.

2.5 Appurtenances inside Vessels

2.5.1 The requirements of Sections 2 and 3 of this recommended

guideline specification shall apply to any item to be installed in-

side a vessel that is to be membrane-and-brick lined. Such ap-

purtenances include agitators, anti-swirl baffles, outlet connec-



Metallic Shells 55

2.5.2

2.5.3

2.5.4

tions, gauging devices, ladder supports, screen supports, support

brackets, etc.

If appurtenances inside the vessel, including nuts and bolts, can-

not be lined, they shall be made of corrosion-resistant materials.Dissimilar metals shall be electrically insulated from the steel

vessel surface if the vessel will contain aqueous solutions or elec-

trolytes. Bolts shall be insulated by the use of dielectric sleeves

and washers.

Heating elements should be attached with a minimum clearance

of 6 inches (15.2 cm) from the lining surface.

2.6 internal Structural Reinforcement Members

2.6.1 Structural reinforcement members should be installed on the

vessel exterior wherever possible. However, if such members are

installed internally, they shall be fabricated of simple shapes

such as smooth round bars or pipe for ease of membrane lining

application.

2.6.2 The use of angles, channels, I-beams, and other complex shapes

should be avoided. If they must be installed internally, these

members shall be fully seal-welded and edges ground.

Note: It is difficult to protect the membrane on such internal

members and failure of the membrane will result in attack on

the metal shell.

2.6.3 Reinforcement pads and stiffening members should be installed

externally.

2.7 Surface Preparation

2.7.1 All interior surfaces shall be sandblasted to a standard (SSPC or

NACE) specified by the membrane manufacturer immediately

prior to application of the membrane.

2.7.2 All exterior surfaces shall be sandblasted and painted in accord-

ance with specifications supplied by the customer or protective

coatings manufacturer.

REFERENCES

1. ASME Code For Unfired Pressure Vessels, Section VIII, Division 1 and Section II

(1982). American Society of Mechanical Engineers.

2. API Standard 620, Recommended Rules For the Design and Construction of Large,

Welded, Low Pressure Storage Tanks, Seventh Edition (1982). American Petroleum

Institute.

3. Ladd, R., Brick-Lined Tanks, Chemical Engineering, V 73 No. 6, p 192-196 (March

14,1966).

4. Pellini, W.S., and Puzak, P.P., Fracture Analysis Diagram Procedure For The Fracture-Safe Engineering Design of Steel Structures, Naval Research Laboratory, p 8 NRL

Report 5920 (March 15,1963).




5. Adams, Ludwig, Relative Metal Economy of Pressure-Vessel Steels, Chemical Engi-

neering,V76 No.27,~ 150-151 (December 15,1969).

6. 26th Biennial Materials of Construction Report-Chemical Engineering, V 81 No. 24,

p 126-128 (November 11,1974).

7. NACE Technical Committee Report 6K157, Acid Proof Vessel Construction With

Membrane and Brick Linings.

8. Sheppard, Walter L., Jr., Chemical Resistant Masonry, CCRM Inc., 2nd Ed. (1982),

Marcel Dekker Inc., N.Y.C., pp 64,73-74,76,77,81 (1982).

9. Carpenter, G., and Pierce, R.R., Linings for Sulfuric and Phosphoric Acid Process

Plants, Paper No. 95, Corrosion 83, National Association of Corrosion Engineers.

10. Physical Properties of Carbon and Low-Alloy Steel,Meta/s Handbook, Vol. 1,9th Ed.,

Bardes, Bruce, E., Ed., American Society for Metals, p 147 (1978).

11. ASM Committee on Wrought HeatResisting Alloys, Properties of Steels and Wrought

Heat-Resisting Alloys at Elevated Temperatures, Lyman, T., Ed., Mefals Handbook,

Vol. 1,8th Ed,, American Society for Metals, p. 490 (1961).

12. ASM Committee on Wrought Stainless Steels, Wrought Stainless Steels, Metals Hand-

book, Vol. 3, 9th Ed., Benjamin, David, Senior Ed., American Society for Metals,

p 34 (1978).

13. ASM Review Committee on Steel Castings, Steel Castings, Metals Handbook, Vol. 1,

9th Ed., Bardes, Bruce, E., Ed., American Society for Metals, p 393 (1978).

14. Focke, A.E., Elevated Temperature Properties of Construction Steels, Metals Hand-

book, Vol. 1, 9th Ed., Bardes, Bruce, E., Ed., American Society for Metals, p 652

(1978).

15. ASM Committee on Wrought Stainless Steels, Wrought Stainless Steels, Lyman, T.,

Ed., Metals Handbook, Vol. 1 ,Bth Ed., American Society for Metals, p 422 (1961).



4

Concrete

Edward G. Nawy

Department of Civil and Environmental Engineering

Rutgers UniversityNew Brunswick, New Jersey

INTRODUCTION

Plain concrete is formed from a hardened mixture of cement, water, fine ag-

gregate, coarse aggregate (crushed stone or gravel) , air and often other admixtures.

The plastic mix is placed and consolidated in the formwork, then cured to facili-

tate the acceleration of the chemical hydration reaction of the cement/water

mix, resulting in hardened concrete. The finished product has high compressive

strength, and low resistance to tension, such that its tensile strength is approxi-

mately one-tenth of its compressive strength. Consequently, tensile and shear re-

inforcement are placed in the tensile regions of a concrete section so that its full

compressive capacity can be utilized. In order to obtain quality concrete for

structural use, a knowledge of the concrete producing materials and their pro-

portioning becomes essential.

This section presents a brief account of the concrete-producing materials,

namely cement, fine and coarse aggregate, water, air and admixtures. The ce-

ment manufacturing process, the composition of cement, type and gradation of

fine and coarse aggregate, and the function and importance of the water and air

are reviewed. The reader can refer to books and papers on concrete such as the

selected references at the end of th is section .

57

CONCRETE-PRODUCING MATERIALS

Portland Cement

Manufacture: Portland cement is made of finely powdered crystalline min.

erals composed primarily of calcium and aluminum silicates. Addition of waterto these minerals produces a paste which, when hardened, becomes of stone-like




(1) Lime (CaO)-from limestone

(2) Silica (SiOv-from clay

(3) Alumina (AI2O3)-from clay

(with very small percentages of magnesia namely MgO and sometimes some al-

kalis). Iron oxide is occasionally added to the mixture to aid in controlling its

com position .

The process of manufacture can be summarized as follows:

(1) Grinding the raw mix of CaO, SiO2 and AI2O3 with the added other

minor ingredients either in dry or wet form. The wet form is calledII II

slurry process.

(2) Feeding the mixture into the upper end of a slightly inclined rotary

kiln.

(3) As the heated kiln operates, the material passes from its upper toits lower end at a predetermined, controlled rate.

(4) As the temperature of the mixture rises to the point of incipient

fusion, namely, the clinkering temperature, it is kept at that tem-

perature until the ingredients combine to form at 2700°F the port-

land cement pellet product. These pellets range in size from Ih6 in.

to 2 in. and are called clinkers.

(5) The clinker is cooled and ground to a powdery form.

(6) A small percentage of gypsum is added during grinding to control

or retard the time of setting of cement in the field.

(7) The final portland cement goes into silos for bulk shipment and a

small percentage is packed in 94 Ibs. bags for shipment.

Strength: Strength of cement is the result of a process of hydration. This

process leads to a recrystallization in the form of interlocking crystals producing

the cement gel which has high compressive strength when it hardens. A study of

Table 4-1 shows the relative contribution of each component of the cement to-

wards the rate of gain in strength. The early strength of portland cement is

higher with higher percentages of tricalcium silicate (C3S). If moist-curing is con-

tinuous, the later strengths will be greater with higher percentages of dicalcium

silicate (C2S). Tricalcium aluminate (C3A) contributes to the strength developed

during the first day after casting the concrete because it is the earliest to hydrate.

When portland cement combines with water during setting and hardening,

lime is liberated from some of the compounds. The amount of lime liberated is

approximately 20% by weight of the cement. Under unfavorable conditions, thismight cause disintegration of a structure owing to the leaching of the lime from

strength. Its specific gravity ranges between 3.12 and 3.16 and it weighs 94 Ibs.

per cu. ft. which is the unit dry weight of a commercial sack or bag of cement.

The raw materials that make cement are:



Concrete 59

the cement. Such a situation should be prevented by the addition of silicious

mineral such as pozzolan to the cement.

The added mineral reacts with the lime in the presence of moisture to pro-

duce strong calcium silicate.

Table 4-1: Percentage Composition of Portland Cements

Type

of . . . . . . . . . Components. % . . . . . . . . . . General

Cement CsS C$ CsA C&F* CaS04

Normal I 49 25 12 8 2.9

Modified 46 29 6 12 2.8

II

High 56 15 12 8 3.9

early I I I

Low heat 30 46 5 13 2.9

IV

Sulfate 43 36 4 12 2.7

resisting

V

l etracalcium alumina ferrite

CaO MgO Characteristics

0.8 2.4 All purpose cement

0.6 3.0 Comparative low heat

liberation. Used inlarge-sized structures

1 .4 2.6 High strength in three

days

0.3 2.7 Used in mass concrete

dams

0.4 1 .6 Used in sewers and

structures exposed

to sulfates

Influence of Voids and Type of Cement on the Durability of Concrete: (a)

Disintegration of concrete due to cycles of wetting, freezing, thawing and

drying and the propagation of resulting cracks is a matter of great importance.

The presence of minute air voids throughout the cement paste increases the

resistance of concrete to disintegration. This can be achieved by the addition of

air-entraining admixtures to the concrete while mixing.

(b) Disintegration due to chemicals in contact with the structure such as in

the case of port structures and sub-structures can also be slowed down or pre-

vented. Since the concrete in such cases is exposed to chlorides and sulfates of

magnesium and sodium, it is imperative to specify sulfate-resisting cements. Usu-

ally type II cement will be adequate for use in seawater structures.

Water and Air

Water: Water is required in the production of concrete in order to precipi-

tate chemical reaction with the cement, to wet the aggregate, and to lubricate

the mixture for easy workability. Normally, drinking water can be used in mix-

ing.

Water having harmful ingredients, contamination, silt, oil, sugar or other

chemicals is destructive to the strength and setting properties of cement paste

and might adversely effect the workability of a mix.

Since colloidal gel or cement paste is the result of only the chemical reac-

tion between cement and water, it is not the proportion of water relative to the

whole of the mixture of dry materials that is of concern in any study, but only

the proportion of water relative to the cement. Excessive water leaves an uneven

honeycombed skeleton in the finished product after hydration has taken place,




while too little water prevents complete chemical reaction with the cement. The

product in both cases is a concrete weaker and inferior than contemplated.

Entrained Air: With the gradual evaporation of excess water from the mix,

pores are produced in the hardened concrete. If evenly distributed, these couldgive improved characteristics to the product. To achieve very even distribution

of pores by artificial introduction of finely divided uniformly distributed air

bubbles throughout the product is possible by adding air-entraining agents such

as vinsol resin. Air-entrainment increases workability, decreases density, in-

creases durability, reduces bleeding and segregation, and reduces the required

sand content in the mix. For these reasons, the percentage of entrained air

should be kept at the required optimum value for the desired quality of the con-

crete. The optimum air content is 9% of the mortar fraction of the concrete. Air-

entraining in excess of 5-6% of the total mix starts to proportionately weaken

the concrete strength.

Water/Cement Ratio: Summarizing the preceding discussion, strict control

has to be maintained on the water/cement ratio, and the percentage of air in the

mix. Since water/cement ratio is considered as the real measure of the strength

of the concrete, it should be the criteria governing design of most structural con-

cretes. It is usually given as the ratio of weight of water to the weight of cement

in the mix.

Aggregates

Introduction: Aggregates are those parts of the concrete that constitute the

bulk of the finished product. They comprise 60-80% of the volume of the con-

crete, and have to be so graded that the whole mass of concrete acts as a rela-

tively solid, homogenous, dense combination, with the smaller sizes acting as in-

ert filler of the voids that exist between the larger particles.

Aggregates are of two types:

(a) Coarse aggregate (gravel, crushed stone, or blast furnace slag)

(b) Fine aggregate (natural or manufactured sand)

Since the aggregate constitutes the major part of the mix, the more aggre-

gate in the mix the cheaper the cost of the concrete, provided that the mix is of

reasonable workability for the specific job in which it is used.

Coarse Aggregate: Coarse aggregate is classified as such if the smallest size

of the particle is greater than ‘/4 in. (6 mm). Properties of the coarse aggregate af-fect the final strength of the hardened concrete and its resistance to disintegra-

tion, weathering and other destructive effects. The mineral coarse aggregate must

be clean from organic impurities, and must have a good bond with the cement

gel.

The common types of coarse aggregate are:

(1) Natural crushed stone: This is produced by crushing natural stone

or rock from quarries. The rock could be of igneous, sedimentary,

or metamorphic type. While crushed rock gives higher concrete

strength, it is less workable in mixing and placing than the other

types.



Concrete 6 1

(2) Natural gravel: This is produced by the weathering action of run-

ning water on the beds and banks of streams. It gives less strength

than crushed rock but is more workable.

(3) Artificial coarse aggregates: These are mainly slag and expanded

shale, and are frequently used to produce lightweight concrete.

They are the by-product of other manufacturing processes, such as

blast-furnace slag or expanded shale, or pumice for lightweight con-

Crete.

(4) Heavyweight and nuclear-shielding aggregates: With the specific

demands of our atomic age and the hazards of nuclear radiation

due to the increasing number of atomic reactors and stations, spe-

cial concretes have had to be produced to shield against X-rays,

gamma-rays and neutrons. In such concretes, economic and worka-

bility considerations are not of prime importance. The main heavy

corase aggregate types are: steel punchings, barites, magnatites, and

limonites.

While concrete with ordinary aggregate weighs about 144 Ibs. per cu. ft.,

concrete made with these heavy aggregates weighs from 225 to 330 Ibs. per cu.

ft. The property of heavy-weight radiation-shielding concrete depends on the

density of the compact product rather than primarily on the water cement ratio

criteria. In certain cases, high density is the only consideration, while in others

both density and strength govern.

Fine Aggregate: Fine aggregate is smaller size filler made, in most cases, of

sand. It ranges in size from #4 to #lOO U.S. Standard Sieves. A good fine aggre-

gate should always be clean from organic impurities, clay or any deleterious ma-

terial or excessive filler of size smaller than #IO0 sieve. It should preferably have

a well-graded combination conforming to the ASTM sieve analysis standards. For

radiation-shielding concrete, fine steel shot and crushed iron ore are used as fine

aggregate.

The recommended gradings of the coarse and fine aggregates are given in

detail in ASTM standards C-330 and C-637.

Admixtures

Admixtures are materials other than water, aggregate or hydraulic cement

which are used as ingredients of concrete and which are added to the batch im-

mediately before or during the mixing. Their function is to modify the proper-

ties of the concrete so as “to make it more suitable for the work at hand, or for

economy, or for other purposes such as saving energy.‘16 The major types of ad-

mixtures can be summarized as follows:

l Accelerating admixtures

0 Air-entraining admixtures

a Water-reducing admixtures and set controlling admixtures

0 Finely divided mineral admixtures

l Admixtures for no-slump concretes




l Polymers

0 Superplasticizers

CRITERIA FOR QUALITY CONCRETE

The general characteristics of quality concrete may be summarized as fol-

lows:

Compactness

The space occupied by the concrete should, as much as possible, be filled

with solid aggregate and cement gel free from honeycombing. Compactness may

be the primary criteria for those types of concrete which intercept nuclear radia-

tion.

Strength

Concrete should always have sufficient strength and internal resistance to

the different types of failure.

Water/Cement Ratio

This ratio should be suitably controlled to give the required design strength.

Texture

Exposed concrete surfaces should have dense and hard texture that can

withstand adverse weather conditions.

In order to achieve these properties, quality control and quality assurance

have to be rigorously maintained in the selection and processing of the following

parameters:

(a) Quality of cement

(b) Proportion of cement in relation to water in the mix

(c) Strength and cleanliness of aggregate

(d) Interaction of adhesion between cement paste and aggregate

(e) Adequate mixing of the ingredients

(f) Proper placing, finishing and compaction of the fresh concrete

(g) Curing at temperature not below 5O’F while the placed concrete

gains strength.

A study of these requirements shows that most of the control actions have

to be taken prior to placing the fresh concrete. Since such a control is governed

by the proportions and the mechanical ease or difficulty in handling and placing,

the development of criteria based on the theory of proportioning for each mix

should be studied. Most mix design methods have essentially become of histori-

cal and academic value.

The most accepted method of proportioning concrete mixes is the American



Concrete 63

Concrete Institute’s method both for normal weight and lightweight concretes.

In addition to the aim of designing a mix to achieve the prescribed level of 28-

day compressive strength, mix design is also intended to produce workable con-

crete easy to place in the forms. A measure of the degree of consistency and ex-tent of workability is the slump. In the slump test, the plastic concrete specimen

is formed into a conical metal mold as described in ASTM Standard C-143. The

mold is lifted, leaving the concrete to “slump,” namely spread or drop in height.

This drop is the slump measure of the degree of workability of the mix.

Mix Designs for Nuclear-Shielding Concrete

Whereas from the foregoing discussion it is seen that the design criteria was

the “water/cement ratio,” in concrete used for shielding against X-rays andgamma rays and neutrons, the criteria is compactness or density of mix regard-

less of workability. To achieve maximum density, tests have been conducted on

various mixes using crushed magnatite ore or fine steel shot instead of sand, and

steel punchings, magnatites, garytes, or limonites instead of stone as discussed

previously.

Tables 4-2, 4-3a, 4-3b (for normal and heavyweight concrete) and Table 4-5

for structural lightweight concrete give the necessary tools for proportioning

concrete mixes.“*”

Results of these tests for both compactness and strength have shown that

the w/c ratio must be limited to 3.5 to 4.5 gallons of water.

QUALITY TESTS ON CONCRETE

Workability or Consistency

(a) Slump test by means of the standard ASTM Code. The slump in in-ches recorded in the mix indicates its workability.

(b) Remolding tests using Power’s Flow Table.

(c) Kelley’s Ball Apparatus.

Only the first method is accepted as ASTM standard.

Air Content

Measurement of air-content in fresh concrete is always necessary especially

when air-entraining agents are used.

Compressive Strength of Hardened Concrete

This is done by loading cylinders 6” in diameter and 12” high in compres-

sion perpendicular to the axis of the cylinder. Cylinder molds must be filled with

the same mix and at the same time that the concrete is placed, and should be

placed at once in the same vertical position, in a place where they will be undis-

turbed until the concrete is hard and the cure sufficiently advanced to accept

traffic. If it becomes necessary to move them, do so very gently and carefully,

but on no account disturb them for the first 24 hours.




Table 4-2: Approximate Mixing Water and Air Content Requirements for

Different Slumps and Nominal Maximum Sizes of Aggregates*

Slump. in.

Water. lb per c” yd of concrete for Indicatednominal maximum sizes of aggregate

!b in. ) $5n. 1 3: in. ( 1 n. 1 1% In. 1 2 1n.t 1 3 1n.t 6 1n.t

1 to 23 to 46 to I

Approximate amount ofentrapped au in non-air-entrained concrete,percent

Non-air-entrained concrete

350 335 315 300 215 260 240 210365 365 340 325 3w % 265 230410 385 360 340 315 265 -

3 2.5 2 1.5 1 0.5 0.3 0.2

1 to 23 to 46 to 1

Recommended average:total air content, percent.for level of exposure:

Mild exposureModerate exposureExtreme exposuretf

305340365

Air-entrained concrete

295

E260305325

SE310

250 240 225 200275 265 250 220290 260 270 -

4.5 4.0 3.5 3.0 2.0 1.51’. Log’*6.0 5.5 5.0 4.0 3.0$!**1.5 7.0 6.0 ::; 5.0

;:;0g**4.00

--~ -

2.54.55.5

*These quantities of mixing water are for use in computing cement factors for trial batches.They are maxima for reasonably well-shaped angular coarse aggregates graded withm brmtsof accepted specifications.

tThe slump values for concrete containing aggregate larger than l!; m. are based on slumptests made after removal of particles larger than l!$ m. by wet-screenmg.

fAdditiona1 recommendations for air content and necessary tolerances on air content forcontrol in the field are given in a number of AC1 documents, including AC1 201. 345. 316. 301.and 302. ASTM C 94 for ready-mixed concrete also gives air content lirmts. The requirementsin other documents may not always agree exactly, so inmust be given to selecting an aw content that will meet

roportloning concrete considerationtf:

the applicable specifications.e needs of the job and also meet

5For concrete containtng large aggregates which ~11 be wet-screened over the l!; in. sievePrior t0 testing for air Content. the Percentage of a~ expected in the 1:; in. nunus materlalshould be as tabulated in the 1% in. column. However, initial proportionrng calculations should

include the air content as a percent of the whole.

‘*When using large aggregate in low cement factor concrete. air entramment need not bedetrimental to strength. In most cases nuwing water reqwrement is reduced sufflclently toimprove the water-cement ratio and to thus compensate for the strength reduang effect ofentrained air on concrete. Generally, therefore. for these large maximum azes of aggregate. aircontents recommended for extreme exposure should be considered even though there maybe little or no exposure to moisture and freezing.

ttThese values are based on the criteria that 9 percent air is needed in the mortar phaseof the concrete. If the mortar volume will be substantially different from that determmed inthis recommended practice. It may be desirable to calculate the needed air content by talcmg 9percent of the actual mortar olume.



Concrete 65

Table 4-3a: Relationships Between Water-Cement Ratio and

Compressive Strength of Concrete

Compressive strengthat 28 days. psi*

6000

50004000

30002000

Water-cement ratio, by weight

Non-air-entrained Air-entrainedconcrete concrete

0.41 -

0.48 0.400.57 0.48

0.68 0.590.82 0.74

*Values are estimated average strengths for concrete contain-ing not more than the percentage of air shown in Table 5.33.For a constant water-cement ratio, the strength of concreteis reduced as the air content is increased.

Strength is based on 6 x 12 in. cylinders moist-cured 28 daysat 73.4 f 3 F (23 ? 1.7 C) in accordance with Section 9(b) ofASTM C 31 for Making and Curing Concrete Compressionand Flexure Test Specimens in the Field.

Relationship assumes maximum size of aggregate about ?i to1 in.: for a given source, strength produced for a given water-cement ratio will increase as maximum size of aggregate

decreases; see Sections 3.4 and 5.3.2.

Table 4-3b: Maximum Permissible Water-Cement Ratios for

Concrete in Severe Exposures*

Structure wet continu-

Type of structureously or frequently

and exposed tofreezing and thawing+

Thin sections (railings.curbs, sills. ledges,ornamental work) andsections with less than

1 in. cover over steelAll other structures

0.45

0.50

structureexposed tosea water

or sulfates

0.40:

0.45:

*Based on report of AC1 Committee 201. “Durability of Con-crete in Service,” previously cited.

tconcrete should also be air-entrained.:If sulfate resisting cement (Type II or Type V of ASTM

C 150) is used, permissible water-cement ratio may be increasedby 0.05.



Concrete 67

The results of all these tests give the designer a measure of the expected

strength of the designed concrete in the built structure.

PLACING AND CURING OF CONCRETE

Placing

The techniques necessary for placing concrete depend upon the type of

member to be cast, namely whether it is a column, a beam, a wall, a slab, a foun-

dation, a mass concrete dam, or an extension of previously placed and hardened

concrete. For beams, columns and walls, the forms should be well oiled after

cleaning them, and the reinforcement should be compacted and thoroughly

moistened to about 6” depth to avoid absorption of the moisture present in the

wet concrete. Concrete should always be placed in horizontal layers which are

compacted by means of high-frequency power-driven vibrators of either the im-

mersion or external type as the case may need. It must be kept in mind, how-

ever, that over-vibration can be harmful since it could cause segregation of the

aggregate and bleeding of the concrete.

Curing

Hydration of the cement takes place in the presence of moisture at tem-

peratures above 5O’F. It is necessary to maintain such a condition in order thatthe

chemical hydration reaction may take place. If drying is too rapid, surface crack-

ing takes place. This would result in reduction of concrete strength due to crack-

ing as well as the failure to attain full chemical hydration.

To facilitate good curing conditions, any of the following methods can be

used :

(a) Sprinkling with water continuously

(b) Ponding with water

(c) Covering the concrete with wet burlap, plastic film or waterproof

curing paper

(d) Using liquid membrance forming curing compounds to retain the

original moisture in the wet concrete

(e) Steam curing in cases where the concrete member is manufactured

under factory conditions such as in cases of precast beams, pipes,and prestressed girders and poles. Steam curing temperatures are

about 15O’F. Curing time is usually one day as compared to five

to seven days necessary for the other methods.

PROPERTIES OF HARDENED CONCRETE

The mechanical properties of hardened concrete can be classified as: (1)

short term or instantaneous properties and (2) long term properties. The short

term properties can be enumerated as (a) strength in compression, tension and

shear and (b) stiffness measured by modulus of elasticity. The long term prop-




erties can be classified in terms of creep and shrinkage. The following sections

present some details of the aforementioned properties.

Compressive Strength

Depending on the type of mix, the properties of aggregate, and the time and

quality of the curing, compressive strengths of concrete up to 15,000 psi or

more can be obtained. Commercial production of concrete with ordinary aggre-

gate is usually in the 3,000 psi to 10,000 psi range with the most common con-

crete strengths in the range of 3,000 psi to 6,000 psi.

The compressive strength, fk, is based on standard 6 in. by 12 in. cylinders

cured under standard laboratory conditions and tested at a specified rate of load-

ing at 28 days of age. The standard specifications used in the United States areusually taken from ASTM C-39. It should be mentioned that the strength of con-

crete in the actual structure may not be the same as that of the cylinder because

of the difference in compaction and curing conditions.

The ACI code specifies for a strength test the average of two cylinders from

the same sample tested at the same age which is usually 28 days. As for the fre-

quency of testing, the code specifies that the strength level of an individual class

of concrete can be considered as satisfactory if (a) the average of all sets of three

consecutive strength tests equal or exceed the required f:, and (b) no individual

strength test (average of two cylinders) falls below the required f: by more than

500 psi.

The average concrete strength for which a concrete mix must be designed

should exceed f: by an amount which depends on the uniformity of plant pro-

duction and its prior documented record of test results.

Tensile Strength

The tensile strength of concrete is relatively low. A good approximation for

the tensile strength f,t is 0.10 fk < f,t <0.20 f:. It is more difficult to measure

tensile strength than compressive strength because of the gripping problems with

testing machines. A number of methods are available for tension testing, with

the most commonly used method being the cylinder splitting test.

For members subjected to bending, the value of the modulus of rupture fr

rather than tensile splitting strength fi is used in design. The modulus of rupture

is measured by testing to failure, plain concrete beams 6 in. square in cross-sec-

tion having a span of 18 in. and loaded at two points, each 16 in. equidistant

from the end supports of the beam (ASTM C-78).The ACI specifies a value of 7.5 f: for the modulus of rupture of normal

weight concrete.

In most cases, lightweight concrete has a lower tensile strength than normal

weight concrete. The following are the code stipulations for lightweight con-

crete:

(a) If the splitting tensile strength f,t is specified fr = 1.09 f,t < 7.5 fk

(b) If f,t is not specified, a factor of 0.75 is used for all lightweight

concrete and 0.85 for ‘sand-light weight’ concrete. Linear interpo-

lation may be used for mixtures of natural sand and lightweight

fine aggregate.




Shrinkage

Two types of shrinkage occur in concrete: plastic shrinkage and drying

shrinkage. Plastic shrinkage takes place during the first few hours after placing

the fresh concrete in the forms. Exposed surfaces are more easily affected by

exposure to the dry air because of their large contact surface. Moisture in such

cases evaporates faster from the concrete surface than it is replaced by the

bleed water from the lower layers of the concrete elements. Drying shrinkages

develop after the concrete has already attained its final set and a good portion of

the hydration chemical process in the cement gel is accomplished.

Shrinkage is not a completely reversible process. If a concrete unit is satu-

rated with water after having fully shrunk, it will not expand to its original vol-

ume. The rate decreases with time since older concretes are more resistant tostress and consequently undergo less shrinkage, such that the shrinkage strain

becomes almost asymptotic with time.

Several factors affect the magnitude of drying shrinkage:

(a) Aggregate: The aggregate acts to restrain the shrinkage of the ce-

ment paste, hence, concretes with high aggregate content are less

vulnerable to shrinkage. In addition, the degree of restraint of a

given concrete is determined by the properties of aggregates; those

with high modulus of elasticity or with rough surfaces are more re-sistant to the shrinkage process.

(b) Water/cement ratio: The higher the water/cement ratio, the higher

are the shrinkage effects.

(c) Size of the concrete element: Both the rate and total magnitude of

shrinkage decrease with an increase in the volume of the concrete

element. However, the duration of shrinkage is longer for larger

members since more time is needed for the drying process to reach

the internal regions. It is possible that one year is needed for drying

to commence at a depth of ten inches from the exposed surface,

and ten years to commence at twenty-four inches below the ex-

ternal surface.

(d) Type of cement: Rapid-hardening cement shrinks somewhat more

than other types while shrinkage compensating cements minimize

or eliminate shrinkage cracking if used with restraining reinforce-

ment.

(e) Admixtures: This effect varies depending on the type of admix-

ture. An accelerator such as calcium chloride used to accelerate the

hardening and setting of the concrete increases the shrinkage.

Pozzolans can also increase the drying shrinkage, while air-entrain-

ing agents have little effect.

(f) Amount of reinforcement: Reinforced concrete shrinks less than

plain concrete; the relative difference is a function of the reinforce-

ment percentage.



Concrete 77

Creep

Creep or lateral material flow is the increase in strain with time due to a sus-

tained load. Initial deformation due to load is considered elastic strain while the

additional strain due to the same sustained load is the creep stain.

Creep cannot be observed directly and can only be determined by deducting

elastic strain and shrinkage strain from the total deformation. Although shrink-

age and creep are not independent phenomena, it can be assumed that superposi-

tion of strains is valid, hence:

Total strain (et) = elastic strain (ee) + creep (ee) + shrinkage (fsh)

The composition of a concrete specimen can be essentially defined by the

water/cement ratio, aggregate and cement types, and aggregate and cement con-

tents. Therefore, like shrinkage, an increase in the water/cement ratio and in the

cement content increase creep. Also as in shrinkage, the aggregate induces a re-

straining effect such that an increase in aggregate content reduces creep.

REINFORCEMENT

Concrete is strong in compression but weak in tension. Therefore, reinforce-ment is needed to resist the tensile stresses resulting from the induced loads. Ad-

ditional reinforcement is occasionally used to reinforce the compression zone of

concrete beam sections. Such steel is necessary for heavy loads in order to re-

duce long term deflections.

Steel reinforcement for concrete consists of bars, wires, and welded wire

fabric, all of which are manufactured in accordance with ASTM standards. The

most important properties of reinforcing steel are:

(a) Young’s modulus, E,

(b) Yield strength, fv

(c) Ultimate strength, f,

(d) Size or diameter of the bar or wire

Steel reinforcement is normally designated as Grade 40, 60 and 80 steels.

They have corresponding yield strengths of 40,000,60,000 and 80,000 psi (276,

345 and 517/Nmm2, respectively) and mostly have a well-defined yield point.For steels which lack a welldefined yield point, the yield strength value is taken

as the strength corresponding to a unit strain of 0.005 for Grades 40 and 60 steels

and 0.0035 for Grade 80 steel. The ultimate tensile strengths corresponding to

the 40,60 and 80 grade steels are 70,000,90,000 and 100,000 psi.

The percent elongation at fracture varies with the grade, bar diameter and

manufacturing source, ranging from 4.5 to 12 percent over an 8 in. gauge length.

For most steels, the behavior is assumed to be elasto-plastic and the Young’s

modulus is taken as 29 x IO6 psi.

Welded wire fabric is increasingly used in slabs and walls because of the ease

of placing the fabric sheets, control of reinforcement spacing and better bond.




The fabric reinforcement is made of smooth or deformed wires which run in per-

pendicular directions and welded together at intersections.

Additionally, fiber reinforcement made of fine elements and of various

shapes are used to produce fiber-reinforced concrete. The fiber material can besteel, fiberglass, or polypropylene in various forms. The fibers are mixed with

the aggregate in the concrete. When the concrete hardens, they tend to increase

the ductility of the reinforced concrete elements and considerably reduce plastic

shrinkage cracking as well as cracking in general. The fiber elements range in di-

ameter from 5 to 500 thousandths of a millimeter and 12 to 25 millimeters in

length.

Table 4-6 gives the standard reinforcement grades and strengths of steel and

wire fabric. Table 4-7 gives the geometric properties of standard steel bars.

Table 4-6: Reinforcement Grades and Strengths

1982 Standard Type

Billet steel

A6 15

Axle-steel

A6 17Low alloy steel

A7 06

Deformed wire

Smooth wire

Grade 40 40,000 70,000

Grade 60 60,000 90,000

Grade 40 40,000 70,000

Grade 60 60,000 90,000Grade 60 60,000 80,000

Reinforced 75,000 85,000

fabric 70,000 80,000

Reinforced 70,000 80,000

fabric 65,000 56,000 75,000 70,000

Minimum Yield Point or Ultimate

Yield Strength (f,), Strength (f, 1,

psi psi

Table 4-7: Weight, Area and Perimeter of Individual Bars

Bar Weight

Designation, per Foot,

Number pound

0.376

0.668

1.043

1.502

2.044

2.6703.400

4.303

5.313

7.65

13.60

89

10

11

14

18

SUMMARY

. . . . . . . . Nominal Dimensions

Cross-Sectional

Diameter (db), Area (Ab),

inch square inch

0.375 0.1 1

0.500 0.20

0.625 0.31

0.750 0.44

0.875 0.60

1.000 0.791.128 1 .oo

1,270 1 .27

1.410 1 .56

1.693 2.25

2.257 4.00

. . . . . .

Perimeter,

inch

1.178

1.571

1.963

2.356

2.749

3.1423.544

3.990

4.430

5.32

7.09

In summary, quality concrete can be produced if adequate quality control

and quality assurance are exercised in all stages of its production and in the se-



Concrete 73

lection of all its constituent materials. As the concrete is placed in the forms, the

curing process has to be fully attained and the sequence of stripping the form-

work (and reshoring if necessary) has to be well planned and correctly executed.

Control test to determine the compressive and tensile splitting strength have tobe in full accordance with ASTM standards and full loading of the finished sys-

tem realized after the concrete has achieved its 28 days strength as a minimum.

Transient loads during the construction process have to be strictly controlled as

they can reach levels higher than the actual design loads when the shored con-

crete can least sustain them. The recommendations given in this section, if fol-

lowed, can result in quality concrete consistent with the environment it is ex-

pected to service.

Acknowledgement

Significant portions of this chapter are adaptations from Reinforced

Concrete: A fundamental Approach, by Edward G. Nawy, 1985,720

p,, Prentice-Hall, Inc., with their permission.

REFERENCES

1. American Society for Testing and Materials, Annual Book of ASTM Standards-Part14, Concrete and Mineral Aggregates, ASTM, Philadelphia, PA, 834 pp (1983).

2. ACI Committee 221, Selection and Use of Aggregates for Concrete,Joornal, American

Concrete/nsriture,Proceedings,Vol.5B,N0.5,pp 113-142 (1961).

3. American Concrete Institute,AC/ Manual of Concrere Pracdce, Part 5 (1985).

4. ACI Committee 212, Admixtures for Concrete, Manual of Concrete Practice, Detroit,

Ml,ACI 212.1 R-B1,29pp (1983).

5. Nawy, E.G., Ukadike, M.M., and Sauer, J.A., High Strength Field Modified Concretes,

Journal of the Structural Division, ASCE, Vol. 103, No. ST12,pp 2307-2322 (Dec.

1977).

6. American Concrete Institute, Super-plasticizers in Concrete, ACI Special Publication,

SPS2, Detroit, Ml (1979).

7. Mindness,S. and Young, J.F.,Concrete, Prentice-Hall Inc. (1981).

8. Nawv, E.G., and Balaguru, P.N., High Strength Concrete, Chapter 5, Handbook of

Structural Concrete, Pitmen Books, Ltd., and McGraw-Hill Book Co (1983).

9. Pennwalt Corp., Pennwalt Standards For Concrete Vessels Designed ro Receive Brick

or Membrane andBrick Lining, Technical Data BMS301 (March 1974).

10. ACI Committee 211, Standard Practice for Selecting Proportions for Normal, Heavy-

weight and Mass Concrete (AC1 211 .l al), American Concrete Institute Standard,

pp l-320 (1981).

Il. ACI Committee 211, Standard Practice for Selecting Proportions for Structural Light-

weight Concrete (AC1 211.281), American Concrete Institute Standard, pp l-18

(1981).

12. Nawy, E.G., Strength, Serviceability and Ductility-Chapter 12, Handbook of Sfructu-

ral Concrete, McGraw Hill Book Co., New York (1983).

13. Nawy, E.G., Reinforced Concrete-A fundamentalApproach, Prentice-Hall, Inc., Engle-

wood Cliffs, NJ, 720 p (1985).

14. Nawy, E.G., Simplified Reinforced Concrete, Prentice-Hall, Inc., Englewood Cliffs, NJ,

324 p (1986).



5

Timber as a Structural Material

to Support Chemical Resistant Masonry


C. C. R.M., Incorporated


The following discussion deals with the use of wood as a supporting struc-

ture for chemically-resistant masonry-a type of construction requiring total liq-

uid tightness and rigid support. Properly designed, unlined wooden tanks have

been and continue to be used most satisfactorily in many services, and nothing

that follows is intended to reflect on such construction. [See, for instance, Oliver

W. Siebert, Materials Performance, Vol. 22, No. 10, p, 9 (Oct. 1983).]

Since the beginning of recorded history, wood has been used as a structural

material for frame, walls, floors and roofs of dwellings, and for the shops and

factories where all manner of end products were produced-including the tanning

of leather, cooking, preparing and packaging of all manner of food products,

chemical treatment of textile fibers and the dyeing of cloth, preparation of med-

icines, and many other crafts and industries involving chemicals.

Wood has also been used for hundreds of years to contain aqueous solutions

of chemicals and food stuffs, as material of construction for anything from staved

barrels to storage tanks and process equipment. During the latter half of the19th century, and for the first two decades of the 20th, rectangular wooden

tanks were used in steel mills to contain the acid pickling solutions into which

steel was dipped to remove scale. The life of wood in this service was reasonably

long, particularly in dilute sulfuric acid which swells wood and makes the struc-

ture tighter, not as good in solutions of halogen acids which tend rather less to

swell, perhaps even to shrink it and cause the tank to leak. But no matter how

well wooden tanks are constructed, in severe service, especially if not carefully

maintained, sooner or later they will leak or weep-long before the economical

life of the wood has passed and, therefore, floors under such tanks require pro-

74



Timber as a Structural Material 75

tection. Strong acids and some other chemicals-particularly alkalis-can ser-

iously damage wood, and without some protection, wooden floors, when such

spillage occurs, will require expensive maintenance.

When, in the 193Os, a system of “acid brick work” over a liquid-tight mem-

brane was first receiving notice as a method of protection of concrete floors and

a protective lining for rubber-lined steel tanks, what more logical than that at-

tempts be made to use “acid brick” in the same manner to protect timber struc-

tures. Brick and sulfur mortar linings over an asphalt membrane were installed

in wooden pickling tanks in steel mills in the latter part of the 3rd decade of this

century, and a number of floors were surfaced with brick and sulfur. Brick and

phenolic resin mortars were applied over timber floors in electroplating shops, a

few breweries, and in a few chemical plants.

Where the floors were sound and well enough braced to prevent the brick-work from flexing under load, many of these floors functioned satisfactorily,

and several of this design are still in service. In the mid 195Os, similar floors in

food and candy plants were constructed, with a surfacing of %” epoxy topping.

Where these floors were sufficiently rigid to prevent the topping from flexing

and cracking, and where adequate provision was made for expansion, many of

these have also survived and given economical service. The record for brick-

lined wooden tanks has not been equally good.

The designer must bear in mind that wood is not dimensionally stable. When

wet (with water and many solutions of chemicals dissolved in water) it swells.

When dry, it shrinks. In a pickling tank, the asphalt membrane would be applied

as a membrane to the interior of the wooden tank to prevent leaking before put-

ting the brick into it. But this barrier membrane keeps water out of the wood, so

the wood dries out and shrinks. When it shrinks, it tears the asphalt membrane,

which now leaks at the tear. Not only is the tank now leaking on the floor, but

the area around the leak is now wet, and the wood in this area swells-usually

not enough to stop the leak, but quite enough to distort the timber, and to cre-

ate more leaks. No tank of this design could be kept tight, and this type of lining

(hot asphalt membrane and “acid brick”) in rectangular tanks was abandoned.

But when the wood is only to be the structural support for chemically-re-

sistant masonry, and the solution to be contained is too strong for unprotected

wood, or is non-aqueous, then the wood must be protected with an impervious

membrane because of the porosity of the chemically-resistant masonry. The

wood will be dry continuously, except for accidental wetting by spills or mem-

brane leakage. Even when originally built with seasoned material, the wood will

dry out further after erection. Shrinkage will take place and cracks will open be-tween the planks in the bottom and between the staves in the walls of cylindri-

cal tanks. (In rectangular, of course, planks are used throughout the construc-

tion.) If a membrane is to be placed directly on the surface of the wood base, it

must have the strength and elasticity to bridge these cracks without rupturing.

Techniques to deal with the cracks, instability and other problems caused

by this dry condition have been developed in recent years by wood tank manu-

facturers. One procedure is the application of marine grade plywood sheets, with

adequate nailing, to the entire inside surface of the wood tank. This may not be

required when properly designed prefabricated PVC bag liners are to be installed,

and such design may be used for other types of membranes.




During filling and emptying or ambient temperature changes, tanks may ex-

perience minor movements and changes of shape in the shell walls, particularly if

the tank is permitted to dry out. The movement may be particularly pronounced

at the juncture of the vertical walls and the bottom, expecially if the bottom is

concrete.

In cylindrical tanks-wood stave design-brick and membrane linings are still

occasionally used. Where they are employed successfully, the hot asphalt-and in

fact all other completely adhered membranes-have been eliminated, replaced by

rubber or other elastomeric bag membranes. The bag is fitted to the interior of

the tank and suspended from the top of the tank as a loose liner, carefully spread

out in complete contact over all the interior face. The flexible PVC bag liners

currently in use have a 300% elongation and so can adjust to structural movement

without tearing. They may be anchored, where desired, by cutting short grooved

slots in the bag, and tacking large head, long shaft, pins or tacks through the slot

into the wood, but not driving the pins home into the wood, thus leaving the bag

free to move the length of the slot in relation to the timber. To prevent the con-

tained liquid from leaking through the slot around the pin, a large rubber patch

is placed over the pin head, with the vulcanized seal beyond the limit of the slot,

so that the movement of the bag around the pin is not obstructed.

PLACE

SUPPO

\ BOTTOM

ADDITIONALCHIME JOIST

STAVETAVE CROSS SECTION OF

HOOPS

LINER, PLYWOOD OR FELT

'RT DIRECTLY

UNDER COLUMNFOUNDATION, SLAB, WALLS OR BEAMS

OF BRICK

Figure 5-1: Typical connection of wood stave wall to wood bottom of round wood con-

tainer ready for membrane and chemically resistant masonry installation.




The brick lining (if one is required to provide thermal insulation or mechani-

cal protection to the bag membrane) is then laid within the bag. In cylindrical

contoured vessels, properly designed, this type of lining has been moderately

successful. It is not often recommended for rectangular shapes since the move-

ment of the wooden walls is somewhat more difficult to control. It is important

that, in such cases, the walls be adequately braced externally to prevent move-

ment. The bands on cylindrical tanks and tie rods of rectangular vessels should

be adjusted to the proper tension prior to the installation of any liner, and

bands on the former be secured to shell wall to maintain their positions.

In tanks where brick wall linings may not be desired, brick floors are some-

times installed in the bottoms to protect the bottoms (and perhaps the bag liner)

from steam jets, mechanical abuse and the like. (Canadian Chemical Processing

for September 3, 1980, Page 21, provides a case history of three rectangularcreosoted Douglas Fir tanks, with 316 stainless tie rods, installed in 1958, and

apparently still used by the purchaser at the date of publication for acid/sul-

furic cleaning of copper and brass bars up to 50 feet in length. The units are

lead-lined, with “acid brick” laid over the lead in the tank bottoms.)

If it is desired to apply either monolithic toppings or acid brickwork to tim-

ber floors, it is best, first, to verify that any anticipated loading will not cause

visual deflection of the floor surface. If any movement at all is visible, additional

supports must be supplied, or the floor and supports rebuilt. Next, sand the

floor surface until a smooth, uniform surface has been attained, then nail over it

sheets of marine plywood, at least %” thick, making sure that all edges are care-

fully matched, with absolutely no open cracks between them anywhere, and that

the nails are all countersunk and covered smoothly with plastic wood to a uni-

form smooth surface.

If “acid brick” is to be used, the glass-reinforced asphalt membrane is now

applied in the usual manner, and the brick laid over it, expansion joints carefully

laid out and placed on the usual centers. If a monolithic, whether a ‘/4” topping

or a polymer concrete, is to be applied, polyethylene separator bars should be

set above the cracks around the periphery of every sheet, the monolithic placed,

the bars removed, and the cavities thus formed filled with expansion joint seal-

ant. If this is not done, you can be certain that, sooner or later, the monolithic

will develop cracks at these points, telegraphing through the surface the pattern

of the plywood sheets below it.

When, in the 1930s and early 194Os, linings of the above types were used

over timber substrates, wood was one of the least expensive, if not the least ex-

pensive, structural material. Long heavy beams and planks were readily available,and could be employed in the construction of large diameters, and tanks with

walls as high as 100 feet. Though very long individual timber is rarely available

today, long heavy beams and planks can still be assembled by “finger jointing”

of shorter units. Wood stave tanks are seen in many industries, and companies

that market such items may well opt for the design and construction of units

with concrete bottoms and wood stave walls, where the diameters are so great

that it is not economical to construct a bottom entirely out of timber. Barring

bad workmanship, tanks of this type have demonstrated long life. Wood stave

pipe is still being installed for chemical wastes and may be used for large diame-

ter ducting as well.




PICKLING TANKS

PLUNCER TYPE..s w an.,

N

c

HI-

0

C

0

a

C

C

C

0

Cl.i

Figure 5-2: Courtesy of Brooks Lumber Co., Bellingham, WA (from The Doug/as Fir Use

Book).




Lug for Tank and Pipe Hoops.

’ Chimr length.

width.

depth

Figure 53: Courtesy of Caldwell Tank Co., Louisville, KY (Successor toThe Hauser-StanderTank Co.).




SELECTION OF WOOD STRUCTURE

The final choice of a support system will, of course, be based on the well

known principles of economic selection. Established manufacturers of wood

tanks, when supplied with dimensional requirements, weights and other forces to

be imposed by the chemically-resistant masonry, operating conditions and any

other pertinent data, should be able to supply cost estimates for consideration.

The design of wood supports for chemically-resistant masonry will be very

similar to that for cylindrical or rectangular wood tanks presently used for con-

taining a variety of aqueous solutions. There will be some differences to accom-

modate the additional loads and requirements imposed by the chemically-resis-

tant masonry and the membrane.

There may be certain situations and site conditions in which wooden con-

tainments and supports for chemically-resistant masonry will offer some advan-

tages and economies over supports of other materials.

The components of wooden structures are relatively small and can be car-

ried by manpower into areas inaccessible to the larger and heavier components

of other materials. Erection can be completed using only manpower and hand

tools.

In confined spaces where spills, overflows or some leakage may occasionally

occur, or where the ambient conditions are mildly corrosive, wood will not beseriously or rapidly affected by mild acids and some other liquids which would

damage other structural materials extensively.

DESIGN NOTES

The design of wood tanks is based more on experience and craftsmanship

than on mathematical calculation and textbook theory. The selection of the

wood and metal components for the structure should be made by experienced

wood tank manufacturers.

When selecting the wood, there are choices to be made to achieve a suitable

and economical tank for the specified service. Some species are better than others

for specific conditions. The grade, or quality, of the lumber chosen will affect

the cost; a lower grade can be considered if the tank is to be lined with plywood

and a membrane. The thickness of the lumber varies with the tank size, but the

judgement of the manufacturer, based on previous experience, may be influenced

by such operating conditions as excessive agitation, super-imposed loads frommachinery, etc.

The size of the metal rods or hoops in unlined wood tanks is determined

partly by calculations related to the hydraulic load imposed by the contents,

but may be modified by dictates of past experience. As noted previously, the

chemically-resistant masonry lining on the walls and the bottom may impose ad-

ditional loads on the walls requiring more tie rods or hoops. The tank designer

should be aware of the possibility of loads on the structure caused by the irre-

versible growth characteristics and the thermal expansion of the chemically-re-

sistant masonry. The accidental soaking and consequent swelling of the dry

wood shell may also be a factor to allow for.



Timber as a Structural Material 8 1

hard clay, concrete. etc.

‘Concr et e Pad

TYPE6 b

Pier or Pileand

Beam construction.

Concrete Piers

Chime Joists

4 TYPEC

W&l

Construction

Figure54: Typical foundation arrangements for wood stave tanks with wood bottoms.

Courtesy of the Canadian Wood Pipe and Tank.




A

STREE

Outlets are furnished in Duriron.

bfonel Metal and Bronze. When In-

stalled in the bottom of the tank

the flange Is countersunk. Ground

plug 1s furnlshed to fit tapered seat.Lag sciew type outlets are furn-

ished In bronze wltb lead plug cast

on bronze “I” bolt.

Piping Diagram for Pickling Tank Outlets.

Figure 5-5: Tank outlets and steam jets. Courtesy of the Caldwell Tank Company.




FILL WITH ACID

RESISTANT MORTAR

COPING TIMBER

ACID RESISTANT

BRICK

LINING TIMBE

IMPERVIOUS MEMBRANE

STIFFENER

ACID RESISTANT

MORTAR

CHAMFER BRICK

Figure 56: Detail of a wood bumper inside a brick lining in a pickling tank. Note that with

this design, all hardware is kept out of the tank to prevent any chemical attack. Courtesy of

the Pennwalt Corp.

POSSIBLE SIZES AND SHAPES

There is an economic and practical limit for the diameter to which a wooden

bottom can be built for a round tank. Though wooden bottoms have been built

in the range of 60 to 70 feet in diameter, it is probable that, today, the alterna-

tive of a flat concrete bottom will have to be considered for economic reasons

when the diameter exceeds 30 to 40 feet.In tanks with concrete bottoms, the wood staves stand vertically on a hori-

zontal ledge around the circumference of the bottom and are sealed against an

inner vertical concrete lip. Many tanks over 100 feet in diameter have been built

in this manner and have given adequate service. However, when the concrete and

the wood staves are supports for the chemically-resistant masonry, the sealing of

the membrane at the junction of the wood and the concrete can become compli-

cated. The wood stave walls will always expand and contract relative to the con-

crete base. The amount of movement is related to the tank diameter and may be

caused by changes in the temperature of the hoops, liquid level in the tank, or

other operating conditions such as vigorous stirring or agitation.




Wood tanks have been built in most common shapes: vertical and horizontal

cylinders, rectangular and square boxes, even vertical stave walls in an elliptical

shape.

Wood has also been extensively used for round and rectangular pipes, ductsand stacks for pulp mill and smelter exhaust fumes and for liquid effluent. Semi-

circular flumes, some with abrasion-resistant linings, have been built for the

transport of mineral slurries.

The coefficient of linear thermal expansion of wood is so small that it may

be ignored in long structures. This property can be most attractive in the con-

struction of long ducts, eliminating the necessity for complicated and expensive

expansion joints. Used alone, many wood constructions have served satisfactor-

ily for very long periods in certain chemical services.

Basic design criteria developed for these wooden structures could be modi-

fied as required to make them suitable for the support of chemically-resistant

masonry.

Finally, it must be stressed that designers, suppliers, and installers of each of

the three main elements: the chemically-resistant masonry, the membrane and

the wooden support must cooperate, discussing and agreeing on the total final

design so that the diverse properties of the materials are combined for maxi-

mum economy, performance and safety. Failure to obtain such agreement can

result in the failure of any structure created by the marriage of such diverseelements.

Acknowledgements

The writer wishes to thank Mr. Fred Cressman, of Waterloo,Ontario,for

his assistance and suggestions, and for authorizing the use of four draw-

ings, numbers 2 through 5, and copies of items 1-3 in the Bibliography.

The current technical bulletins from National Wood Tank Institute

were supplied by the Hall-Woolford Wood Tank Co., Inc., of Phila-delphia, Pennsylvania.

BIBLIOGRAPHY

1. The Douglas Fir Use Book, sections of the 1961 edition reprinted in 1962 by Brooks

Lumber Company, Bellingham, Washington.

2. lnsfrucrions for Erecting Open Top Tanks, Canbar Products, Ltd., Waterloo, Ontario.

3. Wooden Tanks for Every Purpose, The Hauser-Stander Tank Co.4. Technical Bulletin S-82, Specifications for Wood Tanks and Pipe.

5. Technical Bulletin 758.

Both the Technical Bulletins are published by the National Wood Tank Institute, 848 East-

man Street, Chicago, Illinois. They contain useful chemical resistance data and tables for

wood.



6

Some Notes on Plastics as the

Supporting Structure


C.C. R.M., Incorporated


Although not widely recognized by either manufacturers or users, it is pos-

sible to “upgrade” an all-plastics vessel to accept thermal conditions, and per-

haps even some chemical exposures, beyond the limits of the bare plastic by the

use of a lining of chemically-resistant masonry.

One such design, now perhaps seven years old, involves all F RP equipment de-

signed to reclaim spent HCI pickling solution in steel mills. The original designer

perhaps thought that the very hot concentrated acid, as it entered the 6 foot di-

ameter receiver, might be beyond the acceptable limits of the FRP, and he there-

fore inserted a 2% inch brick liner in the unit to accept the impingement of the

entering HCI. Several units have been built to this design and, to date, no com-

plaints have reached this writer’s ears. However, if the equipment had been

larger, the story might well have been different. The high coefficient of thermal

expansion of the FRP in larger units, and in cases where a considerable differ-

ence between operating and ambient temperatures will occur, will inevitably re-

sult in the expansion of the FRP away from the brick lining, resulting in loss ofsupport for the walls and their eventual collapse. A simple brick bottom to with-

stand abrasion and impingement has a better chance of survival.

If the FRP designer plans on a marriage of FRP and masonry, he would do

well to carefully study the following documents:

Custom Contact Molded Reinforced Polyester Chemical Resistant Proc-

ess Equipment (PS15-69), a Department of Commerce Standard 15

years old, but still containing much useful information on materials

and the manufacture of tanks, ducts and pipes.

85




Filament Wound Glass Fiber Reinforced Thermoset Resin Chemical Re-

sistant Tanks (ASTM D-329981)

Contact Molded Glass Fiber Reinforced Thermoset Resin Chemical Re-

sistant Tanks (ASTM D-4097%2)

He must carefully compute the dead weight of all the materials that may be

used in the masonry lining and add this to all other weights that may be con-

tained in the vessel (or other structure) in service. Unless the lining material se-

lected has a coefficient of thermal expansion many times that of “acid brick,”

he will not need to allow for expansion stresses in addition. He must, however,

remember that FRP is much more flexible than “acid brick.” Therefore, if a

masonry lining is to survive within an FRP structure, the structure must be de-

signed to be rigid and inflexible. This will require adequate, strong, rigid sup-

ports and external bracing (and/or banding). If a flat bottom “oil cans” a brick

lining resting on it will break up. If a wall flexes, a brick lining built against it

will crack and probably will fall in. The design should therefore include suffi-

cient reinforcing to prevent any visible (to the unaided eye) deflection.

Because of the vast difference between plastics and masonry in thermal

expansion, masonry components with good to moderate heat transmission qual-

ities have use in few FRP structures-and then primarily in those that will have

operating temperatures in the lower thermal ranges when the vessel exteriors will

be close to ambient. On the other hand, materials with extremely high insulating

values may have a very real future in such design. Here we are thinking of a com-

bination of FRP and closed cell borosilicate glass block. (See the section of this

book on closed cell borosilicate glass block, Chapter 17.)

In contact molding, the block, say 2” thick, can be attached to the inner

mold, and joints between the blocks made with an elastomeric adhesive, and

then the FRP laid up upon, and bonded to, the back of the block. Now when

the molds are stripped, the liquid contact face will be the borosilicate block,which has a top surface operating temperature of 96O’F. In these higher thermal

ranges, the coefficient of thermal conductivity of the block ranges from 0.60 to

0.75. Thus, it is possible to operate a vessel so lined at, say, 600°F, while keeping

the inner surface of the FRP unit at about 32O’F. For greater thermal drop

(cooler FRP), a thicker layer of block would be used.

FRP ducting, pipe and chimney liners have always been limited to use at

temperatures below the acceptable top thermal range of the resins from which

they are made. If cylindrical shaped materials are manufactured by filament

winding on a mandril, the designer may consider first building a layer of closed

cell borosilicate glass block on the mandril, and then winding on it the resin-glass

fabric body. The joints between the block would be made of an elastomeric sub-

stance to permit some movement of the individual blocks with the FRP to which

they are adhered without breaking joints or block. The insulation value of the

blocks has been shown by experience to be sufficient to keep the elastomer alive

at the bottom of the joint even when it is heavily carbonized on the surface.



Section III

Membranes

87



Sheet Linings


C.C. R&l., Incorporated


HISTORY

For three-quarters of a century, and probably longer, rubber manufacturers

have known how to protect metal equipment from corrosion by the application

of sheet natural rubber to the surface of the metal. It was quickly discovered

that, if uncured sheet was bonded tightly to the metal surface and cured in place,the adhesion of the rubber was many times greater than that of precured rub-

ber that relied for bond on the curing of the adhesive alone. Inasmuch as natu-

ral rubber is little affected by sulfuric acid in concentrations below the oxidizing

range, this type of lining was a natural for steel tanks designed for use in steel

finishing mills for the pickling of steel (removal of mill scale), where acid con-

centrations varied from 10% to 15%. and at a temperature of between 12O’and

14O’F.

Hot asphalt applications had been used for many years in concrete tanks, in-

ner lined with brick for similar service, and also, of course, unlined wood tanks

made from timber, and small pickling tanks made by hollowing out cavities in

granite blocks. But the use of hot asphalt as a liner for steel tanks had been un-

satisfactory due to the erratic cold flow of the asphalt which demonstrated se-

lective adhesion to steel and so would tear and open cracks in the membrane

system in the areas of cold flow below the points where it adhered. To overcome

this difficulty, a number of inventive persons experimented with the manufac-

ture of asphalt sheet lining materials, similar in form to the sheets of natural rub-

ber, in which the asphalt was compounded with various admixtures, includingrubber. These asphaltic compound sheets were then warmed sufficiently to make

88



Sheet Linings 89

them flexible and adhered to the interiors of steel tanks as a lining, with all

joints heat-sealed, to provide a liquid-tight membrane lining. This type of sheet

was found to work in many such applications, provided it was protected from

mechanical damage on the exposed surface by a brick lining.In the 193Os, it was generally considered that at temperatures much over

140°F, natural rubber sheets would age at an uneconomical rate, so it was the

usual practice in lining tanks in steel mills to install “acid-brick” as an internal

protection-not only against mechanical damage, but also to provide internal

thermal insulation and to drop the surface temperature of the rubber lining well

below 14O’F so as to increase the life of the linings. By the 1940s. it was gen-

erally considered that natural rubber could be used economically at 160°F sur-

face temperature, and by the 1960s. some manufacturers were recommending

it as giving economical service at surface temperatures up to 18O’F.

In the late 1930s. and early 194Os, a few synthetic elastomers, such as neo-

prene (chloroprene), had been developed which had better resistance to some

corrosives than natural rubber. Then during the second World War, the disrup-

tion of sea lanes created a shortage of natural rubber, resulting in an accelerated

interest in all synthetic rubbers, other elastomers, and in thermoplastic resins for

sheet lining applications. By the 196Os, a myriad of alternatives had been devel-

oped and given field tests so that today, besides the two original sheet linings

mentioned above, a wide variety of materials having different physical, mechan-

ical and chemical properties have become available from a great number of

sources.

In the 195Os, an elastomer made from vinylidene chloride and called Saran

was offered for a number of years as a vessel lining, but the author has not seen

it for a decade and more. This material was cured after installation with am-

monia.

TYPES OF SHEET

The type of sheet most frequently used today is still natural rubber. It may

be compounded with a number of different modifiers or fillers, depending on

the service for which it is intended, varying from soft to hard, and from a uni-

formly calendered sheet to laminates of soft and hard or laminates including fab-

ric-reinforcing.

Many different synthetic elastomers are also compounded and calendered to

form sheet lining materials. Examples are: neoprene, Hypalon, butyl and chlor-

butyl rubber.

Asphalt-based sheets, usually compounded with some rubber, are still avail-

able, and still used in some lining exposures.

With the war years, polyviny/ chloride (PVC) resins came under study, and

plasticized PVC compounds, based on these resins, became available as calen-

dered sheet lining materials-the material of choice for stainless steel pickling and

for chrome plating and other exposure employing mixtures of chemicals including

such strong oxidants as nitric and chromic acid which rapidly attack natural rub-ber. (A higher temperature limit modification now seldom seen is PVDC, for

which the continuous temperature limit is said to be 170°-IgOOF.)




The Germans had researched PVC in depth, and after the war, rigid, unplas-

ticized PVC sheet and pipe became quickly available, first from French and Ger-

man sources, and then in the United States, for the fabrication of vessels and for

many other purposes. The unmodified resin sheet offered a wider range ofchemical resistances than did any other material then available, but the addition

of a plasticizer (necessary if the sheet was to be flexible like rubber sheet) at

once lowered the chemical resistance. However, the usefulness of the unplasti-

cized sheet was limited by its low thermal limit (actually given as 140°F contin-

uous, though one present day manufacturer gives it as 15O”F), its rigidity, high

coefficient of thermal expansion, and its “memory.” It could be warmed to sof-

ten and shape it and make it conform to an irregular surface, then permitted to

cool and harden in that shape. But when it was warmed again to the same tem-

perature or higher, it would slowly return to its original shape, tearing loose

from any surface to which it was bonded.

Further, no really high bond adhesive was found for it, so that the surface

gradually disbonded from the adhesive over a period of time. Efforts to improve

the bond included calendering fabric into the face of the rigid material, but this

was largely abandoned because, in a number of cases, the fabric pulled out of the

sheet so that the sheet still disbonded.

The most successful method to provide an unplasticized PVC face to the

corrosives was found to be a laminate, calendering a plasticized sheet to the un-derside (or back side) of the unplasticized sheet to provide a good surface for

bonding to the substrate, leaving the rigid side exposed to the harsh chemicals.

For many years, this laminate sheet was manufactured in Trenton, NJ, and read-

ily available. Domestic manufacture was discontinued a decade ago, but cur-

rently, the material is available on import from Europe, and is stocked in north-

ern New Jersey.

Polypropylene sheet appeared in the 1950s. first as a plain white sheet,

then, like the early PVC sheet, with a fabric backing laminated to it. No effective

bonding agent was ever found for this material, and this author has not heard of

its use in this manner for a number of years. However, there is available a sheet

lining material having a sheet of polypropylene laminated to a sheet of natural or

synthetic rubber to provide an adhesive accepting surface.

Since the early 1950s. a myriad of sheet materials have appeared, and today

all the following are available from domestic sources. (Yearbook of the Los

Angeles Rubber Group, Inc. and various manufacturers’ literature.)

Natural rubber, (isoprene) (NR), (top temperature variously 140°-150°Fcontinuous, 170”-18O’F intermittent)

Hard natural rubber (top temperature 185’F)

Butyl (isobutylene, isoprene polymer) (IIR) (top temperature 200”-

212’F)

Chlorobutyl

Nordel@ (ethylene propylene) (copolymer and terpolymer) (EPM,

EPDM)



Sheet Linings 91

Nitrile (Buna “N,” butadiene-acrylonitrile copolymer) (top temperature

about 210°F intermittent)

Neoprene (chloroprene polymer) (CR) (top temperature variously

180”-200°F)

Hypalon@ (chlorosulfonated polyethylene) (CSM) (top temperature

variously 200°-220°F)

Viton@ (fluoro elastomer) (FPM) (As of this writing, no tank lining

applicator is offering a Viton sheet lining for a tank as an impervious

membrane lining. Though both calendered sheet and an adhesive to be

used with it are available, they require careful and exact high tempera-

ture vulcanizing under pressure to provide a satisfactory lining under

exacting conditions. Experiments are being conducted on procedures

and methods.)

Chlorinated polyethylene (CPE)

Polyvinyl chloride (plasticized) (PVC) (top temperature 1 40°-1 50°F)

Polypropylene laminate with a backing of rubber (and probably others)

(top continuous temperature variously 200”-230°F)

In addition, available from importers are:

Polyvinyl chloride, rigid/plasticized laminate (top temperature 140°F)

Polypropylene (and system to bond it without laminate backing)

Polyisobutylene rubber (top temperature 180°F), and probably others

LOOSE LINERS

The most successful method of protecting the substrateof a vessel has proven

to be by the use of an impervious sheet lining bonded tightly to that substrate.

But, of course, it is not always possible to obtain a tight bond to the substrate.

Take as an extreme example the lining of a retention pond for chemical wastes

where the substrate may be nothing more solid than compacted soil. Or con-

sider, perhaps, the emergency lining of a badly damaged concrete tank, or a leak-

ing wooden tank. In order to prevent the leakage of contained liquids from such

containers, loose “bag” or “envelope” liners have been used, and so long as thesubstrate remains sufficiently sound to prevent excessive movement and the tear-

ing of the “bag,” and as long as the thermal limits of the bag are not exceeded,

such a procedure has been reasonably successful.

Occasionally, when the chemical exposure or other environmental consider-

ations have dictated the use of a material that cannot be successfully bonded to

the substrate, this same principle has found use even in composite linings em-

ploying “acid brick” or other rigid internal facings to protect the membrane lin-

ing from thermal or mechanical damage. An application of this kind requires the

most careful study and construction if it is to be successful, and should not be

attempted without the advice of experienced persons.




SUBSTRATE REQUIREMENTS

The great majority of bonded sheet linings are applied to rigid, well-sup-

ported metallic substrates, usually carbon steel, though those linings that do notrequire heat curing (vulcanizing) can often also be applied to concrete surfaces.

For the installation to be successful, the following basic requirements must be

satisfied:

(1) The substrate must be, in itself, a liquid-tight, continuous structure,

without any open or “working” seams or joints. (It is not possible

successfully to apply any bonded lining over a void. If there is any

movement-even the pressure of a contained liquid, or thermal ex-

pansion of the structure on either or both sidesof the void, no matter

how small-you can anticipate the eventual rupturing of the lining).

(2) The substrate surface must be very smooth and free of contami-

nants and rough spots. (You cannot expect to obtain sound bond

to a rough or dirty surface.)

(3) The design must be rigid enough to restrain any flexing or bending

that may exceed the ability of the liner to flex or bend with the

structure.

(4) There can be no sharp internal or external angles or corners. Sheet

linings must be rolled or curved to fit all changes of direction and

even the thinnest such linings cannot fit into or over a right angle

corner.

The Rubber Manufacturers Association (see Bibliography) has prepared a

Protective Linings Technical Bulletin which provides specific standards for

welded steel structures to receive such sheet linings. No such standard has been

prepared for concrete, but the engineer who plans to design such a vessel will

find that if the principles enunciated in this steel standard are followed, and the

above four points observed, and if he consults a competent applicator before he

starts to pour the concrete, he should be able to produce a satisfactory vessel.

TESTING THE COMPLETED LINING

In the western hemisphere, it has been customary to test for continuitymost rubber (and similar) sheet linings on carbon steel vessels by using a high

voltage electric spark. The only exceptions have been those sheet (or other) lin-

ings which have conductive fillers, such as carbon. An alternative method some-

times seen employs an electrical conductivity test using an electrolyte solution in

a swab on a copper or other conductive probe completing a low voltage circuit

through an ammeter to another probe grounded to the substrate metal. If the

filler is conductive, obviously neither test method will work, and only a visual in-

spection is possible. Obviously, applications to concrete cannot be so tested.

European practice does not normally include either a spark or conductivity test

and relies solely on visual inspection.



Sheet Linings 93

CURING

Sheet linings fall into four different categories when classified by method

of “curing’‘-a word with many shades of meaning.(1) Precured. This is a sheet lining which undergoes no appreciable change

in application. In this category, we find “precured” rubbers, polyvinyl chloride,

polypropylene, asphaltic sheets and butyl rubber. Here we rely almost totally on

the curing or hardening of the adhesive used to anchor the sheet. Joints be-

tween sheets in some of the applications are made by heat or solvent “welding”

of the laps or lap strips, PVC being such a material. In those where welding of

laps is not possible, success of the lining depends upon the “curing” of the ad-

hesive to a high level of chemical and thermal resistance so as to complement, at

its exposed edges, the resistance of the sheet.

(2) Selfcured. Some elastomeric materials may be compounded and calen-

dered with a chemical curing agent which will, over a period of time, slowly cure

the sheet at ambient temperatures. This type of curing is primarily noted in nat-

ural rubber and neoprene sprayed and troweled coatings, and has not, in recent

years, been, to the writer’s knowledge, employed for total cure of sheet linings.

(3) Cured in Shop. Some sheet linings require high pressure and tempera-

ture to cure, usually under carefully controlled conditions. Such conditions are

best handled in an autoclave, and this type of material, therefore, is only appliedand cured in the shop.

(4) Field Cured. Natural rubber is an example of this kind of material. It

can be cut, fitted, and applied in the field and then cured, either by closing and

sealing the vessel and filling it with steam, or by placing and sealing steam

“boxes” over the surface, section by section, filling them with steam, and so

cure the lining section by section. Repairs can be made in the same manner.

MANUFACTURER

It is not the purpose of this section to advise the reader on the manufac-

ture of sheet lining materials. However, the end user should understand certain

aspects of the process so that he will know how he can and how he cannot ex-

pect such lining materials to perform.

Just as in the manufacture of sheet natural rubber and the asphaltic sheet

linings, the basic material as the sheet lining manufacturer receives it from the

plantation (rubber) or from the refiner or importer (asphalt), the manufacturer

of the synthetic lining materials will receive his synthetic elastomer, thermoplas-

tic or other basic resin from the company that produces it-and will have to

blend it with fillers, stabilizers, plasticizers, and other materials to make a suit-

able compound which will-as a lining-perform its function satisfactorily under

the anticipated conditions, and for an economical length of time. The actual

amount of the basic resinous material in the compound may be as low as 70% of

the total weight.

The compound is then “calendered” between calender rolls, or perhaps ex-truded between dies-perhaps finished by a final rolling-to the thickness of flat

sheet desired, or if a curved section is required, pressed into a mold where it is




held until it has totally conformed and set into the desired shape. If the basic

material lacks strength or the ability to withstand rapid flexing, it may be rein-

forced with layers of a selected fabric (glass, synthetic fabrics, cotton, carbon,

etc.) or a layer of another resinous material.Compounding alters the chemical and thermal resistances of the basic ma-

terials-almost invariably reducing it, so that the finished sheet has less chemical

resistance and often a lower thermal limit than the resin before compounding.

But the principle reasons for selecting these materials in the first place are based

on these same or better chemical resistances and higher thermal limits. There-

fore, in a few cases, some of these materials, in the uncompounded state, are cal-

endered or molded in a composite layer on the exposed side of the sheet or

molded part, so that the compounded side may be used for bond to anchor the

lining to the substrate while the side with better resistance is exposed to the cor-

rosive environment.

DIFFUSION AND ABSORPTION

All protective linings and coatings can, over a varying period of time, be

penetrated by corrosives. Penetration occurs, of course, through voids and holes

in coatings and sheet linings, but it can also take place by diffusion through the

coating or sheet. All materials have the characteristic of absorption, to a greater

or to a lesser degree. Diffusion is the ability of fluids and gases to diffuse or to

pass through them, but is not identical to absorption. There are ASTM tests for

absorption, but at the time of this writing, none has been approved to measure

the diffusion of corrosives through sheet lining materials. Test procedures involv-

ing the use of an “Atlas Cell” are being studied. There is general agreement that

the rate of diffusion through an object is related to its density and its thickness.

Thus, a very dense polymer is penetrated at a slower rate than a less dense one.If, therefore, hydrochloric acid can penetrate regular soft natural rubber sheet

‘/‘I thick at too rapid a rate to be economical, we can compound the rubber with

a very dense filler, making a hard rubber, which in the same thickness will give

many years of satisfactory service.

If a very thin lining-say l/32” sheet-of a thermoplastic resin can be pene-

trated in a year to a year and a half by a corrosive, then the same resin, calen-

dered ‘/‘I thick, should be able to serve for 8 to 12 years before it is penetrated.

An inner lining of brick over the sheet lining surface will create stagnant condi-

tions at the surface of the membrane system and so further extend the economi-

cal life of the lining.

The rate of diffusion through the lining material is then a major criteria in

the determination of lining thickness.

CHEMICAL AND THERMAL RESISTANCE

There is no master document available through which thedesigner can searchin order to select the sheet lining most suitable for his exposure. In fact, those

available to him do not even use a common classification system to distinguish



Sheet Linings 95

the exposures which are economically acceptable from those which are not. And

to confuse matters further, the tables of chemical resistances which are available

in many cases are based on data collected by the manufacturer or supplier on

tests conducted on the basic elastomer, thermoplastic, or other resinous base-not on the compounded material that has been calendered into the sheet. There-

fore, the designer should follow up his material selection from whatever pub-

lished material he uses by consulting with the firm supplying the calendered

sheet and his licensed applicators, to be certain that what he specifies is war-

ranted for the anticipated exposure. In the bibliography at the end of this sec-

tion, the reader will find listed a number of readily available documents that he

may consult for his preliminary screening for both chemical exposure and sur-

face thermal limit. If internal insulation is required in order to reduce the sur-

face temperature into an acceptable range, he can, of course, provide an inner

masonry lining.

DAMAGE OR DEGRADATION

All sheet linings are subject to damage in many ways. No matter how tough,

how strong, a lining is, it can be damaged mechanically-by a sharp object, by

abrasion, or by a blow. Damage can, however, come from an external source-a matter frequently forgotten by management. Before the cutbacks on janitorial

and other services in steel mills, external damage of pickling tanks was little

noticed. However, with the present day housekeeping this writer has noted in

many major steel mills, he has learned by quiet questioning, that as much as 75%

of the leaks in the pickling tanks that have appeared and required repair have

been generated from the outside-the steel shell having been attacked and

“holed,” often by fumes from puddles of waste acid accumulated on the floors

under the bottoms of the tank. The exteriors-especially the underside of the

vessel bottoms-should be kept clean and painted, and the floors under them

should be free of all waste, dirt and puddles.

Linings can be damaged by exceeding the thermal limits, or by changing

the chemical content of the vessel without first checking to see if the lining will

accept the higher temperature or the new chemical. Tank linings-and in fact

entire vessels-have been lost because the purchasing agent changed suppliers

and unknowingly purchased acid-containing trace elements of a chemical that

destroyed the tank lining before anyone realized that it was in the shipment. A

good example of this is the switch in the late 1960s and 1970s in steel from sul-

furic acid pickling to hydrochloric. Much of the acid that was sold to steel mills

in this period was reclaimed and reworked acid that contained trace amounts of

hydrofluoric acid-amounts so small that the vendor never thought of it as a

problem. For its effect on a lining, however, see the photos in the section on

Failure Analysis.

The same type of problem can result from the contamination of the con-

tained liquid with a powerful solvent. In at least one case, small amounts of

chlorinated benzene in waste hydrochloric acid caused swelling and penetrationof the membrane and carried the acid through the membrane into the vessel




wall, eventually holing it and letting the contents of the vessel into a river,

contaminating it before the leak was discovered.

REPAIRS

Almost all sheet linings are repairable, usually following the same proce-

dures by which they were installed. Even shop-cured linings can usually be re-

paired well enough to provide economical continued service, providing the dam-

age is not too great. Consult the manufacturer of the original sheet for advice

before giving a repair contract to anyone, including the contractor who in-

stalled the original lining, unless, of course, the manufacturer himself installed

the original lining.

One must bear in mind that a vulcanized bonded sheet lining has high ad-

hesion-so high that to remove it in order to apply a different replacement is so

difficult that it must be burned off. Consequently, if a high bond vulcanized

sheet lining is penetrated and a leak appears on the outside of the tank, it is

most probable that the point of penetration of the sheet is opposite the hole,

and the minimum amount of inner lining will need to be removed to locate and

repair it. This is, of course, not necessarily true of sheet linings that are adhered

with a selfcuring adhesive which produces a lower strength bond. This writer

believes, however, that a thick sheet lining is normally to be preferred to a fluid-

applied membrane material for any exposure in which either will serve.

SOURCES OF DATA ON CHEMICAL RESISTANCE

Nordel@, Hypalon@ and Viton@ are registered Du Pont trademarks. (Neo-

prene was originally a Du Pont trademark but was lost by court action, and is

now generally used by everyone in the industry.) The Du Pont Company (Wil-

mington, DE) furnishes on request well documented corrosion resistance data

on these three basic materials (not on the compounded mixes).

Warning: Some sheet linings, such as Hypalon@, have limited shelf life.

Check carefully with the supplier and the manufacturer of the lining you select

to be sure that the material installed in your equipment meets the manufac-

turer’s criteria.

Chlorinated polyethylene resistance tables are available from the Dow

Chemical Company (Plaquemines, LA).

Polypropylene laminate sheet chemical resistance tables are available from

the Gates Rubber Company, Denver, CO.

Chemical resistances of the PVC laminate and polypropylene imported

sheets can be obtained from Dinamit Nobel, Rockleigh, NJ.

Chemical resistance data for polyisobutylene rubber is available from Braas,

Mannheim, West Germany.

The rest of the materials discussed are in general manufacture, and chemical

resistance tables covering them are available from all of the major sheet rubbermanufacturers.



Sheet Linings 97

BIBLIOGRAPHY

The General Chemical Resistance of Various Elastomers. See the 1979 Yearbook of the Los

Angeles Rubber Group, Inc., Los Angeles, CA.

Protective Linings TechnicalBulletin, Rubber Manufacturers Association, Washington, DC.

The Vanderbilt Rubber Handbook, R.T. Vanderbilt Co., Norwalk, CT.

Membranes Behind Brick, Walter Lee Sheppard, Jr., Chemical Engineering, May 15, 1972.

ADDENDUM

While this book was in its final preparation stage, two additional types of

adhered sheet linings for chemical exposures have come to our attention. One

is a sheet with, as the exposed face, a Tedlar@* film adhered to a layer of rub-

ber-asphalt blend. The sheet is applied with rollers to a substrate surface that

has been coated with an adhesive primer. Sheet edges are butted with an adhe-

sive lap strip of Tedlar@ applied over the joint to protect it. This is a proprie-

tary product presently available from only one source, which will supply partic-ulars of the application procedure and chemical resistance tables upon request.

The second sheet lining is also a fluorocarbon-Halar@,** but made entirely

of this basic material. Though quite expensive, this material has probably the

best overall chemical resistance of any of the generally available sheet linings.

It is adhered to the substrate with a rubber-type adhesive, and though Hala@

can accept surface temperatures of 300°F and above without damage, the use

of the sheet must be limited to the 220°F range due to the thermal limit of the

elastomer adhesive. Joints are butted, tooled to accept a weld strip, and then anarrow strip is heat-sealed over the joint. Full data on the material, its installa-

tion and chemical resistance is available from the manufacturer.

‘TedlarB is a tradename, property of the E.I. duPont Company for a polyvinyl fluoride

polymer which is manufactured by casting in a sheet and stretching to orient the mole-

cules. The personnel of the Elastomers Division of that company advise that Tedlar@

has excellent resistance to most inorganic acids, bases and salts, and to many, but by no

means all, organic compounds and solvents, especially in the liquid phase. However, some

solvents in the vapor phase can slowly diffuse through it. The Sauereisen Cement Co.,of Pittsburgh, PA, supplies this sheet under the tradename of Sauereisen #90.

**Halar@ is a tradename of the Allied Corporation, Morristown, NJ, for their polytetra-

fluoroethylene sheet (similar material to duPont’s Teflon@,). Allied markets this sheet

through its own sales force.



a

Fluid-Applied Membranes


C.C. R.M., incorporated


INTRODUCTION

One of the three vital components of chemically-resistant construction is

the membrane. The function of a membrane ‘f6 is to protect the supporting struc-

ture (substrate) from attack by liquids (or other environment) to which it is ex-

posed. A true membrane, as used in this paper, is defined as a total barrier to the

penetration of the anticipated liquid chemical environment for the economic life

of the lining. A semi-membrane is defined as one that can be penetrated, but

only very slowly. The brickwork or monolithic inner liner is almost never liquid

(or gas) tight, so that liquids and gases can penetrate through it, though quite

slowly, and reach the membrane behind it. The purpose of the brick or mono-

lithic liner is, therefore, to protect the membrane from extremes of heat, from

mechanical abuse, and from fluid wash.’ If the environment to which the struc-

ture is exposed attacks the structure only very slowly (as, for instance, concen-

trated sulfuric acid contained in a carbon steel tank), then it is not vital that themembrane provide a total barrier. A semi-membrane, one through which gas or

liquid can diffuse or penetrate only very slowly, may be used in such cases to

provide a construction with economical life. On the other hand, if the sulfuric

acid is diluted to 30%, then the attack of the corrosive on the steel substrate be-

comes so rapid that any penetration8r9 of the membrane at all will quickly dam-

age the substrate. In such a case, a true membrane, a total barrier to penetration,

is required.3

During the early years of this century, the most frequently used true mem-

brane was sheet rubber.’ Hot-applied asphalt, at least 3/4” thick, was used on con-

98



Fluid-Applied Membranes 99

Crete floors, and in the lining of concrete vessels. In the latter case, it was rein-

forced with a layer of hot-applied sulfur.4 Applications of hot asphalt to steel

were largely unsuccessful due to poor adhesion to so smooth a surface and due

to the sag caused by cold flow of the asphalt. Many experiments were conducted

with painted or other fluid applications, and over the intervening years, a num-

ber of such materials have been identified, which if applied carefully and in suf-

ficiently thick layers, can function effectively as true membranes. Because dif-

fusion (permeation) rates through different materials are rarely the same, either

for the attacking media or for the generic classification of the coatings, the min-

imum recommended thicknesses of application, in order to obtain adequate pro-

tection, vary considerably with the type of material. Obviously, there is no one

material that is suitable for all exposures. The purpose of this paper is to review

for the reader as many different types of fluid-applied materials as we can, to-

gether with methods of application and of test.

METHODS OF APPLICATION

The earliest methods of applying fluids as membrane applications, as we

would expect, were:

(1) Melt and pour (or squeegee)-used for hot asphalt applications and

some other similar materials.

(2) Brush and mop application-used for thick paint-type coatings and

for hot asphalt.

(3) Air spray-used for thinner or better dispersed dispersion coatings

or solution coatings.

The first two methods were preferred because they delivered the maximummaterial in a minimum time frame, and with minimum labor. However, it quickly

became apparent that mops-though still favored today by roofers and water-

proofers-do not deliver satisfactory results, for two reasons. They vary greatly

in thickness due to the patterns of the mop application, and the strings from the

mop are frequently found in the finished coating, which strings act as wicks and

transmit through the coating the very materials the coatings are designed to act

as a barrier against. Brushes are better,3 but are used today primarily for scrub-

bing a primer into the surface of a substrate or for applications to rough con-

crete surfaces of cold-applied thick paints. Mops are completely prohibited.

Air sprays were used in the 1940s and early 195Os, in attempts to apply

vinyl coatings thickly enough to act as membranes. The advent of the airless

spray equipment about this time made it possible to spray a more viscous ma-

terial, and so to build film thicknesses more rapidly and with fewer coats.

In the 195Os, painters started using rollers to apply paint more rapidly than

by brush or spray. It is often stated that roller application provides more uni-

form coats and smoother finish. While rollers are excellent for smoothing a fin-

ished coat, and may be satisfactory for application on a very smooth substratesuch as steel sheet, they are not as satisfactory for application to rough surfaces

such as concrete where the scrubbing action of a brush may better fill the irreg-




ularities, or perhaps for porous surfaces such as some wood substrates where

the impingement pressure of a spray may provide better wetting.

Through the 19305 and early 19405, the uses of phenolic and furan mortars

had become standard for "acid brick" and much experimenting was done to see

if these same resins could be used as barrier coatings (membranes) .Ambient tem-

perature curing agents were used with the mortars, but these were not as effec-

tive with resins when used as coatings, due to cure shrinkage and cracking. Glass-

lined vessels had been in use for some time, and the baking methods of applying

glass linings were quickly adapted to phenolic resins. For a short period, furans

were also applied in this manner, though such applications are no longer often

noted. With the advent of fluorocarbons, this same method of heat curing of

spray coatings was successfully applied to them.

In the early 19505, the Hercules Powder Company (now Hercules, Inc.) de-veloped a polyether resinous coating sold as Penton@ , that originally showed

great promise (though it has since been abandoned) which was applied in this

same manner .

These additional variations of heat applications appeared about this time:

(1) Heating the target material and immersing it in a thick suspension

of the coating material, a partially cured fluid resin, or even a thick

solution of the resin, so the resin would migrate to the heated object

and gel on the hot surface, then be further baked or ambient cured in

place. Th is is sti II a favored method of applying vinyl plastisols. (Plas-

tisols are, however. more frequently applied by airless spray.)

(2) The Schori Company pioneered hot metal spraying to apply a coat-

ing of hot metal to the surface of another metal. Though originally

planned for melting or spraying metals, this same procedure has

since been adapted to the application of many other coating ma-

terials, including sulfur .

(3) As a variation on these methods, the "fluidized bed" was devel-

oped. Here, a very finely ground powder of the resinous material

is placed in a container and a small volume of air or neutral gas is

blown into the bottom of the container to "lift" the powder and

keep it floating. Into th is agitated bed, the heated target is inserted

so that the resin particles migrate toward and agitate against the

hot surface, melt, and fuse to it. This system was successfully used

with Penton@ and has since been employed with other resins.

We occasionally note applications of coatings by "electrostatic deposition,"

an approach similar to electroplating of metals, where an electric current is

passed through a suspension or solution of the coating material, and the particles

of the coating material become electrically charged and are drawn and migrate to

the target where they deposit and adhere themselves electrostatically.



101luid-Applied Membranes

be fluidized. This means that it must be melted, dissolved or suspended in some-

thing, or be in a partially cured or polymerized fluid state, from which it will, af-ter coating, solidify. Of all the items on earth, only water increases in volume

when it goes from the fluid to the solid state. All dissolved materials occupy less

space after they have separated out of solution or suspension. All resinous ma-

terials used today for coating, as they pass from fluid to solid condition ("cure"),

will shrink in varying amounts. Therefore, in all coatings, a shrinkage stress of

one type or another builds up as the coatings cure, dry or harden. Various pro-

cedures to relieve these stresses, each suited to a particular type of coating, have

been developed .but some residual stress will always remain .The more thick and viscous the coating is-the more heavily it is filled with

an inert filler--the less will be the shrinkage, the less the stress and, therefore,

the greater the resistance to cracking and the longer the life of the coating ex-

cluding chemical degradation. Fillers can also add strength-reinforcing-to the

coating, and depending on the particle shape, may assist in making the coating a

true barrier to fluid penetration (or permeation).

Among the many types of fillers in use are: powdered silica, powdered car-

bon or graphite, powdered resinous material, powdered barytes, nylon and other

textile fibers, carbon fibers, glass fibers, and glass flakes. The powdered materials

act primarily to reduce shrinkage, though they do also add some strength just as

aggregate adds strength to concrete. The fibrous materials add both tensile and

flexural strength to the coating. The flakes or platelets of glass, ultrathin, tiny

slices of glass, do all these things, but also increase the diffusion resistance, be-

cause as the coating is applied and cured, these flakes or platelets orient them-

selves parallel to the surface that is being coated, and overlap each other. After

the coating is cured, for any corrosive that is applied to one surface to pass

through the coating to the underside, it must follow a devious path-reaching thesurface of a glass flake, following the edge of the flake, and down the edge

through the coating to the flake beneath, and then along that surface to the edge

of that flake and down to the next flake, and so on. Thus, a true barrier may be

attained if the coating is fiakeglass-filled by using a lesser thickness of coating

than if the coating is used alone or with another type of filler .

Some coating materials, such as epoxies, are "self-leveling." That is, they

will flow to the lowest point and end up as a dead flat surface-thick on hollow

spots, thinned out over peaks. If they are to be applied to vertical surfaces, ei-

ther very rapid cures or the addition of some agent to make them "thixotropic"

(causing them to hang in place and to prevent running) is necessary. Thixotropy

is often attained by the addition of a fumed silica (for instance, Cab-O-Sil@) or

by the use of a polar solvent. Plasticizers can be added to brittle or hard resins to

make the coating more flexible. Bentonite clay is added to suspensions to assist

in preventing settling and/or caking.

The addition of any of these filling materials, whether inert fillers, plasti-

cizers, solvents or other modifying agents, will, of course, affect the chemical re-

sistance of a resinous coating. The finished coating formulation does not usuallyhave as good a resistance to certain organic materials, or to strong acids or strong

alkalis, as the basic resin before it was modified. Beware of lowered chemical

resistance if there is any indication that the coating materials have been modified

to improve application.

FILLERS

To apply a fluid coating, it is obvious that the material to be used must first




Attached are two tables to help the reader understand the wide variety of

possible fluid-applied membrane liners which, though not commonly thought of,

might be considered for use behind brickwork. The first is a tabulation of ge-

neric types, showing the generally accepted methods of application of each.The second indicates the chemical resistances claimed for principal ones. The

materials for these tables were collected from many different sources, and the

author can make no claim for either completeness or accuracy. The application

table may serve to guide the reader to those items which are practical for the ap-

plication he had in mind, and the resistance chart to those best suited to his con-

ditions. In all cases, the designer and user must rely on the manufacturer and ap-

plicator for specific recommendations and warranties.

Table 8-1: Application Data

A - Squeegee

B - Hot Squeegee

C - Brush

D - Trowel

E - Roller

F - Air Spray

G - Airless Spray

II Hot spray

I - Hot Dip

J - Fluidized Bed

K - Electrostatic

I. Putty ussd to ~~0th substrate

H - Reinforcing used

N - Primer required on Steel

0 - Primer optional

P - Primer required on Concrete

Q - Sa.88 oat required

R - Intermediate coat required

S - Finish coat required

T - Finish coat optional

u - Ambient cure

v - mat clxe

w - Application to concrete possible

Baked Coatings

CEZamiC F. N. Q. S. V

CTFE F. J. K. N, S, V

E-CTFE F. J. K, N, S. V

FEP F. J, K. N. S. V

FEP-Amide F, v

PFA F, J, K, N. S. V

Phenolic C. F, G, Q. S, V

Plastisol F, G, I, N. S, V

PPS F, J. K. N. S. V

PTFE F, K, N. T, V

PTFE-Ceramic F, N, T, V

PVDP F. G, J, K, N, R, 9, V




Acrylic Latex

Asphalt Emulsion

Asphalt Hot

Asphalt Mastics

Aliphatic Polyurethane

Bituinastic

C. E, F, 0, U, W

Butyl

Ccmentitious

Chlorinated Rubber

Coal Tar Epoxy

EF-Y

Epoxy Acrylic

Epoxy Asphalt

Epoxy Ester

Epoxy Phenolic

Epocy Phenolic Asphalt

Epoxy Polysulfide

Epoxy Zinc

Fish Oil Based

Gilsonite Asphalt

High Temp. Silicone

Hypalon

Inorganic Zinc Silicate

Linseed Oil

Long Oil

Neoprene

Nylon

A, C, D. E, F. G, 0, P, U, W

A. B, C. D, M. P. U, W

A, C, D. F. H. M, N, P, U, W

C, E, F, G, 0, P. U, W

C. E, F, G. 0, P. U, W

A, C, D, En G, N. P, U, W

A, C, D, U, W

C, En F, G. U. W

A, C, E, M. U, W

C, D. E, F, J, K, M, N, 0, P. U. V, W

C. E, F, G, K, 0, U, W

A, C, E. M, U. W

C, E. F, G, K, 0, U, W

C, E, F, G, 0, S, U

C, E, F. G, 0, U

C, D, E, N, P, U, W

C, F, G, S, U

C. E, F. P, U. W

C, E. F. G. 0. P, U, W

C. E. F, G, V

C. E. F, M, N, P. U, W

C, E. F, G, S, U

C, E. F, G, U, W

C, E. V, G, u, W

C. E, F, G, L. M. N. 0. P. U. V, W

I, J, K, V

Oleoresinous C, B. F. G. U. W

Oil Modified Polyurethane C, E, F, G, 0, p, U. W

AMBIENT CURED COATINGS




organic Zinc C, E. F. G, S, U

Oxirane polyester

Phenolic

Phenolic Alkyd

Phosphate

Polyester

Polyester Epoxy

Polyurethane

Polyvinyl

C, E. F. G, U, W

F, G. J . S. U

C. E. F, G. U. W

C. E, S. U

PVA

Red Leid

Silicone Acrylic

Silicone Alkyd

Silicone Epoxy

Silicone Polyester

Soya Oil Alkyd

Styrene Butadiene

Tug Oil

Urethane

Vinyl

Vinyl Acrylic Latex

Vinyl Copolymer

Vinyl Ester

Vinyl Latex

Vinyl Phenolic

Viton

Wash Primer

Zinc Chromate

C. D. E. F, G, J, K, L, M, N, 0, P, R, S, U, W

C. D, E. F, G, J, K, L, M, N, 0, P, R. S, U. W

C. E. F. 0, P, U, W

C, E, F, G, I, J. K. L, N, 0, P, U, V, w

C, E, F, G, 0, T, U, W

C, E. F. G, S, U

C. E, F, G, U, W

C, E, F, G, U, w

C. R. F, G, U. w

C, E, F, G. U. w

C, E, F, G. U, W

C, E, F, G, U, w

C, E. F, G, U. w

C, E, F, G. U. w

C, E, F, G, I, J, K. L, N, 0, P, U, V, W

C, E, F, G, U, W

C. E. F, G. U. w

C, D. E. F, G, J, K. L. M, N, 0, P, R, S, U, W

C, E. F, U, W

C, E. F, G, U, w

C, E, N, U

C, E, S, U

C. E. S, U

AMBIENT CURED COATINGS - Page 2




Table 8-2: Chemical Resistance Guide

Acetic acid - 109 and less

Acetic acid - about 10%

*ccetone

Acetate= of alcohols

Aluminum chloride and

5UlfSt.S solurions

Aimmnium chloride, itrate

and sulfate olutions

Anvmnium ydroxide

lvnyl lcohol

imiline

Barium chloride and sulfide

solutions

3arium Hydroxide

Boric acid

Bromi.?e water

Butyric acid

Calcium bisulfite, chloride

and nitrate solutions

Calcium hydroxide to 25%

Calcium hypochlorite solution

Carbon tetrachloride

Chloracetic acid 10%

Chlorine dioxide

Chlorine water

Chlorobenzene

Chloroform

Chromic acid to 5%

Cyanide plating solutions

copper salts, solutions

Ethyl alcohol

Ethylene dichloride

Ferric chloride and sulfate

solutions

Hydrofluosilicic acid

Formaldehyde

Formic acid

GaSOliIlS

2

1

-R

R

C

R

R

R

R

R

N

R

R

R

N

R

R

R

N

R

R

N

N

R

R

N

R

R

R

N

R

R

R

R

I-:/c

‘/P

N

N

R

R

R

N

N

R

R

R

N

N

R

R

w

C

N

N

C

N

N

N

ClR

R

R

N

R

:/

R

:/

IG

eg

-R

R

N

N

R

R

C

R

N

R

N

R

R

R

R

N

R

R

R

R

R

C

N

R

R

R

R

N

R

R

R

R

R

ztB-R

R

N

N

R

R

R

R

N

R

R

R

N

R

R

R

R

N

R

R

R

N

N

R

R

R

R

N

R

R

R

R

R

5E

zkTI-C

L/N

N

N

R

R

C

i/C

N

R

R

It

N

N

R

R

N

N

N

N

/N

N

N

N

R

R

R

N

R

R

N

:I

f%

a5

-

R

R

C

C

R

R

R

R

N

R

R

R

N

N

R

R

/N

NC

N

N

N

N

R

R

R

N

R

R

R

ZNl

ii

:r:6L

I

C

N

N

N

R

R

I/C

R

N

R

R

R

C

N

R

R

R

N

C

R

R

N

N

R

R

R

2/f

N

R

R

R

C/I

4

BL

aB

-

R

R

R

C

C

l/C

R

R

C

R

R

R

C

R

C

N

R

N

R

R

R

C

R

N

c

Zd

zP

E

-R

R

C

N

R

R

R

R

C

R

R

R

R

N

R

R

R

N

R

N

N

N

R

R

R

R

N

R

R

R

I(

C

a

5D

-C

:/N

N

N

R

R

R

L/C

N

R

R

R

N

R

p.

N

N

N

N

N

N

N

R

R

N

N

R

N

N

C

z/w R

N R/C

N R

N N

R R

R R

R R

R R

R R

R R

R R

R R

R N

R

R R

I: R

c R

R N

N C

- N

R c

R N

R N

R N

- R

R R

R R

R/C N

R R

- c

R R

N R

R N

rd

&z

-C

C

N

N

R

R

R

R

N

R

R

R

Y

Y

R

R

Y

”

Y

I

Y

P

R

R

R

N

R

c

C

C

N




CHEMICAL RESISTANCE GUIDE - page 2.

Green liquor (paper ills)

Hexane

Hydrobromic cid

Hydrochloric cid

Hydrofluoric cid

Hydrogen eroxide

.Jet uel

KerDSene

lactic acid ta 20%

Elagnesiumalts solutions

naleic acid

nethyl alcohol

Hethylene hloride

Methyl ethyl ketone

Milk

Nickel salt solutions

Nitric acid to 5% l

Nitrobenzene

Oil.5 Animal

oils - Mineral

Oils - Vegetable

Oleic and Oxalic acids

Perchloric cid

Phenol o 5%

Phosphoric cid dilute

Picric acid to 10%

Wtassium cyanide

Potassium ydroxide o 30%

Potassium ypechlorite o 3%

Potassium alt solutions (other

sodium chromate

Sodium yanide

Sodium ydroxide ea 0\




CHEMICAL RESISTANCE GUIDE - Page 3.

Sodium ypochlorite o 3%

Sodium salt solutions (other)

Srearic cid

Sugar (various olutions~

sulfite iquor (paper ills)

Sulfur ioxide (vet nd dry1

Sulfuric cid dilute

Tall oil

Tartaric cid

To1Uel-M

Trichloroethylene

wea sOlUtions

White liquor (paper ills)

Wine

xy1ene

Zinc salt solutions

i

-t/a

R

N

c

c

R

R

N

R

*/

N

R

R/’

R/

R/

R

j0

4::

-c

R

R

n

R

R

R

c

R

c

N

R

R

R

R

R

-P

B5i:B-N

R

N

R

R

N

R

N

R

N

N

R

R

N

R

i;:;!.L

R

R

/

R

R

R

R

R

R

N

N

R

R

N

R

9

F

N

R

R

R

N

c

R

N

N

N

R

;F

9

R

R

R

R

R

R

c

A

R

R

-I

9c

-

c

R

c

R

c

R

21

‘/

N

N

II

R

N

R

NOTE:- The information surmnarized n this table is taken from many Sources, including

manufacturers' literature. The author can not guarantee it, and suggests that

the user verify, with the manufacturer and by his own tests, the suitability of

any coating hc plans to use for exposure to his anticipated environments, prior

to application.

REFERENCES

1. Membranes Behind Brick, Walter Lee Sheppard, Jr., Chemical Engineering, Vol. 79,

No. 11,pp 122-126 (May 15,1972),Vol.79,No.l3,pp 110-116 (June 12.1972).

2. Chemically ResistantMasonry, Walter Lee Sheppard, Jr., 2nd Ed., pp l-4 (1982).

3. Chemically Resistant Masonry, Walter Lee Sheppard, Jr., cit., pp 14-16.

4. U.S. Patent No. 2.134837, granted 1 Nov. 1938 to Claron R. Payne,on a sandwich of

‘/r+” hot applied sulfur mortars as a reinforcing stiffener between two l/e.” layers of

hot-applied asphalt. This was succeeded in the 1950s by a reinforcing layer of glass

fabric when that material became available.

5. There is a mass of material on sprayed rubber, but perhaps the most useful is the Van-

derbilt Rubber Handbook published by the R.T. Vanderbilt Company of New York.

The author still finds handy the 9th edition of this work, published in 1948, con-

taining 714 pages including useful tables and index. Current edition-1978.




6. Protective Lining Performance, Byron I. Zolin, Chemical Engineering Progress, Vol. 66,

No.B,pp 31-37 (August 1970).

7. Natural Rubber Tank Linings, T.E. Saxman, Materials Performance, Vol. 4, No. 10,

pp 43-115 (October 1965).

8. The Basics of Membrane Permeation, Robert N. Rickles, Henry Z. Friedlander, Chem-ica/Engineering,Vol. 73, No.4.p~ 163-168 (April 25.1966).

9. Permeability of Polymers to Gases, Vapors, and Liquids, Alexander Leborits, Modern

Plastics.Vol.43,No. 3,pp 139-150.194-213 (March 1966).



Rigid Nonmetallic Membranes

Waiter Lee Sheppard, Jr.



As early as the late 1940s. efforts were made to inner-line steel or concrete

vessels with rigid liners made from rigid PVC sheet, or to fabricate such a liner

in place. In that period, there was no other membrane system available that

could withstand concentrated oxidants such as 30% nitric or chromic acid. But

since rigid PVC was limited to service temperatures of 14O’F and below, the

structure required an inner acid-brick liner for insulation. This triple layer sys-

tem, each layer of a vastly different coefficient of thermal expansion from the

one adjacent, developed many problems, and is only occasionally seen today.

Liners of this kind have been fabricated of FRP, rigid plastic, such as poly-

propylene, or even of fluorocarbon sheets. The use of such inset, prefabricated

linings has continued off and on over the years-the most common being the re-

cessing of a small stainless steel vessel in a concrete floor-often adjacent to an

acid-brick or monolithic surfaced floor area. Obviously, there are problems in

making the membranes continuous in such construction, and the best approach,

even though not a cure-all, is given in Chapter 45, Drawing 15. The procedure

there indicated is, of course, applicable to all rigid inserts, and not just stainless

steel.

In the last decade and a half, various manufacturers have started to market

precast and preformed gutters or trench sections of various plastics and polymer

concretes, unfortunately in very limited dimensions, from which the user may

assemble a trench or gutter to handle chemical wastes. The stated advantage of

the use of such materials is quick and easy assembly, but the user should note

that joints between these components are not always liquid-tight, and unless the

109



1 1 0 Corrosion and Chemical Resistant Masonry Materials Handbook

unit is completely assembled on the bank prior to placement, it cannot be tested,

and the user has no assurance that it will not leak.

Units of this type are available from a number of sources, usually manufac-

tured from a polyester or vinyl ester resin, although a few epoxy structures are

also on the market. At least one vendor is casting such units to order from a fu-

ran castable. The standard, off-the-shelf items rarely have a top circumferential

flange-a necessity if they are to be mated with an adjacent membrane system, as

shown in the drawing cited above, and the buyer should make the provision of

such a flange a condition of purchase.

The designer must keep in mind that for chemically-resistant masonry, an

expansion joint (or expansion/contraction joint), is only effective (1) if it is

placed over a membrane, (2) bonded to or fully pressed against the sides of the

joint, and (3) if it is composed of material soft enough to compress, or designedin such a manner that movement in the masonry can take place without opening

a passage for hot gases or liquids to pass directly through the masonry and back

to the bed. Concrete designers have long considered asphalt board and similar

materials as suitable expansion joint fillers. Actually, this type of material-

whether composed of asphalt or any other substance-is totally unsuitable and

unacceptable. Even if it had adequate chemical resistance (which it does not for

most exposures), this type of material is not elastic, is hard to compress,cannot

be bonded to the sides of the joint, and is not any barrier at all to the intrusion

of chemicals.



10

Hot Asphalt



Haverto wn, Pennsylvania

Hot asphalt applications to prevent chemical attack are probably the oldest

of all coatings and surfacing materials. As a natural occurrence, asphalt ponds

and deposits have been found in many parts of the world and from earliest times,

natives have heated the asphalt up to bring it to a flowable consistency, then

spread it on surfaces they wished to protect. With the refining of petroleum

“still bottom residues,” similar to naturally occurring asphalts, were employed

in similar ways, and being waste products, were less expensive to use.

With the development of “coal oil” from coke-making and other coal proc-

essing, a similar product-bitumen-became available. Though useful for many, if

not all, of the same purposes, bitumen is not identical, and in many cases, not

compatible with asphalt, and care should be taken in chemical services not to

mix them. For instance, hot asphalt should not be used with a bitumastic pri-

mer, nor if the supply of hot asphalt runs out before a job is completed, should

it be finished with a bitumen formulation.

Specifications covering manufacture, selection and application of hot as-

phalt are written primarily around highway surfacings and the roofing and wa-

terproofing industries, in which the vast bulk of these materials are used. The

chief purpose of the application in roofing and waterproofing is obviously to

prevent water penetration. In such work, the asphalt is melted in gas-fired ket-

tles from which it is withdrawn in buckets and spread with mops. This is, as one

might guess, very messy, unpleasant work-with always the possibility of an as-

phalt burn, but it is still the least expensive way to handle this type of work.

When employed as a liquid-tight chemical membrane seal, ordinary asphalt

should not be used. As it comes from the still, asphalt contains a lot of unsatu-

1 1 1




rated carbonaceous compounds, which when exposed to oxidizing chemicals or

gases can react to form products that are brittle and can crack. Neither does it

have as good resistance to otherchemicals as does fully “saturated” asphalt. In

order to resolve this matter,the asphalt is “oxidized”or “blown” by an extra treat-ment at the refinery, and all unsaturated bonds in the molecules eliminated.

“Light fractions” or low boiling solvents in the mix are driven off until a “ball

and ring” softening point (ASTM D-36) of 210°-23O’F is attained. All asphalt

has “cold flow.” This means that even at ambient temperatures, a weight stand-

ing on it will very slowly sink into it, extruding the asphalt under it to all sides.

On vertical surfaces, it can sag over a period of time, under its own weight. This

amount of cold flow or tendency to cold flow is, of course, related to the soften-

ing point. The higher the softening point, the less the tendency to cold flow at

ambient temperatures. However, if a material with too high a softening point is

selected, we may find that at the lower temperatures experienced during winter

months the asphalt may become brittle, and (since all things, especially asphalt,

shrink as they become cool) perhaps crack and pull apart, creating voids and

leaks in the membrane system. Such a crack, or break in the membrane will

not reseal when temperatures rise. Experience has shown that at the 210°-

230°F softening point, the best compromise between these two extremes exists.

Lastly, the asphalt should be free of any kind of filler.

The softness (texture) of the asphalt is a secondary and related considera-

tion. Although a quite satisfactory “matrix” asphalt may be obtained by simply

following the requirements that it be “oxidized,” unfilled asphalt with softening

point (ASTM C-36) 2 1 O”-230°F ,” some users like to add to this a penetration

requirement under ASTM D5. This test is run by holding the “matrix” asphalt

at a prescribed temperature, dropping upon it a needle of prescribed dimensions

and weight, and measuring the depth of penetration. If it is desired to run this

test, the following are acceptable results:

At 115’F-50 g weight needle, in 5 seconds, less than 7.0 mm

At 77’F-100 g weight needle, in 5 seconds, 3.5-4.5 mm

At 32’F--200 g weight needle, in 60 seconds, 2.5-3.5 mm

Percentage of material soluble in C&-not less than 97% weight/ft3, 65-

75 Ibs.

Experience has also shown that to obtain an adequate bond between hot

asphalt and the substrate, a primer is required. The cheapest, and also the best,

has proven to be an “asphalt cutback”-a solution of the same matrix asphalt, or

one with only a slightly lower softening point from the same or a compatible run,

dissolved in a high flash solvent fraction-preferably from a related stock con-

taining a minimum of 10% of the asphalt in solution. This primer is applied to

the substrate and allowed to dry until all the solvent fraction has evaporated,

leaving the asphalt residue on the surface and in the pores of the substrate. The

hot melted asphalt is then applied to the primed surface, melting and joining to

the residue remaining, yielding a bond to the surface much exceeding the tensilestrength of the asphalt. If properly applied, the hot asphalt coating cannot be

pulled off.



Hot Asphalt 713

This type of membrane is especially effective as a lining for concrete vessels,

inner lined with “acid-brick.” Tanks so constructed have served well, without

major repairs, for 20 years and more. When repairs have been required, it has al-

most always been due to inadequate, careless or improper installation, externalinjury (such as cracking of the concrete) or to mechanical injury internally. In

the early years of this century, attempts were also made to construct pickling

tanks of steel plate, with hot asphalt membranes and “acid-brick” inner linings.

Without exception, such tanks failed in short periods of time, sometimes in a

few months, by internal acid penetration of the hot asphalt membrane. Except

for obvious poor installation techniques, these failures were due to the fact that

steel, no matter how well-cleaned and primed, does not offer a satisfactory sur-

face to obtain a uniform, sound bond to the asphalt. Due, perhaps, to oils or

lubricants included in the surface, perhaps some other factors, the quality of the

adhesion of the asphalt varies over the surface. In some spots, it bonds tightly-

in others, lightly. As noted above, cold flow slowly occurs. Where the bond is

sound, the sag is very slight or nonexistent. Where the bond is weak, the as-

phalt either pulls loose or stretches, increasing the drag on the tightly anchored

areas next to them. Asphalt does not stretch very well and in a short time, pulls

apart or cracks between the areas of tight bond and poor bond. Acid then pene-

trates to the steel at those points and burns a hole. When bricks are removed to

make repairs, we invariably find a hole in the steel with no membrane directlyin front of it. Consequently, the user is warned never to rely on a hot asphalt

membrane to line a steel (or other metal) tank.

SUITABLE SUBSTRATES

As noted above, hot asphalt may be supplied successfully to concrete. It

may also be applied to properly prepared timber, masonite or other cement

board, or any absorbent surface. Its bond to most plastics, as to steel, is erratic,

and should not be depended upon.

APPLICATION

Concrete (or other suitable substrate) to receive a hot asphalt membrane

must be clean, dry, and free of curing oils and from release compounds.

The primer, defined in the first part of this paper as a cut-back of the same

or a compatible, unfilled, oxidized asphalt dissolved in a high flash petroleum

fraction, should be scrubbed into the concrete surface with a broom or stiff

brush (roller or spray application is not recommended) and allowed to dry to

permit the solvent to evaporate. This usually takes about 3 to 4 hours, at which

time the odor of the solvent will have become faint. This leaves a black deposit

of the asphalt in the pores and on the surface of the concrete. If the black color

fades away, or becomes gray, the concrete is porous, and another coat of primer

is necessary. Repeat until the surface remains black.The asphalt is usually shipped in the open-end paper cartons in which the

manufacturer will have cast it as it was taken from the still. The cartons are laid



Hot Asphalt 115

tor unfamiliar with it, will want to use mops to make this application. Mops are

absolutely prohibited. They invariably shed strings into the melt, which act as

wicks and transmit fluid through the asphalt membrane from face to back. The

squeegee application, properly done, will yield a smooth, pinhole-free surface,without bubbles or blemishes, cleaner than any other application method. Hot

spraying is also barred. If mops turn up on a site, all work should be stopped

until they are removed entire/y from the site, not just the work area.

Occasionally on large jobs, a waterproofer or roofer may try to bid this

work, though it has traditionally always belonged to the brickmasons. When

this occurs, if a jurisdictional dispute arises, the masonry contractor should be

advised that such disputes have always in the past been settled in Washington,

and that the Trades Councils have agreed that acidproofing, as against water-

proofing, belongs without question to the brickmasons.

Application of the hot melt is continued until a thickness, over any high

points, of l/s” has been attained. At this point, a layer of asphalt-impregnated

glass fabric is laid over the asphalt layer and carefully pressed into it using paint

rollers to iron it smooth. Wrinkles must be avoided. Experienced workers can use

long sections of fabric, a yard or a meter wide. Those doing it for the first time,

or just learning, should be advised to use short pieces until they get used to the

procedure. If they do not do this carefully, they will put wrinkles into the fabric

and lumps into the following layers. Edges of all fabric sheets should be lapped

2” applying small amounts of hot asphalt at the laps when needed to cement the

layers together tightly and to prevent them from coming loose or protruding.

When the layer of asphalted glass fabric is completed, a second l/s” of hot

asphalt is applied over the fabric, providing a thickness of %‘I. For floors, this is

the accepted finished thickness for a hot asphalt membrane. However, for the

lining of trenches and tanks, where a hydrostatic head will be encountered, the

normally accepted thickness is 3/s”, and a second layer of glass fabric and a third

layer of hot asphalt should be applied.

GAUGING THICKNESS

The mechanic applying the hot asphalt is also responsible for gauging the

thickness to be sure that he actually has applied the required full %I”. He must

gauge his work as he progresses, and to do this must provide himself with a

gauge. The simplest is a large nail that he has previously marked off with a file

r/s”, %” and 3/s” from the point of the nail. This he carries in his overall pocket

along with a piece of chalk. When he thinks he has applied a sufficient thickness,

he can sound the coating with the nail. If the fig” mark (or 1/4” or 3/s”, depending

on the layer on which he is working) is not covered, he must apply more hot

melt. As he withdraws his gauge, he leaves a hole behind in the asphalt mem-

brane. He circles the hole at once with the piece of chalk, and tests several other

areas for thickness to determine uniformity, circling the holes in each case. Be-

fore proceeding with the next step-more melt or glass fabric, or perhaps the fin-

ish of the job-the test holes must be sealed. To do this, he takes a small propanetorch and lights it, adjusting the flame to yellow. He places the tip of his brick-

mason’s trowel against the membrane, close to the hole, and plays the flame of




the torch on the middle of the trowel. As the heat travels to the tip, it starts

to soften the asphalt, and as this happens, he carefully works the melted material

to close and seal the test hole. Failing to perform this step will result in the fail-

ure of the membrane and chemical penetration of the substrate.

INSPECTION AND REPAIR

Blisters or bubbles in the surface of hot asphalt membranes are not accept-

able as they indicate that air is in the membrane and in voids, and perhaps liquid

paths exist in the membrane. When applying the hot asphalt, the mechanic

should never apply more material over a blister or bubble. If one appears in the

surface, it should be broken (opened) and the cavity repaired in the same man-

ner that the gauging holes were repaired. If more hot liquid is applied over the

hole without repairing it, the air in the hole will expand as it is trapped inside by

the next hot layer, and a blister will appear at the same spot in the new layer. As

subsequent layers are applied, this will repeat again and again, until at the finish

of the application, there exists a hole clear through to the substrate. If this is the

case, the hole will quite likely be too great to repair in the manner in which the

gauging hole was repaired, and that area may have to be cut-a matter of eight

to ten square inches-and each layer will have to be repaired in the same mannerin which the original material was applied.

You may wonder what the source of these bubbles or blisters may be. Blis-

ters are caused by one of two things-water or air. If the substrate is at all por-

ous, it contains air. Or there may be some water inside the concrete, too deep to

see. When the hot asphalt is applied, the heat, transmitted into the concrete,

causes the air to expand or the water to vaporize. In either case, it tries to es-

cape, and in doing so, causes bubbles. An alternative possible source is the ket-

tle. If a few drops of rain get into the kettle, and the pot tender has not stirred

it all out, some foam may have gotten into the pail the mechanic has just used-

and as this hot material is spread, a bubble formed. If the pot is stirred with a

power mixer, or even vigorously by hand, the surface can trap air which can get

into the applied hot asphalt membrane in the same manner. A few random blis-

ters can be repaired without too much trouble-but if there are more than one

per square foot this problem should be corrected before proceeding.

Where the bubbles are caused by air or water in the substrate, another ap-

plication of hot asphalt will again expand the water or air in the substrate and

again cause blisters. Repeated applications will continue to cause blisters as long

as water or air is present. It is, therefore, a waste of time to apply more hot ma-

terial before removing the source of the trouble. The best procedure is to dry the

area thoroughly with heat or with a dessicant or both. If time does not permit,

and there is not a great deal of moisture or air present, it may be possible to seal

the surface with a concrete sealer, such as an amide-hardened epoxy, and then

apply the primer and hot asphalt over this.

In making a repair of the membrane, either after an injury to the lining in

service, or after removal of unsound (blistered) membrane material, always flashthe cold hardened asphalt around the repair with a torch to warm and soften it

up before placing new hot material, so that the new may blend in with the old.



Hot Asphalt 117

Always lap any new cloth over the old in the membrane. Never pour new hot

material directly on the void area, because this can trap more air between the

bare spot and the new melt, resulting in more blisters. Instead, place the melt

adjacent to the bare spot and spread it sideways over the bare spot, pushingthe air in front of it.

LIMITATIONS

Hot asphalt membranes are excellent behind brick or other mechanical pro-

tection. However, even at low temperatures, they can be damaged mechanically,

and when exposed to warm, moving, contained liquids asphalt can often be

picked up and contaminate the liquid. In warm weather, traffic will rut or other-

wise damage asphalt floors. Asphalt can stick to shoes resulting in damage both

to shoes and floors. Consequently, it should not be used as unprotected mem-

brane.

The 3/4” dimension for membranes on floors should not be exceeded. As

noted earlier, hot asphalt membranes have “cold flow.” In thicker dimensions,

especially if unreinforced, heavy traffic, or standing loads, can push the brick

floor under the load into the membrane, causing it to extrude laterally. This re-

sults in a balancing vertical pressure upwards around the brick bearing the load,and a shear stress on the bond between the adjacent brick, and has been known

to rupture the floor. Load limitations have never been formally agreed by ASTM

Committee or other authority. However, most experienced designers agree that

standing loads on a brick floor over a ‘/4” hot asphalt membrane should not ex-

ceed 25 psi at ambient temperature, lesser pressures as the temperature rises.

REINFORCING

In the 193Os, hot asphalt membranes were usually unreinforced. No glass

fabric had yet been developed. However, in 1940, a patent was issued on the use

of a ‘/a” thick layer of hot applied plasticized sulfur mortar as a reinforcing and

stiffening layer between two ‘/s” thick layers of hot-applied asphalt. (See the

chapter on Sulfur in this book.) For the following decade, this design was the

one most frequently followed in vessel linings-until glass fabric became avail-

able. From that time to the present, asphalt-impregnated glass fabric has been

the standard method of reinforcement except where acid fluorides and hydro-

fluoric acid are involved. In those exposures, a polyester or carbon fiber fabric

may be utilized. (See the section on membrane reinforcement for details.)

OTHER APPLICATIONS OF HOT ASPHALT

For almost 100 years, hot asphalt has been employed as a joint filler for

bell-and-spigot vitrified clay pipe used to construct sanitary sewers. The joints in

the pipe are assembled and poured much in the way described for clay industrial

sewer lines in the Industrial Waste section of this book. Where used for this pur-



7 18 Corrosion and Chemical Resistant Masonry Materials Handbook

pose, the fabric caulk is usually waste wool (or “oakurn”) impregnated with

cresol or a similar preservative, and the hot asphalt need be neither an oxidized

nor a high softening point material. However, in a few cases, hot asphalt has

been employed as an external seal, poured in a pouch secured around a leakingbell-and-spigot joint in an industrial waste line. In such use, the higher soften-

ing point oxidized unfilled asphalt is recommended.

Many years ago, expansion joints in concrete floors were frequently filled

with hot asphalt, and it was sometimes used as a space filler in void areas to pre-

vent fluid penetration. Neither of these applications is recommended. If ex-

truded by the two sides of a closing joint, when the structure expands in hot

weather, it stays extruded when the weather cools off, and the structure shrinks

back to its old size, leaving a void to be filled with rainwater, etc. (which can

freeze causing expansion damage) or with chemicals which can attack the con-

Crete.

In any case, the bond of hot asphalt applied in this manner is negligible and

even without expansion or contraction of the substrate, this kind of seal is of

little value.

COLD ASPHALT APPLICATIONS

Asphalt putties of two general types have been available for decades. As-

phalt emulsions (with water) have often been used to coat the tops and outsides

of steel stacks, where they dry to a hard, often brittle, coating. Asphalt coatings

are also available in which the asphalt is extended or softened with a pertroleum

solvent. Coatings and putties of this type are less likely to become brittle. Both

types have occasionally been used as membranes under brickwork where safety

engineers have been concerned that there may be safety hazards connected with

the use of hot asphalt.

The user should remember, however, that when a barrier material is emulsi-

fied or extended with a solvent, the coating made from it does not solidify to-

tally until the water or solvent present in the formulation evaporates, and when

this evaporation occurs, the structure that remains behind has tiny pores, holes

or cavities where the water or solvent was, and chemicals, especially those with

tiny molecules like HCI, can slowly diffuse through it-something they can not

do through the dense hot asphalt. Further, if the brickwork covers this type of

coating or membrane too soon, some of the water or solvent will be blocked or

trapped in it. If water remains so that the emulsion does not harden completely,

any water-borne chemicals can cause the asphalt to reemulsify and so wash

away, destroying the barrier. If solvent remains, the membrane can rather easily

be penetrated,

Asphalt has been used as a major component in many coating formulations.

These include epoxy-asphalts (much used in refineries) and urethane-asphalts.

Of these the urethane-asphalts, some of which are true copolymers, are the most

satisfactory substitutes for hot asphalt. They can be used at exposures higher in

temperature than can hot asphalt due to their freedom from cold flow, and arereasonably good barriers. Like the asphalt emulsions and solvent putties, how-

ever, they can be penetrated, though at a much slower rate, by small molecule

acids. Fluid (cold) applied membranes are discussed elsewhere in this volume.



Hot Asphalt 719

ADDITIONAL NOTES

Asphalt is a culture medium for many molds, especially those produced by

pharmaceutical companies as antibiotics. Therefore, in designing and specifyingflooring for drug houses, the engineer should determine whether this type of

drug is to be manufactured in the area under design. If the answer is “yes,” asphalt

membranes should be avoided. Other types of membranes that are suitable for this

service are furan-glass fabric membranes (most frequently used) and PVC sheet.

Sometimes it is desirable to reinforce an asphalt membrane with an imper-

vious (liquid-tight) reinforcing layer rather than glass fabric. More than twenty

years ago, Robert Pierce obtained a patent on reinforcing hot asphalt membranes

with thin fluorocarbon sheets (Kynar@), the purpose being to handle solvent-

containing waste. This design has had mixed results. The top asphalt surface, di-

rectly under the brick, was exposed to the solvents and rather quickly softened

and damaged. The fluorocarbon sheet is lapped at the edges rather than welded.

Therefore, joints may be penetrated. For floor application, this design is often ade-

quate, but it is rarely acceptable under a liquid head in continuously wet exposure.

Where moisture (or air) in the substrate is so extensive that it appears im-

possible to eliminate it, or where it is fed from a subsurface source, a satisfactory

membrane can sometimes be attained by ignoring the blisters in the first thin

layer of hot asphalt, and then laying over this layer a 6 to 12 mil thick pinhole-free, plasticized PVC sheet, lapping all edges 2” or more, and rolling out all

wrinkles and air bubbles, then laying another l/s” thick layer of hot asphalt on

top of it. The use of visqueen and other stiffer plastic sheets yields mixed re-

sults due to poor bond to both asphalt and mortar, and the difficulty of working

out air pockets and wrinkles.

The following Chemical Resistance Table is based on the use of hot asphalt

as a membrane when used with a chemically-resistant masonry inner liner. lt iS

derived from a number of sources and the author cannot assume responsibility

for its accuracy.

Table 16-l: Hot Asphalt Membranes Reinforced with Glass Fabric

Key: C = Conditional R = Recommended N = Not recommended

* = Reinforce with polyester or carbon cloth, not with glass cloth.

Membrane

Chemical

Acetaldehyde

Acetic acid, up to 10%

Acetic acid, glacial

Alum

Aluminum chloride

Aluminum nitrate

Aluminum sulfate

Ammonium chloride

Ammonium hydroxide

Ammonium nitrate

Ammonium sulfateAmy1 acetate

Amyl alcohol

Temperature

80°F 14O’F

C C

C NC NR R

R R

R R

R R

R R

R C

R R

R RN N

R R

Chemical

Aniline

Aqua regia

Barium chloride

Barium hydroxide

Barium nitrate

Barium sulfide

Benzene

Benzenesulfonic acid,

10%

Benzoic acid

Boric acidBromine water

Butyl acetate

Temperature

80°F 1405

N N

N N

R R

R R

R R

C N

N N

R R

R R

R RN N

N N




Chemical

Butyl alcohol

Butyric acid

Cadmium chloride

Cadmium nitrate

Cadmium sulfate

Calcium bisulfite

Calcium chloride

Calcium hydroxide

Calcium nitrate

Carbon disulfide

Carbon tetrachloride

Chlorine dioxide,water solution

Chlorine gas, dry

Chlorine gas, wet

Chlorine water

Chloroacetic acid, 10%

Chlorobenzene

Chloroform

Chromic acid, up to 5%

Chromic acid, 10%

Chromic acid, 20%

Chromic acid, 50% andover

Citric acid

Copper chloride

Copper nitrate

Copper sulfate

Dichloroacetic acid,

10%

Dichlorobenzene

Diethyl ether

Ethyl acetate

Ethyl alcoholEthyl sulfate

Ethylene chloride

Ethylene glvcol

Fluosilicic acid*

Formaldehyde

Formic acid

Gasoline

Glycerine

Gold cyanide

Hexane

Hydrobromic acid

Hydrochloric acid

Hydrocyanic acid

Hydrofluoric acid*

Hydrofluosilicic acid*

Hydrogen peroxide

Hydrogen sulfide gas,

dwHydrogen sulfide gas,

wet

Iron chloride

Iron nitrate

Iron sulfate

Membrane

Temperature

80°F

R

NR

R

R

R

RR

R

NN

NR

R

C

NNNR

R

C

NR

R

R

R

N

N

N

N

RN

N

R

C

C

C

N

R

R

N

R

R

R

C

C

C

R

R

R

R

R

140°F

R

N

R

R

R

R

R

C

R

N

N

N

R

C

C

N

N

N

C

C

C

N

R

R

R

R

N

N

N

N

RN

N

R

C

C

N

N

R

R

N

R

R

R

C

C

C

R

R

R

R

R

Chemical

Isopropyl ether

Kerosene

Lactic acid

Lead acetate

Lead nitrate

Linseed oil

Magnesium chloride

Magnesium hydroxide

Magnesium nitrate

Magnesium sulfate

Maleic acid

Mercuric acetateMethyl acetate

Methyl alcohol

Methyl ethyl ketone

Methyl sulfate

Mineral oil

Mineral spirits

Muriatic acid

Nickel chloride

Nickel nitrate

Nickel sulfate

Nitric acid, up to 5%Nitric acid, 20%

Nitric acid, 40%

Nitric acid, 50% and

over

Nitrobenzene

Oleic acid

Oxalic acid

Perchloric acid

Phenol

Phosphoric acid

Phosphorous acidPhosphorous trichloride

Phthalic acid

Picric acid

Potassium bicarbonate

Potassium carbonate

Potassium chloride

Potassium cyanide

Potassium ferricyanide

and ferrocyanide

Potassium hydroxide, up

to 30%

Potassium hydroxide,

30% and over

Potassium nitrate

Potassium sulfate

Pyridine

Rochelle salt

Salicylic acid

Silver nitrate

Sodium acetate

Sodium bicarbonateSodium carbonate

Sodium chloride

Membrane

Temperature

8 0 ° F

NNR

R

R

N

R

R

R

R

R

RN

R

N

N

N

N

R

R

R

A

RR

N

N

N

C

R

N

N

R

RR

R

N

R

R

R

R

R

R

C

R

R

N

R

R

R

R

RR

R

140°F

N

N

R

R

R

N

R

R

R

R

C

RN

R

N

N

N

N

R

R

R

R

RC

N

N

N

N

R

N

N

R

RR

R

N

R

R

R

R

R

C

N

R

R

N

R

R

R

R

RR

R



Hot Asphalt 121

Chemical

Sodium cyanide

Sodium hydroxide, up

to 30%

Sodium hydroxide, 30%

and over

Sodium hypochlorite,

up to 3%

Sodium hypochlorite,

15% and over

Sodium nitrate

Sodium sulfate

Sodium sulfide

Sodium sulfite

Sodium thiosulfate

Soya oil

Stearic acid

Sulfur dioxide gas,dry

Sulfur dioxide gas, wet

Sulfur trioxide gas, dry

Sulfur trioxide gas, wet

Membrane

Temperature

80°F 14O’F

R R

R C

C N

C C

N N

R R

R R

C CR R

R R

N N

C N

R R

R R

R R

R R

Chemical

Sulfuric acid, up to 50%

Sulfuric acid, 80%

Sulfuric acid, 93%

Sulfuric acid, over 93%

Sulfuric acid, fuming

Sulfurous acid

Tannic acid

Tartaric acid

Tin chloride

Tin sulfate

Toluene

TrichloroethyleneTrisodium phosphate

Tung oil

Urea

Xylene

Zinc chloride

Zinc nitrate

Zinc sulfate

Temperature

80°F 14O’F

R R

C N

N N

N N

N N

R R

R R

R R

R R

R R

N N

N NC N

N N

R R

N N

R R

R R

R R

Some safety engineers have become obsessed with fears of safety problems

with hot asphalt, although very few injuries or accidents have been traceable to

it over the several centuries that it has been used industrially. As a result, there

have been many efforts to substitute cold asphalt putties for hot asphalt as a

membrane material. These materials and their limitations have been discussed

above. As a membrane for floor installations, such putties are often usable pro-

viding they are never subject to a standing liquid head, but less frequently for

trenches and pits. Remember, if asphalt emulsions are put in service before all

the water has dried out of them, they can reemulsify and may be washed out.

There is no real equivalent or economical replacement for a hot asphalt

membrane system.

REINFORCING FABRICS FOR ASPHALT MEMBRANES

Since the late 194Os, glass fabric has been used as reinforcing in asphalt mem-

branes where they have been installed in association with “acid brick,” both in

flooring and in the lining of concrete vessels. No absolute specifications for thistype of glass cloth have been set up within the industry and about the only

points of general agreement have been that the glass fabric must be manufac-

tured with threads of a loose twist, a weight per square yard of 3 oz or less, and

an open weave. You must be able to see light through it. The fabric must then be

saturated with a liquid containing the same, or a compatible, asphalt as that to

be used for the membrane. For probably 40 years, one major chemical company

has used, with complete success, the following specification:

Strength with warp

Strength with fill

92 psi

64 psi




Weight uncoated

Weight coated

Thread count

Thread gauge

1.33 oz/yd=

2.20 oz/yd=

24 per inch each way

0.0035 inches thick

A major manufacturer/supplier purchases a lighter asphalt-impregnated

cloth to conform to ASTM D1668-73, Type I, and Federal Specification 4666.

These are specifications for roofing fabric, not intended by the writers for chem-

ical service; but since the adoption of this purchasing requirement, the manufac-

turer has reported no delaminations or other problems. Type I material is that

impregnated with asphalt; Type II is impregnated with coal-tar pitch, and Type

III, with an organic resin selected and agreed upon by vendor and purchaser. It

is important that asphalt, and not coal-tar, be used as an impregnant since as-

phalt and coal-tar pitch are not always compatible.

Here are the details of this specification:

Average dry weight 1.4 oz/yd=

Thread count per inch (25.4 mm of width)

Warp threads 20 f 1 minimum 24 _+ 1 maximum

Fill “20 * 1 minimum 24 + 1 maximum

Average weight impregnated 2.0 oz/yd2 minimum 3.0 oz/yd* maximumTensile strength 75 psi minimum, both directions

*May be 10 (1’1) to 12 (;‘I 1 if each thread is double the strength of the warp

thread.

When the asphalt membrane is to be used in an exposure involving acid

fluorides (such as a nitric-hydrofluoric pickling solution in a pickling tank for

stainless steel), the designer should specify that the polyester fabric given above

be used for reinforcing rather than the above glass cloth.



11

Fired Glass and Porcelain as Membranes

Waiter Lee Sheppard, Jr.



For much of recorded history glass containers have been employed to hold

liquids of all kinds, chemicals, and for the manufacture of acids and salts. Their

use has been limited primarily by fragility and by available sizes.

Over the past century, techniques have been developed to fire on metal sur-

faces, glass and porcelain in suitable formulations and in adequate thicknesses to

be a liquid-tight barrier to protect the substrate from chemical attack by con-

tained liquids. In such composite structures, the glass is better able to withstandthermal and mild mechanical abuse. Reactors made in such a manner have given

long economical service over the years, and have been manufactured in sizes

larger than they could have been if made entirely from glass.

Satisfactory repairs of damaged glass linings have been possible, if the dam-

age is limited to small areas, either by the insertion of tantalum plugs, or by the

use of resin mortars.’ When damage is extensive, the fired lining is removed, usu-

ally by sandblasting, any necessary repairs are made in the steel shell, and a new

glass lining is applied and fired.

One of the principal advantages of glass-lined steel reactors is the ability to

heat (or cool) the unit externally. Jacketed reactors obviously are not possible

in masonry-lined equipment, so if internal heating is not desired, circulation of

the contained media through an external heat exchanger is necessary. The co-

efficient of heat transfer through the wall of an allglass vessel is between 6 and 8

Btu/hr/ft’/“F/in, while the coefficient of heat transfer through steel 11/16” thick

lined with a fired glass lining is between 98 and 123, depending on the type,

formula and firing of the glass.

123




Though there are many variant formulations for the glass frit used to coat

metal surfaces, at this time the amorphous borosilicate types appear to offer the

best resistance to corrosive chemicals. In general, such glass-lined vessels can ac-

cept all acids except HF and acid fluorides up to a surface temperature of 35O’F.

Very mild alkalis can also be handled at this temperature. As alkalinity increases,

maximum acceptable temperature decreases. Thus, at pH 12, the normal thermal

limit is 212’F. Deionized water can, especially at high temperatures, damage

glass linings, but salt solutions near the neutral point of the pH scale can be ac-

cepted up to the 35O’F limit of acid solutions.

If the glass type is shifted to crystalline glass rather than the amorphous

borosilicate, there is a decrease in chemical resistance, primarily in the extreme

pH ranges. Higher temperatures may, however, be accepted. Thus, crystalline

glass-lined vessels can handle molten salts up to the lOOOaF range, and depend-ing on other environmental conditions, even some molten metals, such as selen-

ium, gallium and zinc at temperatures as high as 145O’F.

In addition to the other advantages noted, glass-lined vessels are easy to

clean so that down-time between batches is greatly reduced and interbatch con-

tamination is virtually eliminated.

Why, then, with such excellent high temperature resistance and fine chemi-

cal resistance would anyone ever want to install a brick lining in a glass-lined ves-

sel? The answer lies, of course, primarily in the brittleness and poor impact resis-

tance of fired glass linings. If unprotected, they may be damaged by a blow, per-

mitting contained liquid to penetrate through the lining to the steel. Further, in

strong alkalis, there is a thermal limit of 212OF. But if we interline with 9” of

carbon brick and furan mortar in front of the glass, the vessel can be operated at

pH 12 and an internal temperature of 235’F, while having a surface temperature

on the glass lining of only about 173’F. Thus, too, if the operator were to drop

a heavy tool into the vessel, the carbon brick would protect the glass from crack-

ing or chipping-retaining its integrity as a membrane.

Unlike the chemical resistance tables that are available for mortars and plas-

tics which simply advise “recommended,” “not recommended,” or “test,” the

manufacturers of glass-lined equipment offer tables that indicate loss in thick-

ness of the lining per year in a variety of exposures. Table 1 l-l gives examples-

figures taken from graphs of one of the major manufacturers for a borosilicate

glass lining.

The criteria to be followed in designing a masonry inner liner for a glass-

lined vessel are basically the same as those to be observed with any other type of

membrane, except that greater care must be taken by the masons to preventdamage to the fired glass lining when installing the masonry. It is normal to ap-

ply a ‘/B” layer of ceramic fiber paper to the surface of the glass lining before

proceeding, not only as a precaution against damage when laying the brick, but

also to allow a shear plane for movement as the brick expands or grows. Out-

lets should be sleeved with fluorocarbon sheet sleeves. Such sleeves are necessary

so that the sleeve can permit movement of the masonry lining by deforming

without causing stresses in the masonry which could damage the glass at the out-

lets.



Fired Glass and Porcelain as Membranes 125

Table 11-I : Combinations of Concentrations and Temperatures

Showing Greatest Loss in Weight

Hydrochloric acid

Greatest

Loss at Boiling

Percentage- At Point

Concentration LX.S/YlZU Temperature of Acid

8 - 10% 0.1 nun 235OF 224-F

24 - 26% 0.2 mm 271'F 217OF

18 - 20% 0.5 mm 357'F 237OF

20% 1.0 mm 378OF 237OF

(Temperature - % - weight loss said to be fairly typical

Sulfuric acid

also for hydrobromic, hydriodic and chloracetic acids)

18% 0.1 mm 228'F 2260~

21% 0.2 mm 263OF 233°F

370 0.5 mm 333='F 241°F

28% 1.0 mm 407'F 237OF

(Also typical for sulphurous acid)

Nitric acid 35% 0.1 mm 252OF 232OF

31% 0.2 mm 290°F 230°F

33% 0.5 mm 360°F 232OF

36% 1.0 mm 415='F 233='F

(Also typical for nitrous acid)

Phosphoric acid (minimal c rrosive effect at low concentrations, more effect at high.

Tests only run to 85%. Indications are that above 85%, there may

well be areas of greater attack than those noted.)

62% 0.1 mm 19S°F 258OF

74% 0.2 Imu 245OF 290OF

60% 0.5 mm 298'F 255='F

62% 1.0 nun 35S'F 258'=F

Acetic acid (representative of a great number of organic acids)

30% 0.1 mm 292OF 212°F

6.5% 0.2 mm 342'F 212OF

7.0% 0.5 mm 410'F 212'F

6% 1.0 mm 442OF 212'F

Sodium hydroxide pH 10.0 0.1 mm 230°F ___

pH 13.6 0.1 mm 140'F ---

pH 10.0 0.2 mm 260°F ___

pH 13.6 0.2 mm 176OF ___

pH 10.0 0.5 mm 296OF ___

pH 13.6 0.5 mm 212OF ___

pH 10 1.0 mm 320°F ___

pH 13.6 1.0 mm 236'F ___

(Good for pH to 14 at ambient. Typical for alkali hydroxides.)

NaOH 4% by weight is pH 14.




Sodium carbonate

Greatest

Loss at Boiling

Percentage- At Point

Concentration Loss/Year Temperature of Acid

pH 12 0.1 Imu 176“F ___

pH 12 0.2 mm 202'F ___

pH 12 0.5 mm 24S°F ___

pH 12 1.0 mm 284'F ___

(Typical for basic alkali carbonates)

Funmonia pH 13

pH 13

pH 13

pH 13

Clean water * (de-ionized)

Bromine

Ferric chloride,10% solution

15S='F

Boiling

Monochloroacetic acid Boiling

20%

Oxalic acid

Phosphorous acid

70%

302OF

230°F

Succinic acid 392OF

saturated solution

0.1 mm 185OF ___

0.2 mm 226*F ___

0.5 Irun 279OF ---

1.0 mm 320'=F ___

0.1 mm 310'F -__

0.2 mm 345°F ---

0.5 mm 392OF ___

1.0 nun 425OF ___

Thickness loss min/year

Liquid phase Vapor phase

less than 0.1 less than 0.2



less than 0.2 ______



* It may not be understood by some readers that pure, de-ionized water can

penetrate many linings, and can, in some cases, cause more damage than 9

number of corrosive chemicals.

REFERENCES

1. Chemically ResistantA4asonry.W.L. Sheppard, Jr., 2nd Ed., p 213 (1982).

BIBLIOGRAPHY

Composite Engineering Laminates, edited by Albert G.H. Dietz, M.I.T. Press (Cambridge,

MA), See Chapter 16, Glassed Steel by William B. Crandall, pp 317-322.

Tanigawa, T. and Koizumi, K., Properties of Borosilicate Glass and Its Application to Cor-

rosion-Resistant Apparatus, Haikan Gijustsu, Vol. 2, pp 63-70 (1983).

Andrews, Andrew I ., Porcelanin Enamels; The Preparation, Application and Properties ofEname/s,Garrard Press,Champaign, IL (1961).

Lorentz, R., Glass Enamel-Efficient Protection Against Corrosion, Trib. Cebedeau, Liege,

Belgium, No.460,pp 111-115 (1982).



12

Lead as a Membrane

Oliver W. Siebert

Monsanto Corporation

St. Louis, Missouri




Chemical leads (defined by ASTM 829 as 99.85% minimum lead), some-

times called “soft lead,” are used primarily in the chemical industry in environ-

ments that form thin, insoluble, and self-reparable protective films over the metalsurface, e.g., solutions of salts such as sulfates, carbonates or phosphates. Against

more soluble films such as nitrates, acetates or chlorides, lead offers little pro-

tection.

Alloys of antimony, tin, calcium, tellurium and arsenic offer some improve-

ment in the mechanical properties of lead, but its usefulness is limited primarily

by its poor structural qualities. “Hard lead” is lead alloyed with 1 to 13% an-

timony, usually about 6 to 8%. These alloys have greatly increased tensile strength,

fatigue resistance, and hardness. Calcium in the range of 0.03 to 0.12% forms

age-hardening alloys with lead. While these alloys age-harden at room tempera-

ture, that aging process might take 30 to 60 days. The tensile strength and stress-

rupture resistance of the lead-calcium alloys may be improved by the addition

of about 1.5% tin. However, this increases the aging time to 180 days. A 7% tin

addition to lead is used to make bearings. Tellurium lead is chemical lead to

which about 0.04% tellurium has been added. In wrought, and especially ex-

truded lead products, the addition of tellurium retards grain growth and in-

creases fatigue resistance. Arsenic, antimony, and tin act to harden lead and im-

prove its physical characteristics up to about the boiling point of water. Some

127




grades of chemical lead have small percentages of silver and copper added to en-

hance the corrosion resistance and to improve its creep and fatigue resistance.

Lead, a heavy metal, has a low melting point and a high coefficient of ex-

pansion. It is a very ductile material that will creep under a tensile stress as low

as 1 MP (145 lbf/in’).

Because of its relatively poor room temperature creep resistance, lead is

rarely used as a lining in tanks and other process equipment without some sec-

ondary support system.

It is possible to lead-line wood stave tanks but this is not a desirable applica-

tion. Unlined wood tanks depend upon moisture in the process fluid to swell the

wood and maintain the tight fit of the joints. When lined with lead, the wood

staves dry and shrink. The hoops then have to be tightened to maintain struc-

tural integrity. This movement can cause damage to the lead lining.An open steel basket-frame type construction can be used to overcome

some of the problems noted with the use of lead lined wood vessels. Sheet lead

straps are wrapped around the horizontal and vertical structural steel supports.

The lead sheets are formed and weld attached to the noted straps. This type of

construction is advantageous because it may be thoroughly inspected while in

service. Faults are apparent and repairs easily made.

The most common practice is to line the steel vessel with lead as a corrosion

resistant membrane barrier behind a ceramic brick or tile lining. The brick acts as

a mechanical support for the lead as well as a thermal and wear resistant barrier

to protect the weak soft lead from damage.

Tanks may be lead-lined by either the loose (“hung lead”) or the bonded

(“homogeneous”) techniques.

After removing all weld beads, burrs, and other projections from the inside

of the steel tank, the sheet lead is applied to the wall. It should be lapped over

the top edge of the vessel and each sheet extended about 4 inches over those

adjoining. The sheets should be welded together around the entire exposed edge.

After the lead has been installed and tested, a layer of asbestos, ceramic or glassfabric or similar material, %6 to ‘1s inch thick, is added to act as a cushion be-

tween the brick and the lead to protect the lead against abrasion during expan-

sion and contraction due to thermal changes.

A bonded lead lining is an effort to combine the corrosion resistance of lead

with the superior structural strength of steel. Effectively, bonded lead is a layer

of lead bonded to the steel to form a homogeneous or integral metallic structure.

By effectively anchoring the lead to steel at all points of contact, relative move-

ment between the two metals is minimized. The most common method of bond-

ing includes a step by which the steel is “tinned.” Following sand or grit blast-

ing, chloride of zinc, zinc-ammonium chloride, stannous chloride or other flux

materials are applied to the cleaned surface. This is followed by a torch applica-

tion of a 50/50 lead/tin solder. To apply hard or soft lead by means of a torch,

the heat is applied to the tinned steel only long enough to melt the tin coating,

after which the torch heat is applied to the lead being applied. Usually, three

coatings will build the lead thickness up to about ‘/4 inch. This same operation

can be done without the pre-tinning step by using a 6% antimonial lead on the

first coat application.

A more uniform thickness of lead may be achieved by holding a portable



Lead as a Membrane 129

dam a distance away from the prepared surface corresponding to the desired

thickness of the lead lining. Molten lead is carefully poured onto the heated wall

and dam. The dam is moved, and the operation repeated until the entire vessel

is lead-lined. This technique is not unlike that of a concrete slip-form used in the

construction of silos.

Sheet lead linings, at elevated temperatures, in addition to being subject to

accelerated corrosion, tend to fail by some uncertain process, though not crys-

tallization, causing embrittlement and/or inter-granular penetration, at tempera-

tures above 165°F (73°C). If the vessel is to be exposed to such temperatures, a

brick lining of a thickness to provide sufficient insulation to bring the shell tem-

perature below this temperature is advisable. Figure 12-1 shows how such a brick

lining may be installed. Note the layer of asbestos (now usually ceramic) paper

between the lead and the brick, which paper functions to allow movement of the

brick without seizing or abrading the lead.

Asbostoashootl in lmg

1: in. 0, h in. no qaakr fhaa f in.

Lhnt OTbondedI*rr)

kod l in ing

Waldho _

Acid proof br ick

hood

r id . rbod cowr ing

Figure 12-1: When pressure is involved brick and lead lined tank bottoms are dished. Cour-

tesy of Lead industries Association.

Lead linings are most frequently found in the process equipment designed

for sulfuric acid manufacture. As noted at the beginning of this chapter, this

type of membrane is not indicated in exposures where the product of the reac-

tion between the lead and the process chemicals is water soluble.

Figures 12-2 through 12-5 show the increases in the corrosion of lead mem-

brane by various acids and mixtures of acids as temperatures rise. When lead is

exposed to nitric acid, lead nitrate is formed. The resistance of the lead to fur-

ther attack by the nitric acid depends on the solubility of this lead nitrate layer

in the nitric acid, and this solubility in turn decreases with the increase of nitric

acid concentration. This change in solubility is plotted in Figure 12-6.




PER CENT SIJLFURC ACID

Figure 12-2: Corrosion of lead by sulfuric acid as a function of temperature. Courtesy of

Lead Industries Association.

toe

.ool

.Oooo 20 40 SO 80 Km 120 IA0 I60 180 :

TEMPERATURE OF SOLUTION: C.

Figure 123: Effect of temperature on lead in sulfuric acid. Courtesy of Lead Industries

Association.



L e a d a s a Me mb r a n e 1 3 1

: OR ROS l ON, . / MONl N X I O- 4 COR ROS I ON, XL / MONl N X1 0 - 4

150 150

I25 I25

100 100

75 75

50 50

25 25

004 O0 60 80 100

TEmmmJK “C

Figure 124: Courtesy of Lead Industries Association.

: ORROS I ON, H. / MONT H X 1 O- 2 CORROS I ON, N. / MONTH X l o - '

I 6

I

I 6

CORROSION OF LEAD

BY MIXED ACIDS

2 0 I6F cm’ " 2 7

4 0PERCENTNCI

Figure 12-5: Corrosion of lead in mixed H$.O~and HCI. Courtesy of Lead Industries As-

sociation.




PttTI Pb (WO,,,/#o ?ttTs W. PAtlS Ib (MO~)2/100 ?MTS Sm.

70

__..-.-SOLlJBlLllY OF LEAD NITRATE- 60

[f’b(NO&] IN NITRIC ACID.

SO

40

--.---..---- -__. 30

20

0 IO 20 30 40 50 60’

HMO% CONC1NTRATtON. PER CENT

Figure 12-6: Solubility of lead nitrate in nitric acid. Courtesy of Lead Industries Asso-

ciation.

A brick lining has the secondary effect of protecting the lead from abrasion

by contained slurries or suspended matter. The protective surface film of insolu-

ble salts can be thinned or removed by such abrasion, and so the resistance to

acids seriously affected. Figure 12-7 shows graphically how the velocity of a 20%

sulfuric acid solution at 77OF, without any entrained solids, passing over the face

of a lead lining can cause increasing corrosion as velocity increases.

0040

:0035

8<.cmo

3

:f

0025

.

5 0020F

:tw OOlS: \ I

A’ ‘mx n$.o. 01 S.Ca“0 .oolO

_/.-

K2

/’

.mOS./

/+,“‘a

xx)00o 40 80 120 I6o 200 240 280 320 560 400 440

“ELOClTY OF SOLUTION ACROSS SURFACE - FEET/MINUTE

Figure 12-7: Effect of velocity on corrosion of lead in 20% sulfuric acid at 20°C. Courtesy

of Lead Industries Association.



Lead as a Membrane 133

For detailed information about lead Jinings, their physical properties, and

chemical resistance, the reader is referred to Lead for Corrosion Resistant Ap-

plications: A Guide, published by the Lead Industries Association, Inc., New

York, NY.

Caution. Lead is an electrically conductive material. The designer should be

careful not to place carbon brick and/or carbon-filled mortar in contact with or

very close to lead linings where the service includes an electrolyte in solution, as

lead and carbon will form a galvanic couple, with the carbon as anode and the

lead cathodic. This will result in the wasting of the lead. If carbon brick or car-

bon-filled mortars are to be employed in the same design, an electrical insulating

barrier should be placed between them and the lead. Such barriers may be

Teflon@ or other fluorocarbon sheet, a thick layer of a carbon-free, chemically

inert mortar, or a thick layer of ceramic or organic fiber.



13

Glass Fabric Reinforced Furan Membranes




While it is probable that much of what follows can be applied to most glass-

reinforced built-up membranes employing other resinous materials, the furan

(and perhaps occasionally phenolic) resins are those most appropriate to be used

in the most difficult, high temperature services where exposures can be combina-

tions of acids and/or alkalis mixed with organic solvent materials. The installa-

tion of this kind of membrane is labor intensive and furan resins have the best

overall resistance to the majority of such combinations. In the United States,

furans are generally the least expensive of those resins used in chemical service

and so, all things being equal, furans would normally be the first choice for this

type of service with phenolics next, if the solvent materials are particularly ex-

otic, or possibly a vinyl ester or polyester if the corrosives are too strongly oxi-

dizing for either a furan or a phenolic.

The use of glass fabric-reinforced furan membranes was pioneered in the late

1940s for service in chlorinating process equipment operating under high pres-

sures at 200°F, in the presence of HCI and organic solvents. It worked out well,

and though much more expensive to install and requiring a higher degree of ex-perience and care to install correctly, it has become a standard for use in expo-

sures where no satisfactory sheet lining (other than the very expensive fluoro-

carbons) has been found.

The membrane itself must be more resin-rich than are brick mortars made

from the same resin because if it is to wet out and penetrate the fabric, the resin

formulation must be more fluid than a mortar would be. This, of course, means

that there will be more shrinkage in the finished membrane than with the mor-

tars, and except from the stability and strength imparted by the glass fabric, a

134



Glass Fabric Reinforced Fur-an Membranes 135

higher coefficient of expansion. The glass fabric itself has a very low coefficient

of expansion. While the thermal expansion of the membrane as a whole is the

sum of its two parts, the fact that the two parts vary so much in this regard cer-

tainly results in built-in stresses within the membrane.

Glass fabric-reinforced membranes have coefficients of expansion double

those of the steel or the concrete surface to which they may be bonded, and

probably three times that of the brick lining or facing over the membrane.

Sandwiching a high coefficient material between two low coefficient ones can be

a source of real trouble, if the high coefficient material is bonded to both sur-

faces, especially since the two surfaces will be at different temperatures and do

not have identical coefficients of expansion. Sooner or later these stresses can

result in rupturing the membrane. However, this type of built-up membrane

must be bonded to one strong surface if it is to survive. The designer has the op-

tion of bonding it either to the substrate, or to the brick that will be placed on

it. Whichever he decides to do, he must put a bond breaker between the mem-

brane and the surface to which it is not to be bonded. For example, he may de-

cide, in lining a concrete tank, to use a bond breaker between the concrete and

the membrane, and to lay up the brick lining directly against the membrane us-

ing a strong bonding furan bed joint, so that the membrane becomes integral

with the brick lining. This can be done by applying a glass fabric-reinforced hot

asphalt membrane YI” thick first on the concrete and then building up the resinmembrane upon it. If this is done, and the concrete subsequently cracks (per-

haps over a cold seam), the asphalt will provide a slip-plane and prevent the rigid

resin membrane from cracking as well. if the membrane had been bonded to the

concrete, and the concrete cracked, the crack would have telegraphed right

through the membrane. If the membrane cracks, the chemicals from which the

membrane was designed to protect the substrate, can pass right through the

membrane and attack the concrete. Furthermore, concrete is absorbent, so the

entire structure can be penetrated and attacked. Therefore, in lining a concrete

vessel, this writer prefers to anchor the lining to the brickwork rather than to

the substrate.

The reverse is usually true with a steel tank. Here we have as a substrate a

stable structure of high strength. To install the resin glass fabric membrane in a

steel tank, we first sandblast the steel to a near white surface, and then apply a

special adhesive primer, selected for the strength of its bond to steel, and its abil-

ity to develop a high affinity for the resin-glass fabric membrane that is to be

laid up on top of it. After the membrane has been completed andcured, we ap-

ply a bond breaker over it, such as a liquid neoprene or urethane coating, per-haps ‘/a” thick, not only to prevent the bonding of the brick to the membrane,

but to provide a thick enough pad to prevent the brick-slipping over the mem-

brane-from hanging up on any high points and causing the membrane to tear.

The selection of the resin is made in the same manner as the selection of the

brick mortar, covered elsewhere in this volume, with the exception that the

binder of the membrane must be a resin-not a silicate or a sulfur-and the order

of choice is, first, the lowest possible shrinkage furan, then a phenolic and, fi-

nally, only if one of these two is unable to handle the chemical exposure, a

vinyl ester or a polyester.

The usual reinforcing fabric is an open weave, light twist, lightweight glass




cloth. A glass mat is not acceptable reinforcing because it has no tensile strength.

There are varying specifications for this cloth, suggested by a number of differ-

ent installers and users. The following is one that has been found to be satisfac-

tory.

Minimum Maximum

Average dry weight 1.4 oz/yd2

Average weight after treatment 1.6 oz/yd2 2.6 oz/yd2

Average tensile strength (both

directions) at 7O’F 75 psi

Thread count-warp 20 24

-fill* 20 24

*A count of lo-12 is acceptable if the fil l thread has double the tensile

strength of the warp.

This specification is ASTM D-l 668-73, Type I I I (organic resin treated) and

was developed by Committee D-8 primarily for roofing and waterproofing. This

committee is not concerned with chemically-resistant material, and no other

standards handled by this committee are applicable to the subject of this book.

It should be noted that ordinary glass cloth cannot be wet very well by resin

mortars. If delamination is to be prevented, most glass fabric requires a special

treatment. Until fairly recently, when glass fabric was to be used with a furan

resin, a “Volan A” treatment was specified. This material was, the writer is in-

formed,l a chromeorganic complex. The “Volan” material is no longer avail-

able. Current treatments of glass to be used with synthetic resins involve the use

of silanes. There are many different silanes, and it is important to use the correct

one if satisfactory results are to be obtained. These are specific treatments rec-

ommended where the glass is to be used with epoxies, and different ones for

polyesters and vinyl ester. I am informed’ that the ones specified for the poly-

esters, but not those for the epoxies, will also function in contact with furan

resins. No treatment is identified for glass to be used with phenolics, and if this

is required, tests should be run. The glass manufacturer can supply guidance in

the determination of the specific treatments for all other resins.

If hydrofluoric acid is present in the environment, obviously glass fabric

will not serve. In such cases, reinforcement for membranes, whether resinous or

asphaltic, is usually a polyester-type cloth. Where the service conditions are out-

side the limits of polyester fabric (for instance, too high a temperature or a sol-

vent that attacks polyesters), a carbon fabric cloth may be used.

The following is a suitable specification for the polyester fabric:

Dacron polyester cloth reinforcing.

“Nexus Veil” Style 1012 fabric manufactured by Burlington Industries

from Du Pont Dacron #IO6 yarn

Source: Barton Plastics, 170 Wesley Street, South Hackensack, NJ 07606

This is a square woven fabric, coarse open weave. 1.3 oz/yd, 16 mils

thick, used in 1 to 3 plys or layers.

In continuous exposure to high concentrations of strong alkalies, neither



Glass Fabric Reinforced Furan Membranes 137

glass nor polyester fabric is suitable, or there may be solvents present that will

destroy polyester fabrics. In such cases, carbon fabric is recommended. A suit-

able one is offered by the Union Carbide Corporation.

Catalog No. X2215 VCA Carbon Cloth

Width 43-45 inches

Weight per linear yard-O.58 lb (10 oz)

Carbon assay 95%

Will burn in air at approximately 39O’C (734°F)

INSTALLATION

In glass fabric reinforcing a monolithic surfacing (after applying the required

primer), a layer of the topping formulation is spread, 3&l’ to l/s” thick, and

the glass fabric is rolled or pressed into it, covering areas as large as is convenient

to the application, up to the size limits indicated by the manufacturer of the ma-

terial. However, in applying a furanglass reinforced membrane for chemical ser-

vice, it is recommended that a “checkerboard” system, consisting of areas not

greater than 3’ x 3’. be installed, one square at one time, leaving a 2” wide spacearound each. The mortar (in a thinner than brick mortar consistency) is trow-

elled over the square, tapering down the edges, and a square of glass fabric is

carefully placed on it, rolled flat over the mortar, then rubbed and worked with

the hands until the entire white surface of the glass has become black with resin

soaking through it from the other side. Then the next square, 2” away, is laid in

the same manner.

These squares of mortar with the glass cloth over each, are allowed to “cure”

undisturbed for no less than seven days at a surface temperature of 70°F (14

days if the surface is at GOOF-the minimum cure temperature permissible). At

the end of that period, the 2” wide open strips between the squares are mor-

tared and cloth covered in the same manner, lapping the cloth 2” over the pre-

viously placed squares. (For this part of the work, 6” wide strips of glass cloth

are used, and the mortar is extended from the 2” wide bare strip, 2” over the

tapered edges of the squares.)

Another seven days’ cure is recommended at this point, if this is possible.

However, if down time is vital, this may be reduced to an absolute minimum of

three days at 7O’F. After the cure time has elapsed, a final overall application of

the furan mortar, 3/s2” to l/s” thick, is trowelled to as uniform a surface as pos-

sible.

The reason for the procedure as outlined is the cure shrinkage of the resin,

somewhat larger than that of most other synthetic resins, and the fact that this

cure shrinkage continues over an extended period, developing internal stresses

in the membrane material. Failure to follow this procedure can result in the de-

velopment of stress cracks in the membrane system, perhaps as long after appli-

cation as one year, due to the continuing build-up of stress in the resin as itcures. By limiting applications to 3’ squares and permitting seven days’ cure be-




fore putting in place the patches between squares, about half of the cure shrink-

age will have taken place before the patch is placed, and the stress build-up will

be much less.

This cure shrinkage stress build-up is another point favoring the applicationof this type of membrane over a hot asphalt membrane on concrete. The as-

phalt has sufficient cold flow to relieve much of the stresses in the resin squares

during the 7day cures.

The designer should note that if this type of rigid membrane is used, it will

be because no flexible membrane can accept the exposure to the anticipated

chemical environment. Therefore, there is no flexible expansion joint material

that can accept this exposure either. Consequently, any vessel that must be lined

with such a membrane should be so designed that no expansion joints are re-

quired. For such design, see the section on design elsewhere in this volume.

REFERENCES

1. Source of information: Mr. Albert Ralston.

2. Source of information: Mr. Harvey Atkinson.

3. Chemically Resisrant Masonry, W.L. Sheppard, Jr., (2nd Edition) Marcel Dekker, pp

208-212 (1982).



14

EpoxylPhenolics

Al Hendricks

Wisconsin Protective Coatings

Green Bay, Wisconsin

An epoxy/phenolic is a class of material that exhibits outstanding chemical

resistance due to the cross linking that is formed between the reaction of a bis-

phenol with epichlorohydrin and the phenolic/phenol-formaldehyde resin. These

materials can be formulated to be applied at various film thicknesses from 1 mil

to % inch depending on their end usage.

PROPERTIES

Epoxy phenolics can be classified into two classes of materials; bake or

air dried.

The bake systems polymerize by heat generally requiring temperatures

which range between 350° to 400°F (177’ to 204°C). This type of formula-

tion is normally applied by dip or spray application to a film thickness ranging

from 1 mil to 8 mils. Generally, this system produces a very hard finish although

they can be formulated to produce a degree of flexibility, such as those systems

used for container liners.

Air dry or low force cured systems utilize either amines, amine adducts, or

polyamide curing agents for polymerization. They can be formulated for spray,

brush, roller or trowel type applications. Since these materials do use a catalyst

to obtain curing, they will have a limited pot life. This can vary from one-quarter

hour to 24 hours depending on the type of catalyst utilized and the amount of sol-

vent in the formulation. Systems vary in their solvent content generally from 60%

to 0% solvents. As the solvent decreases, the pot life also decreases substantially.

1 3 9




RESIST ANCE

The chemical resistance of epoxy phenolics varies with the formulation de.

pending on type of resins and percentage of modification, total volume of pig.

ment, and type of curing agent used .

Water Resistance

Excellent resistance is normally experienced with epoxy phenolics in var-

ious types of water including potable, demineralized, or deionized, at tempera-o

tures up to 250 F. They also demonstrate resistance to steaming which may be

required for sterilization or general cleaning.

Solvents

The baking systems have excellent resistance to alcohols, aromatics, hydro-

carbons, aliphatics, and ketones. Special formulations with both the air dry or

low force cure type materials can be produced to provide resistance to the same

solvents as the high bake systems. Many of the air dry systems will be resistant

to splash and fumes of the solvents mentioned .

Alkalies

The bake systems demonstrate excellent resistance to alkalies including

sodium hydroxide at concentrations up to 73%. Generally the temperature

resistance to continuous immersion is suitable up to 200°F (93°C).

The air dry systems demonstrate excellent resistance to various concen-

trations of alkalies but are generally limited to a maximum temperature of

150°F (66°C).

Acids

The acid resistance of epoxy phenolics to continual immersion conditions

would generally be poor to fair. Special formulations are available to provide re-

sistance to dilute sulfuric, hydrochloric, nonoxidizing mineral acids, and fatty

acids. Many systems are available for resistance to spillage and fumes from most

acids with the exception of nitric, formic, chromic or hydrofluoric.

Temperature Resistance

Continuous exposure to temperature conditions in excess of 300°F can be

detrimental to many of the formulations. Excessive temperature will normallyresult in cracking of the coating system.

Abrasion Resistance

The abrasion resistance of epoxy phenolics will vary depending on the for-

mulation, but they generally are rated between good and excellent. Special for-

mulations can produce films which are resistant to continual scuffing or heavy

truck traffic .



141Epoxy/Phenolics

and impact when exposed to weathering, although they do have a tendency to

chalk.

TOXICITY

Formulations are available that will not impart taste or odor to commodities

that may be stored in direct contact with the coating systems. These systems

must then meet the requirements as are outlined by the FDA, USDA or EPA.

SURFACE PREPARATION

Surface preparation depends on coating formulation and intended usage.

This could vary on steel substrates from a commercial to a white metal blast.

Profile is also essential to obtain ultimate adhesion. The depth of profile re-

quired is proportional to the total dry film thickness of the coating system.

On concrete surfaces, the general requirement is to remove latents and con-

taminants and this can be accomplished by chemical preparation, scarifying

or abrasive blasting.

APPLICATION

Formulations are available for application by dipping, spraying, brushing,

rolling or troweling. The dipping application is normally limited to the baking

systems since they do not require a catalyst for polymerization. The spray equip-

ment may consist of either conventional air atomization, airless or two compo-nent mixing. Trowel applications are limited to the 100% solid flooring or lin-

ing systems.

USAGE

Bake Systems

Generally used to line containers for food and paint products-heat con-denser tubing-railroad tank cars and storage vessels containing various com-

modities including sodium hydroxide and various solvents.

Air Dry Systems

Generally used to line the interior of railroad tank cars and storage vessels

containing food commodities such as sugar, corn syrup, wine, and other bever-

ages-chemical vessels containing sodium hydroxide, solvents, salt solutions-ex-

terior of vessels and air moving devices exposed to fumes of acids, alkal ies andsolvents-concrete floors and trenches exposed to spillage of acids, alkalies and

solvents.

Weathering

Epoxy phenolic formulations generally show good retention of flexibility



Section IV

Masonry Units

143



15

Acid Brick and Silica Brick

James P. Bennett

U.S. Bureau of Mines

University, Alabama

William M. Eckert

Dow Chemical Corporation, U.S.A.

Freeport, Texas

ACID BRICK (RED SHALE AND FIRECLAY BRICKS)

Properties

Early use of ceramics to handle or store liquids can be traced back thou-

sands of years to terra-cotta wine vessels and sewer pipes. Chemical-resistant ves-

sel liners evolved through the use of metal, sandstone, granite and stoneware to

the present day red shale and fireclay brick. These acid-proof brick were devel-

oped for chemically-resistant masonry use in direct contact with most acids, ex-

cept hydrofluoric, and for limited alkali exposure. They are made primarily

from clays or shales fired to high temperatures, forming a semivitreous structure

that imparts low water absorption and high chemical resistance. Clays or shales

used to make red shale brick give them their reddish hue, being higher in iron

and silica than raw materials used in fireclay brick, which are buff in appearance

and higher in alumina content. The main function of acid brick is to provide a

barrier to abrasion and to shield membranes or other structures under them from

chemical attack or excessive thermal exposure. Due to the porous nature of such

brick, they are usually backed by an impermeable material.

The manufacturing processes for red shale and fireclay brick are very simi-lar. One of three shaping techniques is used in brick fabrication: extrusion, dry

144



Acid Brick and Silica Brick 145

pressing, or hand molding. The clays or shales are crushed, mixed with water in

a muller-type mixer, pugged, de-aired, and extruded. A coarse, nonplastic ma-

terial such as sand or a calcined raw material (grog) may be added during mixing

to control shrinkage or warpage during firing. The extruded material is wire-cutto size, with surfaces occasionally scored or textured to increase mortar adhe-

sion. After extrusion, some manufacturers re-press the brick before drying and

firing to increase dimensional accuracy. Bricks are then fired in either a periodic

or a tunnel kiln in an oxidizing atmosphere. Red shale is typically fired from

1800’ to 2100°F while fireclay may be fired as high as 23OO’F. After firing, red

shale usually is more vitreous and resistant to abrasion and erosion, but poorer in

thermal shock resistance, than fireclay.

Of the other techniques used to fabricate brick, dry pressing provides ac-

curate dimensional control, while hand molding is generally used to fabricate

small quantities of specialty shapes and can result in a more porous piece.

The lower firing temperatures, higher glass content, and lower absorption

generally associated with red shale brick are due to larger amounts of alkali and

iron compared to fireclay, as shown in Table 15-I. Iron content averages over 6%

for red shale, and combined KzO and NazO are over 4%. Also, SiOZ content is

higher and A1203 lower than fireclay.

The crystalline mineral phases present in red shale and fireclay brick are also

listed in Table 15-l. The firing time and temperature determine the degree ofconversion of the starting materials into glass and other phases that provide the

desired physical properties. Both brick types contain similar amounts of quartz,

mullite, and an amorphous (glass) material. The higher firing temperatures of

fireclay can produce a cristobalite phase not present in red shale. Hematite and

rutile exist in the red shale after firing, and both can be leached in certain proc-

ess environments.

Table 15-I: Ranges of Chemical Composition and Mineralogical Phases

Present in Acid Brick (Red Shale and Fireclay)

Property

Chemical composition, Wt %

SiOl

A1203

Fe203

K2O

TiO2

MgO

Na20

CaO

Phases identified

Quartz

Mullite

Cristobalite

Hematite

Rutile

Amorphous

Red Shale

Brick

61.4-67.0 56.868.6

18.6-29.4 22.9-38.7

4.7-6.8 0.8-3.0

2.5-4.6l-3.2

1 .0-l .6 l-2.8

0.7-l .3 0.1-I .2

0.5-0.7 0.2-0.5

0.1-0.4 0.01-0,8

Major

Trace-major

None

Minor

None-trace

Fireclay

Brick

Trace-major

Minor-major

None-major

None-trace

None-trace

Minor-major




The physical properties of red shale and fireclay brick, listed in Table 15-2,

along with chemical composition and mineral phases, determine the brick’s ap-

plication. Generally, red shale is slightly lower in porosity and absorption and

higher in modulus of rupture, cold crushing strength, and bulk density thanfireclay. The red shale brick also has a higher acid resistance, (ASTM C-279l-

H,S04 test) but poorer thermal shock resistance than fireclay brick. Limited in-

formation is available on thermal conductivity, thermal expansion, and modulus

of elasticity and is listed for each brick type in Table 15-2.

Table 15-2: Physical Property Ranges of Acid Brick

(Red Shale and Fireclay)

Property

Apparent porosity, pet

Absorption, pet

Bulk density, lb/ft3

HzS04 acid resistance (C-279), pet

Modulus of rupture, psi

Compressive strength, psi

Thermal conductivity,*

Btu .in/hr.ft’.OF

Thermal expansion coefficient,”

(75”to 8OO’F). in/in “F x 10”

Modulus of elasticity,* IO6 psi

Red ShaleBrick

3.2-12.5

0.4-5

142-156

0.7-6

2 ,ooo-3,800

10,000-22,000

7-9

4-5.5

3.6-13.3

*Limited information available.

FireclayBrick

5-l 3.3

l-6

136-l 50

3-10

1 ,l OO-3,500

5,000-18,000

6-l 0

2-3.5

3-10

Some acid brick develops black coring during production, which may af-

fect brick properties. Black coring is due to incomplete oxidation of carbona-

ceous material during firing, possibly caused by dense kiln stacking or a fast fir-

ing schedule. The core is associated with unburned carbon or iron in a low val-

ence state. Debate has existed in the past as to the effect of black coring on

physical properties. ASTM C-279l includes a statement in its test description

mentioning that black coring may not be a significant factor in brick properties

unless accompanied by bloating and lamination. (Brick having black hearts but

otherwise meeting the physical requirements of ASTM C-279, C-980 and C-410

may provide acceptable performance.)

Volume expansion (also known as irreversible growth or swelling) of acid-

proof brick is a phenomenon causing a dimensional increase over time, and isgenerally thought to be similar to moisture expansion observed in structural

clay products. Firing conditions, exposure environment and brick porosity and

chemistry all affect the amount of swelling that can occur with brick from dif-

ferent manufacturers. Unrestrained linear expansion of up to 0.2% or higher

can occur, although typical expansion of a brick in use has been found to be

less than predicted.2 If a vessel is not properly designed, constructed, or utilized,

swelling stresses may cause the brick to heave off of the flat surface of an im-

permeable membrane backing, or exceed the compressive strength of a con-

toured system.

Brick volume expansion versus time is parabolic, with initial swelling usually



Corrosion and Chemical Resistant Masonry Materials Handbook

t-

J-

?

I-

3-

150Red shale A

KEY

q 20 wt pet HCI

n 30 wt pet HCI

L”” ‘O&O 701 I”” 70&o 74

Red shale B Fireclay A

Figure 15-1: Total ions leached from acid brick samples in 110 days of HCI exposure.

KEY

Hz40 wt pet HNOs

I= 60 wt pet HN03

Red shale A Red shale B Fireclay A Fireclay B

Figure 15-2: Total ions leached from acid brick samples in 110 days of HNO3exposure.




and reactors have these materials as their protective lining. Acid brick performs

well and costs much less than other ceramic materials or corrosion resistant al-

loys. Red shale and fireclay can be used very successfully as materials of con-

struction provided their respective uses and limitations are understood.Chemical Resistance: As the name acid brick implies, red shale and fire-

clay are generally resistant to organic and most inorganic acids at temperatures

generally encountered (with some exceptions, such as HF). Under acidic condi-

tions, fireclay is preferred to red shale when discoloration of a contained chemi-

cal is to be avoided. Fireclay does not have as high an iron content as that which

can leach out of red shale and so does not affect product color. Acid brick is also

resistant to chlorine, organic solvents, and many other chemical reagents. Expo-

sure to alkali caustics or strong concentrations of alkali hypochlorites are to be

avoided. Note that various chemicals in combination can be more aggressive

than the same chemical individually. For example, HCI becomes an oxidizing

acid when chlorine is present. This is one reason why specific chemical concen-

tration limits cannot alone determine serviceability in all exposures. It should

also be noted that the chemical resistance and physical properties of different

brands of red shale and fireclay acid brick are not the same. Clays, firing tem-

peratures and kiln time may vary with different manufacturers, or even with the

same manufacturer. If time and facilities permit, tests should be set up to evalu-

ate performance of specific brick prior to installation.Temperature Limit: The maximum use temperature of these materials var-

ies. Cyclic conditions, lining thickness, physical load, and the brick’s physical

properties can affect it. For continuous operation, red shale can be used up to

16OO’F while fireclay can be used to approximately 18OO’F. However, general

practice should limit both red shale and fireclay to a maximum temperature of

550°F under cyclic conditions. This temperature might seem low at first. There

are several reasons for this. One is that these materials generally have a high mod-

ulus of elasticity and low porosity, especially the red shale. Also their thermal

conductivities are relatively low (6-10 Btu-in/h-ft2-OF). As a result, thermal stres-

ses can cause damage when conditions fluctuate too quickly. These materials

lack the ability to absorb and relieve internal stresses effectively. Fireclay tends

to be slightly more resistant to thermal shock, mainly because of its microstruc-

ture and overall lower thermal expansion. Its microstructure usually has less

glassy phase bonding the brick together, and higher porosity than shale. Another

reason to avoid higher temperature cyclic conditions in some brick depends on

the brick’s mineralogical composition. Alpha quartz is the major crystalline form

of silica in red shale and most fireclay acid brick. At 1063’F, the alpha quartz

phase can transform into beta quartz. This results in a volume increase for that

phase and causes additional stress within the brickwork. The reverse reaction

takes place when the temperature drops below 1063OF. Other crystalline forms

of silica (ex., cristobalite) might also be present in fireclay. These have lower in-

version temperatures and higher volume expansions which can add to the cyclic

temperature problem.

Pressure Effect: Rapid pressure changes can also cause problems with both

materials. Under operating conditions, liquid permeates-into the brickwork. Ifthe pressure inside a vessel decreases suddenly, the liquid trapped within the

brick may try to expand. This rapid expansion can generate critical stresses, and




cracking or slabbing can result. If cyclic pressures pose a problem, another more

porous material (e.g., carbon brick) should be veneered over the acid brick or

substituted for it.

Irreversible Growth: Under certain conditions, red shale and fireclay brick

actually increase their overall dimensions, exhibiting irreversible brick growth.

The growth rate depends on moisture conditions. Wet environments cause the

most rapid rate of expansion, with growth usually occurring within two years.

Several more years are needed if the conditions cycle between wet and dry. Nor-

mally, irreversible growth is not observed when conditions are dry. The amount

of growth varies between brands and production runs. The average growth is

0.16%, but larger increases are not uncommon. Brick linings that are restrained

in an arch configuration do not exhibit much expansion. Once minor growth has

occurred, sufficient back pressure is generated to inhibit further swelling. The

majority of problems are associated with brickwork that is not fully restrained-

floors, trenches, baffle walls, etc. The brick can heave upwards, bulge or actually

fall out. Expansion joints must be incorporated into the system to accommodate

the growth. However, many times expansion joints can be the weak point of a

corrosion proof system. When designing an acid brick system, it is desirable to

try to utilize the concept of restraint to limit the growth factor. For example,

structural walls can be bowed outward (away from the center-continuous

curve) corner to corner instead of straight. Towers which have bricked sidewalls,but an unlined head, should make use of a retaining ring to keep the brickwork

in compression.

Dimensions: The dimensions of fireclay brick may differ from red shale’s.

Fireclay sizes can be modular (9” x 4.5” x 2.5” or 3”) or the same as red shale

(8” x 3.75” x 2.25” or 4.5”). Fireclay acid brick tends to be more dimensionally

true than red shale and is available in a wider variety of masonry shapes (domes-

tically). Fireclay is also used to fabricate many tower intervals such as packing

supports, saddles, spargers, and feed boxes to name a few.

SILICA BRICK

Properties

The use of silica brick in chemical-resistant masonry is limited, because of

high cost, to applications requiring a h.igh degree of chemical resistance where

traditional acid brick cannot be used, such as concentrated phosphoric acid free

of fluorine. Silica brick, however, cannot be used in strong alkaline exposures or

any concentrations of hydrofluoric acid. As with acid brick, its main function is

to provide a barrier to abrasion and to protect other membranes or structures

from chemical attack. Because brick porosity may be as high as 16%, silica brick

is backed by an impermeable material and a support structure.

Early chemical-resistant masonry usage of silica bricks employed them as re-

fractories for steel furnace or coke oven applications. Typically these bricks had

up to 3.5% flux additions (usually CaO), promoting bond formation at lower fir-

ing temperatures.Silica brick of higher purity and improved low-temperature thermal shock

resistance has been developed for acid-resistant usage. These materials are man-




ufactured with SiOs levels approaching 100%. A typical brick uses high-purity

silica, such as the mineral quartzite, that has been mined and washed to remove

impurities. The silica is then fired to a high temperature into a vitreous structure.

The prefired material is crushed and graded to the desired particle size andmixed with an organic binder, water, and in some cases, a flux. The mixture is

shaped by dry pressing, although specialty shapes may be slip cast or air rammed.

The bricks are dried and then fired in a tunnel or periodic kiln at about 1850°F,

promoting intergrain bonding. Care must be taken in firing and in brick usage to

avoid temperatures above about 2000°F, where quartz and cristobalite trans-

formations can occur in the highly vitreous brick.

Chemical analysis of silica brick is listed in Table 15-3. Silica is the major

constituent, with less than 0.5% AlsOs or Fe,Os and less than 0.2% MgO or al-

kali. Phases in the silica brick identified by X-ray diffraction indicate that the

original quartz is predominately converted into an amorphous phase and cristo-

balite.

Table 15-3: Ranges of Chemical Composition and Mineralogical

Phases Present in Silica Brick

Property Range

Chemical composition, wt %SiOz

A1203

Fe203

TiOz

MgQ

CaO

Alkali (Na20, KzO, LizO)

Phases identified

Quartz

CristobaliteAmorphous

98.9-99.6

0.2-0.5

0.02-0.3

0.01-0.02

0.02-0.1

0.02-0.03

0.01-0.2

None-minor

None-minorMajor

The physical properties of silica brick, listed as Type 1 and Type 2 in Table

15-4, depend on silica purity and the manufacturing process used in their manu-

facture. Silica brick is typically higher in porosity and lower in density, cold

crushing strength, thermal expansion, and flexural strength than acid brick. The

brick’s high silica content makes bond formation between grains during firing

difficult, accounting for the low strength and high porosity.

Type 1 properties are for a 98% rebonded vitreous silica brick usually man-

ufactured by dry pressing, although casting or air ramming may be used for non-

standard shapes. This material contains some crystalline silica formed during

firing that is located between grain boundaries, giving the material its high ther-

mal expansion behavior below 800°F. Currently, there are one domestic and sev-

eral European manufacturers.

The second type, called Type 2, is more of a speciality product made from

99.5+% pure rebonded fused silica. This material does not contain as much crys-

talline silica phase as found in Type 1, and has a lower thermal expansion below800°F. The two domestic suppliers use different processing techniques to shape

the material-conventional slip casting and a proprietary method. These differ-




ent processing techniques yield products that have similar chemistry, but differ-

ent physical properties. Standard and special shapes can be obtained.

Table 154: Physical Property Ranges of Silica Brick

Property Type 1 Type 2

Apparent porosity, %

Absorption, %

Bulk density, lb/ft3

HzS04acid resistance (C-279,*

% wt loss

Modulus of rupture, psi

Compressive strength, psi

Thermal conductivity,Btu .in/hr.ft’.“F

Thermal expansion coefficient,

in/in OF x 10%

75” to 800°F

800’ to 2 ,OOO°F

Modulus of elasticity, lo6 psi

*Limited information available

NA = Not analyzed

12-16 7-16

5.5-7.2 3-14

116-120 112-128

1.4

500-800

4,500-7,000

5-8.5

2.2-2.8 0.4-O .65

0.2-0.8 0.4-0.65

1.1 3.5-5

NA

500-2,000

2,000-l 2,000

4.2-8.5

Although published tests such as ASTM C-279 may be used to determine an

acid brick’s chemical resistance, no standard test exists to predict silica brick be-

havior. It is necessary to rely on personal experience or to evaluate a brick’s per-

formance in a simulated test environment.

Some laboratory test results have been reported6J7 on the effects of expos-

ing silica brick to HCI and HN03acid environments for 1 IO days. No significant

trends in cold crushing strength were observed after acid exposure. Weight loss,

as measured by sample weight changes or by the amount of ions leached, was

minimal. Figure 15-3 shows the total ions removed from brick samples in HCI

and HN03 leach solutions during 110 days of exposure. Unlike the acid brick,

no definitive changes in the quantity of ions leached into solution occurred, re-

gardless of temperature or acid concentration. The total amount of ions leached

from the brick averaged below 0.2 wt %.

In general, the Fe and Al ions showed the highest ion removal rates, while

Ca, Mg, Na, K, and Ti ion removal was minor. All ions were removed in amounts

less than 0.06 wt %. Silicon, the predominant chemical constituent in the brick,

was not leached from any samples, indicating that the siliceous bond was not

affected by chemical exposure; this may explain why no trends in cold crushing

strength changes were observed.

Applications

Chemical Resistance: For acid proof construction, silica brick with an SiOz

content below 98% should not be used. Materials that contain lower amounts of

silica usually have a concentration of alkaline earth oxides (e.g., CaO, MgO) in

the glassy bond phase. As a result, the bond phase will have poor resistance to

acid which can lead to failure of the brick in service.




KEY

m= 50°c

m = 7ooc

F-_l= 9o”c

120 20 20 30, 140 40 60 60 60,

HCI, wt pet HN03. wt pet

ACID CONDITION

Figure 16-3: Total ions leached from silica brick in 110 days of acid exposure.

In general, silica brick offers superior acid resistance over red shale or fire-

clay (again with the exception of HF). Silica is also very resistant to chlorine, or-ganic solvents and many other non-alkaline chemicals.

Temperature Limit: Like any other ceramic material, many factors affect

the maximum use temperature of high purity silica products. In general, 2000°F

is the highest temperature limit for cyclic service. When the temperature goes

above 2000°F, the vitreous/fused silica grains will crystallize to cristobalite and

quartz. If the operating temperature is then cycled, the various silica inversions

can take place which will tear the brick apart. When operation is restricted to

continuous service only, then the maximum use temperature is approximately

3OOO’F.

Thermal Expansion and Thermal Shock Resistance: In many situations it

is difficult to directly substitute silica brick for red shale or fireclay. Changes in

design might be needed to avoid subjecting the silica brick to destructive tensile

or shear stresses during operation because of expansion differences. The thermal

expansion of the specialty type silica product (Type 2) is much less than that of

acid brick. The vitreous silica material which contains some crystalline SiOZ

(Type 1) has a thermal expansion that closely matches that of acid brick at tem-

peratures less than 800°F. Above that temperature, the expansion is much less.As a whole, the thermal shock resistance of high silica materials is far su-

perior to that of acid brick, especially the specialty product (Type 2). Some-




times the partially crystalline silica brick has problems in splash situations. If the

material is operating at several hundred degrees Fahrenheit and process liquid

splashes on it (infrequently), enough cooling can take place on the brick’s sur-

face to cause the bond between grains to fracture. This is probably due to in-version of the crystalline SiOz and the resulting volume change of that phase.

Strength and Abrasion Resistance: The strength and abrasion resistance of

silica brick is less than that of acid brick. This is because of both higher porosity

and lower firing temperature during manufacture. As far as the different types of

silica materials are concerned, the brick containing some crystalline SiOz (Type

1) is softer and weaker than the specialty products (Type 2). Overall weak strength

introduces a specific physical limitation with silica materials under wet/dry con-

ditions. If the process chemistry contains salts, alums, etc., these will be de-

posited within the pore spaces of the brick. Under moist conditions, these sub-

stances can hydrate and exert high internal pressure. The silica brick’s weak in-

tergranular bond is easily fractured. Loose grains will be washed away and ma-

terial loss can become excessive.

Pressure Effects: Both types of high purity silica materials seem to tolerate

rapid pressure changes. However, frequent, rapid changes of large magnitude

should be avoided as it should be with any ceramic.

Irreversible Growth: Irreversible brick growth is not a problem with high

purity silica materials as it is with red shale or fireclay.Cost: The cost of the fused silica product (Type 2) is more than that of the

vitreous silica brick which contains some crystalline phase (Type 1). This is be-

cause of higher purity and higher manufacturing costs. When compared to acid

brick, the cost of both types of silica is at least triple and usually more.

REFERENCES

1. American Society for Testing and Materials, Standard Specifications for Chemical-

Resistant Masonry Units. C-279-79 in 1984 Annual Book of ASTM Standards: Sec-

tion 4, Construction; Vol. 4.05, Chemical-Resistant Materials; Vitrified Clay, Con-

crete, Fiber-Cement Products; Mortars, Masonry, pp 170-I 72 (I 984).

2. American Society for Testing and Materials, Standard Specifications for Industrial

Chimney Lining Brick. C-98082 in 1984 Annual Book of ASTM Standards: Sec-

tion 4, Construction; Vol. 4.05, Chemical-Resistant Materials; Vitrified Clay, Con-

crete, Fiber-Cement Products; Mortars, Masonry, pp 743-745 (1984).

3. Ritchie, T., Moisture Expansion of Clay Bricks and Brickwork, National Research

Council of Canada, Division of Building Research, Ottawa, Building Research Note

No. 103 (October 1975).

4. Lomax, J. and Ford, R.W., Investigations Into a Method for Assessing the Long Term

Moisture Expansion of Clay Bricks, Transactions and Journal of the British Ceramic

Society,Vol.82,No.3,pp79-82 (1983).

5. American Society for Testing and Materials, Standard Specifications for industrial

Floor Brick. C41OSO in 1984 Annual Book of ASTM Standards: Section 4, Con-

struction: Vol. 4.05, Chemical-Resistant Materials; Vitrified Clay, Concrete, Fiber-

Cement Products; Mortars, Masonry, pp 264-265 (1984).

6. Bennett, James P., Corrosion Resistance of Ceramic Materials to Hydrochloric Acid,

Bureau of Mines RI 8807 (1983).

7. Bennett, James P., Corrosion Resistance of Selected Ceramic Materials to Nitric Acid,

Bureau of Mines RI 8851 (1984).



16

Carbon Brick



Haverto wn, Pennsylvania

Carbon bricks are used in chemical-resistant construction in exposures

which cannot readily be handled by other kinds of brick. Inasmuch as their cost

is nearly 10 times that of shale or fireclay, and they provide not nearly as much

insulation nor resistance to mechanical abuse, their selection is dictated by only

the most compelling reasons. These reasons may be divided into four categories:

(1) Where HF or acid fluorides will be present in concentrations in ex-

cess of 1,500 parts per million in wet/dry conditions on floors, sub-

ject to spillage followed by washdown, or in excess of 50 ppm

where used in a vessel lining, or in floors continually wet, especially

when subjected to heat, or where there will be exposure to strong

caustic alkalis.

(2) Where extreme thermal shock is anticipated.

(3) Where there are design requirements for the release of compressive

stresses in the masonry lining.

(4) As a facing for brick linings in a high pressure vessel where sudden

loss of pressures may be anticipated.

The first category is self-explanatory. Carbon-filled materials are every-

where indicated under conditions involving HF and strong alkalis. Brick made of

carbon or graphite are, at this time, the only construction units which can with-

stand these chemicals. The relatively high porosity of carbon brick and other

units explains to a large degree their ability to withstand thermal shock and to

dissipate compressive stresses better than any other types of masonry units. The

last category is perhaps the most difficult for the reader to visualize.

Take as an example a pressure vessel lined with 9” of shale or fireclay acid

brick that is put into service and brought up to operating conditions, say, 100

155




psi internal pressure, and 18O”F, then held under those conditions for 24 to 48

hours. The vapors and liquids which are in the vessel will have permeated the

linings and stabilized at this pressure. Now suppose that the operator at the end

of a cycle suddenly opens a valve and the pressure drops to atmospheric in a frac-

tion of a second. The result is an almost instantaneous push for the vapors or

gases and liquids that have condensed from them and absorbed into the brick

under the pressure, to leave the brick and return to the vessel interior. Because

of the density of the brick these pressures are restrained by the face materials of

the brick. This results in the spalling of the brick face. With additional cycling,

more and more face material spalls away, leaving the joints, if made of a dense

resinous very low absorption material, standing out in a waffle pattern.

To the viewer who has not been briefed on the operating conditions, includ-

ing the operator’s action in bringing the pressure down so fast, the surface willlook as if it had been attacked chemically, and in fact the condition has often

been misdiagnosed as due to the presence of hydrofluoric acid in the contained

fluids. The cure, however, is the same. A face course of carbon brick, laid with

bed and side joints of resin mortar, over the face of the existing brick lining, can

preserve the rest of the brick. The carbon brick, with far greater porosity but

good tensile strength, will permit the rapid bleed-out of the vapors from the acid

brick while reinforcing the surface of the shale or fireclay brick behind it and

preventing spalling.

Carbon brick is currently manufactured in the western hemisphere by only

one company and the greatest volume of its product goes into steel millsand into

other metallurgical uses. (At the time of this writing one other manufacturer has

started production of an acceptable carbon brick.) Because it is employed prima-

rily in refractory service, it has always been manufactured in refractory sizes-in the

9” x 4.5” x 2.5” or 9” x 4.5” x 3” modules. All standard shapes-splits, soaps,

arches, keys and wedges-are available. The tolerances in manufacture and supply

are:

Length: + l/s”

Width and thickness: f l/16”

Deviation from plane: l/16” maximum

Out-of-square, any dimension: l/s” maximum

Scoring is available only on the basic straights, not on the shapes. The fol-

lowing are the physical properties.

Table 16-1: Properties of U.S. Bricks

Density 96.7 lb/ft3 1.55 gr/cm3

Tensile strength 1100 lb/in' 77.3 kg/cm2

Compressive strength 7500 lb/in2 527.3 kg/cm2

Flexural strength 2500 lb/in2 175.7 kg/cm2

Modulus of Elasticity 1.7 x IO6 lb/in2 0.119 x lo6 kg/cm2

Thermal conductivity (K-factor) 36 BTu/ft2/in/hr/"F 0.012 Cal/cm2/*/sec/oC

Mean coefficient of expansion 1.5 x 106

(7O'F to 212°F)



Carbon Brick 157

The reader will note that domestic carbon brick, with a high coefficient of

thermal conductivity, gives little insulation to a membrane (if there is one) be-

hind it and, therefore, where such insulation is required, a considerable thick-

ness of these brick must be employed. Note also that the coefficient of thermal

expansion of domestic brick is less than half of that of shale and about half of

that of fireclay. Thus, mating these two types of brick together in a single con-

struction is difficult for the designer, and in the areas of considerable thermal

change, close to impossible.

European-made carbon brick is available in this hemisphere through many

agents and distributors. The major source of imported carbon brick is from the

United Kingdom, though, until recently, German and Polish-made brick were

also offered. There are no ASTM standards or specifications covering carbon

brick, so the user must select the brick that he plans to use on the basis of thephysical and chemical data supplied by the manufacturer. Tables 16-2 and 16-3

give comparative figures for these materials.

Table 16-2: Properties of British Bricks, Two Suppliers

Primary Supplier secondary supplier

Density 93 lb/ft3 1.49 gr/cm3 96.9 lb/ft' 1.55 gr/cm3

Tensile 1000 lb/in2 kg/cm20.5

Compressive 9000 lb/in' 630 kg/cm2 8960 lb/in' 630 kg/cm2

Elasticity 3.6 x lo6 lb/in2 1.06 x 10

Thermal conductivity 20.0 Buu/ft'/in/hr/"F 41.6

at ZOOOF 2.5 x lo3 k cal/m/hr/DC 5.2Tuft24in/hr/OF10 k cal/m/hr/°C

Expansion 3.6 x lS-6/oF 8.0 x 10-6/oC 8.3 x 1o+/.=c

Apparent porosity 21% 18%

Ash 6.5% (also a 0.7% low ash) 6-7% (also a 1% low ash)

Table 16-3: Properties of German Brick (No Longer Available) and Polish Brick

Density

Tensile

Compressive

Elasticity

Thermal conductivity

Coefficient of

Expansion

Apparent Porosity

Ash

GERW.N BRICK POLISH BRICK

Metric units Only

1.45 kp/l

60-70 kp/cm'

300-350 kp/cm'

0.9-1.0 x 102kp/cm2

2.1-2.3 x 10' k cal/m/h/°C

4 to 5 x lo-5/Y

English Units only

97 lb/ft3

1150 lb/in3

10,000 lb/in2

1500 lb/in'

1.6 x lo6 BTU/ft'/in/hr/"F

3.6 x 10-6/oF

25%

6-8 (also a 1% ash)

-

5%

The residue, after burning, (the ash) is the only portion of the brick that can

be attacked by exposures to hydrofluoric acid or to strong caustic. Therefore, a

low ash (under 1%) brick is better for chemical service than the higher ash brick,

though for most chemical exposures, either will provide economical life. Thesources of the carbon used for brick are similar world-wide, and therefore, the

major components of the ash-silica, alumina and ferric oxide-may not be ex-




petted to vary greatly though the proportions may be different and the minor

constituents may not be necessarily the same. The North American manufac-

turer states that he has never run an ash analysis. The German producer states

that he has run an ash analysis, but it is privileged, and he refuses to disclose it.

The two British manufacturers, however, have supplied the following data.

Table 16-4: Analysis of Ash*

Si02

A12o3

Fe2o3

ng0

Ti02

CaO

Kz"

Na20

Major Supplier

34.70

24.0%

20.4%

1.0%0.8%

1.5%

0.2%

0.99

Minor Supplier

39.029

37.27%

17.7%

trace

trace

trace

trace

t r a c e

“ On ly the tw o British sup p liers ha ve sup p lied this

The carbon will, of course, burn if exposed to heat and a source of oxygen.

The manufacturers are all pretty well agreed that carbon brick can be used in

normal atmospheres only to a limit of about 660°F (340°C), though in a reduc-

ing atmosphere (absence of oxygen) it can be used at temperatures as high as

5OOO’F (2760%).

Since all brick linings in vessels are subjected to abrasion, the degree depend-

ing on the contents of the vessel, at least one user has been interested in compar-

ing the abrasion resistance of a standard fireclay acid brick with that of the most

commonly used British brick. Employing the standard abrasion test, ASTM C704,

using the blasting technique, with 1,000 grams (+ 5 grams) of silicon carbide,the standard fireclay brick and the standard British carbon brick yielded the fol-

lowing results, testing three samples of each.

Table 16-5: Comparative Results of Abrasion Test

for Fireclay and Carbon Brick (ASTM C704)

Fireclay brick a loss of weight Carbon brick % loss of weight

6.04 1 5.46 )

1 18.24 1 average 6.74% 10.00 ) average 7.69%

1 )

5.94 1 7.6 )

If the two outside measurements are omitted, the following are the

averages.

5:999 6.538

From the above, it would appear that the carbon brick is not greatly differ-

ent in abrasion resistance from the fireclay brick. Where construction requiresmasonry internals, such as support plates and packed scrubbers, yet the expo-

sures include hydrofluoric acid or strong alkalis, beams, stringers and plates



Carbon Brick 159

made of carbon or graphite are substituted for the ceramic materials. Graphite is

the crystalline allotropic form of carbon, characterized by a hexagonal arrange-

ment of the atoms. It is relatively soft and has a greasy feel (Condensed Chem-

ical Dictionary). Graphite blocks have similar chemical and physical strengths.

These are available, from both the United States and British manufacturers, and

their physical properties closely parallel those of the carbon brick. These physi-

cal properties are readily available from the manufacturer. Plastic, carbon and

graphite packings are also available.

Caution: Do not place carbon or graphite brick or blocks directly against a

lead lining or against stainless steel. Direct contact between carbon and many

metals will set up a galvanic cell with the metal cathodic to the carbon, and

cause the wasting of the metal. For the same reason, avoid contact between such

metals and the carbon-filled mortars used to join the carbon units. A voltagebreaker should be inserted between them. For fuller discussion, see the section

on Design.

BIBLIOGRAPHY

Working, L.C., Formed Carbon and Graphite in Industry, Ceramic Bulletin, Vol. 32, No. 2,

pp 4044 (1953).

Raub, H.S. and Miller, J.L., Designing with Carbon and Graphite, Chemical Engineering,

Vol. 72, No. 11, pp 97-102 (May 24, 1965); Vol. 72, No. 13, pp 119-126 (June 21,

1965).

Schley, John R., Impervious Graphite for Process Equipment, Chemical Engineering Vol.

81, No. 4, pp 144-150 (February 18, 1974); Vol. 81, No. 6, pp 102-110 (March 18,

1974).

Sheppard, Walter L., Jr., Chemical ResistantMasonry, 2nd Edition, pp 8,9,35,36.



17

Closed Cell Foamed Borosilicate

Glass Block Lining System

Mary Lou Schmidt

Penn walt Corporation


A foamed borosilicate glass block lining system is the first major innovation

in inorganic, acid/corrosion resistant lining materials in over half a century. It is

composed of borosilicate glass foamed to 12 lb/f? density with completely closed

cells and cut into blocks providing excellent chemical and thermal resistance. It

is lighter than other types of linings, easy to install and does not support com-

bustion. Table 17-1 lists the chemical composition of the block.

Table 17-I : Chemical Composition of Foamed Borosilicate

Glass Block

Silica 80%

Boric oxide 18%

Potassium oxide 2%

The lining system may be used to protect metal, concrete or FRP substratesfrom deterioration caused by both chemicals and temperature. Applicable to ex-

posures in the chemical processing, metallurgical, petrochemical, pulp and paper,

waste incineration and power generation industries, among others, it can be used

to replace or to augment conventional masonry or cementitious monolithic or-

ganic linings.

*Throughout this paper, when mention is made of “glass block” or other similar designa-

tion, in order to shorten the title, only the subject closed cell foamed borosilicate glass

block is referred to. There are available plain blocks of glass which have no insulating ef-fect, and blocks of foamed glass that are nor closed cell, or are not borosilicates. Only those

block made of borosilicare glass, foamed in a closed ce// (and, hence, liquid and gas-tight)

form, will meet the physical and chemical standards of the subject material.

160



Closed Cell Foamed Borosilicate Glass Block Lining System 161

Some specific applications have been in air pollution control equipment

such as wet limestone flue gas desulfurization (FGD) scrubbers, baghouses,

quench chambers and inlet/outlet ductwork; carbon steel liners of concrete

chimneys and breechings; FRP stack linings; linings for steel or concrete covers

of molten sulfur pits, pickling tanks and acid storage tanks; petrochemical fur-

nace and heater linings; and acid process vessel linings.

installed alone as a semi-refractory material, the foamed borosilicate glass

block lining withstands hot face temperatures up to 960°F. It may also be used

with refractory, chemical-resistant masonry or monolithic internal linings at

temperatures above 960°F providing a unique combination of corrosion protec-

tion and heat conservation with little added weight and a lesser overall lining

thickness. The foamed glass block may also be fabricated into nozzles, T-sec-

tions, elbows, liner inserts and other custom shapes.This foamed borosilicate glass block lining system combines the desired

properties of a number of other lining systems into one. Its features are:

Chemical Resistance-The completely closedcell, foamed borosilicate glass

block is resistant to weak bases, all organic and almost all inorganic acids. It is

not resistant to hydrofluoric acid, acid fluorides or strong alkalies.

Closed-Cell Structure-The closed-cell nature of the block renders it virtu-

ally impermeable to penetration of harsh chemicals. With permeability, capillar-

ity and absorption at practically zero, contact with liquids results in surface

wetting of the block lining only. Since the membrane behind it rarely will come

in direct contact with the operating chemicals, its life is extended.

Wide Temperature Range-The block lining system has high resistance to

low-temperature acid condensates and process chemicals and the thermal resis-

tance to withstand high-temperature corrosive gases or concentrated acid con-

densates at temperatures above the limits of most organic lining materials. This

characteristic is unique among lining materials and allows such a block lining to

be used in applications with widely fluctuating temperatures and acidic condi-

tions.Low Coefficient of Thermal Expansion-A low coefficient of thermal ex-

pansion of 1.6 x lO%/‘F allows the block to withstand the wide range of tem-

peratures without spalling. It is resistant to upset or bypass operations where

thermal shock can damage or destroy other lining materials and the insulation

it provides protects the support structure itself from such damage.

Low Thermal Conductivity-Two. inches of foamed borosilicate glass block

has 5.7 times the insulation power of 2%” of conventional acid-resistant brick;

therefore 2” of block provides the thermal insulation equivalent of about 12”

of brick, even under the longest exposures to completely acidic liquid operating

conditions. This attribute results in a thinner overall lining, reduces energy costs

to keep a vessel at a required temperature and substantially reduces the tempera-

ture at the surface of the membrane giving longer membrane life. Figure 17-1

shows the thermal gradient for various thicknesses of the block.

In process vessels, the foamed glass block can be substituted for several

courses of acid brick. A brick facing over the block serves both to protect the

block against abrasion from mechanical abuse and to lower the temperature

at the face of the block when operating temperatures exceed the limits of the

block. In both cases, the block installed over a membrane and beneath brick re-




duces the amount of brick required and thereby cuts installation time and costs.

Due to its excellent insulating power, the block eliminates the need for ex-

ternal insulation, usually accompanied by high maintenance costs, on process

equipment. The outside surface of the equipment remains cooler and heat losses

are minimized.

(Based on 75O F Ambient. 10 mph wind)

1S” PENNGUARD

5O’F. >

2OO’F. 3OO’F. 4OO’F. 500°F. 6OO’F. 7OO’F. 8OO’F. 9OO’F

HOT FACE TEMPERATURE OF.

Figure 17-1: Temperature gradient for various thicknesses of foamed borosilicate glass

block.

Low Density and installed Thickness-Low density of 12 Ib/ft3 and a thin

installed thickness relative to acid-resistant brickwork, adds only 3 lb/f? to the

support structure. This feature increases design flexibility, reduces steel shell and

structural support costs and permits the construction of tall, free-standing struc-

tures.

INSTALLATION METHODS

The integrity of any lining system depends not only on the quality of the

material used but also on the quality of the actual installation. Therefore, an

experienced specialty contractor is required to ensure a high-quality installation.

Typically, a masonry contractor experienced in the special handling of acid-re-

sistant brickwork construction will have the expertise to follow the block sup-

plier’s application instructions.

Blocks are normally 9” x 6” and supplied in thicknesses of I”, I%“, 2” and

2%” to meet the requirements of a variety of applications. The thickness of the

block for a particular application is determined by the hot face temperature or

operating temperature. The thermal gradient is calculated to ensure that the

membrane or substrate does not experience temperatures beyond its recom-mended limit.

The primary requirement for a high-quality lining system is a properly pre-




pared substrate. First, the uniformity of the flatness of a rectangular substrate

or the roundness of a curved substrate should be verified. Small irregularities can

be marked and the block can be easily cut to minimize the deviation and ensure

full contact of the block.

Carbon steel substrates must be sandblasted to a near-white metal finish

(SSPC-SPIO or NACE #2) and maintained at least 5’F above the acid dewpoint

during installation. Concrete surfaces must be free of any imperfections such as

blow holes or honeycombing. Old concrete must be free of oil, grease or chemi-

cal contamination.

Both carbon steel and concrete substrates must be clean and dry and main-

tained above 5O’F during the installation. Preparation of alloy steel, FRP or or-

ganic-coated surfaces must be specified by the block supplier.

Bonding Systems

There are two different bonding systems employed with the block: a ure-

thane asphalt adhesive/membrane or a special inorganic silica-based mortar. The

choice depends on mechanical considerations and on the chemical and thermal

environment.

Urethane Asphalt Adhesive/Membrane: A urethane asphalt elastomer serves

as both an adhesive and a membrane to protect the substrate. It is a two-compo-

nent material which bonds the blocks to each other and to carbon steel, alloysteel, concrete or other organic linings and also functions as a moisture and

chemical-resistant barrier (or membrane) between the block and the substrate.

Generally, the adhesive/membrane is resistant to organic and inorganic

acids, bases and salts in solution at various concentrations and temperatures

(within the recommended range). The actual chemical resistance may depend on

the specific environment of the application. The adhesive/membrane is not resis-

tant to strong acids or petroleum-derived compounds though the block by itself

is resistant to them. In such exposures, the compatible mortar must be used.

The adhesive/membrane forms an elastomeric bond that serves as a mechan-

ical and thermal stress relieving mechanism by absorbing vibration and any

stresses of expansion and contraction thus reducing the probability of lining

cracks. It remains elastomeric at temperatures as low as -40°F to as high as

180°F continuous at the hot face of the adhesive/membrane line behind the

block.

At continuous operating temperatures above 180°F and up to 400°F. the

adhesive/membrane in the joints between the block will char to different depths

through the joint. Because of the block’s low thermal conductivity, if properly

designed, the bottom of the joint and back joint, serving as a membrane, will be

at 18O’F or below and remain elastomeric. The glasslike char that forms retains

the integrity of the lining. It also retains chemical resistance and, although the

top of the block is “frozen” In place at the charred portion of the joint, the

small block size prevents large stresses from being created that would crack the

block.

To install the block with adhesive/membrane on properly prepared sub-

strates, the adhesive/membrane is applied to the substrate at a minimum l/16”

thickness with a trowel. The adhesive/membrane is then troweled on the back,

sides and end of the block also at a minimum ‘he” thickness. The coated block




is moved back and forth against the adhesive on the substrate as it is slid into

place forming l/s” side and back joints. This action removes voids that may form

between the block and the substrate.

Inorganic Silica-Based Mortar: The completely compatible mortar is a two-

component silica-based mortar used to bed and bond the block when the ther-

mal and chemical environments exceed the capabilities of the adhesive/mem-

brane and where vibration and thermal shock are not serious factors. Its thermal

characteristics and chemical resistance are identical to that of the block. The

cured joints are rigid, dense and abrasion resistant. (See Chapter 22.)

The mortar may be applied to properly prepared concrete or steel substrates

by usual acid-resistant bricklaying methods. An epoxy, urethane asphalt, bi-

tumastic, polyester or vinyl ester membrane is required behind the block to en-

sure corrosion protection of the substrate. Because the mortar joints are rigid,a system of expansion/contraction joints, usually filled with ceramic paper, must

be designed to prevent cracks.

Combination Linings Incorporating Glass Block: A number of lining sys-

tems have been developed that combine the features of the glass block with

those of other materials. These layered ceramic and refractory linings are less ex-

pensive than high-cost stainless steels and other alloys. They resist acids and

abrasion better and reduce heat losses, saving energy. In all cases, the layer next

to the substrate is the proper membrane selected for the operating conditions.

Figure 17-2 shows the block installed with its adhesive/membrane over FRP.

The block extends the temperature limit of FRP and enhances its resistance to

fire, chemicals and pickup of static electricity. The low density of the block al-

loys for this type of design because, without heavy reinforcing, FRP cannot sup-

port the load of other, heavier linings. Depending on the thermal conditions, a

layer of ceramic paper may have to be placed between the block and FRP to

compensate for their large difference in coefficients of thermal expansion.

Figure 17-2: Foamed borosilicate glass block and urethane asphalt adhesive/membrane overfiberglass reinforced plastic.




Figure 17-3 shows a steel vessel lined with block under insulating firebrick

and acid brick. At high operating temperatures, a proper brick thickness reduces

the temperature on the block to 800°F or below. The maximum temperature

limit for the block under brickwork or any other organic lining is 800°F. This

limit, lower than the 960°F for the block alone, is necessary because the load

placed on the block by another lining material may cause the block to creep and

distort at temperatures above 800°F.

1 1 300°F

% Acid-resistant

fireclay

brick

membrane borosilicate

glass

block

Figure 173: Combination lining incorporating foamed borosilicate glass block reduces

courses of brick required to lower temperature to acceptable level at the membrane.

The block takes the place of additional courses of brick in further reducing

the temperature at the hot face of the membrane to an acceptable level. The re-

sult is a thinner overall lining with added chemical resistance because of the

closed-cell nature of the block.

Linings using high-temperature resistant monolithics over the block are

based on the same principles as above:

In heaters and furnaces used for the combustion of wastes or other potential

corrosives, highly insulating ceramic fiber blankets are used to reduce the tem-

perature on the steel shell. The blanket itself is not chemical-resistant but be-

cause operating temperatures are in the 1800”-2OOO’F range, acid condensates

are not thought to be a problem. However, the insulating blanket does its job

too well! The temperature behind the blanket often drops below the acid dew-

point causing acids to condense on and attack the steel shell and saturate the

ceramic fiber blanket. The steel becomes corroded and, because it is wet, the

blanket loses its insulating ability.

A design which incorporates the foamed glass block behind the blanketeliminates this problem. The block prevents the acids from reaching and con-

densing on the steel and adds insulating power of its own to the lining.




The block lining, installed with either its urethane asphalt adhesive/mem-

brane or inorganic mortar, affords a number of improvements over conventional

acid brickwork or other organic linings in many applications. The following are

brief expalantions of those environments where the foamed glass block lining

system is particularly suitable.

Flue Gas Desulfurization Systems

Stack gases generated by the combustion of coal and petroleum coke are

high in sulfur oxides that must be removed before venting the gases to the at-

mosphere. A lining in an FGD system may be subject to low temperature acid

condensates and high temperature gases at alternating intervals. The borosilicate

glass block is one of the few lining systems that combines the thermal resistance

of semi-refractory materials, the acid resistance of chemical-resistant materials

and the thermal shock resistance to fluctuate between the two conditions with-

out harm.

Inorganic monolithics like calcium aluminate, calcium silicate, sodium sili-

cate and potassium silicate gunites are able to withstand the dry flue gases at

high temperatures. Because they are porous and tend to crack, however, they al-

low acid vapors to reach the substrate and condense.

Organic linings such as polyesters, vinyl esters or fluoroelastomers may re-

sist wet acid condensates at low temperatures but will not accept higher tem-peratures where a semi-refractory is needed.

An independent testing laboratory gave the block its highest performance

rating of 10 in FGD systems after an Atlas test cell program and test installations

in online FGD systems. The block lining is expected to give much longer service

than alternative linings many of which have failed in the same environment after

only a year or less.

Waste Incineration

The incineration of liquid and solid wastes produces gases with a variety of

potential corrosives present. Usually they are some combination of nitrogen,

phosphorus and sulfur oxides and some hydrogen fluoride, but the primary con-

taminant is almost always hydrogen chloride. The exact composition oftentimes

is variable and unpredictable in any one incinerator. Before incineration gases

can be vented, they must be scrubbed of these noxious pollutants.

Depending on the particular operation, offgases from the incinerator may

range from 1100’ to 2100°F. Typically, the gases are sent to a conditioning

chamber to lower the temperature to 500’ to 600°F before they enter a scrub-

ber. While the incinerator is in operation, the gases may remain above the acid

dewpoint and corrosion problems will be minimal. But because most incinerators

are cyclic operations with frequent periods of idleness, gas condensation in the

inlet and outlet scrubber ductwork during shutdowns can cause serious deterior-

ation.

Foamed glass block laid in its silica-based mortar over a suitable membrane

is a good choice for lining these areas. During shutdowns, it is resistant to the

wide range of acid that may condense on the surfaces of the ductwork. Whenthe incinerator is operating, the block can withstand the high gas temperatures




coming from the conditioning chamber and scrubber. Its thermal shock resis-

tance allows the lining to alternate between the two environments without

cracking.

Waste incineration systems may use electrostatic precipitators in conjunc-

tion with a scrubber. The precipitator may come before or after the scrubber. If

it comes after the scrubber, usually no special lining is required for it. But if it

precedes the scrubber, the gases from the conditioning chamber enter the precip-

itator hot and are saturated with vapor. This process inevitably produces some

cooling and consequently acid condensates. The glass block lining provides a

lightweight, acid-resistant barrier and eliminates the need for external insulation

on the precipitator.

Smelting Operations

Smelter gases in the 600°-900°F range are carried through ducts to a scrub-

ber to remove most of the contaminants, primarily sulfur oxides, before exiting

through a stack. The efficiency of removal by a scrubber is not 100%; therefore,

some corrosives are still present after scrubbing. Because the scrubbing opera-

tion normally lowers the temperature to the 125’-18O’F range, acid condensates

may form in the exit ducts leading from the scrubbers to the stack. This is an

ideal area to install the borosilicate glass block.

In some smelters, a reheater is installed to raise the exit gas above the aciddewpoint (generally 350°-4500F) so the acid remains as a vapor and exits with

the gas without adversely affecting the ductwork. Even with a reheater, however,

during shutdowns the scrubber entry and exit ducts are subject to chemical at-

tack from acid condensates.

The capabilities of the foamed glass block provide: (1) chemical protection

against acid condensates, (2) lower outer shell temperature that eliminates the

need for external insulation, (3) little added weight which saves on structural

support, and (4) a quick and relatively inexpensive installation and easy repairs.

Baghouses

Baghouses are large rectangular steel structures containing an array of in-

verted cloth filter bags that collect particulates in flue gases flowing up through

them. The flow is interrupted periodically to allow the filter bags to drop their

contents into hoppers.

In certain applications, the exhaust stream may contain sulfuric acid and

other acids that can be highly corrosive. At operating temperatures above 450°F,

these corrosives are in the gas phase and not a problem. However, in intermittent

processes, with frequent shutdowns and startups, these acids fall below their

dewpoint and corrosive condensation eats away the steel baghouse walls.

Borosilicate glass block bonded with its adhesive/membrane can handle both

the high operating temperatures and the acid condensates. Once again, the need

for external insulation on the baghouse is eliminated.

Tall Stacks

Along with all its other features, the block’s lightweight lends itself to lining

tall stacks. Because it adds only 3 Ib/ft2, structural support can be minimized or

eliminated on tall stacks.




Even though the gases entering a stack may be above the acid dewpoint and

safe from a corrosion point of view, if the stack is tall (>200 ft), the tempera-

ture may drop below the dewpoint once it reaches the top. This presents a famil-

iar problem to many lining materials. The wet condition at the top of the stack

causes lining failure and forces frequent maintenance. With the borosilicate glass

block from bottom to top, the stack designer need not try to determine the tran-

sition point and then specify different materials for each section of the stack.

Pickle Tanks

Pickle tanks can be continuous or batch processes that use sulfuric or other

acids at elevated temperatures to condition and clean basic metals products.

Conventionally pickle tanks are lined with two or more courses of acid-resistant

brick set in a suitable acid-resistant mortar over a rubber membrane. More than

one course of brickwork is usually needed to reduce the temperature to the de-

sired level at the hot face of the membrane and to provide stability.

The insulating power and chemical resistance of the glass block allows for

a thinner lining and better membrane protection for pickle tanks where stability

is not a concern. The tank is first lined with the rubber membrane, the block is

bonded over that with its urethane asphalt adhesive/membrane and finally a

course of acid-resistant brick laid in acid-resistant mortar is placed over the block

for mechanical protection.The foamed glass block saves costs at the outset by requiring less brick and

less installation time. It also yields long-term savings in: (I) energy costs by con-

serving heat, and (2) maintenance costs by giving better protection to the mem-

brane against the deteriorating effects of strong acid and heat. The serviceable

life of a block lining is expected to be as long as 30 years-10 years longer than

the typical acid brick lining alone.

Vessel Covers

The glass block system, because of its resistance to acid liquids and vapors

and its lightweight, is perfectly suited to lining vessel lids. Its insulative proper-

ties prevent the loss of process heat through the cover thereby saving as much as

17% of energy costs.

Since the mid-1970s, the foamed borosilicate glass block lining system has

been used extensively in the applicat.ions mentioned. In most exposures, with

proper installation, the linings are performing well. In some cases, they have

solved a corrosion problem in which other lining systems failed. In other cases,

the block lining handled an environment where previously only considerably

more expensive metal alloys have worked.

As industrial processes change and new ones are developed, new solutions to

corrosion must be found. As it continues to be adapted to new applications, the

foamed borosilicate glass block lining system is providing one of those solutions.

BIBLIOGRAPHY

Pierce, Robert R. and Semler, Charles E., Ceramic and Refractory linings for acid condensa-

tion-Part I, Chemical Engineering,81-84 (December 12.1983).




Pierce, Robert R. and Semler, Charles E., Ceramic and refractory linings for acid condensa-

tion-Part II, Chemical Engineering, 102-104 (January 23, 1984).

Carpenter, W. Graham and Pierce, Robert R., Sulfuric and phosphoric acid plant lining sys-

tems, Chemical Engineering Progress, 57-61 (March 1982).

Rittenhouse, R.C., Protective coatings for power plants, Power Engineering, 30-38 (Decem-ber 1982).

Berger, Dean M., Trewella, Robert J. and Wummer, Carl J., Evaluating linings for power

plant SOI?scrubbers,Power Engineering, 71-74 (November 1980).

Sheppard, Walter Lee, Using chemical-resistant masonry in air pollution control equipment,

Chemical Engineering, 203-210 (November 20,1978).



18

Refractory and Insulating Firebrick

Paul E. Schlett

Exxon Research and Engineering Go.

Florham Park, New Jersey

INTRODUCTION

From time to time it becomes necessary to design process equipment in the

chemicals industry to contain high temperature reactions or to incinerate or

process toxic chemicals to more inert substances. These conditions are corrosive

and erosive to metals and require the use of protective barriers to prevent failure

of the equipment. For low temperature «300°F) conditions, various types of

organic membrane linings provide corrosion resistance or special metal alloys

may be used. Certain inorganic monolithic lining materials are also used at in-

termediate temperatures (600°-1000°F). These techniques for protecting against

shell corrosion are discussed extensively in other chapters of this volume. How-

ever, when temperatures exceed the maximum service I mit of these types of I n-

ings, it becomes necessary to consider materials which will either protect the

chemically-resistant membrane from heat so that it will continue to protect

against metal shell corrosion, or to design high temperature linings which of

themselves will provide corrosion protection. These materials are normally re-fractories and are primarily brick, refractory concretes or other chemically-re-

sistant masonry.

This chapter provides the equipment designer with a basic discussion of var-

ious types of refractory brick linings which can be used to 3300°F, depending

on the process .

A number of factors affect the selection of refractories for use in corrosive

170



171efractory and Insulating Firebrick

applications. This section lists and briefly discusses those factors which should

be considered. At the outset, it should be remembered that refractories are the

most vulnerable part of a h igh temperature lining system since they are designed

to protect other permanent parts of the system. Often times, systems are de-

signed with the thought that the permanent parts of the equipment should first

be designed, followed by a decision as to what type of lining should be used. As

a result, lining thicknesses have sometimes already been fixed prior to lining se-

lection since process design requires set internal dimensions, and the metal ves-

sel has already been engineered and, in some cases, purchased. At this point, con-tact is made with refractory suppliers who are expected to provide linings which

will fit the already established equipment, protect the metal, provide the neces-

sary thermal insulation, and last as long as all other unit components. Because

refractories are often taken into consideration last, and despite their own re-

quirements, are made to fit areas that are too small, they often do not last as

long or perform as well as they could have, had they been considered earlier in

the project. Early consideration of refractory linings may also minimize costly

design changes later in a project and reduce future maintenance costs.

Occasions also arise when companies have developed new processes or

changed current operating conditions to increase yields, provide new products,

or reduce generation of environmentally unsafe by-products with existing equip-

ment in an effort to reduce costs. Because these changes virtually always provide

some kind of a competitive advantage, companies are very hesitant to discuss op-

erating conditions with people outside their own company. When refractory per-

formance changes very radically due to process changes, equipment owners often

provide only half the needed information to refractory consultants in an effort

to protect their new formulations and processes. Once again, the resulting new

lining may perform for only a fraction as long or a fraction as well as it could

have, had complete operation information been given, used samples from the

former refractory lining been provided for examination, or samples of feed ma-

terials been provided for comparative performance analyses in laboratory simula-

tion tests.

Enlisting refractory consultants early in process design work is a very wise

step. The designer is frequently faced with early decisions between vastly differ-

ent approaches, all of which appear to be equal in their effectiveness. Conse-quently, the least expensive route is selected in an effort to keep costs down.

Where refractory linings are involved, a seemingly insignificant decision may

have quite an impact on refractory performance and subsequent process re-

liability.It is hoped the above discussion has led the reader to understand that early

consideration of refractory lining design is important in all corrosive and/or high

temperature process design work. Since customized refractory linings can be pre-

scribed most satisfactorily to meet the performance requirements, as complete

and honest a description of operating conditions/requirements as possible should

be provided to the refractory consultant/supplier. The following parameters are

listed as a guide to assist the designer in knowing what is important for the op-

timization of refractory lining performance.

DESIGN PARAMETERS WHICH AFFECT REFRACTORY LINING

SELECTION

A number of factors affect the selection of refractories for use in corrosive



range of service temperatures from ambient to 3300°F. When designing linings

for use at certain temperatures, one should note the performance criteria for thelining (i.e., to contain chemically inert or active gaseous atmospheres, to contain

molten corrosive liquids, to protect a metal shell from impact/abrasion/erosion

by high temperature solid materials, to thermally insulate for process efficiency,

to accept without damage any fluids which may condense when the unit is idle,

or to withstand stresses due to rapid temperature cycling) .

Maximum use temperatures are reported on refractory data sheets in terms

of pyrometric cone equivalent (pce). In essence, this pce defines the temperature

at which a small standard sized cone of the material slumps due to softening.Table 18-1 lists the pce numbers with the corresponding temperature limits and

generic types of brick which fall within the various pce ranges. These reported

pce's indicate a refractory's maximum use limit when exposed to a gas-fired en-

vironment; however, they may actually soften at much lower temperatures due

to reactions with the atmosphere they are containing.

Temperature

A variety of refractory materials are available which provide for a wide

Refractory Brick

Pyrometric E n d P o i n t s

Co n e Nu mb e r “ C OF- -

Br i c k T y p e s

12

13

14

15 -----

1617

18

19

20

23

26

27

1 3 3 5 2 4 4 0

1 3 4 5 2 4 6 0

1 4 0 0 2 5 5 0

1 4 3 0- - - - -

1 4 9 01 5 1 0 2 7 5 5

1 5 2 0 2 7 7 0

1 5 4 0 2 8 0 5

1 5 6 5 2 8 4 5

1 6 0 5 2 9 0 5

1 6 2 0 2 9 5 0

1 6 4 0 2 9 8 5

2 6 0 5, _ - _ - - - - - -

2 7 1 5

29 1 6 6 0 3 0 2 03 1 _ _ _ _ - - - - - - - - - - - _ _ _ _ _

_ _ _ _ _ l _ s ! h _ - 3 ! S . ! J - _ _ _ _ _ _ _ _ _ _

3 1 ' h 1 7 0 0 3 0 9 03 2 1 7 1 5 3 1 2 5

I-E2a

S

8

-

3 3 _ _ _ _ _ 1 7 4 z . _ _ 3 _ 1 L O_ _ _ _ _ _ _ _ _ _ _ _ _3 4 1 7 6 5 3 2 0 5

3 5 1 7 8 5 3 2 4 5

3 6 1 8 0 5 3 2 8 0

3 7 _ _ _ _ _ 1 &2 I ? _ _ ~ ~ P _ _ _ _ _ _ _ _ - - - - - -3 8 _____l65Q__Q3_Q________________

3 9 1 8 6 5 3 3 9 0

I_E2a

8E

-

39.L___M~__Q3S!___________________4 0 1 8 8 5 3 4 2 5

41_____1_97____3580 ______________-_____1 ._-

Fi-E3a

88

-42 _____3J15___36~~_____________________


Table 18-1: Approximate Pyrometric Cone Equivalent (PCE)

Values of Generic Classes of Fireclay and High AluminaRefractory Brick



Refractory and Insulating Firebrick 773

For pure thermal insulation in very clean atmospheres, insulating refrac-

tories may be used. These types of refractories are normally very lightweight and

can be purchased as brick shapes, as castables or refractory concretes, and as cer-

amic fiber.

When operating temperatures are very high, above 28OO”F, it is often best to

design linings composed of several layers of different refractory products. The

layer exposed to the hot gases should have a pee high enough to withstand those

temperatures and strength enough at that temperature to support itself. The fol-

lowing layers of refractories behind the hot face layer may be of lesser refractory

quality and should not be operated above their maximum service limit at their

hottest faces which are against the next hottest layer of refractory toward the

actual lining hot face. In these cases, the back-up layers will shrink and melt at

their hot faces and either cause lining failure or excessive heat losses. If a hotface layer has been over-insulated so that the temperature gradient through it is

level and approaching its maximum service limit, there is a danger that the lining

will soften and slump on side walls or sag when overhead, and eventually fail

catastrophically .

Proper design of multicomponent refractory linings to resist high tempera-

tures involves being sure the hot faces of all components are not exposed to tem-

peratures above their maximum limits, and that the hot face layer is strong

enough to support the weight and stresses imposed on it by the rest of the lining

when highly insulated and heated to its limit. Figures on high temperature creep

and load test data are available from refractory manufacturers to assist in de-

signing around those potential problems.

Proper expansion allowance should also be made according to manufac-

turers’ published data. Heat-setting mortars often provide the necessary allow-

ance in inert atmospheres; however, as atmospheres become more aggressive,

mortar joints are the most vulnerable parts of the lining and must, therefore, be

minimized. This requires that expansion allowances be made in areas away from

the aggressive atmospheres. These kinds of lining details should be thoroughly

discussed with refractory specialists who have had extensive experience in brick

lining design.

Rapid temperature cycling is very harmful to refractory linings since they

are very brittle. Although not expected in most facilities, there have been cases

where rapid cooling of refractory linings have been performed by spraying wa-

ter on the hot face of the lining or. against the metal shell of the equipment.

Such attempts at rapid inspections have led to complete refractory lining re-

placement. Although failures caused by such extreme temperature cycling are

not common, problems are often found on a smaller scale due to thermal cy-

cling. Where inert atmospheres are involved, and when the refractory lining has

not been exposed to temperatures approaching its maximum limit, where sof-

tening, densification and shrinkage may occur, ranges and speed of thermal cy-

cling can be more extreme than where very dense low porosity products are be-

ing used to protect against chemical attack. Linings which are to be exposed to

extreme temperature swings should be designed for such conditions. Suffice it

to say that linings which perform well in cyclic operation are not desirable for

high temperature corrosive applications. Thermal shock-resistant refractories

normally are very weak as compared to corrosion-resistant refractories which are




very strong and dense and, therefore, more thermal shock prone. At times, how-

ever, these properties must be compromised into one product.

To this point, moderate and high temperature lining details for inert atmos-

pheres have been discussed. When impurities are added to the atmospheres being

contained in the form of products of combustion or feed stocks, or when the

atmospheres are oxidizing or reducing rather than inert, refractory lining per-

formance can be radically altered.

Atmospheric Composition

When refractory linings are intended to contain moderate to high tempera-

ture environments having products of combustion or reaction containing com-

pounds of sodium, lithium, potassium, vanadium and titanium and bromides,

fluorides, chlorides, sulfides, phosphates along with the usual COZ, CO, Hz, and

02, extreme care must be taken in their design. In these highly corrosive atmos-

pheres, refractories perform differently than they do in clean environments.

The service life of hot face refractory lining materials may be drastically re-

duced when they are exposed to environments containing sodium, lithium, po-

tassium, vanadium, and/or titanium. These alkali metals flux mostfireclay-type re-

fractories, thus reducing the melting point of the lining, and so reduce the effec-

tive maximum service temperature of a refractory lining. Rapid erosion and abra-

sion results from wear by particulates of the fluid-softened hot face. The liquidformed on the hot face during high temperature operation, when cooled to be-

low its melting point, freezes to form a glass. The frozen surface or reacted zone

of the lining often spalls due to differences in thermal expansion between the

glassy surface and the unaffected lining. Little by little, the complete hot face

material can be attacked by either erosion or spalling due to melting.

Another form of alkali metal attack on the hot faces of refractory linings in-

volves their high temperature reaction with various components of the brick to

form expansive crystalline phases which cause brick to bloat on their hot faces

and, subsequently, erode or spall. An example is the case of alumina brick ex-

posed to sodium at temperatures from about 1700°F to 3OOO’F. Although so-

dium does not form a low temperature melt with alumina, it reacts with the

alpha phase of alumina, corundum, to form beta alumina, sodium aluminate.

Beta alumina has a much greater volume than the very dense corundum and,

therefore, disrupts the brick bonding matrix, causing eventual bond failure.

When alkali metals are present in processes, reduced service life can be ex-

pected over inert atmosphere performance for any refractory material used on

the hot face. However, lining performance can be optimized by judicious selec-

tion of the hot face brick composition and designing the thermal gradient in the

lining to keep the hot face brick as cool as possible.

Alkali metal attack has been studied by a number of refractory companies

and a good data base has been established. When faced with the high tempera-

ture exposure of refractories to these alkali metals, one should contact refrac-

tory suppliers and enlist their help in optimizing refractory selection. Based on

experience and tests which have been conducted, following are some general

guidelines for refractory selection in alkali environments.




Alkalies will react with fireclay and high alumina brick.

In the case of fireclay, the reaction is that of fluxing and melting

the brick.

In the case of alumina, the reaction involves a mineralogical reac-

tion.

High fired, low porosity, high purity super duty fireclay bricks are

suggested for alkali services to 2OOOOF. The low porosity minimizes

penetration of the alkaline vapors into the brick surface and thus

limits the amount of reaction with the brick matrix. High purity

means minimizing levels of TiO,, Fe,O,, CaO, MgO, Li,O, and K,O

within the brick matrix. These impurities would combine with the

impurities in the atmosphere to accelerate attack.

Sixty percent alumina brick seems to perform best in the 2OOO’F

to 2400°F service temperature range. These bricks should also be

high fired, low porosity and low in the impurities mentioned above.

The advantage afforded by the 60% alumina brick over the super

duty fireclay bricks mentioned above is a higher service tempera-

ture limit. The majority of the alumina in a 60% alumina brick is

combined with silica to form mullite, and is therefore protected

from the alkali/alumina reaction.

From 2400°F up, 88% plus alumina brick is suggested. Although

the alkali/alumina reaction will occur, the higher refractoriness of

the alumina brick is necessary to ensure that the lining does not

soften and sag during service in the high temperature exposure.

Another alternative to the 88% plus alumina brick at 24OO’F and

above is aluminachrome brick which performs very well against

alkali but is very susceptible to thermal shock.

Refractory companies continue to evaluate refractory performance in these

services and to develop new products for improved performance. A magne-

sium aluminate spine1 refractory composition has recently been identified as

having good resistance to alkali slags; however, it is also susceptible to thermal

shock damage. When designing a lining which will be exposed to alkali at high

temperatures, refractory manufacturers have the capability to perform tests to

evaluate relative performance of different types of refractories by exposing them

to alkali compositions at temperatures approximating those expected in service.These test procedures, initially developed for the iron and steel industry, are

commonly called slag tests. Variations of these tests have been made to answer

other questions concerning alkali vapor attack and depth of alkali penetration

due to thermal gradients in the lining. An example of a typical cup slag test is

shown in Figure 18-I.

In spite of the knowledge available through current research tests and stud-

ies, the best information can only provide relative performance predictions be-

tween various types of refractories. Unit operation variables also affect the ser-

vice life of refractory linings which contain these corrosive atmospheres.




Figure 18-1: (Upper) Cup slag test on 42%

AI2O3 brick. From Refractories for Hazardou

Caprio and H. Edward Wolfe, 1982 National

tesy of the Harbison-Walker Refractories Co.

High temperature atmospheres containing fluorides, chlorides, sulfides and

phosphates also affect lining performance. Of these, fluorides are the most detri-

mental. Very little information is available for use in predicting service life of re-

fractories exposed to this very corrosive halogen which, while in the liquid or

gaseous state, reacts with refractories to form soluble salts of the bonding ma-

trix and virtually disintegrates the lining. High temperature fiuoride-containing

atmospheres may be experienced when incinerating many toxic chemicals. Flu-

oride levels in the range of very few parts per million may reduce refractory ser-vice life to months or even days. No effort is made here to suggest acceptable

fluoride levels or to recommend a specific type of refractories for the service. Con-

AI2O3 brick. (Lower) Cup slag test on 60%s Waste Incineration" An Overview, James A.Waste Processing Conference, page 148. Cour-




sultants are available who provide additional guidance. Suffice it to say that spe-

cial assistance is required when designing units to handle both high and low tem-

perature fluorides.

Although not as severe as fluorides, chlorides also reduce performance when

they contact refractories in both the gaseous and liquid states. Chlorides also

form soluble salts with most components of a refractory composition though

they do not react with glassy materials. An excellent refractory material for use

in chloridecontaining service where temperatures do not exceed 19OO’F is fused

silica. This refractory performs well in exposures to chlorides because of its vit-

reous or glassy morphology.

Performance of refractories exposed to chlorides can best be determined by

measuring relative performance of different refractory types in actual service

using small test panels of different compositions and physical properties. A mod-ified ASTM C279 acid solubility test using an HCI solution can also give insights

into the relative performance of various types of refractory brick in chloride

containing environments.

Phosphates and sulfides may also influence refractory lining performance,

but are only detrimental in the liquid form. Consequently, refractories are nor-

mally attacked by sulfates and phosphates at temperatures below the gaseous va-

por dewpoint only in the cooler portion of the lining near the metal shell. One

method which limits attack by these corrosive liquids is to design the lining so

that all parts of the lining are above the vapor dewpoint. This may be done by

using external insulation when units are operating at relatively low pressures and

temperatures. However, as operating temperatures exceed design for the metal

shell, the use of external insulation to limit condensation in a refractory lining

becomes unsafe since there is no good means to observe the shell for hot spots or

areas where the shell has corroded through, either from the outside or the

inside. See the section on closed cell foamed borosilicate glass block for an

alternative (Chapter 17).

The condensation of aqueous solutions of fluorides, chlorides, sulfides andphosphates in a refractory lining toward the metal shell can be detrimental not

only to the refractory lining, but also will severely corrode carbon steel shells.

With this in mind, it becomes necessary to consider alternate designs to improve

lining performance as related to both operating temperatures and the thermal

gradient through a refractory lining system.

OPTIMIZED THERMAL GRADIENT DESIGN THROUGH A REFRACTORY

LINING

As stated earlier, the function of a refractory lining is to protect the metal

shell from corrosion and overheating. One normally considers protection against

excessive temperature as the most significant protective characteristic of refrac-

tories; however, a properly designed lining system may also effectively protect

the shell against corrosion when the high temperature process gas stream con-

tains corrosive materials mentioned above. Two lining designs commonly used to

limit metal shell corrosion are hot and cold shell designs.

A hot shell refractory lining has been constructed with lining thicknesses




proportioned in a manner which allows the metal shell to be maintained at a

temperature above the vapor dewpoint of the process. If none of the gases con-

dense, there will be no attack of the metal shell by corrosive liquids which would

condense. But in cases where the gaseous components of the process attack the

steel shell, a hot shell design would not be effective in minimizing corrosion.

Hot shell designs are used in particularly high temperature applications

where high, perhaps greater than 0.5 wt %, sulfides and/or sulfates are present in

the process stream. They are impractical, however, for low temperature proc-

esses such as 12OO’F or less due to limitations in materials and thickness required

to achieve the hot shell. In these cases, it is not uncommon to insulate the shell

externally to raise its temperature above the dewpoint.

A cold shell refractory lining is designed to protect an impermeable mem-

brane on the shell from deterioration to heat exposure. In this design, one con-structs the refractory lining so the hot face material will be resistant to the con-

ditions experienced in the operating environment and thick enough to keep the

metal shell within the effective temperature range of the impermeable mem-

brane. Care should be taken to ensure that the lining design is capable of per-

forming effectively at the maximum temperatures anticipated in the equipment.

Otherwise, the membrane will be damaged thermally and provide no corrosion

protection.

Other kinds of failures are sometimes the result of overzealous efforts to

conserve energy and improve unit efficiency. Three measures can be taken to

minimize the possibility of such a failure. First, the thermal gradient through the

high temperature, hot face refractory brick liner should be as steep as possible,

especially if the maximum use temperature limit of the lining material is ex-

pected, and if a refractory of higher maximum service temperature is not avail-

able, Second, design the lining in such a manner as to allow for thermal expan-

sion without creating excessive stresses in the lining. Third, support the brick by

using a combination of refractory and metal ledge supports back to the metal

shell. Since refractory brick often are very different even within the same com-positional classes, the designer should contact refractory suppliers for assistance

in obtaining the necessary physical properties and in applying the above meas-

ures.

IFB’s used as back-up linings are also subject to shrinkage and melting dur-

ing high temperature operation. Care should be taken in gradient design to en-

sure that the back-up linings are not exposed to temperatures exceeding their

maximum use limit.

Brick Shapes

When designing a refractory brick lining, one should consider using brick

shapes which are readily available and which provide the most structurally sound

lining. To have bricks custom-made to allow a precise lining fit into a vessel in-

volves the costly fabrication of molds to fit onto power presses for brick manu-

facture. Other special shape alternatives involve air ramming brick compositions

into wooden/metal molds and firing. The latter method normally results in costly

brick shapes of proper dimension, but of inferior quality to the machine pressed

brick. Special shape delivery times are often very long as compared to those for

standard shapes.




Bricks are commonly made in standard configurations known as straights,

arches, keys, wedges, rotary kiln blocks, etc. Numerous guides are available from

refractory suppliers which provide assistance in selection of standard brick shapes

and combinations required to provide structurally sound linings.

With the above guidelines, the designer should examine carefully the compo-sition, analysis and physicals of the brick of all manufacturers offered for use

in the thermal ranges required for the processes in which the equipment is to be

used, and select for use those brick that fit the description and requirements

spelled out above.

REFERENCES

1, Caprio, J.A. and Wolfe, H.E., Refractories for hazardous waste incineration, an over-

view, 1982 National Waste Processing Conference (Book No. 100150). Am. Sot. of

Mech. Engrs., New York, NY.

2. Modern Refractory Practice, Harbison-Walker Refractories Co., Pittsburgh, PA,



1 9

Specialties

PART A

PORCELAIN BRICK




Porcelain brick are used as linings very occasionally where the need is pri-

marily for (1) ease of cleaning, (2) product purity, (3) high wear resistance,

and (4) high strength, all in combination with (5) best chemical resistance. In the

dye industry, in particular, there is concern about inter-batch contamination andpurity of colors. Porcelain brick are white, so that residues from earlier batches

are easily visible. They have zero porosity, and the surfaces are glass smooth, so

they may be easily cleaned.

The Chemical Dictionary defines porcelain as “ceramic wear made largely

of baked clay (kaolin) coated or glazed with a fusible substance.” Kaolin is de-

fined as “(china clay; white bole; argilla; porcelain clay; white clay). A white-

burning clay, which, due to its great purity, has a high fusion point and is the

most refractory of all clays.” It gives the composition as “mainly kaolinite (40%

alumina, 55% silica) plus impurities and water.”

In the manufacture of chemical and electrical porcelain, the manufacturer

blends together sand, clay (a mixture of kaolin and ball clay) and spar to con-

stitute the body of the product he will form and fire. Ball clay, as defined in

the Chemical Dictionary as a “general term for those clays that possess good

plasticity, strong bonding power, high refractories, and which burn to a white

or cream-colored product. These clays are fine grained, relatively pure, hydrated

aluminum silicate . used as bonding and plasticizing agents or chief ingredients

of . . porcelains . ., floor and wall tile.” Spar is primarily a sodium and po-

180



Specialties 181

tassium silicate and is used as a flux, and to lower the firing temperature. The

purer the ingredients and the higher the percentage of alumina in the mix, the

higher must be the firing temperature.

Because the mix used to form the bodies that are fired to produce the prod-

ucts are made in this manner from naturally occurring mixed or quarried ma-

terials, the chemical analyses of the bodies varies considerably, not only from

manufacturer to manufacturer, but from year to year, as the deposits of the

basic materials will vary, and compositions can only be indicated in general or

relative terms. What they do determine is the crystalline phases of the mineral

content, and all analytical data is based on the identity of these phases. The

only characteristic that is an absolute with porcelain brick (or tile) in compari-

son with other forms of fired chemical-resistant blocks is zero porosity.

As most chemists know, glass and porcelain make very satisfactory labora-

tory equipment, resistant to almost all harsh chemicals except hydrofluoric acid,

acid fluorides, and fused alkalis. Some strong corrosives, such as hot concen-

trated alkalis and boiling concentrated halogen acids (other than hydrofluoric)

will slowly etch or attack them, but they can still serve, even in such exposures,

economically for long periods.

In selecting the particular porcelain (other than a “regular” body) for a

specific service, the percentage of alumina (A1203) present is a determining fac-

tor. As the percentage of alumina increases, the hardness of the end product also

increases, the softening point rises, and the firing temperature must be increased.

For example, a “regular” body, with probably less than 15% alumina, up to a

high strength body (38-40% alumina) will be fired at approximately 2200’-

2400°F (1200’-13OO’C). An 85% alumina body is fired at about 2700°-28OO’F

(1500’-155O’C) and a 95-98% body at 2900”-3100°F (1600’-1700°C). Hard-

nesses on the Mohs scale vary from 6-7 for a regular body, and 7-7.5 for a high

strength body, to 9 at 98-99% alumina. Compare these figures with those for

acid brick which are fired in the ranges 1900’-195O’F (1040’-1070°C) for shale,

and 2 1 OO’-2200°F (11 50°-1 2OO’C) for f ireclay.Obviously, the higher the alumina content, the higher the cost of a porcelain

brick lining. For example, the cost of “regular” body porcelain brick for lining

a vessel will be roughly 10% of that for porcelain brick of the 85% alumina class,

and except for services involving very high temperatures (which can be approxi-

mated as a percentage of the firing temperature), there will be little difference

in the performance of the materials.

The following table provides a comparison of the physical properties and

mineralogical composition of the “regular” body and the “high strength” body

(3840%) porcelain brick.

In manufacturing, after selecting the raw materials, and proportioning and

mixing them, brick may be formed, prior to firing, either by casting or pressing.

Pressing may be done in a number of ways, but whatever system is used, the end

requirement is zero porosity. Any number of shapes are available from the man-

ufacturers, and in a variety of thicknesses, glazed or unglazed. The reader desiring

more detailed information may be referred to either Introduction to Ceramics,

by W.D. Kingrey, M.I.T. (John Wiley and Sons), or Ceramics: Industrial Process-

ing and Testing, by G.T. Jones and M.F. Berard (Iowa State University Press,Ames, Iowa).




FIRED SPECIFIC GRAVITY

DENSITY

HAP.DNE?& (Mh Scale)

POROSITY (Fuchsine Dye Test)

COMPRESSION STP.EXGTH

Regular Body

2.41

.087 lbs/cu.in

6-7

TENSILE STRENGTH

MODULUS OF RUPTIJFE (Unglazed)

MODULUS OF RUPTURE (Glazed)

MODULUS OF ELASTICITY

LINEAR THERMAL EXPANSION

PUNCTURE STRENGTH (3/S" Section)

(l/SM Section)

DIELECTRIC CONSTANT (1 mc)

POWER FACTOR (1 mc)

Zero at 100,000 lbs/sq.in.

100,000 psi

5,000 psi

10,500 psi

15,000 psi

10.4 x lo6 psi

3.2 x 10-6 in/in/OF

400 kv/in.

-___

5.6

0.89

THERMAL CONDUCTIVITY 8.4 BTU/sq.ft./in/hr/'F

GLASSPHASE

HULLITE (3A120j*2Si02)

QUARTZ (SiO,)

ALUMINA (A1203)

BODY PROPERTIES

COHPOSITION (Fired)

75.0%

15.0%

10.0%

100.0%

High Strength eody

2.80

.lO lbs/cu.in.

Zero at 100,000 lbs/sq.in.

140,000 psi

8,000 psi

20,000 psi

25,000 psi

17.0 x lo6 psi

3.7 x 10m6 in/in/OF

____

400 kv/in

6.9

0.63%

approximately 10.0

50.00

10.0%

2.0%

38.00

100.0%

The designer may note that if he requires the most cleanable surface, yet the

least expensive lining, it is entirely feasible to mate porcelain brick as a facing

with an acid brick lining, since their coefficients of thermal expansion are quite

similar.

The author wishes to thank Mr. Zoltan Szilagyi, of the Lapp Insulator Company,

LeRoy, NY, for his assistance in preparing the above paper.



Specialties 183

PART B

BASALT BRICKS

Hans J. Hoffmann

Abresist Corporation

Urbana, Indiana

WHAT IS RAW BASALT?

Raw basalt deposits can be found in many parts of the world with varyingexternal characteristics and mineralogical compositions. For example, the raw

basalt deposits out of the tertiary era are subvolcanic rock and occur in the form

of cylindrical plugs or bedded veins.

The cleavage face of basalt is usually column shaped. These columns stand

at right angles to the cooling surface. Generally, only olivine and augite appear

as phenocrysts. The base materials for these basalts are composed of plagioclase

augite and magnetite; glass is relatively rare.

MANUFACTURE OF FUSED CAST BASALT

Dense, select basalt with uniform structure is required for the manufacture

of fused cast basalt.

The raw basalt is mined, crushed, and melted at 2300°F (125OOC) and

poured into sand or iron molds. The solidified material is placed in the anneal-

ing furnace, where temperature is raised and lowered in a specific range, for up

to two days to achieve a uniform and fine crystalline structure. This gives thematerial its extreme hardness and resistance.

Fused cast basalt is cast in many shapes. Standard flat surfaces can be lined

with square or rectangular standard flat tiles. Cylinders for pipe systems are

made in static or centrifugal casting procedures. Wall thickness ranges from 21

mm for centrifugal spun cast cylinders to 30 mm thickness for the statically

mold cast cylinders and tiles. Thicker liners can also be made.

CHEMICAL ANALYSIS

The average analytical composition of basalt is:

Name

SilicaAlumina

Iron oxides

Calcium oxide

Magnesium oxide

Potassium and sodium oxides

Titanium oxide

Manganese and sulfur

Formula

SiOz

A’203

Fez03and Fe0

CaO

MgOK,O and NazO

TiOg

Mn and S

Amount

-45-48% I

-14-16%

-12-14%

-lO-12%

-8%

-6%

-2%

Trace




About 45% of the iron is as magnetite compound, Fe304, and about 55% in sil i-

cates (primarily augite).

THE USE OF FUSED CAST BASALT

The manufacture of the fused cast basalt was pioneered in West Germany

about 60 years ago. Fused cast basalt, also known under the registered trade-

mark ABRESIST, is abrasion and corrosion resistant. The material is used world-

wide in virtually all industries to protect equipment from the destructive forces

of wear.

Typical equipment that may be lined include, but are not limited to: chutes,

hoppers, flumes, conveyors, tanks, vessels, cyclones, separators, mixers, etc.

Pipe systems can be operated under a liquid head. under pressure or vacuum

or under gravity conditions.

In general, it may be said that basalt linings provide long-maintenance-free

service life.

PROPERTIES OF FUSED CAST BASALT

Hardness Mohs scale (diamond = IO)

Density

Water absorption

Compressive strength

Bending strength

Modulus of elasticity

Linear thermal expansion (at 2OO’F)

Thermal conductivity (at 200°F)

Operating temperature limit

Electrical resistance

About 8

175 lb/ft3

0% by weight

71,000 lb/in2

4.2 x b3 lb/in’

14-17 x 1061b/in2

4 x IO-‘in/in OF

8 Btu/in/ft2/hrloF

About 7OO’F

(tested at 3 volts and 1 mm distance) 10,000 ohms

CHEMICAL RESISTANCE OF FUSED CAST BASALT

Fused cast basalt does not degrade and maintains a smooth surface at all

times. The chemical resistance of the material is very good. Typical test results

are shown on the following pages. Though chemical resistance data to many spe-

cific chemicals at specific temperatures has been determined, the user is advised

to run his own tests to be certain of resistance under his own specific conditions.

Varying concentrations of the chemicals and the operating temperature may re-

sult in different influences on the lining.

Choice of Setting Material

Another consideration for proper application of fused cast basalt tile under

chemical attack is the proper choice of the bonding and setting material. The

type of mortar required will vary depending on the exposure and the operating

conditions. Setting materials may include: hydraulic mortars, silicates, resins,

sulfur or mastics.



Specialties 185

Type of Tile Construction

Plain (nonplug type) tile for installation with a mortar is recommended under

chemical conditions. A membrane system may be required. Mechanically attached

tile is generally not recommended under a liquid head.This holds true under chem-ical situations. The fluids or moisture will penetrate through a bolt or welded hole,

causing attack of the base material,and resulting in premature failure of the lining.

This holds true for all types of ceramic tile lining materials, be it fused cast

basalt, high alumina ceramics, silicon-carbide ceramics, or any other.

RESISTANCE OF FUSED CAST BASALT TO BASES

The following tests were made to demonstrate the resistance of the fused

cast basalt to various bases. The values cited are average values.

Base

Potash lye (25% KOH)

hot, flowing

Potash lye (10% KOH)stationary

Soda lye (25% NaOH)

hot, flowing

175°F

Soda lye (10% NaOH) 70°F

Soda solution (5% Na,C03)

Calcium chloride (CaCl2)

pasty and flowing

stationary

*Plate test.

Test

Temperature

175’F

70°F

7O’F

7O’F

Resistance

I%)

100

100

Almost lOO*

Almost lOO*

Almost lOO*

RESISTANCE OF FUSED CAST BASALT TO ACIDS

Test Procedure

Operational test; no

weight loss after

112 days.

Material TestingInstitute, Neuwied,

W. Germany; no

weight loss after

30 days.

Operational test;

weight loss of 0.6%

after 9 months.

Materials Testing

Institute, Neuwied,

W. Germany, 0.9%weight loss after

30 days.

Materials Testing

Institute, Neuwied,

W. Germany, 0.2%

weight loss after

30 days.


weight loss after

25 days.

The following tests were made to demonstrate the resistance of the fused

cast basalt to various acids:




Acid

Hydrochloric acid (25%

HCI), flowing

Hydrochloric acid (38%

HCI), stationary

Sulfuric acid (40%

H$OQ), stationary

Sulfuric acid (94%H,S04), stationary

Sulfuric acid (HzSOa)

Nitric acid (65%

HN03). stationary

Hydrofluoric acid

(20% HF)

Hydrofluoric acid

(40% HF)

Propionic acid,

stationary

Lactic acid (8%)

flowing,

stationary

*Plate test,

CONCLUSION

Test Resistance

Temperature (%)

60°F Almost 100’

ProtectiveLayer

60°F

60°F

60°F

60°F

60°F

60°F

60°F

60°F

60°F

Almost 100”

1 0 0

Almost 100”

Almost lOO*

loo*

Limited

resistance*

Limited

resistance*

Test Procedure

Operational test up

to 41 days, weight

loss less than 0.2%;weak bleaching of

surface.

Materials Testing

Institute, W. Ger-

many; 0.6% weight

loss after 30 days.


weight loss after

60 days.

Materials TestingInstitute, Neuwied,

W. Germany; 0.4%

weight loss after

30 days.

0.003% weight loss

after 7 days (19 Dec.

1968).

Materials Testing

Institute, Neuwied,

W. Germany; no

weight loss after

30 days.

Operational test; 0.5

mm was etched away

at surface after 20

days

Materials Testing

Institute, Neuwied,

W. Germany; 22.8%

weight loss after

30 days.

Materials Testing

Institute, Neuwied,

W. Germany; no

weight loss after

30 days.

Tests by many dairies

and the Kiel Testing

Institute, W. Ger-

many; no weight

loss after 3 years.

Fused cast basalt has an established place in the field of chemically resistant

masonry. These linings will work particularly well when the chemical attack is

combined with the abrasive action of sharp, hard particles. Worldwide, many in-



Specialties 187

stallations operate under such conditions. U.S. installations include pickling lines,

desulfurization vessels, etc.

Acknowledgement

Technical data was taken from the Handbook of Abrasion and Corro-

sion ResistantABRESlST Linings by Abresist Corp., S.R. 13 North, Ur-

bana, Indiana 46990, a subsidiary of Schmelzbasaltwerk, 5461 Kalen-

born, West Germany.

PART C

CORROSION OF SILICON CARBIDE PRODUCTS

John A. Bonar

Refractories Division

Sohio Engineered Materials Co.Niagara Falls, New York

INTRODUCTION

Silicon carbide is a man-made mineral which has high hardness, is generally

chemically inert and can be obtained in the form of refractories and special com-

ponents. Refractories made from silicon carbide can be obtained with a wide

range of bond systems while specialized components have a few types of bond

systems.

BOND SYSTEMS

Bond systems are generally the key in assessing how any refractory, includ-

ing silicon carbides, will perform in contact with a corrodent. Permeable silicon

carbide refractories can be classified as:

Oxide bonded (SiOz, A120sSi02, silicate glass)

Si20Nz (silicon oxynitride)

Si3N4 (silicon nitride).

All of these refractories are permeable to gasses and liquids. The relatively

high surface area allows the bond system to be readily attacked if it is suscepti-

ble to dissolution by the corrodent.




Several silicon carbides are available as fine grained impermeable high toler-

ance components. These products can be classified as:

Reaction Bonded (Sic bond with residual Si)

Sintered (either alpha or beta SiC bond with a sintering aid).

All permeable SIC refractories start with alpha silicon carbide grain which is

formed by standard forming methods such as pressing, tamping, vibrating or cast-

ing into shapes with binders added in the mixing stage. After firing at elevated tem-

peratures in either air or nitrogen, the desired final bond phase is formed,

Reaction bonded silicon carbides are formed by all of the above techniques.

They are then fired in an atmosphere where large amounts of silicon metal is

available to react with carbon in the compacted part to form a silicon carbidebond at high temperatures. Residual silicon is left in the pores of these products

after firing.

Sintered silicon carbides are formed by all the traditional methods as well

as standard plastic forming techniques such as injection molding. These com-

pacts are sintered with small amounts of additives at very high temperatures in

inert atmospheres to form essentially a single phase silicon carbide structure.

Table 19-1 details typical properties of permeable and impermeable silicon

carbides.lA4

Table 19-1: Typical Physical Properties of Commonly Used Silicon Carbide

Property

Modulus of rupture

(psi at 70°F)

Density (g/cm3)

Porosity (%)

Thermal expansion

coefficient (mean)

(in/in/OF) x 10”

Thermal conductivity

(Btuin/hr/‘F/ft2)

Specific heat

(mean cal/g/“C)Permeability

(cc of air/min/in2/in

in H20 pressure)

Chemical analysis

SIC

SiO;?

A1203

SisN,

Si,ONsSi

Al2%

SiO2 SiO2

Bond Bond

3,000 3,500

2.57 2.58

14 14

2.6 2.6

109 109

0.28 0.28

3.5 3.2

90.0 88 .o

8.5 9.6

0.7 1 .6

- -

SisN,

SisN4 Si20N2

Bond Bond

6,200 6,200

2.62 2.60

15 15

2.6 2.6

113 113

0.28 0 28

3 .O 3.8

75.0 86.0

0.5 0.6

0.3 0.3

23.5 -

13.0-

SIC SIC

Reaction Sintered

Bond Alpha

47,000 80,000

3.09 3.10

0.0 0.0

2.8 2.2

174 170

0.34 0.22

imp.

92.0

Imp.

100.0

-

8.0



Specialties 189

CORROSION MECHANISMS

In general, corrosion resistance is determined by the stability of the various

phases present and the surface area available to attack.

Permeable refractories are thus generally more susceptible to corrosion dueto their porosity and the consequent high surface area of bond phase exposed to

the corrodent.’ There are very few corrodents which would significantly attack

SIC by dissolution in an aqueous medium. If Sic is attacked, the general mech-

anism is one of oxidation of the SIC to SiO*. The SiOz is usually then removed

as a reaction product exposing fresh SIC surfaces to corrosion.

ACIDIC SOLUTIONS

Attack or corrosion of the permeable silicon carbides in aqueous media is

generally concerned with corrosion of the commonly used bond phases. Gener-

ally, SiO;? bond phases are the most stable in contact with all acids except hydro-

fluoric. Even then, concentrations up to 200 to 400 ppm can be handled safely

by silicon carbides bonded by SiOl for long periods of time if temperatures are

generally below 200°-250°C,

Mixed oxide, A12036i02, bond phases are generally the next most corrosion

resistant to acids including low quantities of HF. Silicon nitride and silicon oxy-

nitride bonded silicon carbides perform similarly to mixed oxide bonds. Table

19-2 shows typical weight loss and retained strength values for these products

in contact with common acidic solutions for the times and temperatures shown.6

Table 19-2: Typical Corrosion Resistance of Permeable Silicon Carbides

Bond Phase Corrodent

SiO,

Al,03-SiO,

Si3N4

Si3N&i,ON,

SiO;!

Al203-Si0,

Si3N4

Si3N&i,ON,

SiOz

Al203-Si02Si3N4

Si3N&i,ON,

SiO,

Al,03-SiO,

Si3N4

Si3N,-Si,ON2

SiOl

A1203-SiO,

Si3N4

Si3N4-Si20Ns

10% NaOH -0.6 65 96 336

10% NaOH -1 .o 74 96 336

10% NaOH wo.05 96 96 336

10% NaOH -2 .oo 74 96 336

10% HCI -0.6 84 96 336

10% HCI -0.3 82 96 336

10% HCI -0.4 81 96 336

10% HCI -0.4 91 96 336

10% HN03 0.4 85 105 336

10% HN03 -0.1 85 105 33610% HN03 -0.2 78 105 336

10% HN03 -0.3 99 105 336

40% H,S04 -0.4 100 110 336

40% HzS04 -0.2 81 110 336

40% H,S04 -0.1 71 110 336

40% H$O, +0.1 85 110 336

99% H,S04 +0.2 74 220 100

99% H,S04 -0.1 63 220 100

99% H,S04 -0.1 74 220 100

99% H,S04 +0.3 91 220 100

Weight

Change

%

% Initial

Strength

Retained T, “C

Time of

Test, hr

(continued)



1 9 0 Corrosion and Chemical Resistant Masonry Materials Handbook

Table 19-2: (continued)

. .30ppmHF . . . IOOppmHF. . . .200ppmHF. . .Weight Strength Weight Strength Weight Strength

Change Retained Change Retained Change RetainedBond Phase Corrodent % % % % % %

SiOs 80% HzS040.5% HN03 -0.3 93 -0.3 100 -0.02 91

SisN4 80% H,S04

0.5% HN03 +o .7 97 +0.6 95 +0.2 73

SisN4SisONs 80% H$040.5% HN03 +4.4 100 +2.4 a5 +2 .a 93

T=150°C,t=200hours.Samples were 3/4” x 3/4” x 4X” bars.

impermeable sili con carbides of both types, sintered and reaction bonded,

perform generally better than the permeable refractories as shown in Table

19-3?f6 Both reaction bonded and sintered produ cts can be exposed to higher

temperature for longer periods of time with lower weight loss than the oxide,

Si3N4 or Si20N, bonded refractories. This is due to the lower surface area avail-

able for reaction and to the greater relative inertness of their bon d phases.

Table 19:3 Typical Resistance of Impermeable Silicon Carbides

Corrosion Rate (mils/yr)

Corrodent

25% NaOH

50% NaOH10% Nay30310% NasS04

20% HCI

37% HCI

70% HCI

30% HN03

50% HNOs

70% HN03

70% H NO3

60% HsSO,80% H2S04

95% H *SO4

95% H$SO4

Reaction

Bonded

73

0.0

0.2

0.1

0.0

0.2

4.0

1.0-I .9

0 .o0 .o1 .2

40% H ,PO; 0.0

60% HsP04 0 .o

85% H3P04 2.385% HjP04

40% HF/lO% HNOq 100

10% HF/57% HNOj -

53% HF

Sintered

2.5

0.2

0.2

I .a

0.2

0.2

0.2

Boiling 144

100 144100 1,000100 288

Boiling 1,000

Boiling 144100 144

Boiling 144

200 144

200-225 144

100 144

200 144Boiling 144225 144100 125-300

Boiling 144

Boiling 144

Boiling 144

100 144

60 57625 100

25 100

Time of Tests

(hr)



Specialties 191

BASIC SOLUTIONS

Silicate, Si3N4 and Si20N, bonded permeable refractories do not perform

well in contact with sodium hydroxide. Even the reaction bonded and sintered

products suffer large relative weight losses compared to their performance in

acids. Sintered products do perform acceptably in this environment up to about

100°C. In general, Na&Os and NH40H solutions do not attack any of these re-

fractories up to the boiling point of even high concentration solutions.

DIFFUSION REACTIONS CONTROL CORROSION

All of the reactions in acidic and basic solutions are generally controlled by

diffusion of the reactant through the boundry layer existing on the exposed sur-

faces of the aggregate or bond phase.’ Elevated temperatures usually increase the

reaction rate. Thus, elevated temperatures and high local fluid velocities tend to

increase the corrosion rate of silicon carbides as the corrosion products are swept

away from the active surface sites.

CHOOSING SILICON CARBIDES FOR CORROSIVE SERVICE

When evaluating silicon carbides for potential use in corrosive service, it is

preferable to look at both weight and strength changes before deciding on a ma-

terial of construction. Retained strength after exposure to the operating environ-

ment developed by a laboratory screening study or from published information

of actual exposures is the preferred criteria.7 Retained strength is an excellent

indicator of whether the bond phase has undergone attack and how extensive

the attack may have been. This is especially important in permeable refractories

where the inside of the part is exposed to the corrodent as well as the outer sur-faces. Retained strength information can then be used for design purposes by im-

posing a safety factor on the retained strength level found from tests.

Where retained strength data is unavailable, weight loss and, if possible, vol-

ume change affects should be used as general selection criteria.

For impermeable materials such as the reaction bonded and sintered prod-

ucts, true corrosion rates can usually be calculated, as the reactions generally oc-

cur only on the surface of the parts.

Examination of the microstructure of the material after testing is also desir-

able to check for reaction deposits in pores, initiation of phase alterations not

detected by weight loss measurements, or initiation of microcracking due to

phase alteration reaction deposits having physical properties different from the

original products.

Data should generally be for a test conducted for as long as practical but al-

ways for a minimum of 300-500 hours or more. Short time tests may mask in-

cubation periods for attack on interior bond phases which might differ in sus-

ceptibility to corrosion as compared with the bond phases of the outer surfaces

of parts, especially in Si3N4, Si,0N2 and reaction bonded products.




DESIGN

Silicon carbide brick are dimensionally stable and thus do not shrink or

grow during service unless significant amounts of reaction products are present.

Reaction products generally are of a lower density than the silicon carbides andmay cause swelling or cracking depending on their concentration and the strength

of the silicon carbide shape and the lining design.

Lining design using suitable and compatible mortars is necessary for proper

performance.8 The most superior performing lining is doomed to fail if the mor-

tar is attacked, the mortar reacts with the brick, or the lining is not allowed to

expand and contract freely during service.

REFERENCES

1. Advanced Refractories, Form A-2380, Niagara Falls, N .Y ., Sohio Engineered Materials

Company (1981 ).2. Hexoloy High Performance Engineered Silicon Carbide, Form A-12024, p 23, Niagara

Falls, N.Y ., Sohio Engineered Materials Company (1981) .

3. Cast Refrax Silicon Nitride Bonded Silicon Carbide, Form A-2379, Niagara Falls,

N.Y ., Sohio Engineered Materials Company (1981 ).

4. Treseder, R.S., NACE Corrosion Engineers Reference Book, pp 217-220, Houston,

TX, National Association of Corrosion Engineers (1980).5. Kingery, W .D ., Introduction to Ceramics, pp 332-335 and 614-618, New York, N .Y .,

John Wiley & Sons, Inc. (1967).6. Chemical Resistance of Carborundum Refractories, Form A-2587, Niagara Falls, N.Y .,

Sohio Engineered Materials Company (1981).7. Fontana, M.G., and Greene, N.D., Corrosion Engineering, New York, N.Y., McGraw-

Hill, Inc. (1967).8 Sheppard, W.L., Jr., A Handbook of Chemically Resistant Masonry, Havertown, PA.,

C.C.R.M. Inc. (1977) , 2nd edition (1982) Marcel Dekker, N .Y .C.

9. Corrosion of KT Silicon Carbide in Acids, Form A-12003, Niagara Falls, N.Y., Sohio

Engineered Materials Company (1979).

PART D

GRANITE AS CHEMICALL y RESISTANT MASONRY

Dorothy A. Richter

GEOSS

Salem, New Hampshire

INTRODUCTION

Granite is a naturally occurring, chemically resistant masonry. The silicate

minerals comprising granitic rocks are not soluble in many commonly used in-dustrial solutions and the rock has desirable physical properties such as high



193pecialties

DEFINITION OF GRANITE

Granite is a natural rock that crystallized from a silicate fluid within the

earth's crust and consists of visibly interlocking crystals of quartz and two feld-spars with lesser amounts of minerals such as micas, amphiboles or pyroxenes.

The term granite as used commercially includes a much wider range of mineral

compositions than the term granite used by geologists. However, most commer-

cial granites used in applications where resistance to chemical deterioration is im-

portant are from the quartz-rich end of the range of igneous rock compositions.

They may be geologically defined by such terms as granite, quartz monzonite

or granodiorite. The so-called "black granites" are chemically and mineralogi-

cally very different from quartz-rich granites and are not considered here.

INDUSTRIAL USES OF GRANITE

Granite is most commonly used in applications where physical stability,

durability and strength in a mildly acid environment are required. Historical uses

of granite as a chemically resistant masonry include its use as flooring in places

where "oil of vitriol" (sulfuric acid) was made. In the nineteenth century, gran-

ite blocks hollowed out to form tubs were employed by steel wire companies tohold dilute HCI baths for pickling off mill scale from the wire. Some of these

tubs are still in use today.There are currently three main areas of granite use in industry, although it

could be used more widely.

Granite Surface Plates

Precision ground flat slabs of granite are used in a variety of industries as in-

spection surfaces and machine bases. Surface plates range in size from a fewsquare inches of surface to single plates weighing 60 tons. The surfaces can be

ground to tolerances of a few 100 thousandths of an inch per square foot of sur-

face. Granite is specified for surface plates because of its stable physical proper-

ties, resistance to corrosion and abrasion, and its availability in large homoge-

neous slabs.

Granite Press Rolls

Cylinders of granite are used in pressing pulp webs in the manufacturing ofnewsprint. The granite rolls range in size from 5 feet long by 2 feet diameter to

30 feet by 6 feet. The temperatur~ in the newsprint making machines range from

strength, low permeability and low thermal expansion. Granite is a cost effective

material for many industrial applications because the manufacturing process re-

quires only the shaping of components by sawing and lapping. A further advan-tage is its availability in large slabs and blocks for particular industrial require-

ments.




ambient to around 175OF and the pH may be as low as 5.5 from the release of

sulfuric and phosphoric acids by the pulp. Granite is used to make pulp press

rolls because of its resistance to deterioration under those conditions and the

desirable release characteristics of the pulp web from the granite surface.

Granite Skid Caps and Tank Liners in Steel Pickling Lines

Granite is used to form tank liners (bottoms, walls and covers) and skid caps

and skid bars in and between tanks in continuous acid pickling lines for the de-

scaling of steel. The acid baths are commonly IO-15% solutions of HCI or HzS04,

and FeCi3 or Fe,(SO& at temperatures of about 200°F.’ The granites selected

for use as skid caps and tank liners are generally quartz-rich because they are re-

sistant to the abrasive and impact wear of the sliding steel as well as the corro-

sion from the acid baths.

PROPERTIES OF GRANITE

In Tables 194 and 19-5, the chemical and physical properties of granite

masonry are given. Because the values vary greatly from granite to granite, the

range in values for granite is given together with the values for Barre, Vermont

gray granite, a widely used industrial granite. The ranges of values given in Ta-

ble 19-5 are not absolute but are a guide to possible values for all granites. It is

recommended that the properties for a particular granite be obtained and evalu-

ated before using it as chemically resistant masonry.

Table 19-4: Chemical and Mineralogical Composition of Granites

Chemical Composition Range for Granites’

SiO;?

Ti02A1203

Fez03

Fe0

MnO

MgO

CaO

Na20

K2O

Hz0

p205

co2

66.0-72.0 68.1

0.2-0.5 0.313.2-17.0 16.5

0.2-l .5 0.3

1 .2-2.7 1 .3

0.0-0.1 tr

0.7-l .7 0.8

1 .8-3.8 2.4

3.5-3.8 3.6

2.7-6.0 5.3

0.5-0.9 0.6

0.2-0.7 tr0.0-I .o 0.7

Barre, VT Granite3

Mineral Composition

Mineral Name Chemical Composition Range for Granites Barre, VT Granite

Quartz SiO2 IO-40 26.5

Microline KAISi30, 15-50 15.2

Plagioclase NaAISi30&aAl2Si20S 15-50 43.1

Biotite K(Mg,Fe)3(AiSi,0,,)(OH)2 O-18 9.3

Muscovite KA13Si~OI~(OH)2 o-15 5.5Amphibole (Na,Ca)~(Mg,Fe,Al)~(Al,Si)~O~~~OH)~ O-25

Pyroxene (Ca,Mg,Fe)&06 O-25



Specialties 195

Table 19-5: Physical Properties of Granites

Absorption (%)

Porosity (%)Permeability (darcies)

Density (lb/ft3)

Shore hardness

Compressive strength (psi)

Shear strength (psi)

Modulus of rupture (psi) average

Coef. of thermal expansion (in/in/OF)

Thermal conductivity (Btu/hr-ft-°F)

*From Reference 7

Range for Granites4’5

0.1-0.4

0.4-2.0Not available

157-170

70-l 00

14-47 x lo3

3,700-4,800

1,430-3,060

3-5 x 10%

l-3

Barre, VT Granite6

0.23

0.510%”

165

89

28.6 x lo3

4,632

2,484

3.8 x IO”

2

The properties that make granite an attractive chemically resistant masonry

are its naturally low permeability, thermal expansion (in generally the same range

as that of “acid-brick”), high strength and the insolubility of its component min-

erals in dilute HCI and H2S04. Hydrofluoric acid is the only acid in which quartz,

feldspar and mica, the major constituents of most industrial granites, are easily

soluble. Contact with HF must therefore be avoided.

Granites containing more than trace quantities of certain minerals should be

avoided when selecting a granite for industrial use. Carbonate minerals such as

caicite (CaC03) and siderite (FeC03) are highly soluble in HCI. Sulfide minerals

such as pyrite (Fe&) are soluble in HzS04. If present in veins and crack fillings,

the presence of these minerals can significantly affect the life of the industrial

product.

In general, a fine grain size (<5 mm) is desirable in an industrial granite be-

cause it evens out the varying physical properties of the individual mineral crys-

tals in a smaller area. There are no major chemical changes and no crystallo-

graphic phase changes in the major components of granite below 1063’F (573OC).The physical properties of granite are generally not isotropic. The degree of

anisotropy varies in different granites from almost 0 to 30%. The anisotropy of

physical properties is due to the differing stress histories of granite bodies caus-

ing a preferred orientation to mineral grains and/or the microcracks in the gran-

ite. The three principal directions are called “rift,” “grain” and “headgrain” in

order of increasing difficulty in splitiing the stone. Because the headgrain is the

strongest direction, it is usually oriented in the vertical direction in surface plates

and skid caps and oriented on the end of paper rolls. The values of the physical

properties in Table 19-5 are perpendicular to the headgrain for those properties

that are a function of specimen orientation.

GRANITE FABRICATION AND LIMITATIONS

Granites can be quarried in blocks weighing up to 100 tons. The size limita-

tions are controlled by natural fractures in the quarry and in the lifting capacity

of the quarry equipment. In most cases, however, smaller granite components

are acceptable. The rough blocks are sawed and ground into the desired shape.




Granite can be finished to desired surface roughness by lapping. Precision grind-

ing can produce surfaces flat to within 25 millionths inch per square foot surface.

Little maintenance is required of granite components other than cleaning.

Worn surfaces can be reground if necessary.

REFERENCES

1. Smithells, C.J. Ied), Metals Reference Book, 5th ed., London: Butterworths & Co.,

Ltd. (1976).

2. LeMaitre, R.W., The chemical variability of some common igneous rocks,J. Petrology,

17:589-637 (1976).

3. Murthy, V.R., Bedrock Geology of the East Barre Area, Vermont., Vermont Geological

Survey Bulletin 10,121 p (1957).

4. Kessler, D.W., Insley, H., and Sligh,W.H., Physical mineralogical and durability studies

on building and monumental granites of the United States, National Bureau of Stand-

ards, Research Paper 1320 (1940).

5. Clark, S.P. (ed), Handbook of Physical Constants, Geological Society of American

Memoir 97 (1966).

6. Krech, W.W., Henderson, F.A., Hjelmstad, K.E., A standard rock suite for rapid ex-

cavation research,U.S. Bureau of Mines RI 7865 (1974).

7. Kranz, R.L., Frankel, A.F., Engelder, T., and Scholz, C.H.,The permeability of whole

and jointed Barre granite, Int. J. Rock Mech. Min. Sci. & Geomech. Abstr., 16:225-

234 (1979).

PART E

PORTLAND CEMENT/AGGREGATE BRICK

Larry C. Stephans

Rochester, New York

Portland cement exhibits good resistance to attack by some chemicals, par-

ticularly those with a basic pH. This chemical resistance allows its use in the

chemical resistant masonry linings of pulp and paper mill vessels. For example,

in lined kraft digesters, portland cement is used in the mortar mix for setting the

carbon brick lining and in the backing grout for these linings. Kraft digesters op-

erate under very alkaline conditions and at temperatures as high as several hun-

dred degrees farenheit. It is also used in vessels storing concentrations of caustic

as high as 40%. Because of the relatively low cost of portland cement/aggregate

mixes and the corrosion resistance to media with a basic pH, it would be advan-

tageous if this type of mix could be used for an entire lining.

The use of a portland mortar as a trowel applied lining is impractical be-cause it will not bond to a steel substrate. A structural concrete tank is also im-



Specialties 197

practical for containing a highly alkaline liquid because of the difficulty of build-

ing a liquid tight concrete tank and the problems that would be caused by leak-

age of an aggressive chemical. The problems of containing a liquid in a concrete

tank are compounded if the tank is above ground and the chemicals are hot. A

practical method for creating a complete lining using a portland cement mix is

to make dense portland cement aggregate brick.

Portland cement brick is being manufactured and used to line some pulp

and paper mill vessels. These bricks are composed of portland cement and a highly

alkali resistant aggregate. The portland cement brick presently available measures

19.37 cm (7.625 inches) by 22.86 cm (9 inches) by 6.35 cm (2.5 inches). The

aggregate is specially selected for its alkaline resistance and is sized to produce a

brick of optimum density. The density achieved in the currently available brick

is 2.2-2.3 g/cc (138-145 lb/ft3). The compressive strength of these brick is ap-proximately 4,220-5,625 kg/cm’ (6,000-8,000 psi) with a cold water absorption

of 4-6 weight percent.

The bricks are manufactured by combining the portland cement, aggregate,

and water in carefully controlled proportions. The bricks are then pressed and

cured under controlled conditions to form a portland cement brick which is ex-

cellent for lining use.

These bricks find relatively frequent use in Kraft mills because of the amount

of alkaline media encountered. They are used in the liquor regeneration systems,

the smelt tank, the lime slaker, the causticizer, the liquor storage tanks, and the

caustic storage tanks. They, of course, can be used in any industry having cor-

rosive alkaline conditions. As with any corrosion resistant material of construc-

tion, proper care must be exercised to insure the proper application of portland

cement brick.



Section XDesigning Chemically-Resistant

Masonry Constructions

541



45

Designing with Chemically=Resistant Masonry




Putting a sheet rubber lining in a steel or concrete tank is pretty straight-

forward. There are standard specifications to follow. Although the procedures

vary to some degree, depending on the type of sheet stock involved, the type of

adhesive to be used, whether or not the lining is to be done in the field or in the

shop, there are generally published instructions for one to follow.

The principal decision the user must make is the generic type of sheet stock

to use-the one best suited to the environment in which the tank is to be em-

ployed. He usually can narrow the choice down to a very few candidates through

the use of published chemical resistance tables. Thus, a few phone calls will

probably determine for him which one of these he will use, and with which sup-

plier/installer he will deal.

If a brick lining is to be installed in the tank to protect the sheet lining or

other membrane, the matter becomes slightly more complicated. The designer

(usually not the end user) must determine which bricks and mortars are best

suited for the environment, and then consider how well the bricks and mortarswhich he had selected for the environment will mate with each other, and with

the sheet lining, how well their coefficients of thermal expansion will mate with

that of the steel or concrete tank in which the system will be installed and,

finally, which combination will provide the best protection for the sheet lining.

If the brickwork does not provide sufficient thermal insulation for the sheet

lining, and if the tank is overheated, the sheet lining can be seriously damaged.

If the brick lining expands much more than the steel or concrete vessel, it could

conceivably rupture the vessel. If it expands less than the vessel walls, so that

the wall moves away from it, the wall no longer supports the brickwork, and it

can break up and fall in.

542



Designing with Chemically-Resistant Masonry 543

The more complicated the structure, the more varied the components that

go into its design, the more study the design will require because the designer

must consider all possible interactions between these components that can affect

the life, strength, stability-the satisfactory performance-of the structure.

THE BASIC PRINCIPLES

There are four basic principles that the engineer must keep in mind in de-

signing a chemically-resistant masonry structure.

(I) Strength. A structure composed of “acid brick” or block in any other

chemically-resistant masonry unit cannot be reinforced. Although it has good

compressive strength, it is weak in tension and shear, and depends for its in-tegrity on the bond of the mortar to the masonry face.

(2) Porosity and/or absorption. With all chemically-resistant masonry

materials under a continuous hydrostatic head or other continuously wet condi-

tions, the masonry units and the mortar used to bond them together will slowly

absorb fluids until the structure is saturated. At that point, the underside of the

structure is wet with the same chemicals as those on the surface. If the liquid is

acid, then acid is present on the underside of the structure. It should, therefore,

be clear that although a structure of this kind is strong and can support heavy

loads (such as piers and pedestals to support equipment), especially in areas of

chemical spillage, this type of structure cannot be used to hold liquid without

leaking, nor employed to stop leaks in an existing structure. If a vessel is leaking,

the leak cannot be stopped by putting an “acid brick” lining inside of it, or by

smearing “acid-resistant” mortar over the area of the leak.

(3) Brittleness. Structures composed of “acid brick,” block or other chemi-

cally-resistant masonry units cannot be flexed or bent (which would cause tor-

sion or shear of joints). They are all somewhat brittle, and if the supporting

structure around them bends, they are certain to break. For the same reason,they cannot accept excessive vibration.

(4) Growth. Irreversible growth or “swelling.” Fireclay or red shale “acid

brick,” the two most common types of chemically-resistant masonry units,

often grow up to 0.16% of any dimension. The reasons for this “growth” are

not proven, but experience indicates that it can happen with most “fired” clay

brick, unless they have been fully vitrified. Such growth takes place more quickly

in cycling, hot, wet environments, and slowest in static, dry, cold exposures. But

it does eventually happen to all “acid brick” and other such masonry units made

in North America (see Side Effects at the end of this section).

What about monolithics and castables? Depending on the type of com-

components (bonding or cementing agents and fillers), structures made of these

materials have many of the same characteristics to a lesser or greater degree.

Occasionally, we find someone designing a structure entirely out of “acid

brick” or a monolithic castable. When the structure will be continuously wet for

extended periods, such a design will not provide a liquid stop, and the liquids

with which it is in contact will very slowly, but eventually, pass through it.

(There are a very few exceptions: polymer concretes made with very dense, very

low shrinkage polymeric resins.) If the function of the structure is merely to




supply support, and not protection for some underlying surface, such a design

can function satisfactorily.

With these four basic principles in mind, for what purpose(s) would we wish

to use chemically-resistant masonry? Here we have four specific uses.

(I) As a load-bearing structure subjected to corrosive chemicals. Examples:

(1) Tall brick chimney liners, subjected to corrosive exit gases. (2) Piers resting

in corrosive wastes and supporting a bridge, or a piece of equipment. (3) Outer

wall of a building (supporting the roof stringers) where the wall is subjected to

splash or spray of strong corrosives.

(2) As an internal insulation in a process vessel, reducing the surface tem-

peratures on the membrane to an acceptable level. Examples: (1) Steel pickling

tank in a steel mill, lined with rubber sheet. Top service temperature of the

rubber 160°F, but bath temperature 21O’F. The brick lining provides sufficient

insulation to get the surface temperature of the rubber sheet down to 14O’F. (2)

The same system to protect the membrane in process vessels or (3) to prevent

live steam from cutting out the asphalt membrane on a floor.

(3) Protection against wear or abrasion. In use 2 (I), if the “work” (steel

plate, etc.) bangs the side of the tank and the brick were not there to protect the

rubber, the “work” could cut or puncture the rubber sheet. In use 2 (3), traffic

over an asphalt membrane can cut or deform it, but a brick floor over it will

protect the membrane from such damage.

(4) If the environment sIow/y attacks either the substrate or the membrane,

the interposition of a brick lining between the contained liquid and the substrate

or membrane will reduce to a tiny trickle the amount of chemical that reaches

the membrane or substrate. Corrosion products, if any, are trapped behind the

brick and cannot be washed away to uncover further material to be corroded, so

that the corrosion slows down and may eventually stop. Example: In a dished

bottom, cylindrical steel tank containing a mixture of acid and oil, the steel was

lined originally with sheet natural rubber. The rubber lining swells as the oil

enters it, but the brickwork holds it in place until the rubber has swollen into all

the pores of the brickwork and blocked them preventing any more of the con-

tained liquid from passing behind the brick.

With the limitations of the basic principles, we note that only the first men-

tioned use can involve a structure composed of chemically-resistant masonry

alone. The other three employ it in combination with a supporting structure

(steel or concrete, or very occasionally, wood or plastic), and unless the sup-

porting structure is in itself a liquid-tight barrier to the environment to which

the structure will be exposed, a membrane over the supporting structure andunder the masonry is necessary. The supporting structure provides the strength to

permit the structure as a whole to accept internal loading or surface loading, which

would otherwise put the chemically-resistant masonry in tension or shear, and

cause it to break up. It must be designed with adequate strength in itself to sup-

port, with an adequate safety factor, all the loading to which conditions may

subject it, plus the weight and stresses of the masonry lining, whether dead load-

ing or stresses induced by growth or thermal expansion.

The design considerations of the supporting structure are covered in earlier

sections of the book; consideration of the selection of specific materials is dis-

cussed later in this section.




DESIGNING BRICKWORK WITHOUT REINFORCING-CONTOURING

Chemically-resistant masonry cannot be designed in tension because of the

problem of reinforcing it. The only bonds that hold brickwork together are the

adhesive bonds of mortar to brick, and the tensile strength (cohesion) of the

mortar and of the clay (or brick). Various fabrics, such as glass, ceramic, poly-

ester and carbon, may be used to reinforce monolithic surfacing materials; and

chopped ceramic fibers, glass platelets and the like are used in some coatings

and thin membranes. Expanded metal, wire cloth, and stainless or other types

of anchors are used to reinforce or strengthen gunned and cast linings and some

polymer concretes. Other polymer concretes have even employed standard steel

reinforcing rods, usually with special coatings on the reinforcing. The section

in this volume on paper mills describes a hybrid design of hollow tile with re-inforcing placed through the tile, a design widely used in paper mills twenty or

more years ago, but less frequently seen today.

The use of reinforcing in any of these materials introduces into the struc-

ture another generic material with completely different physical and chemical

properties. The marriage of the reinforcing to the rest of the structure, while it

provides some of the strength that the system requires, at the same time brings

additional stress and strain into the system. It immobilizes cure shrinkage, and

with a different coefficient of expansion, introduces further stresses with anysizeable changes of temperature. If the stresses resulting from the reinforcing

overbalance the cohesion of the system, it will crack even though the reinforcing

steel holds the parts together. Therefore, before deciding to use reinforcing,

consider whether your purpose can be accomplished without it.

Can tension be avoided? With brickwork, it usually can. By designing so

that the brick linings are on the inside of curves (as they are in lining a cylindri-

cal tank), the brick can be kept in compression, provided that the brickwork is

sufficiently thick so that the thermal drop through it to the substrate is large

enough to keep the substrate (e.g., steel, coefficient of thermal expansion

7 x 10”) at a temperature low enough to prevent it from expanding away from

the brickwork (coefficient of thermal expansion 4 x IO”). In this manner, the

brickwork is kept in compression and cannot pull apart. This same, principle

can be used in designing a large rectangular concrete tank, by changing the

straight walls to curves, bowing them outwards at the middle. If this is done,

as the brick expand they move ever tighter against the tank wall, kept in com-

pression by this “arch” effect. (See Figure 45-1 and Drawing 1.)

Conversely, if the concrete contractor is careless, and the braces of his formsslip, the weight of the concrete can bulge the wall inward at the center-perhaps

not everywhere, but in only one short section. If this is not corrected, and if the

membrane and brick are laid over this reverse curve, as the brick grow they will

push into the tank, away from the supporting wall, so the brick wil l separate

from the membrane and wall, and eventually fall in.

No concrete contractor likes to use curved forms to build contoured vessel

walls. This slows down construction, reduces productivity, and thus increases

costs. Therefore, many will decide to bid the construction with straight instead

of curved walls in the hope they can argue the purchasing agent or contracting

officer out of them. If successful, they will pocket a larger than average profit.




SECTION B-BNOT DRAWN TO SCALE

Drawing 1: Concrete vessel outline, wails and bottoms contoured. Used by permission of the

Pennwalt Corp.

If the customer insists, however, they will lose money, and so they will try to

complete the work by various ruses.

One way they may try to get around this design-and unfortunately it has

been suggested by some engineers in the past, so that it appears in a few techni-

cal papers-is to make the curve with a series of straight forms placed together at

a slight angle. See Drawing 2.

Drawing 2

This results in a polygon instead of an elliptical shape. The designer should

remember that the whole purpose in curving the walls is to create an arch over

the membrane so that, as the masonry grows, it will arch against and press into the

membrane uniformly, tightening itself against the supporting structure. The reason

for this design is to eliminate the flat surface because if we have a flat surface,

we can have lateral growth movement over it, restrained only at anchor points-in

this case the angles between the flat surfaces. Just as the brick will grow and




bulge up away from a flat floor, they will eventually bulge away from the flat

sections anchored only in those angular points. If the contractor follows such a

design, the surface is not acceptable for the installation of the brickwork as it

stands. The angles must be filled in, and the continuous, smooth curves estab-

lished by resurfacing the structure.

In an existing rectangular vessel, the curves may be accomplished by “gun-

ning” concrete into the four corners and building the curves into the walls using

gunite techniques, then trowel-finishing the surface. A similar procedure may be

followed to correct the flat areas if flat forms are used. But the designer must

bear in mind that, unless this is done, the design shown in Drawing 2 is un-

acceptable.

Naturally, when designing a long brick-lined trench, the walls cannot be

“bowed .‘I A succession of bows would merely result in the brick separatingfrom the walls at the juncture of the bows, although this tendency might be re-

duced if the bowed sections were short and “thrust blocks” (see later in this

section) were used at the juncture point. However, the expense of such form-

work and the laying of the brick would be uneconomical when compared to the

cost of construction with dead straight walls with expansion joints every 15

feet. The designer, however, should warn the contractor as part of his specifica-

tion that after forms are stripped, the concrete surface shall be checked by an

independent inspector, and any bulge found in the wall-any surface bulging

inward out of dead straight-must be removed by chipping or grinding before

the concrete can be accepted.

On a flat surface such as a floor, if a sufficient number of expansion joints

of adequate width are not provided, the expansion joints will close up and, as

the expansion continues, the brick will heave upward off the flat surface. In

older designs, dating back to the turn of the century, it was often suggested

that when it was impossible to “bow” the straight walls outward, a design

“battering” the walls by sloping the plane of them outwards about 7’ from

vertical should be followed. In that period, there was no concern with the ir-

reversible growth of brick which was first noted about 1954. It is presumed

that gravity was supposed to hold the wall down if it expanded thermally into

the expansion joints. A moment’s thought, however, will tell today’s designer

that with today’s irreversible growth, if the brick on expanding, heave off of the

floor, they can also heave off of the battered wall. However, as long as the walls

are dead straight and the designer has supplied adequate thickness to support the

free standing wall on its base (see below) and an adequate number, size and

placement of expansion joints, the problem of movement away from the con-crete supporting walls will not arise.

When designing a floor, we can provide for expansion-dimensional changes-

of the brickwork with expansion joints. This same rule is followed in designing

the bottoms of tanks or the bottoms of trenches. If the liquids that will be held

in the tanks, or which wll flow through the trenches, contain oil, greases, fats,

solvents, for which there is no adequate expansion joint sealant, then we cannot

plan to use this method of providing for the brick movement. In a tank, we can

contour the bottom-that is, dish it. If we do this, just as we have contoured the

walls, we will keep the brick in “arch” configuration and keep it pressed tightly




against the membrane and, hence, against the supporting wall, eliminating the

expansion joint,

With a trench, if we curve the bottom, so that it is deeper in the center than

at the sides, we will not require a longitudinal expansion joint. We will, however,

if the walls are not contoured, require an expansion joint across the trench-

down one wall, across the bottom, and up the other side, on the average of every

15 feet, as well as at other points designated below, under “Expansion Joints.”

STABILITY

When chemically-resistant masonry is installed as a liner inside a membrane-

lined supporting structure, the chemically-resistant masonry must be free tomove or slide on the surface of the substrate, relieving stresses, expanding or

contracting with thermal changes, independently of the substrate, if it is to

retain integrity. This means (I) that there cannot be anchors penetrating both

substrate and chemically-resistant masonry lining. If such anchors were to be

employed, any corrosive in the environment could follow the shaft of the anchor

back through the membrane and into the substrate. Further, if the substrate has

a different coefficient of expansion than the chemically-resistant masonry, and

it usually does, then these anchors would prevent the chemically-resistantmasonry from expanding or contracting at a different rate than the substrate,

and if one of the elements of chemically-resistant masonry is “acid brick,‘! it

would create stresses within the structure as the brick would try to expand in

their irreversible growth, which differential expansion is provided for by ex-

pansion joints. In order for this movement to be free of stress, and as uniform

as possible, (2) the surface of the membranecovered substrate must be as

smooth as possible, and any obstructions must be suitably provided for. This

second point will be discussed later.

In cylindrical or curved body vessels or structures, stability of the lining is

also obtained by the arch effect which has eliminated the need for reinforcing.

However, in straight line designs, as in rectangular walled vessels or trenches,

stability must depend on the ability of the structure to balance upon its founda-

tions, just as does the wall of a brick house, or any other masonry structure. This

means that as the chemically-resistant masonry wall gets higher or longer (or the

lining of a vessel gets deeper or longer), its thickness must be increased so that

the wall retains stability. While no one has found a way to compute the exact

thicknesses that are necessary to stabilize specific heights and lengths of brick-work, some rules of thumb exist (see Table 45-l) which have received general

acceptance, and which, if followed, can be considered adequate. This does not

mean that using somewhat lesser thicknesses insures failure, nor that success is

guaranteed if these rules are followed. It does mean that past designs that fol-

lowed these rules were usually successful, while ones that employed much less

thicknesses had considerably shorter lives or required considerable maintenance.

It should be noted that, if interlocking expansion joints are to be used, it is

generally advisable to go to an 8” lining. The reasons for this will be discussed

under that heading.




Table 45-1: Thicknesses Needed to Stabilize Heights and Lengths*

Depth (ft)

<I

<2

l-2

2-6

2-6

>6

Length (ft)

<30

<I5

15-30

<I5

>15

any

Thickness (in)

2-x

2-x

4

4

8

8-12

*For extremes of length and depth, greater thicknesses are advisable. From Chemically Re-

sisrantMasonry, Walter Lee Sheppard, Jr., 2nd Ed., Marcel Dekker, NYC (1982).

The second point mentioned above, that of providing for obstructions to

movement that cannot be eliminated, requires further consideration at this

point. Let us consider, for instance, the selection of a sheet rubber lining as

membrane. The application of sheet linings means that, at regular intervals,

there will be joints between sheets. These may be laps of one sheet over the

adjacent one, or butted edges with a seal strip on top of the butt joint. In either

case, there is a double thickness of sheet at that point. If a brick (or other chemi-

cally-resistant masonry) lining is applied directly over this sheet lining, these

ridges will act as anchors, protruding into the mortar joint between the brick

and the membrane. If the chemically-resistant masonry lining tries to moveunder such conditions, one of two things can happen. The chemically-resistant

lining can tear the joint in the membrane, causing leaking. This is the most

likely result. If the membrane is strong and the chemically-resistant masonry

lining is thin or weak, the chemically-resistant masonry lining can crack and pull

apart. To prevent damage to the structure, the protrusion of the membrane lap

must be provided for. Drawing 3 shows how this is done. Two sponge pads of

the same thickness as the lap or protrusion, and at least 2” wide, are cemented

to the membrane, one on each side of the protrusion prior to the installation of

the chemically-resistant masonry linings. The brick (or other masonry unit) that

is to go over this joint must be notched-a large enough notch to cover the com-

bined lap (or protrusion) and the sponge on each side of it-so that when it is

mortared in place, the masonry can slide (move in either direction) by com-

pressing the sponge pads. If this is done, the chemically-resistant masonry lining

will be able to slide one inch in either direction without hanging up on the

protrusion.

We have earlier supplied the reason why “battering” is not a satisfactory

way to resolve the problems of irreversible growth. Another idea favored by

many designers is to design the flat concrete wall with pilasters protruding from

it at regular intervals or, alternatively, to leave the wail dead flat but to build

pilasters into the brick lining to give the wall greater stability.

If the pilaster is built into the concrete wall itself, it acts as an anchor and

prevents movement over it. If there are no expansion joints in the brickwork it-

self, this design will require sponge expansion pads on both sides in just the same

manner as on both sides of the cap strip in the sheet lining (see Drawing 3) if the

brick is not to heave off the wall and fall in. The detail over the face of the pilas-ter will be even more difficult because it will have to include an expansion joint,




which will introduce weakness into the wall at that point. The alternative is to

place expansion joints in the brickwork midway between all these pilasters and

to leave the brickwork anchored on them as points of no movement-all of

which is as expensive as, or more expensive than, contouring the concrete.

Brick

Elastomeric

Closed cell spongeChemical Resistant

Mortar

Drawing 3

Frequently designers seek to resolve this matter in another manner-by

building a brick pilaster into the brick lining. A moment’s consideration of this

idea will quickly tell the designer why this will not work. The on/y strengthening

the pilaster gives to the lining is the vertical weight of the brick in it. Standing

by itself, only the weight of the brick holding it in place has any stabilizing

effect. If the column stood alone-to a height of, e.g., IO feet-a strong man

should have little trouble pushing it over by pressing against the top bricks in the

column. Figure 45-6 shows how little stability the pilaster has provided in one

case where the brick is pushed away from the wall at the furthest point exact/y

at the pilaster, unbalancing the pilaster inward.

EXPANSION JOINTS-GENERAL

On any structure composed of two or more dissimilar components, therewill be a difference in the coefficients of thermal expansion of those com-

ponents. Take, as an example, a steel tank lined with a sheet rubber lining and

inner-lined with 8 inches of “acid brick.”

As the internal temperature rises to 200°F, the brick try to expand. The

brick act as thermal insulation so that if the tank is standing in a room with an

ambient temperature of 70°F, the steel shell temperature will be approximately

12O’F. Although the steel has a much higher coefficient of expansion than the

brick, it is only 50” hotter than it was when the brick lining was installed at

70°F. However, the brick (and mortar) on the inside face are now 130°F hotter

than when they were installed, and they will expand accordingly. In addition,




the irreversible growth mentioned earlier must be provided for. Therefore ex-

pansion joints are needed to permit this expansion to take place without disrupt-

ing the steel shell of the tank. This means that some compressible joints must be

installed at appropriate spots to allow the brick to squeeze together. But sincethe steel shell and its rubber lining will be solid-without expansion joints-if

the brick on both sides of the compressible expansion joints are to move to-

gether closing the joints, then the brick must slide over the face of the rubber

lining.

This is the first law of expansion joints-every expansion joint in chemically

resistant masonry must end in a sliding joint or another expansion joint. If it is

not so designed, the expansion joint will not function. See Drawing 4 of the

wall of a brick-lined trench, below.

CUtbTiC* o fit.mge Of floor

soldier cour*e. Closed cell 8Do”qef- lCO”cret.2 or brick)

Closed cell sponge




The upper right-hand sketch shows the way a draftsman first designed the

expansion joint. Note that the joint is totally immobilized because where the

joint ends in the concrete above the brick lining, the concrete abuts the brick

and holds the top course of brick in a fixed position. If the top brick cannot

move, then neither can the brick below it.

In the upper left sketch, the brick on the left side of the expansion joint

cannot move to the left because to do so would force it into the capping on the

top of the trench wall. It will, however, be able to close the expansion joint-

moving to the right if a shear plane-a sliding joint, such as a Teflon sheet, exists

under the capping. None is shown in the drawing.

The lower right hand sketch shows the corrected design, freeing the brick

to move in both directions, and the joint to open and close. Note that there are

examples of both the compression joint and the sliding joint. The lower leftsketch shows the sliding joint necessary under the cap for the joint to function

in this design.

There is a great difference between a compressible expansion joint material

and a deformable joint material. A true compressible material is one that can be

squeezed together without extruding from the joint. The majority of the useful

compressible joint fillers are closed-cell sponges or foams of the type best suited

for the environment in which they will be employed. (They are required in

totally enclosed joints where materials may not be extruded without disrupting

the masonry.) They are installed by compressing them about 25% of their vol-

ume and then sliding them into the joint.

Deformable materials, on the other hand, are materials of a soft or putty-

like texture, of a constant volume. When this type of material is used to fill a

joint, as the joint closes, the material is squeezed upward and extruded out of

it. As the joint opens, the, deformable material is sucked down into jt (see Draw-

ing 5).

Compressible materials rarely have a good bond to the sides of the joint but,

if installed under pressure, will expand to release that pressure if the joint

opens, or squeeze together if it closes. Without a good bond to the joint sides,

this type of filler is rather easily penetrated by contained liquids. It is, therefore,

common practice to fill the joint to within 3/4 in. to % in. of the top with the

compressible foam, then seal the top space with the deformable sealant, applied

in putty or fluid form and bonded to the sides of the joint. It is important that

the sides of the joint are truly vertical., at 90” from the floor surface, so that as

the the joint opens or closes, the movement is at right angles with the sides.

If the sides of the expansion joints are not truly vertical, so that they slopeeither inward or outward, as the joint opens the filler material in the joint will

be pulled away from the walls diagonally-a tearing motion to restrain which

requires far greater adhesive strength than does the pull at right angles. The

result will be the rather early disbondment of the joint filler. If the joint closes

and the sides are sloped inward (from bottom to top), any deformable material

in the joint will be squeezed downward, resulting in an upward pressure on the

brick around them, tending to lift the brick off the membrane. If the sides are

sloped outward (from bottom to top) and the joint closes, the filler material

is forced upwards and in shear along the sides, causing a loss of bond, eventually

resulting in the filler popping out of the joint.




cement bed joint

Note dimensional changes of deformable filler in each

case, as joints close, and as joint opens.

Drawing 5

If the joint is made in this manner in a food plant, such as a dairy, and milk

(or other fluid food) penetrates the joint, it will form a static pool on top of a

properly installed membrane, in the area of the joint, and slowly become rancid

or ferment, creating odors, and causing troubles with the food inspector. Forthis reason, it is common practice in food areas to fill the entire joint with de-

formable material rather than use closed-cell sponge at the bottom, leaving no

void in which the milk (or other food materials) can collect. As the joint closes,

the sealant is extruded at the joint top. Any excess can be removed with a sharp

knife leaving the joint full, but not protruding.

If there is no membrane under the joint, as in an expansion joint in a tile

floor laid directly over a crack in the concrete slab, the deformable sealant will

adhere to the bottom as well as the sides of the joint. If this happens, the de-

formable material will not function properly. The joint cannot open without

pulling the filler off the sides of the joint at the bottom, or close without tearing

it loose at the bottom and top of the joint.

Where a masonry surfacing is laid over a membrane (as for instance brick

over a hot asphalt-coated concrete floor), the membrane provides the sliding




joint. The expansion joints in the brickwork need only to be compressible closed

cell foam or sponge, topped with a deformable sealant, placed at adequate dis-

tances apart to accommodate the brick movement which will be the algebraic

sum of irreversible growth and thermal expansion. Normally, this means with

“acid brick,” the placement of expansion joints on floors at a 15 ft. to 20

ft. distance apart depending on the range of temperatures to be accommodated.

However, it must be remembered that if the area involved is broken into smaller

units by pump bases, building columns, piping through the floor, drains, etc.,

the brick cannot move at the point where the interruption occurs. These fixed

points, then, will require an expansion joint between them if “heaved” floors

are to be avoided. If such fixed points are single interruptions in an otherwise

continuous floor plane, they can be handled simply by isolating them by placing

a single continuous expansion joint around them.Where the space between such fixed points is 3 feet or less-for instance,

two pump bases-and there is little likelihood of temperatures cycling over 20’

to 30°F, it is possible to dispense with an expansion joint between them. How-

ever, if there is a steam jet that can play on the floor, or the possibility of the

spillage of very hot, possibly boiling, liquids, then an expansion joint should be

installed even in that small a space. The rule to follow is, install an expansion

joint over (1) all points of movement: expansion, control or construction joints

or moving cracks in the substrate, (2) around or between all fixed points, in-

cluding changes in direction or elevation of trenches except drains.

Drains are fixed points, but they are at the lowest point in a floor, and ex-

pansion joints are the weakest, and most easily penetrated parts of a floor. There

is more likelihood of a leak developing at a drain than anywhere else on a floor,

especially if the drain is stopped up. If an expansion joint is placed around a

drain, as the joint closes, the sealant is extruded upwards, where it acts as a

dam, obstructing the liquids running toward the drain. The result will be a stand-

ing puddle at the weakest place on the floor. Therefore, it is best to place the

expansion joints at the higher elevations, midway between drains. They shouldbe designed to run crosswise of the direction of fall-not with the slope-so that

drainage will flow across them, not along them.

As a rule of thumb, in designing expansion joints, the engineer should make

the expansion joint twice as wide as the maximum expansion that he anticipates

will take place, that is, the sum of the amount of growth of the brick, and the

thermal expansion of the brick in the temperature range for which he is plan-

ning. In floors, if the expansion joint is wide, the edges will be pounded by

heavy traffic passing over them, and can crumble or spall, causing failure of the

joint and requiring frequent repairs. Therefore, the maximum size practical for

expansion joints is about 3/2 in., to accommodate % in. of movement. Consider-

ing the amount of growth that can take place in the brick available today, that

means we are planning for % in., which can be reached in about 15 to 20 ft., the

latter being the size of the most frequently designed bay in the old buildings.

The rule of thumb, then, as previously stated, calls for an expansion joint at

least every 15 to 20 ft. of brickwork-more frequently if large thermal changes

are anticipated (for instance, in steel pickling tanks operating at over 200°F,

spacing is at 7.5 to 8 ft. apart). As stated earlier, they should also be placed

between or around all fixed objects except drains.



Designing with Chemically- Resistant Masonry 555

One of the most frequent errors committed by both designers and con-

tractors in the placing of expansion joints in floors, is the failure to carry the

expansion joint through the bed joint (the mortar under the brick) down to the

membrane between the brick floor and the substrate. The error most often re-

sults from the practice, primarily of tilesetters but often of brickmasons as

well, of troweling the mortar for the bed directly over the membrane, then

buttering the edges of the brick, laying it in the mortar troweled on the mem-

brane, and tapping it to tighten the joint and to level the brick face with the

other brick already laid. When the location planned for the expansion joint is

reached, the side of the brick that will act as the face of the expansion joint is

left bare, but the mason or tilesetter may have already spread the mortar over

the membrane and either forgotten it or ignored it. If the mortar is left there,

in the bottom of the expansion joint, the brick are locked into a fixed positionby the continuous bed under the expansion joint, and the expansion joint can-

not function.

The designer should make clear on his drawings that the expansion joint

must extend all the way down to the membrane (through the bed) and may con-

tain absolutely no hard or rigid material-only the specified expansion joint

filler.

THRUST BLOCKS

A thrust block may be defined, for our purpose, as a ceramic anchor, set in

the substrate to prevent the movement of a brick facing placed over it. It is used

to direct the expansion of a brick lining (or surfacing) in one direction only,

rather than in both. On a floor, this may be used to prevent damage to the

capping and brick lining of a trench or pit when it is undesirable to place an

expansion joint adjacent to it.

Let us take as an example a very wet area of floor, draining into a trench,

and carrying, perhaps, very small amounts of solvent. Inasmuch as the weakest

point in a floor-that most likely to be penetrated-is the expansion joint, it is

best not to have an expansion joint close to the trench where all the liquid spill-

age will flow over it. It should be back at the highest point, or along the wall of

the room, Yet normal construction calls for an expansion joint to be parallel

to the trench, and back three brick from it. Much less could result in the brick

expansion creating sufficient back pressure from the joint to tend to push the

brick capping of the trench wall, and the trench wall below it, into the trench.If, however, an anchor is designed into the brickwork along the edge of the

trench, the brick can be forced to expand away from it and toward the expan-

sion joint at the high point. Drawing 6 shows how this is done.

Note that the concrete is placed with a slot cast into it, back about three

brick from the edge of the trench or pit and running the length of the trench or

pit, parallel to it. The pit is wide and deep enough to accommodate two brick

standing soldier course-one with the narrowest dimension and one with the

width dimension parallel to the trench wall. The depth may be the full length of

the brick less the floor thickness, if desired, or it may be less than this, but not

less than 3 in. If less than the full length of the brick, obviously the brick will




have to be cut. If the floor is 4 in. thick, it would probably not be worthwhile

to expend the labor to cut off 1 in., but if the floor is only 13% in. thick, it is

certainly less expensive than to form a slot the depth of the length of the bal-

ance of the brick and adjust the reinforcing accordingly.

The membrane is applied to the floor in the usual manner, carried down

into the slot, across the bottom, up the opposite side, then to the trench, down

the wall, across the bottom up the opposite side, all in the normal manner, with

all corners carefully squared, and properly reinforced throughout. The brick are

then laid in the usual manner, except for the soldier course at the slot. The con-

crete between slot and trench wall is now encapsulated in brickwork, and the

cap and wail of the trench are effectively anchored and will not come loose.

:*rane

brick

Drawing 6

This leads to another design requirement-that of tying the trench, gutter

or sump wall lining to the adjacent floor. Obviously, the membrane must be con-

tinuous-passing from the floor, over the trench edge, down the wall, across the

bottom, and up the other side. The brick protection also must continuous. But,

in addition, it is important to avoid placing a brick joint at a stress point, if at all

possible. See Drawing 6. The left-hand sketch shows the joint between the floor

and the cap brick on the trench wall coincides with the back joint of the brickwall-the joint next to the membrane. As you will note, from the possible

growth (or expansion) factors in the brick both on the trench wall and on the

floor, this joint will be subject to more stress than any of the other joints in the

structure. We should, therefore, avoid this design and place brick at this location

only in “stretcher” configuration, as shown in the right-hand sketch. The half-

brick should be laid next to the thrust block (or if no thrust block, several

courses back from the edge).

This same rule regarding cut brick applies to all brick adjacent to expansion

joints or any change of direction. The rule is use whole brick in such locations

to the maximum extent possible. Under no circumstances, use less than a half




brick. In no case whatever use a “soap” or other brick of less than the full width

or thickness in such a location. Set back all cut or part brick one brick or more

from the expansion joint or from any change of direction.

Where a removable cover is to be set over a trench or pit,or a steel grating

to support traffic, it is important that it does not rest direct/y on the brick lining

of the trench. See Drawing 7. Sketch 1 shows a faulty design frequently in-

corporated into construction drawings. Note that at Point A, we have an even

weaker construction than we do on the equivalent part of the unsatisfactory

left-hand sketch in Drawing 6. The weight of the grating or cover rests directly

on the brick lining. The cover cannot fit tightly if it is to be easily removable for

cleaning, and therefore, there will be some play in it, and chattering when

wheeled traffic passes over it. The consequences of this are: (I) probable disrup-

tion of the joint at Point A, (2) with damage of the membrane behind it and atleast some chemical leakage into the substrate at that point, and (3) probably

early collapse of one or perhaps both trench walls.

Drawing 7




To prevent this from happening, a step is designed into the concrete adja-

cent to the trench wall as shown in Sketch 3. The floor membrane is carried

continuously through the steps so there is no interruption in the membrane

between floor and trench, and two whole brick are laid: the first in the step,

and capping the top of the trench wall, the second carrying the floor over the

first to the midpoint of the first or beyond, to the point designed for the cover.

Now the weight and vibration of the traffic over the cover is transmitted back

into the structure as a whole and not directly on the trench lining.

The detail as drawn frequently indicates that the floor will be laid first, then

the brick walls erected on the floor. Sketch 1, at Point 6, indicates this thinking

since the joint between the bottom brick on the wall and the one above it seem

to lie in the plane of the top of the floor. This is not the strongest design for a

trench (pit or vessel) wall. It is best practice to lay the bottom wall brick first,stretcher course (lying parallel to the wall), then to lay the floor brick inside

this. This is the sequence indicated at Point B in Sketch 2.

A moment’s reflection will tell the reader why this is stronger. If the bottom

joint of the wall is on top of the floor, it is possible for this joint to fail and the

wall to slide inward or for the joint to crack open and wall to fall in. If, on the

other hand, the joints are staggered-by placing either a “split” or a “double” as

the bottom brick on the wail and laying the floor inside this, we have removed

the joint from the fulcrum of the lever.

Please note the detail at the same point in Sketch 2 which shows the method

of installing a peripheral expansion joint on the bottom of a trench or pit at the

walls. We can, as is usual with compression joints, put foam in this joint. But in

a trench or pit bottom rubbish can easily find its way into the joint, immobi-

lizing it. By turning the second brick in the wall header course, so that it extends

over the joint and the edge of the floor, and by using a release agent or other

sliding joint at this point, the joint is protected, and rubbish cannot enter it

to prevent it from functioning as intended.

Where a monolithic rather than a brick floor adjoins the trench, a modifica-

tion of this design is employed to prevent leakage at the junction of the mono-

lithic and the trench membrane. See Sketch 3. Note the following lining sequence.

(1) The monolithic is carried down both steps and to the edge of the trench wall.

(2) The hot asphalt membrane is applied up the trench wall (hot asphalt is

always carried up from the bottom to the top, never down from the top to the

bottom) and across the steps on the top of the monolithic, to the vertical wall

of the top step. (3) The brick are laid up the wall, over the membrane to the

top, the last brick being placed on the top step. (4) Unless the pit or trench isvery small and will involve little or no thermal changes, an expansion joint is

placed between the top brick edge and the vertical wall of the last step.

TRENCHES

Open trenches and gutters are the most common devices for handling bulk

spillage in work areas. If there is much traffic in the area, trenches require

covers. If they are to be kept clean, they must be accessible, preferably in aisles

and not under heavy equipment where it will be difficult to remove covers and

to get into them to clean them. If they are to drain satisfactorily, trenches must




have reasonably smooth, uniform interior surfaces and a continuous slope with

no low spots. In order to conserve working space, the designer usually selects the

minimum width combined with the maximum depth he can arrange that will

accommodate the fluid volume anticipated.

With those limitations on which to base design, the designer seeks the least

expensive construction methods to accomplish the end result. Obviously, if he

can use a precast plastic unit, setting it into forms and pouring concrete around

it, or a prefabricated stainless steel or other special metal unit, this would be an

acceptable space-saving and labor-saving device. The use in such areas, of half-

round or “channel pipe,” is not recommended. The discussion of such a design

in the chapter on waste handling will not be repeated here.

Consider first the special metal design. The coefficient of thermal expansion

of concrete is 5.8 to 6.2; that of carbon steel is a little higher. However, thethermal expansion of stainless steel and of most of the chemically-resistant

alloys is much higher-for some, nearly double that of concrete. If a prefabri-

cated stainless steel or other alloy trench or pit is bedded tightly in the concrete

floor and hot liquids run into it, the alloy will expand more than the concrete.

This will result in wrinkling of the structure and quite possibly in damage to the

welds. Although such a trench system is installed with some small clearance at

the sides into which the metal can expand when hot liquids enter, the real

problems will be at the ends and intercepts of the trench since the greatest

movement will be in the lengthwise dimension. A small pit may, quite possibly,

be lined with an undersize alloy liner set against a foam cushion to accept ex-

pansion. Unfortunately, this is not practical with a trench 10 ft. long, and

certainly not in a trench with intercepts.

Even if the expansion problems are resolved, there will be great difficulty

in applying the membrane in the adjacent floor to make it continuous into the

trench. Failure to make the membrane continuous will result in chemical wastes

from the floor getting down into the concrete around the metal and under the

metal structure, undermining it and damaging the building structure.

Now, let us consider the use of a preformed unit made of a castable plastic.

In this case, if the castable plastic is made from a mix designed to a coefficient

of thermal expansion similar to that of concrete (and this can be done by the

use of suitable fillers), then it can be set in the concrete and mated to the floor

membrane system. This can be done by designing a wide flange into the top of

the unit, setting the flange directly on the membrane of the floor surrounding

the unit, then applying more membrane over the flange and merging the upper

layer of membrane into the membrane under the brick floor. Thus the flange issandwiched into the membrane. This type of preformed trench (or pit) is practi-

cal and, if properly designed and cast from low expansion materials, will work.

With this design the brick will end over the membrane on top of the wide

flange, in line with the interior of the steel or plastic wall. Provision must be

made to keep the brick in the floor from expanding and pushing the brick on

top of the flange into the trench. This is done by installing a thrust block two

brick lengths away from the trench edge so that all movement will be directed

away from that point. (See Drawing 15.)

Thrust blocks are also necessary when two intercepts enter a trench close

together, or at opposite sides of the trench a few feet apart. Standard design

calls for an expansion joint in the brickwork not closer than 2 ft. or further




than 3 ft. from the intersection to absorb the movement of the brick without

developing sufficient back pressure to dislodge the brick on the outside corner.

If the intercepts are so close together or at staggered opposite locations so that

these guidelines for expansion joints cannot be met, then the brickwork must

be immobilized in that area with the thrust blocks. Along the feeder trenches,

back from the intercepts, however, expansion joints should be located in the

usual manner.

Do not expect to accomplish the same results with a prefabricated FRP

gutter or pit. The coefficient of thermal expansion of such a unit is far too great

for such a design to be successful except in very small areas.

Where the trench or pit is large, and/or when mechanical abuse is antici-

pated (i.e., shovels at clear-rout, etc.), the best and longest life protection is still

“acid brick.” Since, to function properly, trenches must slope so that the depthof the brick lining will vary continuously, it is obvious that it will be necessary

to cut brick continuously as the lining proceeds in order to complete the linings

of the walls and to mate them with the cap brick and the floor. As an example,

see Drawing 4 earlier in this chapter. This is one way of handling the problem

although there are about as many other designs as there are brickmasons. But

whatever the design, there will be a need to cut brick.

Years ago, it was thought that if the concrete were poured at a uniform

depth throughout, the membrane applied, and then the brick walls installed,

more concrete could be poured on the bottom, and it could be graded to estab-

lish the proper slope. Next, a membrane would be applied over the concrete and

side to side bonded to the acid brick walls already installed, then a final course

laid on the bottom on top of the membrane and cemented to the brick walls.

Obviously, these trenches failed. The membrane on the floor was discontinuous.

Acid got into the concrete used to establish the slope, through the acid brick

walls, destroying it, and the bottom collapsed.

The next method was to form slots for the brick at a uniform depth next

to the walls, and a layer of concrete properly sloped in the center. The mem-brane would then be applied to the entire interior, including the slots. The brick

would then be laid for the walls, buttering the brick and pushing them down

into the slots. After this, the floor would be laid. When completed, the mem-

brane was continuous. The only problems: (I) the high cost of forming the

concrete and (2) the tremendous labor cost in applying the membrane properly

in the slots and installing the brick in the slots. This method worked but cost

more than cutting the brick. The next idea was to go back to the first design,

but instead of establishing the slope with concrete, to use a heavily filled highmelting point hot asphalt, similar in appearance to an asphalt road surface, then

put the acid brick on top of this. Where temperatures have not been excessive

and there was little or no weight on the bottoms, this has worked reasonably

well.

A final possibility. Design once again as in the first instance with a uniform,

,constant depth, place the membrane and lay the walls, then use a polymer

concrete castable to establish the slope. If the trench is a long one, the con-

crete bottom can be stepped at each point where the depth increases by exactly

one brick depth. Now, after applying the membrane, the slopes can be estab-

lished with a polymer concrete without having to worry too much at the material

cost of a larger volume of polymer concrete.




Locations of expansion joints in trenches must be planned, not only to

accommodate thermal expansion and brick growth, but to protect brick at

outside corners from being pushed off the membrane by back pressure from

deformable elastomeric material in the expansion joints. In trenches, therefore,

in addition to the normal spacing of expansion joints and the placing of expan-

sion joints around fixed objects and over all points of movement and cold seams

and control joints in the substrate, at not more than 20 ft. intervals (or evenly

spaced apart at lesser distances if the length does not divide evenly into such

intervals) they should be placed in both directions at not more than 3 ft. or less

than 2 ft. from all changes in direction and intercepts, and before all step changes

in depth in trenches.

If the trench lining will be exposed to very hot liquids for more than 15 to

20 minutes at a time, or more frequently than once in an hour, it will probablybe necessary to place expansion joints at shorter intervals. It should be kept in

mind, however, that straight-through expansion joints, such as those we have

considered up to now, have very little strength. Of course, any variation from

a straight line, such as bulge toward the center of the trench, will practically

assure the collapse of the wall, but it will happen soonest at a straight-through

expansion joint.

In 20 ft. trenches, with squared ends, it is often possible to eliminate inter-

mediate expansion joints by the use of end pads of closed-cell foam rubber as

shown in Drawing 8. This, in effect, “floats” the brick lining between the two

foam pads, absorbing its expansion in both directions. The thickness of the

two pads must be calculated to accept the maximum movement anticipated in

one-half the thickness to be employed in the end pads.

.CO”C

c




As the depth of the straight-walled trench or pit increases beyond the

ability to line it successfully with 4 in. of brick, and it is necessary to go to two

courses, it will be possible to employ the interlocking design expansion joint,

which has been in use in steel mills since the 1930s. Drawing 9 shows this

design. Note that although there are compression and sliding joints in both

courses of brick, the joints are staggered in location so that no two coincide,

and the wall retains its strength. Although this drawing shows the expansion

joints in both inner and outer courses as winding with the brick contours from

course to course, there is an optional way of laying out the expansion joint

without excessively weakening the wall by cutting the brick on the face course

only, to make the face course expansion joint straight, and only following the

brick contours on the back course, so that the rear expansion joint passes back

and forth on each side of the joint in the face course.

(Blast Furnace and Steel Plant, November 1968)

Drawing 9

Penetrations through the trench or pit wall or bottom must be so designed

as to prevent penetration or bypass of the membrane. In drains, this is accom-

plished by the selection of a unit of the Josun type. See Sketch 1 on Drawing

10. Note that this type of drain has a wide collar on the shaft at the surface of

the concrete, the thickness of a brick, plus membrane, below the floor level.

The membrane is applied over the surface of the floor and under the collar,

then an additional thickness of membrane is added over the collar, sandwichingit into the membrane. Above the membrane over the upper face of the collar are

weep-holes through the shaft of the drain, so that any liquid that may collect




under the brick and over the membrane will drain through the weep-holes and

down the drain, effectively preventing any puddling at the low point.

Drawing 10

The brick are then laid over the membrane and up to the drain, making sure

that all joints, including those between brick and drain body, are completely full

and with no voids. The top of the drain should now be % to l/s in. below the

surface of the brick.

Sketch 2 shows the method of handling pipe entries through the side of the

trench (or pit) to drain surface liquids from the area above into the trench (or

pit). Note here that a similar type of seal is involved. The pipe extends into the

trench ‘16 in. or more beyond the design thickness of the brick lining. The shaft

of the entry pipe is threaded, the threads going back into the wall area, and the

concrete recessed a % in. minimum at that entry. The hot asphalt membrane is

applied, the reinforcing being cut to fit around the pipe up to the pipe shaft, and

out along it for almost 1 in. beyond the concrete face. A collar threaded to mate

with the threading on the pipe shaft is now screwed down tightly against the

membrane in the prepared recess in the wall, and an additional layer of hot

asphalt membrane (and fabric) placed over the collar and up to a l/z in. along

the shaft. Asphalt must NOT be permitted to get on the rest of the pipe shaft.

The shaft should be absolutely clean from % in. out from the collar to the endof the pipe. The brick is then laid up to and cemented to the shaft. Heat should

be applied to the pipe to warm it until it is just too hot to touch the metal-to

100’ to 120°F. This will cause the mortar between it and the brick to flash-cure

and bond tightly to the metal. The backs of adjacent brick must be notched to

provide for the thickness of membrane and collar, as well as the bed joint.

In placing expansion joints, it must be remembered that drains and pipe

entries are both points of no movement, and that they should be centered be-

tween expansion joints to prevent the existence of any unbalanced stresses in

the lining.




WEIRS AND OVERFLOWS

When the designer wishes to install a weir in a trench, perhaps to allow sus-

pended matter to settle out and be trapped, he should remember that the level

(and weight) of the liquid in the trench upstream from the weir will not be

balanced by an equal level on the downstream side. Therefore, a straight all-brick

wall, built in the normal fashion, will probably have a short life. It is important,

therefore, to design it in a curve, with the center upstream from the sides, just

as a civil engineer designs a power or water-retention dam on a river. However,

unlike a concrete dam,’ in this case the design must provide for the anticipated

growth of the brick. The way this is done is illustrated in the left-hand sketch in

Drawing 1 I.

Drawing 11

Note that the wall in this area is built to a thickness greater than that indi-

cated in the guidelines given earlier for pit and trench walls. Since this wall must

.sustain loading on one side, it is never less than 8 in. thick; at a depth of 6 ft.

and deeper, it should be 12 in. thick. These thicknesses are for a wall length (or

trench width) of not more than 4 ft. At greater width of trench (and length of

wall), a greater thickness will be required. The concrete trench bottom and sides

should be recessed in a smooth curve, approximately 2 in.; 3/4 in. wider than the




anticipated width of the wall. After the membrane has been applied through the

trench and the recesses, and a single thickness of brick 2% to 2% in. thick is,laid

in the recess area, a strip of Teflon film 3 to 5 mils thick is laid in the recess

in the bottom of the trench. The brick wall is then laid in the usual manner in

the floor recess, on top of the Teflon film and the brick in the bottom laid up

to it on both sides. However, instead of mortaring the floor brick directly to

the wall, Teflon film is placed against the bottom side of the wall, in the slot,

and up the side of the wall to the top of the floor brick. The floor brick are

mortared with a full joint and laid tightly against the Teflon film. As the wall

is built, a uniform space, ‘/4 to l/z in., is left between the ends of the wall and

the brick in the wall slot, and this space is filled with a closed-cell foam (or other

compressible joint filler) selected for the anticipated service. The trench wall

brick is next laid up against the partition wall brick, once again imposing aTeflon film between the mortared trench wall brick and the sides of the divider

wall.

Now, as the weir wall brick grow and expand, the brick can release thermal

stress by sliding outward on the Teflon film under them, and slide into the brick

slots in the wall, compressing the foam. This curved design provides for both the

thrust against the wall from upstream and the expansion of the brick in the weir

wall. The designer should bear in mind that like other all-brick structures, this

wall will not be liquid-tight and will weep into the downstream side. It will,

however, act to trap any suspended material that settles out.

An all-brick divider wall should never be used to make two chambers out of

a single concrete structure. If the two chambers are filled to much different

depths, the wall is sure to fall down toward the low level side. In addition, the

wall can never be made liquid-tight. There will always be leakage from one side

of the wall to the other. There should always be a concrete divider wall installed

in such a vessel, the membrane made continuous throughout each cavity, and the

brick lining installed over it in the same thickness and design as in the rest of the

vessel.

When a weir or overflow is to be installed over such a divider wall, the

section of the overflow should be designed as a slot in the concrete wall, and the

membrane carried through the slot, sides and bottom, and sealed continuously

to the membrane in the adjoining vessel. Then the brick is laid through the slot,

protecting both sides and bottom and tightly bonded with the brickwork on

both sides. Remember that this is a fixed point-an area of no acceptable move-

ment-so it should be centered between expansion joints. If the vessel is a deep

one, it may require a circumferential expansion joint around the inside of eachvessel to prevent vertical growth from pushing the bricks off of the bottom of

the slot and disrupting the brick on the sides of the slot.

VESSE Is

This naturally leads into a consideration of vessel design. The importance of

contouring and of expansion joints has been covered earlier; other design details

common to vessels and trenches have been touched on in Drawings 1, 3, 4, 5

(for sloping bottoms), 6 (where there may be a need to control the direction of




expansion movement), 7 (if a removable cover is required), 8 and 9 for the ex-

pansion joints themselves, and 10 for entry pipe for concrete vessels-preferably

above the normal liquid level.

Divider walls in concrete tanks have just been discussed. It is appropriate

here to mention an additional limitation of this kind of a design. At the begin-

ning of this study, it was said that a major use of chemically-resistant masonry is

to provide thermal insulation to the membrane. If this is hot asphalt, and in nine

out of ten concrete tanks it is, then the top service temperature acceptable is

135’F. It is possible to operate a concrete tank lined with hot asphalt at boiling

(212OF) if the asphalt i’s inner-lined with an adequate thickness of acid brick to

bring down the surface temperature of the asphalt to the acceptable range. How-

ever, if a common divider wall or a brick-covered baffle wall is put in the tank,

the wall (or concrete baffle) will be heated from both sides, so that the fullthickness will eventually reach the same temperature as the interior, and there

will be no cooling effect. The asphalt temperature will rise to the temperature of

the contained liquid, and it will flow, squeezing upwards and out under fluid

pressure, causing the failure of the tank. Therefore, with a common wall in a

concrete tank, the internal temperature of both sides of the wall should never

exceed 135°F. This rule does not hold true for steel tanks because it is possible

to design a divider wall in a steel tank with a ventilation arrangement. See Draw-

ing 11, Sketch 2.

The design indicated in this sketch has been a successful standard in steel

mills for well over 40 years for use in 300 ft. and longer steel strip pickling tanks

of five or more compartments, operating at close to the boiling temperature and

lined with rubber sheet, top limit surface temperature, 160°F. Two or more

courses of acid brick are laid over the rubber, and steel strip is pulled at a uni-

form speed through the cavities from one end to the other, over the common

walls, passing from strong, hot acid at the start, to hot water rinse at the end.

BOTTOMS

Above, with Drawing 5, various methods of attaining slope in the bottom of

concrete trenches were discussed. Unfortunately, there is a school of thought

that applies a similar approach to the design of tanks with sloped bottoms. The

theory is that it is more costly to fabricate a steel tank with a flat bottom sloped

to one side than to fabricate the vessel with a dead flat bottom and attain the

slop with a false bottom, because a sloped fabricated bottom would require the

bottom stiffeners and supports to be designed in different lengths to provide

rigid support and to keep the sides vertical. By fabricating the steel as a right

cylinder, or a true rectangular box, the bottom dead flat, all supports and stiff-

eners can be uniform in size and thickness. The desired slope is then attained by

pouring an additional bottom of concrete into the vessel and sloping the con-

crete to the desired low point, finishing the concrete to a true, smooth plane.

After the concrete has cured, the membrane, whatever the type, is applied to the

steel walls and continuously across the concrete and up the opposite side. (See

Drawing 11 .)

Sometimes, when the design calls for a sheet rubber lining, the steel vessel




is lined completely with the sheet rubber before the concrete is installed. Then

after the concrete has cured, an additional membrane is placed over the concrete

and sealed (continuously it is hoped) to the rubber sheet already applied to the

steel walls, encapsulating the triangular section of concrete in the bottom.

The engineers who favor this design fail to take into account several im-

portant factors. (I) The application of the membrane system over the concrete

surface, and its continuous sealing to the wall membrane is a more difficult

operation than the continuous lining of a steel tank with its bottom properly

fabricated to the required slope. It is impossible to verify the liquid tightness of

the seal between the wall membrane and that last applied over the floor. In other

words, there is no test available to prove that this joint will not leak and permit

chemicals from getting down into the concrete fill. (2) The coefficient of expan-

sion of carbon steel is about 5 to 10% higher than that of concrete, It will also

heat and expand a little faster than concrete. Thus the sides (which are steel) will

heat up a little faster than the bottom and try to move away from the concrete

fill. This will result in stretching the material used at the seal. If there are any

weak points in the joint, they may be ruptured, and if any holidays, they may be

enlarged. (3) With the bottom of the tank thicker than the walls by the thickness

of the concrete fill, the bottom will absorb heat, not radiating it as fast as the

walls, and the membrane at the bottom will be hotter than on the walls. This is

important only if the vessel is operating at a temperature near the upper limit ofthe membrane.

Whether to line the steel completely before putting in the concrete or to

wait until the bottom concrete is installed is arguable. One school of thought

points out that if acid gets into the concrete through the failure of the mem-

brane on top, if there is a complete lining on the steel, the acid cannot reach the

steel and “hole” it. The thinking of the second school is that if acid gets into the

concrete and damages it (but is held in the tank by a membrane below it), it

will result in the deflection of the brick lining over the membrane-and the loss

of both membrane and brick, and subsequently of the vessel, before the operator

is aware that he has a problem. On the other hand, if there is no membrane over

the steel below the concrete, the bottom will hole and start to leak in time to

warn the operator to shut down and repair before the vessel is lost. A better way

is to (I) preline all the steel with the appropriate membrane, then (2) place the

wall brick, and (3) cast the slope into the bottom using a polymer cement such

as a furan, vinyl ester, or epoxy, as may be suited to the chemistry. If it is always

on the acid side, and no fluorides are present,a silicate castable may sometimes

be used. If this is done, it may be possible to avoid having to use brick in thebottom. Of course, the thermal problem mentioned above will still be present.

Regardless of which reasoning is preferred, obviously the best answer is to

have the tank fabricated with the bottom already sloped, and to avoid the use

of two totally dissimilar materials joined together.

From the standpoint of long life and freedom from maintenance, dished,

hemispherical and cone bottoms are the best for cylindrical tanks, and are the

designs of necessity if a vessel is to be “prestressed” (see Chapter 47), or if there

is a desire or necessity to eliminate expansion joints. Flat bottoms, unless pro-

vided with properly designed expansion joints, will heave upward with brick

growth. In addition, adequate and frequent stiffening is required if flexing and




“oil canning,” which can damage brickwork are to be avoided. Flat bottoms,

however, are the cheapest to fabricate and, therefore, are the most frequently

designed-especially by those engineers who have not fully analyzed their dis-

advantages.

A favorite method of support for flat bottom tanks-to avoid using the

l-beams that should be welded at frequent intervals across the bottom-is to

pour a good smooth flat concrete foundation, cover it with a % in. thick layer

of soft asphalt or tar, and set the tank on it, allowing the tank’s weight to

squeeze asphalt out on all sides. If the vessel is to be used only for ambient

storage, this will be acceptable. But if the temperature of the tank’s contents is

much more than IO’F higher than that of the surrounding air, the designs may

experience trouble. The sides of the tank are in contact with the air, and will

cool off, keeping the wall temperature down. The bottom, however, is in directcontact with the support pad and its asphalt cover, and cannot radiate the heat.

It becomes a heat sink, and will slowly heat up until it and the contact surface

below it, have reached the same temperature as the contents. Now, at more than

IO’ hotter than the walls, the steel bottom will expand. It is restrained, however,

around its entire periphery by the hoop of the steel walls, which are 10°F or

more cooler so it cannot press outward. It cannot flex downward because it is

continuously in contact with the pad. Therefore it flexes upward at the center

to relieve the expansion stresses, and in doing so cracks the brick,exposing the

membrane. If the interior is operating at a temperature above the maximum

service temperature of the lining, the membrane on the bottom will already be

overheated. The destruction of the bottom brick lining makes the problem

worse, and the membrane will eventually hole-probably near the center of the

tank. Chemicals now leak under the tank. Sooner or later, they get through the

asphalt and into the concrete-usually about the center of the pad. Before the

operators realize that it is leaking, it will have weakened and probably seriously

damaged the bottom of the tank, and the support pad will most likely be be-

yond repair. There will be no way of rehabilitating the tank, and it will have tobe scrapped and replaced.

As noted earlier, when a common wall divides a single concrete vessel into

two, that wall is heated from both sides. The structural support of the wall and

the membrane protecting it will come up to the same temperature as that of the

contained liquids, while the outer walls, which can dissipate heat to the sur-

rounding air, will be considerably cooler. (The mathematical formula used to

compute the temperature of the surface of the membrane is given in the chapter

on prestressing, and so will not be repeated here.) Therefore, if a common wall

is to be included in the design, the membrane must be selected to accept the full

temperature of the contained liquids. If there is no membrane that can handle

the contained liquids at this temperature, this design must be abandoned. If

this design is used, and expansion joints cannot be used in the brickwork, due

either to temperature or contents, the divider wall must be contoured.

For the same reason, care must be taken in the design of any baffle walls

that may intrude into the vessel. If the baffle will only extend a short distance

into the vessel, it may be constructed of masonry, with the brick so laid as to

interlock it into the wall brick lining. With no membrane, the heat sink problemceases to be a limitation. Where the baffle extends much more than a foot into




the vessel and agitation is planned, structural support (steel in the case of a steel

vessel or concrete in a concrete vessel) is usually requred. In this case membrane

protection is needed, and the membrane must accept the temperature of the

contained liquid. See Drawing 12 and Drawing 14 for suggested details of baffle

design. If the baffle is a long one, the structural support should also be con-

toured and be dumb-bell shaped (with a rectangular head) so as to keep the

brick on the shaft in compression. (See also Figure 45-2.)

6 mrta$,

x1

rubber-lined steel w- brick 6 mortar

angle irons+ -

Lketch Y4

direction of flow

channel-

brick 6 mxtar

ts’Sketch X2 (see Figure 45-21

Sketch Y3Sketch 16

Drawing 12




Earlier in this chapter there was mention of the importance of ventilation

under the tank if the vessel is a heated one (to eliminate a heat sink effect), and

the methods of supporting a fiat-bottomed steel tank on I-beams at frequent

intervals to permit this ventilation. In addition, it is important for the walls to

be rigid so that they will support without distortion the masonry lining of a

rectangular vessel. There are several ways of accomplishing this. Angle irons

continuously welded around the top and waist of the walls are frequently used

as an inexpensive way to provide stiffness. However, spillage over the top, or

drips from work carried out of the tank can be puddled on such girth angles or

migrate to the welds, and “hole” the tank or damage the weld at that point. The

use of a channel at the top, so that drips fall free of the tank wall, rather than

following under the angle and down the tank side is an improvement. Best of all

are gusset plates welded vertically against the walls, under the channel at the top,

and to the .I-beam supports under the tank, with the I’s extended to meet the

base of the gusset plates. The gussets must be welded to the center of the I oppo-

site the web, and not to the edge of the I. (See Drawing 12.)

Occasionally vertical support stiffeners have been designed and specified

as channels, placed with the flat body away from the tank wall and both of the

ends welded to the steel wall plate. This design encapsulates a column of air

against the outside of the tank wall. Aside from the insulating effect on the

wall, preventing this area from cooling as much as the area around it,with con-sequent local overheating of the membrane in this area, and the stresses in the

steel caused by differential expansion, there is a column of air that may be or

become contaminated with corrosives held against the outside of the tank wall,

an enclosed area that cannot be reached to be serviced. This is not good design.

Concrete tanks, properly designed and reinforced, need no stiffeners either

on walls or bottoms. However, if the bottoms are not to be “heat sinks” and

require a high temperature membrane, provision must be made for ventilation

under them, such as designing the tank to stand off the floor on a series of piers,

or have supports with air spaces between them.

Obviously, cylindrical vessels require no vertical external stiffeners, as

their contour provides the necessary rigidity. But they still, of course, require

bottom support.

Outlets and inlets-penetrations through walls and bottoms-are the most

frequent sources of trouble-and failure-in vessels. It is, therefore, preferable,

to load and unload vessels over the top of a side, and to have no outlets or inlets.

It is especially important to avoid unnecessary penetrations such as thermal

wells and heater or agitator entries. Also, heat exchangers and the like may beserved over the top of a side rather than through it. This way, it is unnecessary

to spend the extra funds on membrane lining and thermal sleeving on inlet

nozzle. (See the nozzle details in Drawing 13, and those in the manhole details

in Chapter 46 on waste handling.) It is necessary, however, to protect the pipe

or conduit leading to a heater, thermocouple, steam jet or other instrument,

from bumping, from abrasion or from other mechanical damage by the contents

of the tank or by equipment. This may be done by setting headers into the brick

lining to provide a pocket in which the piping or conduit can lie. (See Sketch 3

in Drawing 12.)




Membranes should be continued out through all nozzles (inlets and outlets)

and over the exterior flange, so that the membrane has no discontinuity.

Failure to do this will eventually lead to failure. Some membrane systems

of differing types that may be lapped and the lap pressure-sealed are occasionally

used in a compromise design. (See the manhole outlet designs in Chapter 46, and

the details in Drawing 13.) The detail in Sketch 2 is not as safe and foolproofas that in Sketch 1, but in exposures that are not subject to a continuous liquid

head, it may have an economical life expectancy.




CAPPING

In designing concrete tanks, it is common practice to carry the reinforced

asphalt membrane up the wails and over the tops of the concrete, and to con-

tinue the brick lining in the same manner-over the top of the wall. Often the

membrane is carried down the outside of the tank, the outside is veneered with

brick as well, and the membrane and brick continued onto the surrounding

floor. If such a system is properly designed and constructed, the life expectancy

of the system will be a long one. This is a closed system, with no discontinuities

in membrane, and except for mechanical injury there is no way corrosives can

enter the building structure.

However, there is a problem in such design that must be provided for. The

interior temperature of the tank will almost certainly be higher than the ex-terior temperature. The brick capping has two horizontal outside corners-the

one at the top of the interior wall which will be hot, and the one at the top

of the exterior veneer, which will be at ambient temperature. Therefore, the

interior portion of the cap will expand due to the thermal difference, and shear

cracks will develop in the capping, parallel to the side walls unless a sliding

expansion joint is provided in the cap to permit this differential movement.

(See Drawing 14.) The interior vertical expansion joints in the walls are con-

tinued up to this sliding joint to permit the interior expansion joints to close

and open as the tank is heated up or cooled down, while the cap brick over the

top of the wall moves with the brick in the wall. The balance of the capping

remains in place closing up into the provided compression joints for the cap

which are only required to handle brick growth.

If there is no veneer on the outside-only the brick cap-then the sliding

joint should be placed between the cap brick and the top of the wall brick

parallel with the membrane on the top of the wall.

If the tank is steel rather than concrete, a rigid capping such as brick is not

recommended. The membrane system, such as a rubber lining, is carried up the

walls, over the channel (or angle) at the top and down and under the channel

before terminating. A timber bumper, the same width and length as the walls,

not less than 1 in. thick, preferably 2 in. with corners mitered, is placed over the

top of the channel and bolted down tightly to it using alloy bolts and nuts,

passing through the timber and through rubber-lined holes in the channel. (See

Figure 5-5, page 82). it is recommended that the head of the bolt be counter-

sunk into the wood, and covered with resin mortar to limit the chemical pene-

tration along the shaft.

COVERS

Brick cannot, of course, be used to line the underside of a flat cover. If the

cover is fixed in place, and is a dome, then it can be brick-lined. What, then,

can be done to provide insulation protection for the underside of a flat cover?

From at least the first decade of the 20th century to 1975, no insulation over

the membrane could be provided. The following procedure has been used for

concrete tanks.




Typical rectangular concrete vessel design with bowed walls to keep brick lining “in arch”.

Note design of baffle wall extending Into vessel, sides contoured and hammerhead design

to keep brick lining in compression.

Floor juncture with glazed block wall.

Interlocking expansion joint in vessel lining

ends at rubber inverted “T” (Tj at brick

cap. Shaft of rubber “T” shear pad per-

mits lateral movement at this point in-

dependent of brick veneer on outside of

vessel. Cross bar of “T” is set flat on mem-

brane covering top of tank wail, and brick

are laid up to and against the shaft on

both sides.

see “r3v.xnicall.y Resistant Masonry”, W. L. Sheppard, Jr. (1981)

Drawing 14

The concrete vessel-whether rectangular or circular-has been completed,

lined completely with a hot asphalt membrane and acid brick. If the vessel islarge, an all-brick column or support for the cover may also be constructed in-




side the vessel, to the same height as the top of the walls. A collapsible flat form

is then built up in the cavity between the sides and/or next to the column, with

the top of the form flush with the top of the sides and of the column top. Flat

rib-back clay liner plates (ASTM C-479) are laid flat, face down on the top of

the form, as if one is laying floor brick, and the edges mortared with the same

mortar used to lay the brick in the vessel. From the edges of the form to the

outside of the walls (and over the column, if there is one), the liner plates are

laid and mortared to the brick masonry. After the joints have cured, the joint

surfaces are coated with a layer of l/4 in. thick hot asphalt. Finally, over the

liner plates concrete is poured, reinforced with steel reinforcing. When all this

is cured, the manway of the tank is entered, the form collapsed and removed,

and the tank is ready for use.

As the reader will realize, this procedure will not be very satisfactory fora cover for a steel tank. If it is a fixed dome or conical cover, it may be lined

with brick, but if the cover is to be removable, the cover may be steel, em-

ploying a high temperature membrane, or a precast polymer concrete or pre-

fabricated FRP construction.

The liner plate lining of the underside of a concrete cover does not offer

permanent protection. For one thing, there is no membrane between the liner

plates and the concrete-only the layer of hot asphalt over the mortar joints.

The liner plates are not as dense as, have a higher absorption than, acid brick-

6% allowable-and they are thinner than acid brick. The absorption testing of

liner plates is accomplished under ASTM C-301-by no means as stringent a

test as that used for acid brick. Consequently, the economical life of this kind

of a cover is limited. In vessels handling ambient temperature wastes, the cover

may last a number of years. But if the vessel operates at an elevated temperature

and contains a volatile corrosive such as hydrochloric acid, tile may start falling

off in less than a year. In the past the only alternative was the same kind of

covers used for steel tanks.

In the early 197Os, light, closedcell foamed borosilicate glass block (see

Chapter 17) were developed. These block, with a mass of only 12 Ib/cu.ft., will

adhere to the underside of a concrete or steel cover by using a urethane asphaltic

adhesive; all joints between them are made the same way. Insulation of this type

has been applied to the underside of both concrete and steel covers and has func-

tioned successfully for a decade.

PRESTRESSING

Prestressing is a process employed in design to make sure that under antici-

pated operating conditions, the steel outer shell of a vessel does not expand

away from a brick or other masonry lining, leaving the lining without support

and in tension. Designs of this type are used where there may be insulation on

the outside of a vessel, or there is to be a thin lining-too thin to provide suffi-

cient internal insulation to keep the skin temperature low enough so that the

steel will not expand faster than the brick.

This procedure finds primary use in the dye manufacturing industry, but is

also used occasionally elsewhere in other chemical processes. It is done by em-




ploying a mortar for the masonry units that follows two different setting cycles.

The brick (or other block) are laid up using wide joints at ambient temperature

inside the vessel, and the mortar goes through its primary cure and becomes hard

to the touch. However, it retains a certain amount of elasticity. The vessel is

then filled with a neutral solution such as sodium chloride, and slowly heated

internally until the internal temperature has reached the anticipated operating

temperature. During this slow heat-up, the shell warms and expands, and reaches

the temperature and expanded dimensions that it will attain under the service

conditions. As it expands, the weight of the contained liquid presses the brick

lining outward, keepirrg it in contact with the supporting shell; the mortar joints

stretching to permit the movement.

The vessel is held at or above, the operating temperature for 48 hours,

during which period the mortar undergoes its secondary “cure’‘-hardeningtotally in its “stretch” condition. After 48 hours when the heat is removed and

the tank cools down, the steel tries to shrink back to its original dimensions but

cannot do so because the brickwork is now solid and immovable. From then on

the vessel can be cycled through this thermal range without damage to the vessel

or the masonry lining.

In order to design for prestressing, computations must be made carefully

to determine what stresses will be built into the vessel, and what amount of

“stretch” will be required in the mortar joints. This is discussed in Chapter 47.

From the data computed, the designer will determine the required parameters

for this vessel design. He must then refer back to the mortar supplier for the

“quellung” factor, or amount of stretch that the semicured mortar selected for

the lining will accept without joint fracture. From this factor and the amount of

expansion that the lining must accommodate, the number and size of the joints

are determined. The installer must be very careful in laying the brick, to use

spacers in the joints to be sure that they do not close up or tighten under the

weight of the lining, and so make the joints smaller than designed. Failure to

follow exact design and joint size will result in failure of the lining.

EXPANSION JOINTS IN VESSELS

Design and location of expansion joints in vessels follow the same rules as

those in floors and trenches. The designer must remember, however, that there is

less opportunity for the lining to cool where liquids are contained (held) than

when they are transient and, therefore, the maximum movements must be de-signed for. As in trenches, inlets and outlets are fixed points and, therefore,

should be centered between expanion joints. Therefore, in a tall vessel with

inlet pipes penetrating the walls near the top, circumferential expansion joints

are indicated. If there are no inlets and no capping or cover, the designer may

decide to allow the lining simply to expand-sliding up the walls. If there is an

inlet, however, the lining of the inlet will be sheared off. If the tank is not deep

and the expansion will be minor, he may opt for lining the inlet with a flexible

liner so that it can accept such movement without damage. Teflon sleeves have

been employed for this purpose.




MORE ABOUT FLOORS

Back on the subject of floors, there are a number of matters that must be

discussed:

(I)

(2)

(3)

(4)

(5)

Monolithic surfacing.

The difference between expansion joint design and location in

floors protected with bonded tile or brick, and monolithic toppings

and surfacings, and in floors protected by “acid brick” laid with

chemically-resistant mortars over an impervious membrane.

How to determine the appropriate thickness of a brick floor over a

membrane.

Curb design.

Walls subject to spray or splash of corrosives, adjacant to acid-

resistant floors.

Monolithics

To this point, the discussion has centered on “acid brick” and similar “unit

construction.” Monolithics require quite different design criteria. Monolithics

may be subdivided into three types:

(I)

(2)

(3)

Toppings and surfacings applied to the surface to be protected

(usually concrete, occasionally steel, and very rarely, wood) in

thicknesses usually of ‘1s to ‘14 in., although very occasionally as

much as % in. or slightly more, most often by troweling.

Grouts and polymer concretes, placed most often by pouring or

casting, in depths of 1 to 4 in., sometimes more, and often used to

repair or fill deep holes in a substrate.

Gunned linings, which are covered in other sections of this book.

The first two types are materials that shrink after placement as they cure

and harden. The usefulness of these will be limited by their ability to maintain

their integrity-a continuous, undamaged, fracture-free structure-and to provide

adequate resistance to the diffusion through them of the corrosives to which

they will be exposed. In addition, in the great majority of cases, these materials

will have different coefficients of thermal expansion than does the substrate towhich they will be applied.

The principal difference between the two types is that monolithics, if they

are to survive, must be tightly bonded to the substrate, relying on the rigidity of

the substrate and that bond for their integrity, so that there may not be a liquid-

tight membrane placed between the substrate and the monolithic. A polymer

concrete or grout, on the other hand, because it is used in adequate thickness to

provide good physical strength and to be self-supporting, may be separated from

the substrate by a membrane which will continue to protect the substrate if the

polymer or grout should crack.

It should be noted at this point that concrete designers have developed




many different and varied additives to include in concrete formulations to affect

cure speed, water content, strengths, density, etc. Rarely, if ever, do they con-

sider the chemistry of a surfacing material which the designer may plan to place

over the concrete and bond to it. A number of these additives have been found

to react with a component of the surfacing material and impair its cure or the

bond to the concrete surface. Care must, therefore, be taken in mixing and

placing the concrete that absolutely nothing other than portland cement, sand

and aggregate that has been approved by the manufacturer of the monolithic be

included in the concrete mix.

In the materials section of this book, there is a general summary of the cure

shrinkage and expansion characteristics for toppings and for polymer concretes

of the various types used at this date in chemical service, together with the kinds

of corrosives and the thermal ranges they can accept. Where continuously wet

conditions and/or a standing head are anticipated, the possibility of diffusion

through a monolithic surfacing should be kept in mind. Under such conditions,

a membrane should probably be included in the design-eliminating the possi-

bility of using a monolithic surfacing.

It is not usual to use reinforcing in polymer concrete, although if reinforcing

material suitable for the specific environment is available, there is no reason why

it should not be used if desired. Most polymer mortars are, however, sufficiently

strong so that reinforcing is not necessary. Monolithic applications, on the otherhand, are frequently reinforced with glass or other ceramic fabric, or a carbon or

a synthetic fiber if the exposure will include acid fluorides. Opinions are approx-

imately evenly divided as to the desirability of such reinforcing. The least cure

shrinkage is experienced when the resin content is the lowest and the amount of

filler is greatest. Fabric, however, is hard to wet with resin, and in order to wet it

out and get good bond to the fabric reinforcing, more resin and less filler must

be used. Therefore, in such formulations the cure shrinkage will be greater.

The fabric imparts strength to the structure and distributes the stresses as

the material cures adhered to the substrate, but there will be more shrinkage

stresses in this structure than there would be if less resin and more filler were

used. By distributing the stresses, there is less tendency to crack in the thinner

sections. Many designers who do not regularly recommend fabric reinforcing,

will make an exception of locations where there are changes of direction, and

suggest reinforcing be done in such areas, extending 2 to 4 in. on each side of

the direction change.

When a monolithic surfacing is applied to a concrete substrate, in most cases

much of the cure shrinkage of the concrete has already taken place, However, theconcrete contractor will have, perhaps, installed expansion joints in the slab, and

should have cut in or formed control joints as well, so that any future shrinkage

will occur at these intentionally weakened parts of the slab rather than in ran-

dom locations. In addition, there will be “cold seams”-locations where a concrete

pour was completed one afternoon and another pour made a day or so later,

or fresh concrete was poured against dry, partly cured concrete. This joint is also

weak, and with shrinkage of concrete over the years will probably also crack.

When monolithics are applied to this slab, if they bridge these points of

movement, or bridge a working crack in an old concrete slab, such movement in

the substrate can be expected to crack the monolithic directly over it. In other




words, the crack in the substrate will telegraph through the topping. For this

reason, it is vital that if the floor is to function as it was designed to, expansion

joints be placed in the monolithic surfacing directly over these points, filled with

the correct selection of expansion joint sealant for the anticipated exposure, so

that the surfacing on each side of the crack can move with the substrate without

damaging the topping and still prevent liquids from entering this crack and

undermining the topping.

These expansion joints isolate sections of concrete and topping from each

other. If these sections are large, however, they may not provide for all the

stresses in the structure. As topping materials cure and shrink, internal stresses

will accumulate over the full uninterrupted distance of the topping, while the

topping is kept from pulling its surface together by the bond between the topping

and the concrete. Experience has shown that where the cure shrinkage of amonolithic is in the vicinity of 0.05 to O.l%, and that monolithic is applied to

a dead flat surface more than 20 ft. long without an expansion joint or other in-

terruption in its 20 ft. length, these accumulated stresses can exceed the strength

of the adhesive bond to the substrate at the thinnnest section, or the area of the

concrete substrate that is the weakest, or a portion of the topping that was not

uniformly mixed or has a little less curing agent in it than another, or any of a

number of other characteristics, that would make that area a little weaker than

the surrounding ones. When this happens, disbonding occurs, and at that point

the stresses now concentrate as tensile stresses, and cause the cracking and even-

tual break-up of the topping.

Where this 20 ft. linear distance is exceeded, therefore, it is wise to install

“stress relief joints.” These are, quite simply, cuts through the topping to the

surface of the slab filled with elastomeric expansion joint sealer. The stress lines

in the topping cut in this manner prevent the accumulation of sufficient stresses

to exceed the strength of the bond of the topping to the substrate. If there are

expansion joints at 15 to 20 ft. intervals, obviously there is no need for such

stress relief joints. But if the expansion joints are at 30 ft. intervals, then a stress

relief joint of this kind should be placed at the midpoint of this 30 ft. span to

prevent such stress buildup.

If quarry or ceramic tile is adhered to the concrete substrate with a strong

adhesive, exactly the same rules as for the monolithic should be followed, in-

cluding stress relief, since the adhesive functions in an identical manner. The tile

must be cut to place the expansion joint in the tile exactly over the one in the

substrate. On the other hand, if the floor is protected by “acid brick” laid on a

membrane, the membrane acts as a “sliding joint” as described earlier, and the

expansion joint in the brickwork may be offset by as much as a brick length

from the point of movement in the substrate-saving the installer the cost of

cutting brick to match exactly the expansion joint in the slab.

Where cure shrinkage is expected to be greater than 0.05 to O.l%, more

frequent and larger expansion joints should be planned, with distances between

joints reduced proportionately.

Experience also indicates that the optimum size for expansion joints is % in.

across. At this dimension, wheeled traffic (with 6 in. or greater wheel diameter)

over the joint-if the joint is filled with a reasonably hard sealer such as a flexi-

bilized epoxy, but with an elongation of 50%-can be accepted without damag-

ing the sides of the joint.




Elsewhere in this section, we have discussed the irreversible growth of acid

brick, usually considered to be about 0.16% of any dimension (about 3/s in. in

20 ft. of 8 in. brick). Some brick, especially underfired ones, may grow more

than this. From design experience with the brick of the particular manufacturer

the contractor plans to use, the engineer should compute the frequency and

width of expansion joints in any brick floor that he plans, to be certain that

there is adequate provision for such movement so that “heaving” of the floor

as a result of brick growth and thermal changes will be avoided.

Differences Between Expansion Joints in Bonded Brick and Brick over a Mem-

brane

The first choice, all things being equal, in selecting protection for a floor is

“acid brick” and mortar laid over a suitable liquid-tight membrane. The mem-

brane most often is hot asphalt, although, depending on conditions, another

type may be chosen. The membrane system provides a sliding plane so that as

brick grow irreversibly, or expand and contract under thermal changes, the floor

area can relieve the stresses in the brickwork by sliding toward suitably placed

expansion joints causing the joints to close up under growth and thermal ex-

pansion, or open somewhat as temperatures drop. When this type of protection

is selected, and the brickwork is thus free to slide the fraction of an inch neces-

sary to relieve the stresses by moving into or out of the expansion joints, it isnot necessary to match exactly the expansion joint in the brickwork to the

expansion joint, control joint or moving crack in the substrate. If the expansion

joint is offset a half a brick from the joint in the substrate, the brick can still

move into and out of the expansion joint, and it can function satisfactorily, pro-

viding the substrate surface is smooth, and there are no irregularities to anchor it

at some point and prevent movement.

It has been learned by sad experience, however, that if the thickness of the

brick on the floor is less than 1 in., traffic over it, even light traffic, can flex the

brick by pressing it into a soft membrane like asphalt and cause the brick to

crack before too long. Therefore, when the brick thickness is to be less than 1 in.,

the brick is bonded directly to the slab by using a bonding bed joint instead of a

membrane and regular bed joint under the brick and over the membrane. These

bonding bed joints are usually a nominal l/s in. thick, made of an epoxy resin for

high bond strength, and are troweled, on the surface as a continuous, uninter-

rupted layer into which the thin brick or tile is set. All grooves in the back of the

tile or brick should be completely filled with the bed material. If this design is to

be followed, the concrete substrate should be finished to grade, without low

spots, and prepared to receive the bed material just as carefully and to the same

specifications and standards as those required for a monolithic surfacing ma-

terial. This type of bonding bed is very dense, and if applied carefully, in a ‘18 in.

thickness, will, in most cases (but not all), function as a membrane. It is not

advisable to try to correct holidays, low spots, and other imperfections in the

substrate by increasing the thickness of the bed. Epoxies, in particular, are self-

leveling resins, and this can cause settlement and sag, resulting in low spots if

the tile or brick are set on too thick a bed.With the tile or brick bonded directly to the substrate, we have in effect




applied a monolithic topping where the tile or brick set in it function like over-

size aggregate. From this, it must be apparent that we no longer have a sliding

plane under the brick or tile, and so we can no longer offset the expansion joint

in the brickwork (or tile) from the joint in the substrate. The former must be

exactly above the latter-no matter what this may mean in the cutting of brick

to make this fit. Be sure, however, that all cut brick are set back from the ex-

pansion joints and only whole brick used on each side.

This also means that stress relief joints will be required on this type of floor

to break the lines of stress from the slow growth of the brick or tile, and so pre-

vent disbonding, followed by heaving, just as the stress relief joints in a mono-

lithic floor provide for the cure shrinkage of the monolithic. It should also be

remembered that, unlike brick on a membrane, if brick (or tile) are bonded to

the substrate, and if the substrate cracks, so will the tile or brick structure.

Determining Floor Thicknesses

As was mentioned above, a brick or tile less than 1 in. thick should not be

applied over a soft membrane because traffic will cause it to flex and eventually

to crack. In addition, asphalt has cold flow. Thus, a very heavy weight standing

permanently at the same spot on an acid brick floor laid over an asphalt mem-

brane, will, after a time, cause the asphalt to squeeze out-cold flow-from under

the weight to the area under the adjacent brick. This kind of movement can, ifexcessive, cause the floor to break up. No two batches of asphalt membrane

material are exactly alike, nor are any two areas of the membrane identical in

thickness and reinforcing, so it is impossible to make any absolute statements as

to the size and weight of acceptable loads. What can be said is this: under con-

tinuous load-a fixed tank, etc., a permanently parked heavy vehicle (the worst

case would be something like a steam roller)-the probable load limit for a ‘14 in.

thick asphalt membrane with a single layer of reinforcing glass fabric is probably

about 25 lb/in’.

To translate this figure into the conditions in a specific case, the following

factors should be borne in mind:

(I) The height of the load above the membrane. (With a vehicle,

this means the distance between the face of the wheel and the

center of the axle,plusthe thickness of the brick and the thick-

ness of the bed joint.)

(2) A pinpoint load on the brick itself will spread the load laterally

around the joint in a cone pattern as the stress passes through the

thickness of the brick. We cannot be exactly sure of this load

distribution because of the nature of the brick and its composition,

but we can assume as probably worst case a 30’ angle from the

vertical at the apex directly at the point of load. The higher this

load can be elevated, the more it can be spread out. This can be

done in two ways: (1) increase the thickness of the brick (which at

the same time adds more shear strength and less flexibility to the

structure) and (2) use larger diameter wheels with wide faces andpreferably large pneumatic tires.




Anticipate, therefore, in your design, the worst load conditions and plan

for them. Under column supports or tank pedestals where heavy loading is anti-

cipated, do not use soft membranes, and plan instead on bonded construction.

Where you are concerned only with traffic and standing loaded vehicles, be

sure that you have adequate brick thickness to accommodate it without break-

ing up.

Curbs

Curbs are included in floor designs usually to retain spills and to prevent

flooding of adjacent areas. For this reason, the usual curb design is like that in

Sketches 1 through 5 of Drawing 15. A curb is formed into the floor construc-

The above, "Chemical Resistant Masonry", W. L. Sheppard, Jr. (1982).

Drawing 15




tion when the floor is laid, and the reinforcing is continuous throughout. The

membrane is continued along the floor to the curb, up the side and across the

top to the other side. This design stays liquid-tight, and is the most suitable for

those areas where there may be frequent spills and large volumes of liquid.

Where it may be desirable to localize a spill, but there is not too much concern

if some small amount of the liquid reaches the outside of the curbed area, setting

double brick into the floor as a barrier wall extending above the normal floor

surface might handle the matter (Sketches 6 and 7). If the floor is an old one,

or it is desired to add a curb to a new floor, one can be created by following

the design in Sketch 7. Here, double brick are bonded with an epoxy mortar to

the concrete substrate to build the curb. The asphalt membrane is then laid up

to this brick curb, and the floor laid over the membrane and bonded to the brick

curb just built. Obviously, without a membrane on the face of the brick curb,this curbed area will probably leak through the curb. If we want to stop such a

leak, the membrane can be carried up from the floor to the top of (Sketch 8),

and over, the brick curb, in effect modifying the design to equate with that of

Sketch 4.

Walls Subject to Spray or Splash

In chemical plants where corrosive, wet conditions are anticipated, walls are

protected with membranes and brick veneers in the same manner as floors. Al-ternatively, a divider wall between two rooms, or one that is to support a roof

or other load, may be built entirely of “acid brick” and mortar. A different,

more attractive system, is usually followed in food plants such as dairies, often

employing glazed tile or block. The latter are laid just as are regular cement

block, except that the face joints are left void to a depth of %I in. or more, or

raked back to that depth before the joints set up. After cure, the surfaces of the

joint are cleaned usually with dilute hydrochloric acid, and the joints pointed

full with a furan mortar. See Drawing 14 to see how this kind of a wall is mated

to an “acid brick” floor and membrane.

Tile*

Tile, rather than brick, is often used where (I) the designer is dealing with

fixed elevations and doesn’t have the room to accommodate brick thickness,

and/or (2) where appearance is paramount and a “show floor” is wanted. The

designer should carefully read those portions of this book that cover tile and

brick before deciding which to use, and certainly before he starts detailing the

structure. Although they are similar in nature, tile and brick will not provide

identical end products, will not accept identical conditions, and are not installed

in the same manner.

Tile has been used for decorative purposes for thousands of years. Of the

many types manufactured, three varieties are most frequently employed in

chemical service: (I) Quarry tile, which much resembles a thin brick, most often

used in laboratories, kitchens and food plants; (2) Ceramic tile, small, thin,

*See W.L. Sheppard, Jr., Chemically Resisfanf Masonry, 2nd Ed., Marcel Dekker, NYC, pp5568 (1982).




often ‘/4 to 3/s in. thick vitrified shapes, usually supplied mounted on an open

weave cloth or paper backing, laid in sheets on a semisoft bed, which is allowed

to cure, then the backing removed and the balance of the open joints filled by

grouting; (3) Glazed tile, which can be a multitude of sizes and shapes such as

4 in. by 4 in. porcelain bodies with a glazed face, or even ceramic blocks of

which one face has a fired glaze. These are most often used in areas that must be

kept very clean, the smooth glaze making it easier to sanitize and disinfect.

Unlike brick, which are buttered on the contact faces with mortar and then

laid, tilesetters have, for hundreds of years, prepared a semisoft bed-most often

of portland cement and sand-and set the tile in it, laying a straight edge over it

and tapping the straight edge to adjust the elevations of all the tile to provide a

uniform, level, surface. Concrete contractors are accustomed to supplying the

tilesetter with a rough slab on which to place the bed, and in many cases apply-ing a “waterproofing” layer of paper and low temperature asphalt to the slab

before the bed is placed. No matter what “grout” (a loose mortar mix “grouted”

into the open joints after the bed has set and anchored the tile in place) is used

with the tile, this design is not adequate for wet chemical service, under dilute

conditions with weak corrosives. All hydraulic materials must be replaced with

materials that are chemically resistant, and the “waterproofing” must be re-

placed by a sound, liquid-tight membrane, if this tile floor is to have an eco-

nomic life.

This means that the designer must make certain that his specifications are

not misunderstood. He must carefully specify what the exact surface of the slab

must be in order to be accepted, exactly what membrane shall be used instead of

the waterproofing and how it shall be installed, exactly what bedding material

shall be used to set the tile, and exactly what “grout” shall be used in the open

joints. If a thin bed is to be used to bond the tile directly to the concrete sub-

strate, he must indicate acceptable thicknesses for it and specify that the applica-

tion is to be made with a flat trowel-not a ribbed or serrated one that will lay

ribbons of bed rather than a smooth, continuous, void-free bed on the concrete.

All materials should be identified generically so that there is no mistake and so

that if later another product said to be “equal” is substituted, the installer will

be able to determine whether it is indeed equal.

SUBSTRATE

A separate section of this book discusses the selection and design of sub-strate structures which are required to support chemically-resistant masonry.

This section will not duplicate what appears therein, except to warn the designer

of three things. (I) The designer must verify that the substrate selection and

design are adequate to provide the necessary support for the full load anticipated

with a safety factor of not less than l%, without visible deflection. (2) He must

check with the materials manufacturers and installers of all the materials he has

selected which will be in direct contact with the substrate to determine what

surface strength and surface preparations of the substrate should be provided,

and then be certain that these requirements are included in his specifications.

(3) He must verify that there is nothing in the materials that will be in contact




with the substrate that can interact with anything in the selected substrate to

prevent full cure and/or adequate adhesion from taking place.

This third item is often overlooked. The following are examples. Some ad-

mixtures, curing agents, air entrainment agents, and other materials added to

concrete mixes can react with and deplete the curing agents in epoxy toppingsand bonding agents, preventing adequate cure and resulting in disbondment.

Furan and phenolic mortars use acid curing agents. If they are placed directly

against carbon steel and/or concrete, the acid curing agent can react with the

substrate depleting it in the surface layer and preventing full cure. When pointing

joints in portland cement-bedded quarry tile with a furan mortar, it is customary

first to paint the portland cement joint face with muriatic acid, which prevents

the depletion of the hardening agent and accelerates the cure. Heat applied to

the carbon steel surface can accelerate the hardening of the mortar before thesurface reaction can deplete the hardener, and so ensure fast and complete cure

and a bond to the substrate. These are but two examples. Be sure that the manu-

facturers of the materials accept your specifications as clear and concise, and as

protection against any such incompatibility.

Lastly, in concrete construction, all vertical sections are poured against

forms. Contractors lubricate forms to prevent adhesion of the concrete to the

forms. Be certain that the lubricant or form release materials used are com-

patible with the materials to be installed and acceptable to their manufacturers

and applicators. If they are not, your specification must include provision for re-

moving, probably by brush sandblast, any residue left on the surface of the con-

crete after the forms are removed as well as provision for inspection to insure

uniformity and integrity of the structure. The use of a solvent to remove oil or

grease from the surface of formed concrete is not recommended since it drives

some dissolved material into the concrete surface.

SIDE EFFECTS

Galvanic Corrosion of Lead and Stainless Steel Due to Proximity to Carbon and

Carbon-Filled Mortars and Grouts

Years ago, college chemistry textbooks used to contain tables listing in

order of electrical potential the metallic elements and carbon. For some odd

reason, the tables used in schools and colleges today omit carbon. This is even

more strange because the most common of the dry cell batteries until only a few

years ago, made use of the electrical potential between zinc and carbon-a rela-tionship illustrated by the table. Reproduced below are two such tables, one of

which includes carbon.

Table 45-2 is taken from John Schley’s paper published in 1974 by Chemical

Engineering. I have been unable to locate any of the old textbooks that showed

carbon in relation to the metallic elements. Table 45-3 is from a college text-

book currently in use. Note that there is disagreement in the relative order of

some of these metals (due to the differences noted in oxidizing and reducing

environments), particularly in the placement of aluminum. However, this does

not alter the relationship between carbon and these metals. The reader will

observe, however, that when stainless steel (188) is passivated, it becomes




more “noble”-very close to silver and graphite, while if not passivated, it is

close to lead in potential.

Element

Potassium

Sodium

Barium

Strontium

CalciumMagnesium

Aluminum

Manganese

Zinc

Cadmium

Iron

Thallium

Cobalt

Nickel

TinLead

Table 45-2: Galvanic Series of Metals and Alloys

Anodic or least noble

Magnesium

Zinc

Aluminum 25

Cadmium

Steel or iron

Cast iron

Ni-resist

18-8 Cr-Ni-Fe (active)Hastelloy alloy C

Lead

Tin

Nickel (active)

lnconel (active)

“Hastelloy” alloy A

“Hastelloy” alloy B

Brasses

Copper

Copper nickel alloysTitanium

Monel

Nickel (passive)

lnconel (passive)

188 Cr-Ni-Fe (passive)

Silver

Graphite

Cathodic or most noble

Table 45-3: Galvanic Series

Potential Difference

Electrode-Electrolyte

-3.20

-2.82

-2.82

-2.77

-2.56-2.54

-1.276

-1.075

-0.770

-0.420

-0.340

-0.322

-0.232

-0.228

<-0.192

-0.148

Element

Hydrogen

Arsenic

Copper

Bismuth

AntimonyMercury

Silver

Palladium

Platinum

Gold

Fluorine

Chlorine

Bromine

Iodine

Oxygen

Potential Difference

Electrode-Electrolyte

0.000

<+0.293

+0.329

<+0.391

<+0.466+0.750

+0.771

<to.789

<to.863

<+1.079

+1.96

t1.417

+0.993

+0.520

+1.119




observations, that the amount of “swelling” and the speed with which it takes

place results from water absorption of the clays from which the brick are made,

and that it bears some relation to the temperature of firing of the brick. Little

has been done in refined testing to eliminate the variables, to determine what,

if any, relationship exists to the exact temperature of the firing, together with

the duration of firing, and to any phase changes that may take place in the

composition of the body of the brick. It is noted, however, that brick which

are “restrained” expand (swell or grow) less than those that are not subject to

loading or restraint.

It has been noted that steel cylindrical tanks lined with “acid brick,” have

in some few cases actually been split apart, apparently by stressesresulting from

this brick growth. On the other hand, where the steel was fabricated of heavy,

well-reinforced metal, the brick have grown only until they were tightly pressedagainst and into the membrane, after which growth stopped. When a single brick

in such a lining was damaged by a blow or in some other manner, and had to be

replaced, it was noted that upon its removal and the release of the restraint that

brick had supplied, the brick on all sides grew or swelled slightly into the void,

so that a replacement brick always had to be trimmed on all four sides to fit into

the same space. One of the same size as the brick that was removed could not be

used. Exactly where the stressesof growth are balanced off against the restraint,

no one has yet determined, although at least one company has a project underdevelopment to plant strain gauges in such linings to determine what pressures

are reached before equilibrium is attained.

We do know that most hard burned, low absorption “acid brick,” meeting

Specification ASTM C-279, will grow irreversibly over an extended period of

time by approximately 0.16% of any dimension. We also know that such growth

takes place more slowly under cold, dry, static conditions, and most rapidly in

hot, wet, cycling exposures. We have also noted that brick with the higher ab-

sorption-ones outside the limits of Type L-seem to expand more than the

0.16% limit, and that this growth appears to be more noticeable with the lower

firing temperatures and the shorter kiln time. However, without conclusive test

data, checking the effects of all variables individually, no absolutes are available,

and only generalizations can be made.

In design, it is important always to plan to accommodate this growth, based

on the normal 0.16%, especially on flat surfaces like floors, with adequate ex-

pansion joints, or, where suitable, such as in cylindrical designs, by adequate

restraint. Failure to do so can result in “humping” (bulging upward or outward)

of flat surfaces, or rupturing the walls of inadequately designed cylindricalvessels.

Bibliography-Swelling of Brick

1. Schurecht, H.G., Methods for Testing Crazing of Glazes Caused by Increases in Size of

Ceramic Bodies, J. Am; Ceram. Sot., Vol. 11, PP 271-277 (1928).

2. Schurecht, H.G., and Pole, C.R., Effect of Water in Expanding Ceramic Bodies of

Different Compositions, J. Am. Ceram. SOL, Vol. 12 (1929).3. Hueber, H.V., and Milne, A.A., Expansion and Deterioration of Ceramic Bodies,

Nature, No.4480,~~ 509 (Sept. 10,1955).4. Young, J.E., and Brownell, W.E., Moisture Expansion of Clay Products, J. Am. Ceram.

.Soc.,Vol.42, No. 12 (Dec. 1959).




5.

6.

7.

8.

9.

10.

11.

12.

13.

13.

14.

15.

16.

17.

18.

Hosking, J.S., and Hueber, H.V., Moisture Expansion, Moisture Movement and Dry

Shrinkage of Structural Clay Products, Trans. British Ceram. Sot., (1960).

Demediuk, T., and Cole, W.F., Contribution to the Study of Moisture Expansion in

Ceramic Materials, J. Am. Ceram. Sot., Vol. 43, pp 359-367 (1960).

Cole, W.F., Moisture Expansion Relationships for a Fired Kaolinite-Hydrous Mica-

Quartz Clay,Nature, No. 4804, pp 737 (Nov. 25,1961).

Hosking, J.S., and Hueber, H.V., Dimensional Changes due to Moisture in Bricks and

Brickwork,ASTMSpecia/ Technical Publication, No. 320 (1962).

Cole, W.L., Possible Significance of Linear Plots of Moisture Expansion Against Log of

a Time Function,Nature, No.4853, p 431 (Nov. 3,1962).

Hosking, J.S., White, W.A., and Parham, W.E., Long-Term Dimensional Changes in

Illinois Bricks and other Clay Products, Illinois State Geological Survey Circular,

Vol. 405 (1966).

Wyatt, K.J., Restrained Moisture Expansion of Clay Masonry, J. Austral. Ceram. Sot.,

Vol.12,No.2,pp3437 (Nov.1976).

Ritchie, T., Effect of Restraining Forces on the Expansion of Masonry Mortars, Materi-als Research and Standards (Jan. 1964).

Jessup, E.L., Moisture, Thermal, Elastic and Creep Properties of Masonry, Cenrre for

Research & Development in Masonry Tech. Pub. (Calgary, Alberta, Canada), No.

TP-9 (July 1980).

Ritchie, T., Moisture Expansion of Clay Bricks and Brickwork, National Research

Council of Canada, Div. of Bldg. Research - Building Research Note No. 103 (Oct.

1975).

McReilly, Tom, Brick Expansion: Aspects of the Australian Experience, Trans. British

Ceram.Soc.,Vol.82,No.l,pp 14-1611983).

Grimm, C.T., Moisture Expansion in Brick Masonry, Trans. British Ceram. Sot., Vol.82,No.l,pp 16-17 (1983).

devekey, R.C., Moisture Expansion in Clay Masonry, Trans. British Ceram. Sot., Vol.

82, No. 2, pp 55-57.

Fisher, K., Moisture Movement in Brickwork: A Further View, Trans. British Ceram.

Soc.,Vol.82,No.2,pp57-59.

Papers presented at the Building Materials Section, Brirish Ceram. Sot., Nottingham,

England, 8 April 1983: Lomax, J., and Ford, R.W., Investigations into a Method for

Assessing the Long Term Moisture Expansion of Clay Bricks; Beard, R., Dinnie, A.,

and Sharples, A.B., Movement of Brickwork-A Review of 21 Years’ Experience.

Other Related Articles

1. Powell, B., and Hodgkinson, HR., Determination of Stress/Strain Relationships in

Brickwork, Proc. of 4th International Brick Masonry Conference, Bruges (April

1976).

2. Base, G.D., and Baker, L.R., Fundamental Properties of Structural Brickwork, J.

Ausrral. Ceram. Sot., Vol. 9, No. 1 (1973) (formula for compression and bending).

3. Jessop, E.L., Shrive, N.G., and England, G.L., Elastic and Creep Properties of Masonry,

Proc. North American Masonry Conference, Colorado, p. 12 (1978).

4. Sorenson, C.P., and Tasker, H.E., Cracking in Brick and Block Masonry, Tech. Study

43, Department of Construction, Expeimenal Building Station, 1976 (Canada)

(causes).

5. Thompson, J.N., and Johnson, F.B., Design for Crack Prevention, National Academy

of Science, National Research Council, Washington, DC.

6. The Design of Clay Brickwork Expansion Gaps, Brick Development, Research lnstirufe

Techniques, 2nd Ser., No. 4, Melbourne (December 1973).

7. Grimm, C.T., Design for Differential Movement in Brick Walls, Journal of he Srruc-

tural Div., Amer. Sot. Civil Engineers,Vol. 101, No. ST1 1, pp 2385-2403 (November

1975).

NOTE: To determine lining thickness, number of layers of brick and selection of types, toinsulate membranes, see mathematics in Chapter 47, and especially Editor’s Note, page 623.




Fi~re 45-1: Example of a contoured wall tank. See Drawing 1

Figure 45.2: Illustration of a baffle built into the brick vessel wall. See Drawing 12,Sketch 2




Figure 45.3: One of the earliest acid-resistant tile floors in a brewery pasteurizer room(1940), laid in a portland cement bed with a phenolic resin mortar grout.

Figure 45-4: Examples of floors laid with high bond, high strength furan mortar in whichcure shrinkage of the mortar has caused the brick to break. The cracks so created have been

filled with expansion joint sealant. See Chapter 25.




Figure 45.5: Steel floor plate plant in the cold storage room of a dairy. The steel plates are

cemented to the concrete substrate with an epoxy adhesive.

Fi~re 45-6: Example of what happens if a designer makes no provision for brick growth

and designs substrate surface flat instead of curved {see Drawing 1) .Note the pilaster, sup-

posed to strengthen the wall, was completely ineffectual.




Fi~re 45-7: Building the "Isabel" H2SO4 chamber plant at Copper Hill, Tennessee, 1916-18,

using the first fast-5etting sodium silicate mortar, DURO@.

Fi~re 45-8: In a modern food plant, a properly designed and laid floor tile (8 in. x 3!/4 in.

x 1!116 n,) floor, using a '/4 in. thick glass cloth-reinforced hot asphalt membrane and a furanresin bed and grout. Note the fiexibilized epoxy expansion joint.



Section XI

Uses of NonmetallicChemically Resistant Materials

in Waste Handling

593



46

Uses of Nonmetallic Chemically Resistant

Materials in Waste Handling




Industrial wastes-acids, alkalies, salts, bleaches, all sorts of corrosive and

noncorrosive waste products-have been with us since the earliest days of man.

Leftovers from savages’ community meals and from battlefield dead, have been

handled by animals and insects. What was not consumed was “biodegraded” to

fertilize plant growth. As man became “civilized” and learned to make things,

the wastes remaining from the processes he developed were no longer consum-

able by animal or insect, and most were not biodegradable either. Trash was

simply dumped in pits, and liquid wastes poured into holes in the ground from

which it ran off, or filtered into subsurface streams. (Perhaps this is a reflection

on what civilization means.) As population expanded and man became less mi-

gratory, tending to settle in specific areas, various efforts were made to move

the trash and liquid wastes away from towns and villages. Solid wastes were

hauled off, then dumped. And ages ago someone thought of piping liquid wastesaway from their sources to a collecting spot.

PIPING

Small diameter baked clay piping, formed and fired in the same way that

clay pottery and tile or brick were made, has been available from the earliest

times. Larger diameter vitrified clay pipe which must date from revolutionary,

perhaps colonial, days has been unearthed in the United States. Sections of pipe,

made with bell and spigot ends, three to six feet long were fitted together,

caulked with “oakurn” (treated wool waste) and this packing backed with hot

594



Nonmetallic Chemically Resistant Materials in Waste Handling 595

poured tar or asphalt. This was the usual method of constructing sanitary and

industrial sewer lines well into the third decade of this century.

Human and animal wastes are biodegradable and are still the main sources

of fertilizer in the largest areas of the world. Therefore, it was reasoned, joints inpipe that leaked a little (exfiltration) would not be harmful. On the other hand,

joints that were too porous would allow the entry of ground water (infiltration)

in times of heavy rainfall and flooding, and would mean handling larger volumes

of fluid at the receiving end which would be costly. In addition, because the

waste was good fertilizer, tree roots would find their way through such leaks

following back on the track of the leaking “fertilizer” and would expand and

develop more roots inside the pipe, eventually blocking the flow of the sewage

and forcing operators to open and clean out the line-an expensive proceeding.

Thus at about the turn of the century engineers who designed waste han-

dling sewers agreed on an “allowable leakage” which was generally accepted as

a standard throughout North America. This was 200 U.S. gallons per inch of

(internal) diameter per mile of pipe per day. This appears to have been satis-

factory for sanitary sewage during this period and as industrial wastes were at

this time generally (there were exceptions) considered rather innocuous, it was

usual (with the same few exceptions) to handle them in the same manner. Pipe-

lines were, therefore, designed to this standard.

In the early 1950s it became apparent that serious contamination fromliquid industrial wastes was becoming a problem. Fish no longer were found in

many streams and rivers. Greasy, oily slicks covered the surface of some ponds

and waterways where children used to swim. In many locations, it was im-

possible to use water from the customary sources for household purposes.

Therefore, the allowable leakage standard was seen as not acceptable for in-

dustrial wastes, and in many areas it was cut by 75% to 50 gallons. This still was

not good enough, and in recent years it has been further cut so that, in many

cases, any visual leakage from a 5 pound test load, was unacceptable. Sanitary

sewage is still allowed a bit more latitude, but the design engineer should re-

member that since small amounts of industrial wastes often find their way into

sanitary lines serious damage may occur before it is found, if care in assembly

and inspection is not taken.

Obviously oakum packing with a hot asphalt pitch or tar backing cannot be

used for present day industrial wastes, nor can one expect to get fully tight

joints in this manner even for gravity sanitary lines, whether they are backed

with a hot poured sealant or packed with portland cement. In present day de-

sign, joints in vitrified clay pipe are most often specified in the manner shown

in Sketch 1.

In Water and Sewage Works magazine, December, 1975 (Vol. 122, No. 12,

pp 64-67) the writer discussed the methods of making joints in vitrified clay

pipe, the materials that are or can be used to make these joints, and the prob-

lems inherent in making the joints liquid tight. Clay pipe in this hemisphere is

generally made to ASTM C-700. In the manufacture and firing of clay pipe a

certain amount of distortion must be anticipated. From the variations in dimen-

sions that can exist in pipe made to meet this standard it can be seen that thejoint sealant must be able to hold the pipe together and function satisfactorily in

a pipeline assembled in a dead straight line with considerable dimensional differ-




Sketch 1 : Acid-resistant joints for terra-cotta pipe.

ences at each of the available sizes shown in Table 2 in the subject standard.

Table 2 of the standard in the year of publication of the article supplied full

figures of the variations of acceptable pipe including the barrel thickness from

which the outside possible range of annular space at the opposite sides of the

joint could be determined. In 1975 when the article was written this showed thepossible variation in a 4 in. joint to be 3/2 in. and variations increasing with in-

ternal diameter until at 42 in. the possible variation is 33/4 in. However, in the

latest revision (1978) of this standard still in use at the time of this writing,

the table has unfortunately been much abbreviated, omitting tolerances of barrel

thickness, and outside dimensions of the barrel, so that with the current specifi-

cation it is not possible to determine exact/y what the possible variation in the

annular space is. Accordingly, whether there is or is not an intention on the part

of the manufacturers to adhere to the same dimensional tolerances is not known.

For the benefit of the reader, and the better to illustrate the problem this omis-

sion creates, both sets of tables are here reproduced; first the table from the

issue of 197 1, second the current issue (the edition of 1978).

Refer back to Sketch 1. Before assembling the pipe, the outside of the

spigot end and the inside of the mating bell, including the end of the spigot and

shoulder of the bell, should be sanded to remove the hard burned surfaces. The

end of the spigot and the shoulder of the bell are then buttered with a stiff mix

of resin mortar, usually a furan. The spigot is then seated in the bell and shoved

home against the shoulder of the bell.Next a long enough section of random ceramic fiber (or very lightly twisted

roving) thicker around than the largest section of the annular space is wide, into

which has been worked a slightly thinner mix of the same resin mortar, is

caulked into the annular space to form a ring around the shaft of the pipe, with

ends overlapping at least 2 in., and, with a caulking tool, driven home tightly

against the shoulder of the bell, so that the ring is tight/y in contact with the in-

terior of the bell, all the way around the pipe. Next, a second ring of ceramic

fiber saturated with the resin mortar and thicker than the width of the widest

section of the annular space, is driven in on top of the first, with the lap of the

ends at the opposite side of the bell. A third ring follows the first two in the

same manner.




c700

TABLE Z DIA of clay PIP

Laying Length’ Outside Diameter of Barrel.in. (mm~~’

NominalDiffercncc in

Inside Diameter of

Size.Limit of Length of Two

Socket at K in.

in.O,’Minus

min. It(m) Variation.Opposite Sides,max. in. (mm) min max

( 1 Bmg)mAov

in./11in. (mm~~

(mm/m)

4

6

a

IO

I2

IS

I8

21

24

27

JO

33

36

39

42

2 (0.61) % (20)

2 (0.61) % (20)

2 iO.6lj

2 (0.61)

2 (0.61)

3 (0.91)

3 (0.91)

3 (0.91)

3 (0.91)

3 (091)

3 (0.91)

3 (0.91)

3 (0.91)

5 (1.52)

5 (1.52)

s zoi

% (20)

% (20)

y1(20)

% (20)

% (20)

?i (30)

K (30)

?i (30)

)L (30)

% (30)

s (20)

?i (30)

%. 8) 4?4 (124)

?i (9) 7x. (179)

%r (II) 9% (235)

%r (II) 11% (292)

%‘ (II) 13% (349)

5!4 (130)

7%. (189)

9% (248)

t:x, I%,’

5k (146)

8);. (208)

IOH (267)

12% (324)

15!4 (384)

K (13) 17%‘ (437) 17’ti. (452) I8?4 (473)

H (13) 20% (524) 21%. (545) 22% (565)

n* (14) 24% (613) 25 (635) 25W (657)

%b (14) 27X (699) 28!4 (724) 29% (746)

?i (16) 31 (787) 32!4 (816)

?i (16) 34% (873) 35% (905)

X (16) 37% (956) 38’f;l (989)

1%. (17) 40% (1035) 42% (1073)

33 (838)

36s (927)

39% (1013)

43% (1099)

x (19) 45J( (1152) 47% (1200) 48% (1232)

M (23) 48% (1232) 51 (1295) 52!4 (1333)

Thickness of Socket atDepth of Socket’.’ Thickncns of Bar&,’ Kin. (I3 mm) from

NominalOuter End’

Size.

in.*,’nominal. min.

Extra Strength Standard Strengthnominal. min.

in. (mm) in. (mm) nominal. min. nominal. min.in. [mm)’

in. (mm) in. (mm)

in. (mm) in. (mm) iti. (mm)

4 I% (44) I Ih (38) +‘a (16) %r (14) Yz (13) %‘ (II) %r (I I) % (9)

6 2 ‘A (57) 2 (51) 1x1 (17) %r (14) % (16) %r (14) (13) %‘ (11)

8 2% (64) 2% (57) % (22) % (19) % (19) “A. (17) t (14) ‘h (13)

IO 2% (67) 2% (60) I (25) % (22) % (22) 1%‘ (21) w (16) %I (14)

I2 2% (70) 2% (64) 1%‘ (30) 1x6 (27) I (25) 1~~ (24) % ((9) “A‘ (17)

I5 2% (73) 2% (67) I Ya (38) I% (35) I% (31) I% (29) ‘%b (24) % (22)

I8 3 (76) 2% (70) I% (48) 1% (44) I% (38) I% (35) 1% (29) 1%. (27)

21

:: (83) 3(76) 2% (57) 2 (50 I% (44) I% (41) (I(6 (33) 1%. (30)

24 (86) 3Ya (79) 2 % (64) 2% (57) 2 (51) I% (48) 1% (38) I% (35)

27

30;; I;;; 3% (83) 2% (70) 2% (64) 2% (57) 2’/, (54) I’%* (43) 1%. (40)

3% (86) 3 (76) 2% (70) 2% (64) 2% (60) 1% (48) I% (44)

33 3% (95) 3% (89) 3% (83) 3 (76) 2% (67) 2% (64) 2 (51) ISi (44)

36 4 (102) 3% (95) 3% (89) 3% (83) 2% (70) 2% (67) 2%r (52) I% (48)

39 4 % (105) 3% (98) 3% (95) 3% (86) . . 2% (70) 2% (67)

42 4 % (105) 3% (98) 4 (102) 3% (89) .., 2% (70) 2% (67)

‘Specilicrs should be aware that all pipe sizes arc not universally available.

‘Sizes on perforated pipe apply only to nominal sizes 4 through 24 in.

‘There shall bc no maximum kqgth. Shorter lengths may be used for closures and specials.

l Pipe having the nominal thickness of barrel shown in Tabk 2 may have smalkr inside diameter than the nominal

sizes.

‘The outside diameter of the barrel may be greater than the maximum ligurer stated in Table 2. provided the other

dimensions are varied accordingly within the specification tolerances.

‘The minimums lor inside diameter of socket and depth of socket may be waived where such dimensions arc conducive

10 the proper application of the joint.

* Plain-end pipe shall conlorm to the dimensions in Tabk 2. except those dimensions pertaining lo sockets.

“The requirement for minimum barrel thickness may be waived when satirfacto~ evidence is prcsenled that the pipe

cm meet the required crushing strength and all other requircmcnts of this specification.

(continued)




TABLE ZA Dimensions of Vitritied Clay Pipe (SI Units)

Nominal SW. mm ’Laying Length

Limit of Mmus

Variation. mm/m

Difference in

Length of Two

Opposite Sides

max. mm

Limit of MmubVariations

from Nommal

SIX I”

Average InsIde

Diameter. mm

75

loo

I 5 0

200

250

300

375

450

525

600

675

750

825

900

975

1050

20 820 820 9

20 II

20 II

20 II

20 I3

20 I?

20 I4

30 14

30 I6

30 I6

30 16

30 17

30 19

30 23

9

II

I3

I5

I7

I9

21

22

22

22

” Specifiers should be aware that all pipe stzes are not universally available.

After the third ring is caulked into the space, there should be, if the rings

are placed as described, a 3~ to 1 in. space left in the depth of the bell of a 4 in.

line up to a 1% in. space or larger in the 42 in. pipe. This space is now filled with

a mortar caulk, either of hot poured sulfur mortar or a low shrinkage resin mor-

tar, hand packed into place. The liquidtight seal cannot be accomplished with

the mortar between spigot end and the shoulder of the bell. A look at the large

space that can exist between one side of the spigot and the shoulder of the bell,

if the pipe is laid in a straight line, will tell you that you can never hope to seal

the joint at this point. Neither can it be accomplished with the caulk at the end

of bell. This mortar can shrink on curing and leave voids through which liquid

can pass. The seal relies totally on the quality of the workmanship in installing

the three rings. The caulk at the end of the bell acts merely as an anchor to ho/d

those rings in p/ace. The mortar applied first between spigot end and bell shoulder

functions only to reduce fluid approach to the rings, and to fill or smooth the

cavity at the inner surface of the pipe. Therefore, the rings must be composed ofsoft enough, deformable enough material to caulk tightly into the annular space.

A quick look at the tables reproduced above will show the reader at once that a

hard material such as the “braided rope” specified in the past by many manu-

facturers can never be caulked into the annular space tightly enough to accom-

plish the purpose. A look at the cure shrinkage shown for sulfur mortars and for

resin mortars (see Section V) also makes it clear that the final caulk at the end of

the pipe cannot be depended upon to seal the pipe.

So that the reader will have adequate information to prepare proper specifi-

cations for the pipe he is to purchase, I quote from my cited article, to provide

those exceptions he should take, beyond the minima given in the standard.




The clay pipe used for conveyance of industrial wastes should be un-

glazed, extra strength pipe, conforming to ASTM specification C 700-71.

From this specification it will be evident that the pipe itself, if it conforms

to the specification, will be adequate in strength for gravity and low pressure

waste handling, and that it is now available in sizes from 4 to 42 in. internal

diameter. There are, however, three limitations that the buyer, if he plans to use

the pipe in nonleaking industrial sewers, must bear in mind. In this specification:

(1) Section 9, Fractures and Cracks, permits the manufacturer to

furnish pipe that has no cracks in the barrel, but does have a

single crack in the spigot end not exceeding 75 percent of the

depth of the socket, or a single fracture in the socket end notexceeding three inches around the circumference nor two inches

lengthwise. Chips and fractures on the interior shall not exceed two

inches in length, one inch in width, and/or a depth of l/4 of the

thickness of the barrel. Yet no cracks, fractures, or chips whatso-

ever are acceptable if a liquidtight line is to be attained.

(2) Section 4, Physical and Chemical Requirements, subsection 4.2

Absorption and 4.3 Hydrostatic Pressure Test. The effect of these

two subsections is to permit a water absorption of the clay pipe ashigh as eight percent and a hydrostatic test of ten psi that accepts

beads of “sweat” on the outside of the pipe, but no running liquid

to appear under a test duration ranging from 7 minutes for 4 to

10 inch pipe, 21 minutes for 36 to 42 inch pipe. An absorption

this high will not provide a liquidtight line, and the pressure test

should be maintained for at least three days (72 hours) regardless

of the diameter. Most first quality pipe will be well below the

above maximum absorption and will easily meet a three day pres-

sure test.

(3) Section 10, Finish of Ends, states “the ends of the pipe shall be

square with their longitudinal axes within the tolerances provided

in Table 2.” This same section also defines the scoring on the inner

surface of the bell and the outer surface of the spigot and permits

the elimination of scoring “when it is conducive to the proper

application of the joint to be used.” The engineer should be certain

that the scoring is provided on pipe that he buys.

Originally the fiber specified for the three ring seal was African blue as-

bestos, as the best chemically resistant material for this work. Today asbestos,

whether blue or white, is rarely available, so that current specifications call only

for a soft random ceramic fiber made from the same clay sources as various

“acid brick” such as FibrefraxB or KaoWool@. This may be a three strand,

lightly twisted mass of material, provided that the three strands are separated

and used independently. The material of choice is the loose fiber mass (usually

called “roving” by textile manufacturers or “sliver” by asbestos manufacturers)which may be lightly twisted to retain integrity, but is soft enough to saturate




fully with the soft wet resin mortar mix and to caulk tightly into the joint to

provide a plug in tight contact with all sides.

The selection of resin mortar to use to fill the contact area between shoulder

of bell and end of spigot, and to saturate the ceramic caulk depends on the

chemical exposure anticipated for the sewer. The usual material is a furan resin.

However, if strongly oxidizing material is likely to be present, the designer

should consider using a vinyl ester or polyester resin. Strong solvents are in most

cases best handled by phenol formaldehyde or furan resins, and if oxidants and

solvents are both to be encountered the choice would probably go to the former.

In all events the designer should discuss the anticipated chemical content of the

stream with the resin manufacturer before making his decision.

Strong alkalies will damage the pipe. If the alkali content (pH) is expected

to be high enough to destroy a vinyl ester mortar, it will probably be too high

for the pipe itself. If this possibility arises the matter should be discussed with

the pipe manufacturer or the National Clay Pipe Institute. Consider also the

temperature at which liquid streams may enter the pipe. The cited standard

limits service conditions to 14O’F or lower. If very hot liquids are to enter the

system, this too should be discussed with the pipe manufacturer.

Finally, the selection of the caulk at the end of the bell, which will hold

in the three rings must be made. Here hot poured sulfur mortar plasticized with

1.2% Thiokol@ is the most commonly employed material. This, as previouslynoted, cannot be expected to in itself yield a liquidtight joint, but it will provide

a sound anchor for the rings. It has three specific advantages over most other

materials. (1) Being poured hot, joints can be finished with it in an unheated

trench in freezing or even sub-zero weather. (2) If the rings were caulked in at a

temperature below the lowest cure temperature of the resin, but not as low as

freezing, the heat of the sulfur pour will provide sufficient heat to finish the cure

of the resin material in the three rings. (3) A poured joint is a completely full

joint, providing a “pouring gate” is employed. Pouring of the joint isdoneslowly,

but continuously and steadily, filling the gate so that cure shrinkage takes place

in the gate and not in the top of the joint, to assure that the joint is completely

filled. If the joint is hand caulked, common labor being what it is, only by moni-

toring and careful inspection can it be certain that the bottom of the joint is

completely filled. The only disadvantage is the high degree of shrinkage of sulfur

mortars (>4%) on hardening from liquid to solid.

If it is vital for the caulk to act as a safety seal behind the three rings, then

the sulfur must be replaced by the strongest and lowest shrinkage resin mortar

available-an epoxy (<O.l% shrinkage). If this is to be used, great care in moni-

toring and inspecting the installation will be required to be certain that the joint

is completely full-especially at the underside which cannot be seen from the top

or from the side of the pipe. Although not yet noted, it may well be that a pour-

able epoxy grout can be developed which can accomplish this purpose and solve

this problem.

A common joint design for clay pipe, one which the pipe manufacturer will

probably try to sell, is a “pressure joint.” For this kind of joint an elastomeric

or flexible collar is set into, and usually cemented to, the inside of the bell. Theinside dimension of the collar is smaller than the outside dimension of the

spigot, so when the spigot is seated in the bell the collar squeezes tightly against




the shaft of the pipe, in theory making a tight joint. The collar is often made of

neoprene or PVC, although there are other, usually synthetic, materials that

may be employed. This type of joint is flexible and allows some independent

movement of the two pipes.

There are two limitations to this kind of “pressure joint.” (I) As pressures

increase on the inside of the pipe, and even in some cases merely the weight of

the liquid stream, the contained liquid can squeeze past the collar along the shaft

of the pipe and the joint will leak. (2) Many of the waste streams contain sol-

vents or other chemicals that can and will attack these collars, causing them to

swell, or to disintegrate, or which can destroy the material cementing them to

the inside of the bell, resulting in the loss or popping out of the seal and com-

plete failure of the joint. For these reasons “pressure joints” although often

employed in sanitary lines should not be used for industrial wastes or for sani-

tary lines which may receive streams of industrial wastes.

SUPPORT AND BACKFILL

Chemically resistant masonry joints in clay pipe are rigid. Ground movement,

such as settlement, can therefore break the pipe. For this reason it is important

that a// industrial waste lines be laid with continuous support. No matter whatopinion others may have of the stability of the soil in the area where the pipe is

to be laid, this writer has never seen any trench excavation, no matter how well

prepared, that did not require adjustment to attain the suitable smooth surface

and slope after the trenching operation had been completed. These adjustments

require fill in some spots and further surface removal in others. In addition bell

excavations are required to provide working room to make the joints. After the

line is in service, heavy rains, flooding and even percolation of groundwater can

cause soil movement above and around the pipe, and eventually, without uni-

form support, movement will take place that breaks the pipe.

The only way to insure long life and satisfactory operations of the line is to

provide continuous support by pouring a continuous concrete pad a few inches

wider than the outside diameter of the bell, the full length of the trench. In addi-

tion saddles should be provided under the shaft of the pipe at the bell end so

that the saddle, besides acting as support for the pipe, holds it steady during the

caulking. In lengths beyond six feet, additional intermediate saddles should be

added to distribute the load. One of the major chemical companies used to

require that all clay pipe of 12 in. diameter or less be fully concrete encased andall clay pipe of larger diameter be given continuous full support up to the spring

line. Suffice it to say that while these specifications were followed this company

never lost an industrial sewer.

All spoil from the trench that is to be used in backfill, to the depth of 1 ft.

above the pipe should be screened to remove all rock or stone greater than % in.

in diameter. Backfill should be carefully tamped at frequent intervals to be sure

that it is solidly placed around and under the pipe between saddles and tightly

between the walls of the ditch, and such fill and tamping done carefully and

after every few inches of backfill until one foot above the pipe line, at which

time the unscreened spoil may be used, and as needed to fill the space, stone




screened out earlier may be added. Compacting should be done carefully and

continuously as the fill is added. Failure to keep stone away from the shaft or

bell of the pipe will almost certainly result in cracked pipe.

In most specifications, testing of joints is required after backfill and tampingis complete. The designer should understand, however, that if a leak shows up on

testing, it will be necessary to uncover the line to make repairs. This writer has

found it far better to test before backfill, make repairs if necessary, then back-

fill, tamp and test again. In the long run it is generally far less expensive to test

twice, especially considering the quality of the labor used to caulk the joints.

MANHOLES

The greatest individual source of trouble with industrial waste sewers has

been maldesign of manholes. Through the first three decades of the twentieth

century engineers used the same specification for manholes, whether they were

to be used in sanitary or industrial sewage. They were most often built entirely

out of common red shale brick laid in portland cement mortar, usually with con-

crete bottoms, into which the ends of the clay pipe were set. Often the clay pipe

line was laid first, concrete poured around it up to the spring line or the mid-

section of the pipe then the brick laid in a circle over the section where themanhole was to be. After all the brick was laid, the workmen would go back

onto the manhole with hammer and chisel and break out the exposed top of the

clay pipe. When it became apparent that most chemicals in the waste lines,

especially those with low pH, would penetrate through the brick and concrete

and channel back along the clay pipe where it was in contact with the poured

concrete, they tried to seal or line these structures with coatings of hot asphalt

and occasionally with acid brick over the coating. It is a waste of time and

money to try to build one from block or brick. In doing so they violated three

of the principles of chemically resistant masonry: (1) Chemically resistant

masonry is no good in tension or shear. It must be supported. The common

brick/Portland cement outer structure is unreinforced and has no strength in

tension or shear either, so it cannot give support to the lining. As the manhole

fills with liquid, or the filled ground outside it moves, the brick manhole itself

must crack so any lining inside it will also crack. (2) The masonry is not liquid-

tight, and therefore, a liquidtight membrane is a necessity over the supporting

structure prior to putting in the “acid brick” lining. The coating or asphalt

applied is called a “sealer,” but it is rarely thick enough or sufficiently uniformto be liquidtight. (3) In addition, there is no way to seal the joint between the

edges of the clay pipe and the concrete or the brick walls, so even if the mem-

brane is tight and the contained liquids cannot get back to the substrate, it can

bypass the membrane at those juncture points which cannot even be protected

properly with the brick lining.

The only satisfactory manhole design is one that is monolithic. It is a waste

of time and money to try to build one from block or brick. A monolithic man-

hole should be formed and cast, properly reinforced, of concrete in which all

pours are wet to wet or the cold seams protected by a continuous water-stop and

a concrete adhesive employed on each wet to dry pour. Such design requires that

the bottom slab be an integral part of the structure. The next alternative is to




construct the manhole of preformed sections, put together with tongue and

groove type joints and employing an epoxy mortar continuously and generously

in all joints. A prefabricated concrete manhole may be used, providing there are

no cold seams discoverable in the structure. Regardless of type, the manholeshould be tested liquidtight before being accepted for lining. (See the instruc-

tions for this test in Section X on Design.) If the designer decides on the use of

FRP pipe or other plastic, a standard on a prefabricated FRP manhole, made

from polyester resin is available. (See ASTM D 3753-79).




Note that neither A nor B provides either the continuous external support required to keep

the brickwork tight, C supplies support but none have an interior continuous lining of a

liquidtight membrane.

Sketch 2: From Chemically Resistanf Masonry, 2nd Ed., Marcel Dekker (1982)

Inlets and outlets must be so designed that all joints between the manhole

body and the fitting be tightly sealed with a liquidtight seal so that the mem-

brane surface is continuous and completely uninterrupted. In addition, the

fitting should be totally immobilized so that any movement of the connecting

line, whether thrust, pull or sideways, will not disrupt the connection with the

body of the manhole or rupture the membrane. Note the details in Sketch 3

which show both how they should not be designed and what designs are best.

TRENCHES

Liquid waste transmission above ground is often handled by gutters and

trenches which pick up pollutants and chemicals dripping or spilling on floors

and around equipment. The section on design covers the principles of design

and construction so they will not be repeated here. However, space must be

given to a design frequently suggested, especially by those unfamiliar with the

limitations of chemically resistant masonry, which can cause difficulty for the

designer and owner if the wastes conveyed in it are to be kept out of the sub-

strate and out of the soil below it.




ick

ortar

Brick

Mortar

Membrane

G

Membrane

, Fills

Notch

A-With concrete outer shell, we now have support for the brick, but note that

the membrane is discontinuous at the bottom where it terminates at pipe edge.

B-This is a typical inlet design, with the entry pipe simply embedded in the wall,

membrane brought to pipe edge and brick laid around the intru,ded pipe. Ground

movement or expansion/contraction of the pipe can push or pull the pipe through

the cavity in the concrete and cause the joint and membrane to be disrupted, and

contained liquid to get back to the concrete.

C-A slight improvement over B in that the pipe cannot be pulled out, but it can

be pushed in.

D-This is a much improved design. The membrane is carried through a cavity in

the concrete to the outside. The pipe is carried through the cavity, inside the mem-brane, centered by seal rings of caulking, installed in the same manner as the seal

rings in the pipe joints, and the balance of the annular space packed full of furan

resin mortar. The brick is laid up to and bonded to the intruded pipe with the

same furan resin. The only difficulty with this design is that the pipe can still be

pushed in or pulled out, so disrupting the joint. However, if this happens, the con-

tained fluid can only leak along the shaft to the outside, without getting through

the membrane to attack the concrete manhole.

E-This design prevents “pull out,” but not “push in.”

F-Here the pipe is successfully anchored against movement in or out, and &he

membrane is still continuous to the outside. This is the best design.G-If the pipe line is plastic or steel, this design, although less perfect than F, may

be used. It holds the pipe rigidly in place to prevent movement but relies for

membrane tightness on the seal at the internal notch so that any leakage at that

point can enter the concrete along the shaft.

Sketch 3: From Water & Sewage Works, Vol. 127, No. 2, PP 51.

The normal design of a trench is rectangular, with brick lining on the

bottom and the two sides. In order to lay brick in the bottom of a narrowtrench, especially if it is deep, the mason must kneel along side of it and reach

into it. If the concrete forms are not set exactly on multiples of the brick size,




there will also be a lot of cutting of the brick required to fit the bottom. Years

ago, someone came up with what he thought would be a great way to save these

labor costs by casting “half round” pipe (also called “channel pipe”) manufac-

tured to C70082a. into the concrete to form the bottom of the trench, and to

set ceramic “liner plates ” inside the forms for the wails. Rubber separators,

l/i in. wide, would be set between the plates. When the forms were stripped,

all that would have to be done to finish the trench would be to remove the

rubber separators and point all the joints with a resin mortar appropriate to the

chemical exposure. See Sketch 4, Drawing A.

applied

air renlbrrnc

CWh-UCtlClfl

Co”ltnJCllorl

,Ol”ljOI”

A B

Sketch 4

Note that in Sketch 4, Drawing A, there is no membrane at all. If any of the

joints leak, the chemical waste will get into the concrete behind the tile and soon

the layer of concrete bonding the tile to the wall will be attacked and the tile

will fall into the trench. Note also, that vitrified clay liner platesare manufactured

to conform to ASTM Standard C479-82 which allows an absorption of 6%.

According to this standard, although an acid-soluble limit is set at 0.25%, no

specific test is specified to be run, and further, the standard says that this (un-

described) test is only to be run if specified. In addition, some surface defects

(including small cracks) are permissible. It must be evident, therefore, that even

if the contained liquids fail to penetrate through the joints, they will certainly,

in not too long a time, get through the bodies of the tile. Without a membrane,

one can expect attack on the substrate. So we next find a modification of this

design, Drawing B, where a membrane is applied on the walls, and “acid” brick

laid over the membrane and bonded to the half-round pipe in the trench bottom.

Just as in the case of the manholes, we are dealing here with a discontinuous

interrupted membrane, and there will be leaks in the bottom just as there were

in the manholes of the old design, but through the channel pipe (ASTM C700)and at the termination of the membrane against the edge of the channel pipe.




To prevent such leaks in the bottom, the membrane must be continuous

down the sides and under the channel pipe. Thus the concrete may be formed to

accept the channel pipe, including depressions at the correct locations to accept

the bells of the channel pipe, then the membrane applied, and finally the channel

pipe installed, making the joints between sections as we fit the sections. By the

time all this is done, it is likely that there will have been consumed as much, or

even more, labor cost (including some expensive concrete work) than if brick

had been laid.

Where half-round pipe is merely set in the floor to create a gutter, the floor

is poured around it. Anyone who designs a gutter this way should bear in mind

the following: (1) If the half-round pipe is set in the forms as part of the laying

of the floor, the pressure of concrete poured next to it and under it will “float”

out the pipe unless it is heavily braced. (2) The acid-resistant joints will have to

be made before the concrete is poured under it to prevent the intrusion of port-

land cement concrete into the pipe joints. But these joints are hard and brittle,

so if the pour causes any movement in the half-round pipe, the joints will be

broken. (3) Trenches and gutters are designed to run only at halfdepth, so as

to accommodate surges without overflowing. At half-depth, only one-third of

the capacity of half-round pipe will be provided because it will be half as deep as

it is wide-so the gutter will have to be wider for the same capacity as if designed

rectangular-using a lot of floor space for a minimum capacity. (4) If liquids runrapidly over the floor toward the gutter-as from a spill, when they splash into

the gutter-they will cross the top of the gutter and strike the other side. In a

rectangular cross section gutter, this rapidly moving liquid will splash across to

the other side-which is vertical. From the opposite side, the liquid will splash

back and down into the trench.

In the case of half-round pipe, the opposite side of the gutter is not vertical,

but sloped down and back toward the source of the liquid, so instead of bound-

ing into the gutter, the waste will be reflected upward and out of the gutter,

onto the floor on the other side. Therefore, for all these reasons, even with the

amount of brick cutting that may be required, this design is not recommended.

HOLDING, “EQUALIZING,” OR NEUTRALIZING TANKS

The usual construction material for tanks to contain or process liquid is

concrete, with suitable linings. Concrete is the material of choice if the vessels

are set on or partly in the ground. (See the section on Design for information onthis type of construction.) Alternates are plastic or rubber-lined steel, FRP, or

even wood. The paper on wood in the Supporting Structures section provides

some design data on this material, and chemical resistance data for wood tanks is

supplied in the two Technical Bulletins of the National Wood Tank Institute

cited in the bibliography of that section. If above ground storage tanks or

process tanks or process equipment is planned, the designer should be sure that

it is elevated above ground to provide for ventilation under the bottom, external

cleaning and inspection, so that if leaks develop, they may be discovered quickly

and repaired before extensive damage can occur.




SCRUBBERS AND ANCILLARY EQUIPMENT

Many scrubber designs make effective use of chemically resistant masonry,

especially in the contact area between the scrubbed gases and the scrubbingliquid. The receiver may also be brick-lined as may trenches carrying the waste

liquid. If bleeding of the waste and recirculation are planned, additional equip-

ment may also be considered for lining. The Design section covers the recom-

mended procedures to be followed.

INSPECTION AND REPAIRS OF MANHOLES AND CLAY PIPE

During installation of clay pipe and manholes, careful inspection and rigidcompliance with specifications is essential. It should be borne in mind that after

installation, it is impossible to inspect the workmanship from the outside, and

internal inspection is possible only for the exposed surface. There is no way that

an inspector can verify that either the membrane or the substrate of the manhole

comply with specifications, that holidays do not exist, and that membrane

thicknesses are as specified. The inspector should check all work carefully as it

progresses, including all membranes prior to brick installation, and all joints in

pipe as they are caulked.Water tests on pipe should be made, both before and after backfill. If back-

filling is done before testing, there is no way to identify which joint is leaking,

and the entire line will probably have to be uncovered-a most difficult task

when one remembers that the most common point of leakage is the bottom of

the joint. On the other hand, if no test is run after backfill, the owner may not

find out for some time that the pipe and/or the joints were disturbed during

backfill and tamping, and that the line now leaks. Such damage is often noted

when stone is included in the backfill, and where heavy equipment is used in

compacting the soil.

Where interruptions in the membrane lining in the manholes occur, waste

chemicals get back into the concrete manhole body and damage or destroy it over a

period of time, resulting eventually in the collapse of the manhole. It is usually a

waste of effort to try to repair a manhole that leaks because by the time the leak

is discovered, the waste chemicals have usually saturated the concrete, and

damage is too widespread. It is better to a bandon the manhole completely.

During the following repair, the temperature of the area and all components

must be kept to a minimum 60°F.The flow through the system is stopped off upstream at the next manhole

or point of entry, and the damaged manhole is bypassed, bringing the wastes

back into the line downstream. The old manhole construction is completely ex-

cavated, removing all contaminated soil and exposing the pipe ends. Plugs are

put in the pipe ends to prevent the intrusion of rubbish, and the outsides of the

pipes are cleaned and sanded. Inner and outer concrete forms are built around

the pipe with the ends passing 3 to 4 in. through the inner form, the inner space

and bottom is poured with new high-early concrete. If pressed for time, the new

manhole body may be completely poured with epoxy grout. Although this is

quite costly, it will cure in 24 hours, and if properly done may not require a

membrane and brick lining, depending on the chemical exposure.




If joints in the pipe leak badly, it is a waste of time to try to fix the leaks by

caulking or with the use of sealers, or with a so-called “diaper joint” wrapped

around the joint and filled with hot sulfur or asphalt. Repairs from the outside

will assist in stopping infiltration, but the seepage of exfiltration will eventuallystart again, pushing off any kind of seal applied on the outside. The only way to

stop a leaking joint is to cut it out and replace it. If all, or most, of the line leaks,

the pipe should be replaced. 90% of the time, doing the job over again is less

costly, and faster, than trying to save what was done wrong to start with. There

is now, however, a possible way to make a repair internally, and this will be

covered later.

Armoring

If the shaft of the pipe, or even a joint, is cracked or otherwise damaged,

and the line is leaking through the crack, the line can often be saved, or at least

kept in service for a considerable length of time by “armoring” it with glass

fabric and furan mortar.

This is done in the following manner. During all the following steps, the

pipe must be kept at 60°F or higher.

(1) Clean the entire exterior of the damaged section around the full

circumference and for 4 in. each side of the fracture, and then sand

it carefully to remove all the hard burned surface of the pipe.

(2) Measure out three lengths of light, soft, loose weave, glass cloth (as

described in Chapter 13), each long enough to go twice around the

pipe, and wide enough to cover the entire cleaned area.

(3) Prime the pipe surface with a primer recommended by the manu-

facturer of the furan resin mortar you plan to use.

(4) Mix the furan resin mortar in a soft mix, using 10 to 15% moreresin than in the bricklaying mix (but first check with the manu-

facturer to obtain his agreement) and with your hands, work it into

one of the strips of glass cloth until the cloth is completely satu-

rated, and the entire cloth is black.

(5) Starting at one end of the cloth, wrap it tightly and smoothly

around the pipe, covering the fractured area completely twice with

layers of cloth. Apply a C-clamp or an equivalent to hold it in place

until it cures. Keep it warm (6O’F minimum).

(6) 24 hours later, this bandage should be hard. If it is not, apply heat

until it is hard.

(7) Remove the C-clamp and repeat steps 5 and 6, but this time wrap

the cloth tightly in the opposite direction.

(8) Repeat these steps once more making a third bandage with the

third piece of cloth, once more counterwrapped. The shrinkage of

each bandage will cause it to tighten up. Counterwinding the band-

ages prevents upper ones from loosening the one below it, and

causes it to pull even tighter.




Although this repair is not a cure-ail, properly done, it can last for many

years.

Internal Repair

In the last few years, a procedure has been developed for placing a seal on

the inside of a leaking clay pipe line. The procedure is as follows:

(1)

(2)

(3)

A “sock” is manufactured of a soft feltlike fabric heavily impreg-

nated with a fluid resin into which has been mixed a hardening (or

curing) agent, the reaction with which is initiated by heat in the

150°F range, but which remains unaffected at ambient tempera-

tures. The outside of the “sock” is completely covered with a

urethane coating. The diameter of the “sock” is made identical

with that of the pipeline to be repaired and the length the same as

the distance between the interiors of the manholes on each end of

the section requiring lining.

The “sock” is turned inside-out as it is pulled into and through the

pipe, and cold water is pumped into the “sock” to inflate it fully,

and to press the resin-soaked felt side against the walls of the pipe.

As soon as the sock is fully inflated, the water in the “sock” is

circulated through a heat exchanger bringing the internal tempera-

ture up to 180°F, at which temperature the water is held until the

resin is fully hardened and cured.

The entire interior of the pipeline should now be covered by a liquidtight

lining. The closed end can now be cut off, the two ends sealed into the manhole

linings, and the waste line returned to service.

This type of lining was originally designed for the repair of sanitary services,

and the first resins used belonged to the terephthalate polyester class. Interest at

once centered on repairs to industrial waste lines and in some cases, it was ob-

vious that better chemical resistance was required than that offered by this resin

type. Although considerably more expensive, this same general system, but em-

ploying epoxy resins, is now also available. Of course, neither type resin is

suitable for all waste exposures.

Service experience is still too short for long-term test data, but what has

been seen so far appears to be most encouraging.

BIBLIOGRAPHY

I. Sheppard, Waiter Lee, Jr., P.E., Chemically Resistant Masonry, 2nd Ed., especially pp

86-l 11, Marcel Dekker, NYC (1982).

2. Haworth, B.C., and Stokely, J.M., A Better Way to Joint Stoneware Pipe, Chemical

Engineering, Vol. 66, No. 18,~ 182 (September 21,1959).

3. Sheppard, Waiter Lee, Jr., P.E., Acid Proof Joints in Terra Cotta Industrial Sewer

Lines, Water & Sewage Works, Vol. 122, No. 12, pp 64-67 (December 1975).

4. Clyburn, Harry, and Sheppard, Walter Lee, Jr., P.E., Uses of Chemically Resistant

Masonry in Lining Air and Water Pollution Control Equipment, Proceedings of the

North American Masonry Conference, Boulder, Colorado (August 1978).




5. Sheppard, Walter Lee, Jr., P.E., Redesign Controls Manhole Leakage, Water & Sewage

Works, Vol. 127, No. 2, pp 50-52 (February 1980).

6. Applications of Chemically Resistant Masonry in Liquid Waste Handling, Materials

Performance, Vol. 20, No. 3, pp 34-39, NACE Annual Meeting, Chicago, Il linois

(March 1980).



Section XII

Prestressed Brickwork

613



47

Prestressed Brickwork

Keith R. Pierce

Department of Mathematical Sciences

University of Minnesota

Duluth, Minnesota

INTRODUCTION

Brick Linings-A General Discussion, and the Problem of Tensile Stresses

The installation of a brick lining in a process vessel is a common design tech-

nique for protecting the vessel jacket from corrosive environments. A variety of

highly chemically resistant bricks and mortars are available.

Since brick and masonry do not resist tensile stresses very well, the designer

must be careful to ensure that tensile stresses are avoided over the entire range

of operating and shutdown conditions. If a vessel will be operating at elevated

temperatures or pressures, tensile stresses in the brickwork will be encountered,

unless special design techniques are used. This is due primarily to the fact that

the coefficient of thermal expansion of brick is typically half that of the sur-

rounding steel jacket. Thus at elevated temperatures the steel jacket will try to

expand away from the brickwork, causing the brickwork to be under tension.These tensile stresses will cause cracks in the brickwork, weakening the chem-

ically protective barrier it affords, and also will cause the brickwork to pull

away from the steel shell.

A Solution-Prestressing

These tensile stresses can be avoided by subjecting the vessel to a prestress-

ing cure, which induces an artificial compression in the brick lining and a tension

in the steel shell. When properly designed, the brick lining never is subjected toexcessive stresses over the entire range of operating conditions.

614



Prestressed Brick work 615

Description of the Prestressing Process

The prestressing process depends for its success on the existence of mortars

which possess the ability to be cured in two stages. In the first stage, the mortars

set hard enough to prevent the collapse of the brick lining, but are still deform-

able. The second stage cures them to a rigid, nondeformable state, but not be-

fore they have undergone a permanent swelling. It is this swelling that provides

the prestressing.

The prestressing cure proceeds as follows: After the lining is installed and

the first stage cure has occurred, the vessel is subjected to elevated temperature

and pressure. The brickwork encounters tensile stresses due in part to the in-

ternal pressure and in part to the higher coefficient of thermal expansion of the

steel jacket. The prestressing mortar swells, or stretches, to counteract the ten-

sion and to retain contact with the steel support. When the second stage of cure

is complete, the mortar becomes rigid in its swollen state. After cooling, the

brickwork is in compression and the steel jacket is in tension. When the vessel

is subjected to elevated temperatures and pressures, compression recedes in the

brickwork, but it never undergoes tensile stresses unless operating conditions

more severe than the cure conditions are encountered.

Mathematical Analysis

The successful design of a prestressed brickwork lining must depend on a care-ful and somewhat elaborate analysis, as can be seen by the following factors

which must be considered in the design:

(1) The prestressing mortars must have enough swelling capacity to

accommodate, without disbonding, the tensile stresses imposed

during the second stage of cure.

(2) The brickwork must be able to withstand the resulting higher

compressive stresses that it will be subjected to during both oper-ating and shutdown conditions.

(3) Prestressing will impose higher tensile stresses in the steel shell,

which it must be designed to withstand.

(4) During operating conditions, the thermal gradient across the brick

lining will cause bending stresses in the brickwork, which must not

exceed material stress limits.

There are a great many variables in the design of a lining: choice of mate-

rials with differing physical characteristics, number and thickness of brickwork

layers, width of brick and mortar joihts, use of an impermeable membrane be-

tween brick and steel, and perhaps the use of an insulating jacket.

The mathematical techniques needed to analyze a design will be described

next. Simplifying assumptions will be made so that the calculations can be car-

ried out by hand. These assumptions will not produce significant errors in the

analysis as long as the lining is thin relative to the radius of the vessel. Ideally,

a computer program should be available, to avoid simplifying assumptions, tomake it possible to analyze many designs quickly, and to eliminate the possibil-

ity of mistakes.




The analysis described is a refinement of that found in Reference 1.

METHODS OF ANALYSIS

Suppose now that the designer has developed a tentative design for the ves-

sel, which includes the number of layers, material specifications for each layer,

and the thickness of each layer, as well as the determination of the installation

temperature, cure and operating conditions, and the maximum and minimum

ambient temperatures that will be encountered both during operation and when

idle. These operating and cure conditions to be specified are inside temperature

and pressure, ambient temperature, and inside and outside heat transfer coef-

ficient.The analysis can be broken down into the following steps:

(I)

(2)

(3)

(4)

Compute the composite physical properties of brick/mortar

layers.

Compute the cure temperatures and stresses in each layer.

Check that the prestress swelling that will occur during cure does

not exceed the capacity of the materials in the lining to swell. If

swelling exceeds the maximum allowable, the lining will breakup. Redesign and compute the analysis again.

Calculate the temperatures and stresses in each layer for the ex-

tremes of operating and shutdown conditions. If stress limits are

exceeded, redesign.

Composite Properties of Brick/Mortar Layers

Each layer composed of both brick and mortar must have its composite

physical properties calculated as a combination of the properties of the brick

and mortar components. The equations are: (See Table 7 for the key to the

notation)

(I) E = (Wb + W,)/(Wb/Eb + W,/E,)

(2) k = (&,kb + ‘+,,k,)/(Wb + w,,,)

(3) o = (W&, + W,‘+,)/(Wb + W,)

(4) 9 = W,n,/(Wb + W,)

The composite value of Poisson’s Ratio can be taken to be that of the brick.

Thermal Gradient Calculation

Temperature drops across each layer are calculated by standard heat transfer

techniques. It is assumed that coefficients of thermal conductivity, as well as all

physical properties, are temperature-independent (that is, uniform within the

thermal range of operation).

The total thermal resistance, per axial foot in a cylindrical vessel, is given byN

(5) R = 1/(2iTrihi) + 1/(2?‘rr,h,) + C R,

ll=l




The first two terms are the thermal resistance of the inner and outer film, Ri and

R, respectively, and the third is the sum of the thermal resistance of each layer,

computed by

(6) Rn = [(ln(rn + dn) - In(rn)ll(2nkn)

The temperature drop across the inner and outer film and across each layer is

computed by the equations:

(7) 6Ti = (Ti - T,)Ri/R

(8) 6To = (Ti - T,)R,/R

(9) 6Tn = (Ti - T,)Rn/R

The temperature on the inside of the innermost layer is

(IO) To = Ti - 8Ti

The temperature on the boundary between layers n and n+l is given recursively

by

(11) T, = T,_j - 6T,

Finally, the average temperature in each layer is

(12) T, = tT,_t + T&2

Stress and Strain Calculations

The exact calculation of radial and circumferential stresses in each layer re-

quires the solution of N+2 linear equations in N+2 unknowns, namely the N+l

radial displacements of the layer boundaries, and the longitudinal strain of the

vessel. We simplify by assuming that the internal pressure is applied only to the

steel shell, and that the other layers follow the expansion of the steel. We also

assume a condition of plane stress; that is, no stress in the axial direction of

the cylindrical vessel. We also consider the layer as being flat when layer stresses

are being computed.

We now give formulas for computing the changes in stresses and strains in

each layer when temperature-pressure conditions change. Suppose that, in

changing to a new condition, the system undergoes a change Ap in inter_nal

pressure, and each layer encounters an average temperature change of ATn.

First we calculate the total change in strain, which can be expressed as the sum

of strain changes due to temperature changes alone, and that due to pressure

changes alone:

(13) Ae = AET + Aep

The two strain components are computed separately. First the pressure-induced

component: It can be shown that a thin cylindrical shell of radius r, thickness

d, and elastic modulus E, subject to inner pressure Ap, undergoes strain given by

(14) Aep = AprIEd




In a bonded lining, the effective elastic modulus is given by

(15)

NE = (~ Endnlfd

n = 1

where

(16)

N

d = }:; dn

n = 1

The value of r is taken to be that of the steel shell.

Next the temperature-induced strain is computed: The change in stress in

each layer due to temperature change in that layer is determined by the differ-

ence between the total strain and the free thermal strain of the layer due to itsaverage temperature change:

(17) ASnT = En(AcT -QnAT n)

Equilibrium considerations imply that the average stress in the lining must be

zero:

(18)

N

}:; ASnT = O

n = 1

Substituting in the above equation, the temperature-induced strain can be corn

puted. Combining this with above calculations produces

N

L\pr + }:; Endn£xnL\T nn = 1

(19) ~e =N

}:; Endnn=1

The average change in stress in each layer is thus

(20) ~Sn = QEn(~E -Qn~T n)

Finally, the temperature difference between the inner and outer surfaces of a

layer produces an additional stress distribution, which varies from a maximum

compression on the hot side to a maximum tension on the cold side. The maxi-

mum values are given by

(21) Sng = Y2anEnOT n/(1 -Jl.n)

Thus the boundary stresses in layer n are given by

(22) Sn = Asn -Sng (hot side)

(23) Sn = ASn + Sng (cold side)



Prestressed Brickwork 619

ing from installation conditions to all other conditions of cure, shutdown, and

operation, as long as there is no prestress swelling. However, this procedure can-

not be employed during a prestressing cure since the layers with swelling capac-ity are not perfectly elastic until the cure is complete.

The method for mathematically simulating the cure process is as follows:

First, compute the layer stresses in moving from installation to cure conditions,

assuming that all materials are perfectly elastic. The resulting stresses are ex-

amined, and the layers that appear to be under tensile stresses and which con-

tain swellable materials are noted. These are the layers that will swell during cure

to neutralize the tension.

The swelling is simulated mathematically by repeating the stress calcula-

tion with the elastic modulus for the noted layers temporarily considered as

zero. This second calculation reflects the actual stresses in the layers at the end

of the cure phase. For subsequent calculations the elastic moduli are restored

to their original values.

Finally, it is necessary to check that the swelling that occurs in the noted

layers does not exceed their maximum swelling capacity. The actual swelling

is the total strain of the system minus the free thermal strain of the layer, thus

the following condition must be satisfied :

(24) qn~~e -Qn~Tn

If any of these conditions fails, the lining must be redesigned by substituting

different mortars, making the side joints thicker, us!ng smaller-size bricks, and

so on.

Stresses at Operating and Shutdown Conditions

Once the cure temperature distributions and stresses have been calculated,

the stresses at various operating and shutdown conditions can be easily com-

puted using formulas (13) to (24) by viewing the conditions simply as changes

in temperatures and inner pressure.

Stresses must be checked for the severest possible conditions that the ves-

sel will undergo. This may be at maximum operating temperatures and pres-

sures at the extremes of idle and/or ambient temperatures.

If any layers are found to exceed temperature or stress maxima, the ves-

sells lining must be redesigned.

SAMPLE CALCULATION

Assume that specifications for the design of the vessel are as in Table

47-1, the lining consisting of three layers: one brick layer, a mortar bed layer,

and the steel shell. This table also displays the calculated composite physical

properties of the brick/mortar layers, computed according to equations (1 )

to (4).Table 47-2 shows cure and operating conditions to be used in stress cal-

culations.

Stresses During and After Cure

The above formulae can be used for calculating the stresses induced in mov-




Table 47-1: Proposed Vessel Design

Shape: Cylindrical

Number of layers: 3

Radius: 35.0 inches to inside of layer number 3

CF TH

Inner EXP Therm

Layer Description Radius Thickness “E-6 Cond

1 4.5” Sample brick 33.5 1.25 2.56 8.06

0.25” Sample mortar - - 13.3 11.3

Composite properties - - 3.13 8.23

2 Sample mortar 34.75 0.25 13.3 1 1.3

3 Sample steel 35.0 0.375 6.5 312.0

Elastic Swell

Modulus Poisson Maximum Maximum Coeff

Layer *E+6 Ratio Compress Tension ‘E-5

1 Brick 6.12 0.2 1600.0 400.0 0.0

Mortar 0.426 0.17 2000.0 1800.0 700.0

Composite 3.59 0.2 1600.0 400.0 36.8

2 0.426 0.17 2000.0 1800.0 700.0

3 29.0 0.3 13750.0 13750.0 0.0

Table 47-2: Installation, Cure, Operating, and Shutdown Conditions

Installation temperature

Cure conditions

inside temperature

Inside pressure

Ambient temperature

Inner film conductance

Outer film conductance

Operating conditionsMaximum operating temperature

Maximum pressure

Ambient temperature range

70°F

24O’F

20 psi

80°F

300 Btu/ft’-hrwoF

3 Btu/ft2-hr-‘F

220°F

15 psi

O”-1 OO’F

Table 47-3 shows cure calculations . The temperature gradient is computed

by equations (5) to (12). Stresses are calcu lated us ing equations (13) to (24),

first assuming all materials are perfectly elastic, and using changes i n cond itions

from installation to cure (note the ambient temperature change of IO”, Ap = 20,

installation stresses are zero). It is found that, among the layers containing

swellable materials, only the brick/mortar layer is under tension , all owing the

layer to swell. The last part of Table 47-3 shows the stresses calculated assuming

a zero elastic modu lus in those two layers.

Table 47-4 displays the stresses in the layers after the cure phase has coo led

to the installation temperature. These stresses can be used as a base from which

stress changes can be calculated for all other cond itions.

Tables 47-5 and 47-6 show the temperatures and stresses, again calcu lated

by equations (5) to (24), for various operating and shu tdown cond itions. It is

seen that the stresses under all cond itions are with in specified limits .




Table 47-3: Cure Temperatures and Stresses

. . . . . . . Layer Number. . . . . . . .1 2 3

. . . . . . . . . . . . . . .Assuming No Swelling . . . . . . . . . . . . . . .

Hot side temperature 238.9 190.3 183.3

Cold side temperature 190.3 183.3 183.0

Hot side stress 565 -386 -962

Percent of maximum 141 19 7

Cold side stress 1247 -338 -862


. . . . . . .Assuming Swelling (Layer 1 Elastic Modulus= 01

Hot side temperature 238.9 190.3

Cold side temperature 190.3 183.3

Hot side stress -341 -342

Percent of maximum 21 17

Cold side stress 341 -294

Percent of maximum a5 15

Percent maximum swell 96 -

. . . . .

183.3

183.0

2028

15

2129

15-

Table 47-4: Stresses After Cure-Cooling to 7O’F

Average stress

Percent of maximum

. . . . . . . Layer Number. . . . . . . .1 2 3

-906 44 2991

57 2 22

Table 47-5: Stresses Under Extreme Operating Conditions

Maximum Summer Operating Conditions

Inside temperature: 220°F

Outside temperature: 1 OO’F

Pressure: 15 psi

inner film conductance: 300.0 Btu/ft*PF

Surface conductance: 3.0 atu/ft*PF

Hot side temperature

Cold side temperature

Hot side stress

Percent of maximum

Cold side stress

Percent of maximum

. , . . . . . Layer Number . . .1 2

219.2 182.7

182.7 177.5

-285 -319

18 16

227 -284

57 14

. . . .3

177.5

177.2

1660

12

1736

13

Maximum Winter Operating Conditions

Inside temperature: 220°F

Outside temperature: O’F

Pressure: 15psi

Inner film conductance: 300.0 Btu/ft*PF

Surface conductance: 3.0 atu/ft*PF

. . . . . . . Layer Number . . . . . . .1 2 3

Hot side temperature 21 a.5 151.6 142.1

Cold side temperature 151.6 142.1 141.6Hot side stress -966 -222 3113


Cold side stress -27 -157 3251Percent of maximum 2 a 24




Table 47-6: Stresses Under Shutdown at Ambient Extremes

. . . . . . . Layer Number . . . . . . .

1 2 3

. . . . . . . Winter Shutdown-Ambient Temperature: O’F . . . . . . .

Average stress -1520 275 4884


. . . . . .Summer Shutdown-Ambient Temperature: 100°F . . . . . .

Average Stress -643 -55 2179


E

k

q

0

IJh

N

RT

Tn

sT

A

S

E

d

W

Table 47-7

Symbols and Notation

Elastic modulus, Ib/sq in

Thermal conductivity, Btu/ft’-hr-OF

Swelling coefficient, dimensionless

Coefficient of thermal expansion, in/in-OF

Poisson’s Ratio, dimensionless

Film heat transfer coefficient, Btu/ft2-hr-‘F

Number of layers in the lining

Thermal resistance, per axial footTemperature

Temperature at outside of layer n

Average temperature in a lining

Temperature drop across a layer

Change in a parameter when conditions change

Circumferential stress

Circumferential strain

Thickness, inches

Width of brick or mortar, inches

Subscripts

Ambient, or outer surface

Brick

Mortar

inner surface of lining

nth layer

Radius

Stress due to temperature difference across layer

SUMMARY AND CONCLUSIONS

The calculations described in this chapter apply only to cylindrical vessels

whose lining is thin relative to the radius of the vessel. Thick-walled vessels, and

vessels of other shapes such as rectangular or spherical, will require considerably

more complex mathematical analysis which is beyond the scope of this hand-

book. In such cases, exact formulae are difficult or impossible to obtain, and the

designer must resort to computer programs for performing the complex calcula-tions.



Prestressed Brickwork 623

This chapter also does not consider the analysis of stresses around piping,

connections, supports, attachments, and so on. While the experienced engineer

can design a vessel to prevent failure at these locations, accurate analysis requires

elaborate techniques such as the Finite Element Method. This method has been

applied with great success to analyze complex vessels such as nuclear reactionvessels. The reader should consult appropriate references if he wishes to pursue

this area. References 2 and 3 are basic textbooks in the field of finite element

analysis.

REFERENCES

1. Honigsberg, C.A. and Eschenbrenner,G.P.,Prestressed non-metallic VeSSel inings, Chef?XEng. Prog., Vol 58, September, 1962, pp 81-84, and Vol 58, October, 1962, pp 97-

101.

2. Desai, C.S. and Abel, J.F., lnrroduction to the Finite Element Method, Van Nostrand

Reinhold, New York, 1972.

3. Tong, P. and Rossettos, J.N., Finite-Element Method, The MIT Press, Cambridge, 1977.

Editor’s Note: In determining the insulation (number and thickness of masonry layers)

required to keep the surface temperature of the membrane at acceptable levels, the designer

may make use of a simplified calculation which is sufficiently accurate for this purpose. The

procedure is detailed in Chemically Resisranr Masonry, by Walter Lee Sheppard, Jr. (2nd

Ed., 1982, Marcel Dekker) pages 112-113.

It may be summarized thus:

(1) Insulation factor of system,

R = thicknessof layer + thickness + thickness- “. (RI)

K factor of layer K factor K factor

(2) Thermal drop of system,

DT = operating temp. - ambient temp. (usually 7O’F)

(3) Thermal drop for each inch (or other unit) of lining then is,

DT, =+; while for each layer DT) = Rl x DT,

Applying these simplified formulae the designer can quickly determine if his design pro-

vides sufficient insulation (thickness) or if he requires another layer. The cited reference

provides examples of these calculations.



Section XIII

Special Subjects

625



4 8

Chimneys

Brian Cooley

Peabody ContinentalUeine Company

Des Plaines, Illinois

INTRODUCTION

It is probable that if the subject of utility or industrial plants is brought

up, the image that would form in one’s mind would be of one or more chimneys

belching endless streams of smoke into the skies. Whether or not the connota-

tion would be pleasant depends upon your relationship to the industry. Regard-

less, most people would picture chimneys because of their visual impact, andrightly so, because they are an integral part of the power process. Today, how-

ever, they are more than just the simple “exhaust pipe” of years gone by.

Thanks to modern power technology, today’s more efficient plants are now

able to squeeze nearly all available &u’s from their fuels before exhausting

them. Couple this effect with today’s tight emission standards requiring scrubbers

and the result calls for an entirely new concept in chimneys. All the years of

successful operational experience so proudly hailed by chimney constructors

and owners mean very little in the new game where scrubbers are the big stars.

There are no “track records” to fall back on, and the majority of experienced

consulting engineers have had to abandon old sets of specs which had been use-

ful for so long. The chimney specialists, also, have little information as to ex-

actly what to specify. This chapter, it is hoped, will furnish some information

concerning the effects of modern conditions on chimneys.

Concept

In power and heavy industrial application, most chimneys are constructed

as a “tube in a tube,” typically cylindrical, owing to the airflow advantages of a

626



Chimneys 627

circular surface. The outer shell is intended to shield the inner flue or “liner”

from the forces of wind and the effects of weather. In many cases, it is also used

to furnish gravity support for the liner itself, as in the case of hanging steel liners

and corbel supported brick linings (see illustrations). The inner flue in turn

protects the outer shell from the effects of the flue gas heat and negates the

problems of acid condensation which would occur if the gases were to come in

contact with the cooler external shell. This concept represents a synergistic

relationship in that neither element could function adequately and economically

without the other. Together they complement each other to the point that their

combined value is not simply additive, but rather is multiplied several times over.

When you consider how long an unprotected structural shell made of either re-

inforced concrete, common brick masonry, or carbon steel would last under the

effects of highly concentrated boiling acid on its walls, you realize the impor-tance of the interior flue. Similarly, if one attempts to design a large free stand-

ing structure of corrosion resistant material such as acid resistant masonry, alloy

steel, or F RP, he soon realizes the economy of incorporating the support function

of a normal high strength support system of common building materials.

PAST DESIGN CONSIDERATIONS

In the past, specifically prior to the required installation of SO2 scrubbers,

most chimneys were subjected to hot, dry, seldom acidic conditions. Typical

flue gas temperatures exceeded 4OO’F and were therefore above the acid dew

point during normal plant operation. Furthermore, the plant itself experienced

fewer shutdowns due to the intermittent operational difficulties inherent within

the scrubbed gas systems themselves. Thus, chimney linings were not exposed to

severe acidic conditions other thanat infrequent start-upsand shutdowns. For this

reason, wet acid corrosion was not a major design factor, and chimneys were

relatively simple to design, construct and maintain. There were a few relativelycommon designs, which will be briefly described.

Corbel Supported Brick (Figure 48-l)

In this method, a concrete shell would be utilized, constructed with regu-

larly spaced shelves or “corbels” upon which segmental thin walled cylindrical

brick linings were laid up. This design represented an economical usage of brick

as a means of insulating the exterior shell while having the concrete support the

gravity loads, enabling the constructor to use far less brick than would be presentin a self-supporting independent brick liner. A typical specification for this con-

cept would call for approximately 4 in. thick brick linings separated from the

outer shell by an airspace ranging from a few inches to somewhat less than a

foot. The airspace, if insulated, would usually be filled with a poured granular

insulating material such as expanded shale. In many cases, it was simply a dead

airspace. The brick linings themselves were designed to taper and overlap each

other so that the concrete corbels upon which they sat would be protected

against direct flue gas contact. Since these chimneys were nearly always under

a negative pressure condition due to the higher values of stack draft associated

with the hotter flue gases, not much concern was given to the sealing details of




the linings because any leakage tended to result in suction of infiltrated ambient

air rather than exfiltration of flue gas. Furthermore, flue gases under negative

pressure do not normally come into contact with the surface of the brick lining

because of the existence of a thin film of stagnant air acting as a boundary at

the brick. This boundary layer, created by brick surface roughness and surfacefriction effects, is washed away as the pressure inside the flue becomes positive

and effluent gases are pushed through at high velocities with the help of power-

ful fans.

Up until the introduction and common usage of acid resistant mortar, the

linings were laid up in the usual portland cement/lime/sand mortar mixes. Al-

though subjected to occasional acid attack conditions, these linings were able to

last many years, due to the fact that they were kept mostly dry and could be

repaired as needed by simply sandblasting and tuckpointing the damaged mortar

areas. They are seldom specified today, because of their inability to resist acid

attack in combination with low flue gas temperatures and the effects of positive

pressure conditions as described above.

Figure 48-l: Corbel supported brick lined concrete chimney.

Independent Brick (Figure 48-2)

In this instance, brick was also used as a protective layer to shield the struc-

tural shell from the effects of heat. The flue itself was designed to stand alone

against the forces of gravity and earthquake. An airspace was provided ranging

from a few inches to a few feet, so that access could be provided to the exterior

surface of the brick liner, a maintenance advantage not possible with the corbel

supported brick lining. The structure itself was laid up in either acid resistant

silicate or common portland cement mortars, as previously described. It wasbasically unreinforced axially, but was corsetted with steel tension bands cir-



Chimneys 629

cumferentially to maintain stability against buckling failure of cracked vertical

segments. This type of design is still quite commonly specified, using acid re-

sistant brick and mortar.

Figure 48-Z: Concrete chimney with independent brick liner.

Shell Supported Steel (Figure 483)

As recognized in the above described designs, heat was practically the sole

factor in liner design. Given that a steel flue insulated by either an externalblanket or internal refractory lining could furnish a similar or better insulating

characteristic than brick, these were often specified in lieu of brick as an eco-

nomic alternate, particularly in tall chimneys where independent brick liner wall

thicknesses became prohibitively thick and expensive. A typical design would

consist of a fairly thin steel plate flue being carried on grillages supported by the

outer structural shell.

In most cases, although the steel flue could be designed more economically

if carried in tension, the liner would be supported slightly above the horizontal

duct entry and allowed to act in compression. Horizontal bracing levels were

placed at intervals spaced to resist lateral buckling while still allowing the flue to

expand upward without restriction by the outer concrete shell. This approach was

taken as a measure to avoid the necessity for expansion joints to account for the

large difference in thermal growth of an insulated hot steel flue versus its cooler

outer support shell. Today’s design of steel flues or other shell supported linings

also recognizes the need to account for such differential growth; however, since

expansion joint design technology has advanced considerably, the desire to

eliminate such joints becomes an economic consideration rather than an opera-tional limitation.




Figure 483: Concrete chimney with shell supported steel or FRP liner (shown as tensionsupported).

PRESENT CONDITIONS

Throughout the 1970s and into the 198Os, the most profound effect on in-

dustrial boiler and flue gas systems has been that of governmental legislation

regarding restrictions on emissions. The former usage of extremely tall chimneys

to vent SO, and NO, into the upper atmosphere for dispersion has come under

strong attack by the environmental authorities of practically all nations. As a

result, mandatory flue gas scrubbing systems create a major design consideration

in all large industrial facilities burning coal and/or oil in the U.S. In selecting a

fuel plan, the operator of a power plant quite naturally has economy in mind.

Factors such as sulfur content, freight cost, availability, and a myriad of other

fueling considerations govern the operational characteristics of a boiler and

its flue gas disposal system. Since Btu’s are directly related to investors’ costs,

reheating of scrubbed flue gas to a point above its dew point is seldom a feasible

economic approach. We therefore see an entirely new environment within the

modern chimney, that of a wet acid saturated gas at such low temperatures that

natural gas buoyancy and stack draft are of little benefit. In fact, today’s chim-

neys more resemble tanks or vessels than they do our previous concepts of

stacks. To design them, the engineer must be highly knowledgeable in the areas

of material technology, fluid flow mechanics, heat transfer, and many other

considerations beyond the normal function of a structural engineer. For this

reason, the team concept of owner, A/E and constructor must come into strong



Chimneys 631

interaction so that the chimney system does not fail due to faulty or incomplete

design criteria.

OVERALL SYSTEM DESIGN-THE OUTER SHELL

In selecting the outer shell for a “tube within a tube” system, the goal of the

designer is to provide adequate protection against the effects of wind, weather,

and seismic forces in the most economical manner. Typically, materials such as

carbon or stainless steel, reinforced concrete, and engineered brick masonry have

been utilized. Each has its own particular strengths, weaknesses, and economies

which can result in the obvious usage of a given type in a given situation or a

choice based upon preference. The usual factors considered in such choice are:

(1) Cost of original construction.

(2) Cost of maintenance.

(3) Aesthetics.

In the case of aesthetics, it is not unusual that an owner or architect has a

preference for a given material to match or compliment the appearance of his

plant. For this reason, the cost of original construction and maintenance some-times take on a lesser importance. Generally, however, they are the major factors

and should be considered on a “hand in hand” basis. For example, although it

may be obvious that a steel outer shell for a reasonably short,small diameter stack

is cheaper than either brick or concrete, consideration should also be given to the

effects of atmospheric corrosion or possible flue gas attack attributable to aero-

dynamic downwash, (i.e., the downward trailing flow pattern of the stack efflu-

ent attributable to its low exit velocity relative to the crosswind velocity at the

top of the stack). It may be that a lesser “up front” construction expenditure

will be more costly over the service life of a chimney than a properly evaluated

and planned system approach. Since it is not possible to describe all conditions

of economy regarding maintenance of the outer shell, this chapter will simply

touch on some factors influencing the original cost of construction.

Steel Shells

Generally, if the geometry of the shell is of a size that can be shop fabri-

cated resulting in a minimum number of segments being shipped to its erection

site, steel stacks will be the least expensive. This, of course, is a very general

statement in that the plate thickness and unit price of material will be a much

greater consideration for taller stacks (150 ft. and above) and those which are

not constructed of plain carbon steel.

Brick Shells

Due to the relationship between the cost of brick production and natural

gas prices (for the kilns), fired clay structural brick for chimneys has become

considerably more expensive than in the past. Couple this effect with the rela-

tively small number of sources for the production of wedge shaped radial chimney




blocks, and freight costs may also have significant impact on the cost of con-

structing a brick outer shell. For these reasons, it is not possible to generalize

on costs of construction for this type of chimney in this chapter. Consultation

with one’s preferred constructor(s) for the particular application and location is

recommended.

Reinforced Concrete Shells

For most utility and large industrial chimney applications, reinforced con-

crete chimney shells have been specified because of their relatively low costs of

initial construction and subsequent maintenance. In chimneys where a fairly

large outer shell diameter s required (IO to 12 ft.), the cost of a cast-in-place

concrete structure is typically less than field welded steel. Since this chapter

must necessarily lfmit itself to that approach most popularly specified, it willdescribe in further detail only the cast-in-place reinforced concrete outer shell

without further consideration of steel or radial brick. (See Figures 484 and

48-5).

Figure 484: Chimney construction-Slip-form technique. The slip-form technique is a

method for building a concrete column monolithiclv. During construction, concrete is

poured continuously into four-foothigh forms that are steadily rising or slipped up the con-

crete structure using hydraulic jacks. The steady upward progress of the forms is timed so that

the concrete is relatively firm before the bottom of the form slips bv.This method of construc-

tion is well suited for projects where time is of critical importance. It also has proved eco-

nomical for structures of large diameters and for chimneys of extreme height. To reduce

labor overtime costs, work is often done on a round-theclock, five days/week basis. Lasersconstantly monitor alignment of the emerging chimney to assure proper plumb is main-

tained. Hydraulic jacks control taper and chimney wall thickness.



Chimneys 633

Figure 48-5: Chimney construction-Jump-form technique. The jump-form technique of

concrete chimney construction has been in use since the turn of the century and has been

refined to a remarkably efficient construction method. Specially designed steel forms are

raised in regular increments for each pour. The forms are raised by the crew using chain

falls connected to overhead beams on the derrick-a structure that incorporates a work deck

and is hung by cables from the inside of the concrete chimney. For each new pour, thederrick is raised using chain falls and reattached by cables to the concrete structure. Then

the outside forms are raised, as one piece. Reinforcing steel is secured and the inside forms

are raised, again as one piece. After alignment and plumb are checked, the concrete is

poured. Taper and wall thickness are adjusted by changing the circumference of the forms.

The design and construction of reinforced concrete chimney shells is de-

tailed by ACI Standard 307. This particular specification is the result of many

years of successful experience and is quite conservative in its approach. Although

it is presently geared only to static design criteria and does not include detailedanalyses for the effects of dynamic wind or earthquake responses, the ratios of

calculated actual quasi-static stresses versus ACI allowable stresses for the given

materials are sufficiently low that when dynamic criteria are considered they do

not change the shell design drastically. The reason for this is that while a suf-

ficient compilation of dynamic design data for the more sophisticated analyses

has not been accomplished at this time, the contributory committee is well

aware of these effects and has compensated for them by conservatively limiting

the allowable static stress values. The specification is continually under review,

and it is expected that the abovementioned design considerations will eventually

be included. A brief discussion of each effect is as follows.




Dynamic Wind: It has been observed by many researchers that when a canti-

levered cylinder is subjected to a steady wind flow, there is a certain velocity at

which the cylinder begins to oscillate in the direction transverse to the wind axis.

This phenomenon has been attributed to the effect of vortex shedding. These

vortices, commonly referred to as the Von Karman effect, are eddies of windsuch as you’d see in water when rowing a boat. (See Figure 48-6 and 48-7).

I!st Mode 3r d Mode

Figure 48-6: The effect of vortex shedding on a stack subjected to a steady wind is oscilla-

tion of the cantilevered cylinder in a direction transverse to that of the wind (left). Theorysays that vortices are shed intermittently from each side of the stack, causing the motion,

Studies of such dynamic wind effects show only the first vibration mode to be significant

in design (right).

Figure 48-7: Designers treat radial wind forces as a static load on the stack. Such forces act

this way: As a steady wind flows across a cylinder, there is an uneven pressure distribution

and a reversal of force, creating a suction on the leeward side.

In theory, they are intermittently shed from each side of the cylinder causing

pressure drops across the diameter as they are released. The resultant pressure

drop causes a lateral force having both crosswind and along wind components

which must be resisted by the cantilevered column. At the condition of reso-

nance, I.e., when the frequency of the wind excitation corresponds to the

natural frequency of the cylinder, these forces are at a maximum. This generally



Chimneys 635

occurs within a time span of 15 to 30 sec. at the critical velocity. Since the

critical velocities for most chimneys are fairly high, and the nature of the winds

at these higher velocities is unsteady, resonance has a relatively low occurrence

probability, hence the normal design for such loading utilizes the maximum

strength values for the materials involved. In many cases, the critical velocity,

by calculation, is considerably higher than any likely steady state wind velocity,

and dynamic wind effects can be neglected. In other cases, such as an extremely

tall slender structure where the critical velocity is low enough to anticipate

resonant wind occurring, the quasi-static wind forces may still be higher than

the dynamic loadings anticipated. In short, not all chimneys will be subject to

the likelihood of vortex shedding, and some that are will not be governed by

their induced forces. Only a detailed analysis of the specific geometry of the

shell will yield a determination.Seismic Loads: After having completed the design of the shell for wind

requirements, the seismic response of the structure must be considered. For low

risk areas, the criteria contained within ACI 307 furnish a conservative set of

quasi-static values for shears, moments and their distribution. Further, the chim-

ney code allowable stresses for static earthquake are also very low, limiting the

maximum tensile stress for Grade 60 reinforcement to 18 ksi. In general, for

seismic zones zero through two, a design based on ACI 307 requirements will be

quite safe and free from doubt. For the more severe risk zones, however, a dy-

namic analysis should be performed. Historically, two methods have been

employed for such analyses. The first method, a time history response record,

utilizes data related to several of the more severe earthquakes of recent local

history and applies their recorded accelerations to the structure under con-

sideration. While this seems to be a reasonable approach, it is not necessarily the

best solution since it may not be representative of the actual site area. For this

reason, the majority of consulting engineers specify an analysis utilizing the

local seismic response spectrum as furnished by various research groups such as

universities and committees associated with the Government or other scientificorganizations. A design, per this method, considers factors related to the soil

depth and its primary interaction with the structure as well as other geological

effects of a local nature.

In summary, there has been a great deal of research and analysis pertaining

to the concrete chimney shell. All known effects have been studied thoroughly

and can be incorporated in design. Both the owner and consulting engineer can

feel confident that, when properly constructed, the exterior shell of a reinforced

concrete chimney will provide a long and trouble-free service life.

OVERALL SYSTEM DESIGN-THE LINER

In contrast to the thoroughness afforded to the design of the outer shell of

the chimney is the relative lack of documented standards for liner specifications.

This incongruity is highlighted when you consider the service requirements for

each. Under normal conditions, the concrete column is stressed by moderate

wind pressures or by dead load alone to a very slight percentage of its strength.

The lining, on the other hand, is constantly subjected to thermal stresses, me-




chanical vibrations and acid attack. While we do have some data and experience

upon which to base our engineering, the design of chimney linings has been, for

the most part, based upon past operating successes which may not hold true for

the somewhat new and/or unknown scrubber conditions. Of the commonly used

liner types, only the steel flue has a universally recognized standard for design.

Even this paper, The Design and Construction of Steel Chimney Liners, as pre-

sented by a task force of ASCE in 1975 is a state of the art treatment based

upon the high percentage of problems from prior years. Similarly, the design of

fiber reinforced plastic (commonly referred to FRP) liners will soon be governed

by a state of the art document to be produced by the industry. For the present,

however, virtually all FRP liner designs are proprietary; produced by those few

companies engaged in their fabrication and erection. In short, since there is so

little liner technology available, this chapter is intended to provide the most

recent discussion of liner designs and their limitations. Since, as stated above,

steel and FRP liners are either covered by a published design document or are

simply designed by the fabricator, their designs will be only briefly discussed. A

general discussion of each type of liner specified today is as follows.

Acid Resistant Masonry

As stated earlier, acid resistant brick masonry (ARBM) has been a long

standing workhorse in the industry. While the corbel supported brick liner has

likely seen its last days with the passing of the hot, dry chimney, independent

brick liners remain those most commonly specified today.

Typically, they are used because of their versatility in resisting either the

cool wet gases produced in normal scrubber operation or the hot, dry gases re-

sulting from bypass conditions. They are, quite simply, designed as self-support-

ing cylinders separated from the outer shell by an annular space sized to accom-

modate shell and liner deflections so that no solid contact occurs between the

two. Under the temperature effects of the flue gas, the liner is allowed to expand

vertically upward without restraint by the outer shell. Precluding seismic loading

it is primarily stressed by dead weight alone to a few hundred psi, a small frac-

tion of its ultimate material strength.

The major limitations of an independent brick liner are those related to

seismic response and leakage of flue gas. As to its seismic limitations, it’s im-

portant to note that the usual chimney masonry consists of very dense, inelastic

structural units laid up in extremely thin (average l/s in.) mortar joints. While the

mortar itself is extremely strong and adherent, such joint dimensions do not

allow the use of embedded reinforcement against overturning moments. Theresultant structure is basically a stack of bricks reinforced only by hooplike

bands to provide stability of cracked vertical liner segments. While some allow-

ance is made for tensile capacity of the masonry, the overturning moments de-

veloped by the seismic response characteristics of these massive structures

generally preclude their use in the higher earthquake risk areas. For seismic

zones 0 and 1, the structures are generally safe, and occasionally, depending

upon the liner geometry, zone 2 loadings can be accommodated. In most in-

stances where an independent brick liner is to be subjected to semisevere seismic

responses, it’s important to note that “thicker isn’t always better.” That is, the

specifier should be aware that one goal of good seismic design is to produce a



Chimneys 637

lighter, more flexible structure. This factor should replace the old practice of

constructing brick liners with “rule of thumb” values for height versus thick-

ness ratios of masonry segments, which may, in fact, subject the structure to

greater seismic damage. In a nutshell, it’s best to let the experts in structural

design determine the wall thickness for a chimney liner rather than imposing

previously used values from a “standard” specification.

The limitations of brick liners related to flue gas leakage will be discussed

further in the chapter, in the section entitled “Annulus Pressurization.”

Steel and FRP Liners

In discussing the historical approach to hot gas chimneys earlier in this

chapter, the concept of steel liners was described. Basically, these flues were

simply thin walled conduits for the gases, supported against buckling forces by

the outer shell. The concept has not changed much for modern steel flues or

for the newer fiberglass flues, only the temperatures of their conveyed gases.

Today, the temperature factor remains the key concern in specifying these types

of flues. Not only normal operating temperatures, but overheat conditions, such

as may occur due to the loss of preheaters (described in Chapter I), have major

bearing in the decision of which liner to use.

FRP liners must generally be ruled out when overheat temperatures above

350°F are anticipated for extended periods of time, as they lose their strengthunder high heat. The duration of overheat conditions may, however, be of such

reasonably short length that these liners may withstand a limited amount of such

cycles. Another approach which has been considered is the use of a water

quenching system to reduce overheat temperatures on an emergency basis.

Typically, however, there has been little success experienced with these types

of liners under severe cyclic temperature conditions, particularly when the acid

dew point is traversed on a regular basis. They do, however, remain a viable

means of wet acid flue gas conveyance for those systems in which operating

temperatures can be kept cool and well controlled.

As to the concept of mild steel liners, the main problems have been due to

coating failures. When you consider the service conditions within a tall steel

liner, it’s not hard to see why certain surface applied systems have not held up.

As opposed to the normal ductwork for which most coating systems have been

developed, steel chimney linings exhibit the following characteristics.

They generally feature a much longer span of uninterrupted tube length.

The use of expansion joints has been kept to a minimum because of the difficul-

ties of gaining access to them within a tall chimney structure. This tends toaggravate conditions wherein the coefficient of thermal expansion of the coating

is even slightly different from that of the steel substrate.

Owing to usual flow conditions, there are many areas within steel liners that

are subjected to uneven temperature impingement effects. These distinct areas

face surface bonding stresses much more severe than normal ductwork.

Under everyday conditions, the liner is constantly flexing due to the in-

duced wind and solar movements of the outer shell. Coupling these movements

with the thermal effects of the flue gas, it is easy to imagine how many cycles

of flexure a chimney liner experiences in its lifetime. It is also easy to under-

stand how even a perfectly applied coating system can fail, since even the tiniest




breach in the coating surface can lead to acid attack of the substrate with its

related peeling, blistering, and delamination. Even the tensile stress induced in

the coating material by its own cure shrinkage can lead to minute cracks in the

coating, as well as loss of bond to the substrate.

Aside from the innate problems of operation under the conditions stated

above, one must also be aware of the realities of chimney construction. It is

relatively easy to apply a coating system under perfectly controlled shop condi-

tions. However, one can imagine the difficulties involved in regulating tempera-

ture, humidity and other important factors influencing coating application

while working from a suspended deck in a steel liner several hundred feet tall

enveloping several hundred thousand cubic feet of air, which when heated tends

to become quite transient due to its own buoyancy. Any coating systems con-

sidered for steel chimney liners must, of necessity, allow liberal margins for less

than perfect application conditions or they will be of little use.

Those coating systems most commonly specified for chimney linings have

been either cementitious gunites or those which will be described in the “breech-

ing ductwork” section of the brick liner discussion, which follows. It is not the

aim of this chapter to indicate which system the reader should select, since

their successes have varied to a great degree. Selection of any coating system

should always be done by experts in the specific field, based upon detailed

knowledge of the specific conditions to be encountered.

Cost, of course, is another major factor in the use of steel and FRP liners.

While mild steel liners made of A36 or A242 plate are not prohibitively expen-

sive, the cost of providing and maintaining coatings to protect against acid

attack can raise the price of the overall system to two or three times that of the

plate itself. Similarly, the material cost of high alloy plate and FRP resin gener-

ally raises the cost of these linings to a point substantially higher than that of

the commonly specified brick lining.

Refractory Liners (Gunite or Cast)

In contrast to the basic refractory services provided by their predecessors,

today’s gunited or cast liners are much more dependent upon the ability of the

applied material to resist possible chemical attack. Additionally, the fact that the

cementitious materials utilized in these applications are somewhat absorptive

and brittle causes another type of concern which should also be considered when

they are specified for “wet” chimneys. (Figure 48-8 illustrates a gunned lining

placed over a membrane as a lining of a concrete shell. This same design may be

followed in application to a steel liner.)Since there is no airspace between the lining and structural shell in this type

of structure, any absorbed moisture in the lining itself will eventually reach the

interface between them. In the likely event of crack formation, such as that

which may occur due to cure shrinkage stresses, the gases can also come into

direct contact with the inner exposed areas of the liner. Further, as they pene-

trate deeper into the lining, they cool and condense to form rather strong acidic

deposits which attack the lining and structural column alike. We shall discuss

the acid attack on the lining further along, but at this point, we will consider

the protection of the structural column.



Chimneys 639

Figure 48-8: Refractory lined concrete chimney.

In Japan and Europe, there are many steel stackswith refractory linerswhich

have been constructed in the following manner: The steel shell is fabricated and

erected, gunite anchors installed, and then the interior coated with an acid-

proof elastomeric mastic. A cementitious lining is then gunned or cast over mesh

connected to the anchors, the end result being that between the potential cracks

in the lining and the structural shell there is an acidproof membrane. Since this

mastic adheres as well to concrete as it does to steel, and since ample mechanical

bonding devices can be easily furnished, this concept is also feasible for concrete

chimneys with refractory linings. Of course, there are mechanisms through

which this acid resistant membrane can be penetrated by corrosive condensation.

Care must be taken when applying the membrane in the vicinity of the gunite

anchors to ensure a smooth and complete seal around and to the anchor. Other-

wise, acid can travel along the anchor to its base in the structural shell, attacking

the shell from behind the membrane.

As to the chemical effects on these types of linings, it is necessary to con-

sider the materials commonly used. Refractory linings can be comprised of a

variety of materials including portland cement, calcium aluminate cement and

various silicate compounds in combination with normal or lightweight aggre-

gates. The types most commonly used consist of calcium aluminate cement with

lightweight aggregate. They exhibit good strength and refractory characteristics

and are somewhat resistant to acid attack, but are not recommended for pH

values of less than 4.0. Since most fuel sulfur contents produce acid conditions

far more severe than this, calcium aluminate liners are generally not suitable for

operating temperatures below the acid dew points of the gases. There are prod-




ucts on the market, however, suitable for wider pH ranges which could be applied

as a refractory lining for steel liners and ducts or for the concrete shell alone.

Some of them will be discussed in other sections of this handbook. For the

purposes of this chapter, however, the following factors should be considered

in the selection of a refractory lining:

(I) How likely is the possibility of acidic moisture condensation within the

flue? Bearing in mind that the acid dew point of a flue gas is dependent upon its

acidic oxide content, with strong acids condensing at high temperatures and

weak acids condensing at relatively low temperatures, the specifier should have

realistic information about what conditions the chimney will actually experi-

ence. Since the scientific prediction of dew point temperatures is difficult, due

to the nonuniform contents of sulfur, nitrogen, vanadium, and other acid in-

fluencing elements within a fuel, empirical data gained from previous experienceor laboratory testing is generally the best indicator of what to expect. Armed

with experimental or operational data linking the specific fuel for a given in-

stallation to its dew point, the designer can move to the next step.

(2) If the flue is expected to be “dry” under operating conditions, how

much control over the flue gas temperature doesthe operator have? In a smoothly

operating plant experiencing few shutdowns and startups, there are minimal

worries about traversing the acid dew point as flue gas temperatures remain

fairly constant. Typical temperature differences between gases entering the

chimney and exiting are within a small range (less than lOoF) for a refractory

with a coefficient of thermal conductivity between 1 .O and 3.0 Btulft’linlhrPF.

Even during a shutdown and startup cycle, not much acid attack is witnessed

due to the fact that the acids which condense on the vertical flue surfaces simply

run down the walls, having no “pooling effect” hence little time to penetrate

deeply into even a nonacid resistant surface. On the other hand, if there are

frequent excursions below the dew point, the likelihood of acid attack is mag-

nified. Not only with the lining experience more surface attack due to thegreater

instance of condensation, but it will also suffer a reduction in its insulatingcapacity if moisture is absorbed and not given adequate time to evaporate. This

is because virtually all refractories are somewhat absorptive, and any liquid ab-

sorbed tends to be more conductive than the typical lightweight aggregate filler

present within the material itself. The resultant lowering of the insulating char-

acteristics will then cool the surface further and cause more moisture to con-

dense. It is recommended that if frequent excursions below the dew point are

expected, the lining should be constructed of an acid resistant material and con-

sideration should be given to the addition of the previously described membrane

between the lining and the outer shell.

(3) For a completely dry stack, the main considerations for refractory

linings are generally insulating value and crack control. It is desirable to provide

a reasonably stiff outer shell for installations in which a refractory lining is to be

used. This will limit the amount of flexural cracking induced into the lining by

movements of the outer shell. It is also desirable to use reinforcing mesh or en-

gineered anchorage devices to limit crack width so that the insulating character-

istics of the lining will not be diminished by local “cool” spots which may be

present at severely cracked or missing refractory sections.



Chimneys 641

Unlined Independent Concrete Liners (See Figure 48-8)

Without going into great detail on this subject, it is important to note that a

few specifiers of chimneys which could be subject to wet gas conditions, have

simply specified unlined independent reinforced concrete liners as a means of

conveying flue gases. They have generally called for an additional amount of

plain concrete thickness between the innermost layer of reinforcing steel and the

exposed interior surface of the liner. The additional thickness, intended to be

sacrificial, has been observed to be attacked and degraded by the acid to a depth

of a few inches whereupon the by-products of such chemical reaction have re-

portedly formed a passive resistance layer. The largest amount of research on

this subject has been performed by engineers of the Tennessee Valley Authority,

who have had the best sources of operational experience. However, since the

practice has not been widely accepted, it is prudently recommended that inde-

pendent concrete liners be treated in a manner similar to a concrete chimney

unsubjected to wind loads but still in need of temperature and corrosion pro-

tection.

Last in the discussion of liner types, but most often the deciding factor in

their selection, is economy. Considering the initial cost alone, the cost progres-

sion for a medium height chimney lining about 400 ft. tall is likely as follows:

Refractory (cast or gunited), brick, steel and FRP. With the inclusion of antici-

pated maintenance costs, the progression is altered since we have seen deficien-cies in gunite, FRP, and coated steel liners that have required major repair ex-

penditures. From the standpoint of economy alone, considering initial and

expected maintenance costs, independent brick liners offer the best solution.

When designed and constructed properly, they can provide effective service for

decades without significant maintenance.

SPECIFIC DESIGN RECOMMENDATIONS-BRICK LINER

Having keynoted the term “proper construction” as pertaining to brick

liners, we must consider far more than the masonry itself. While it is not too

difficult to specify materials or seismic design criteria for a given locale which

should result in a safe structure, such things as bands, buckstays, breechings,

annulus pressurization systems, and many other appurtenances can have a great

effect on the service life of a liner. In this section, some of the major appurte-

nances shall be elaborated upon.

Banding System

As anyone who has inspected a brick liner can attest, virtually all liners

exhibit cracks after being in service. This is to be expected since, under operating

temperatures, a substantial thermal gradient exists through the thickness of the

wall. As a result of this condition, the differential rates of expansion, when ex-

perienced by a nonductile material such as brick, place high internal compressive

and tensile stresses on the extreme fibers of the wall which can only be relieved

by crack formation. Since these cracks could ostensibly reach a point at whichthe entire height of the liner would be broken up into segments much like the




staves of a barrel, a system of regularly spaced steel bands is generally installed

to provide stability to the structure. A secondary aim of the banding system is

to control the magnitude of cracking about the perimeter of the liner. At this

point, it is important that we look at the actual mechanism of this concept.

Consider a brick liner having a 12 in. thick wall and an internal diameter of 20ft.Suppose a temperature gradient of 15O’F exists between the hot and cool face.

Theoretically, the interior face of the liner would expand toward a limit equal

to its circumference multiplied by the temperature at that point and the coeffi-

cient of expansion for the brick. Assuming a value for this coefficient approxi-

mately half that of steel, this change in circumference would be only a small

fraction of an inch. The steel band, assuming negligible expansion in itself,

would then be called upon to resist this strain, or a portion of it, to control

crack formation. It is easy to see that the effectiveness of a banding system in

controlling cracks is directly related to the degree to which the bands are in

tight contact with the brick around the liner circumference. In the past, we

have seen bands installed in such a manner that gaps large enough to insert

one’s finger between the brick and steel are present. These bands are of no value

whatsoever. In specifying an independent brick liner, the purchaser would be

well advised to ascertain what methods the chimney constructor intends to use

to insure proper banding procedures. Special attention should also be given to

the transfer members placed adjacent to openings in the liner where bands are

to be interrupted. They are, in effect, beams upon which the bands react, and

their deflections should be stringently controlled so that the relatively small

“stretch” of the bands, as described above is not lost to high magnitude bending

deflections. The use of shear keys is recommended as one possible method of

controlling buckstay deflections at their connection to the banding corset. See

Figure 48-9.

Figure 48-9: Shear keys protruding from the liner face permit relatively light structural sec-tions (buckstays) to transmit uniform band reactions directly into the liner brickwork as

compressive stresses.



Chimneys 643

Breeching Ductwork

To the layman, it would appear that this relatively small segment of duct-

work leading from the exterior of the shell to the interior of the liner would be

of small consequence in the design of a chimney. Those with experience know

better. Improper layout and detailing of the breeching system leading ,~p to and

entering the chimney is very important in that it could affect the service life of

both the chimney and its tributary ductwork.

To begin with, consider what happens at each boundary of the breeching.

At the onset of operation of the chimney, this simple hollow stiffened box is

subjected to many different movements. The support points upon which it sits

grow vertically at differential rates, causing it to rotate with respect to the hori-

zontal axis. Depending upon the elevation of the breeching entry, the outer

shell may simultaneously deflect in any horizontal direction due to wind, seis-

mic, or solar effects while the liner remains stationary. At its interface with the

adjacent ductwork, it may also be subjected to other induced boundary forces

due to wind loading or thermal expansion of the tributary ductwork. Combining

all these effects with its own thermal growth makes it necessary to provide a

flexible support and connection system which must also be relatively gas tight.

This is no small design problem.

To meet these requirements, the typical individual breeching arrangement

consists of a hinged vertical support fixed against axial movement at the con-

crete shell, coupled with a sliding or rolling support detail at the lining. At both

places, the supports are detailed to allow selfgrowth of the breeching. A vertical

expansion joint is positioned just outside the shell so that neither the chimney

nor adjacent ductwork is subjected to induced loadings from the other. The

resultant system allows all of the previously described movements, and the seal-

ing measures are accomplished through the use of packing and/or gaskets.

Of equal importance to the mechanical aspects of chimney behavior are the

corrosive conditions to be considered. Steel breechings for brick liners must be

coated with a suitable acid resistant coating system, just as must mild steel liners

themselves. The prerequisites for such a coating are as follows: It must be re-

sistant to strong acids or alkalies and to heat. It must be flexible enough to

resist cracking under thermal stresses, thereby providing a continuous unbroken

vapor seal against corrosion. It must have the ability to resist abrasion, and,

finally, it must exhibit strong adhesive properties to the steel so that sections do

not peel off or blister. There have been many attempts to provide suitable coat-

ing materials including various pitch or polyurethane epoxides (with or without

glass flakes), as well as inorganic silicate paints, silicone, furane or epoxy resinsand each has its limitations. The few coatings that have actually been applied to

steel surfaces have had varied successes and failures due to acid penetration,

thermal degradation, chemical attack on the material itself, or poor surface

preparation. We have seen many instances of failures and suppliers withdrawing

their coatings from the market for seemingly irresolvable deficiencies. It should

also be noted, however, that more research is being done presently and that

some progress has been made, particularly in the areas of fluoroelastomeric

coatings and composite membrane/borosilicate block systems, which may pre-

sent more suitable solutions to the steel coating problem. FRP or alloy breech-




ings may also provide a solution to the corrosion problem by eliminating the

need for a coating.

Having discussed the specifics of a single breeching unit, we will now turn

to the overall arrangement of multiple flue entries into a single shaft. In this

area, the factors to consider are those related to structural design and gas mixing.

Structurally, the preferred arrangement calls for either single openings at

different elevations or diametrically opposed openings where multiple breech-

ings must enter at the same elevation. Varying from this arrangement generally

results in thicker shell wall sections due to higher localized stresses.

As to the mixing of gases within a brick liner, there are a few precautions.

Recent developments in scrubbed gas chimneys where multiple flows of differing

temperatures and moisture contents have been mixed within the brick chamber

indicate that it may be unwise to mix gases within the liner. Refer to the sectionof this chapter entitled “Recent Problems Due to Wet Gas Conditions” for

further discussion.

In cases where a uniform gas flow has simply been split for purposes of con-

veyance, it may be necessary to include baffles, turning vanes, or other flow

devices, depending upon the intended entry configuration. In some instances,

model studies are recommended to determine proper performance requirements

particularly when it is felt that stratification of gas flows are anticipated.

Annulus Pressurization

As we have witnessed over the years, brick liners are relatively unaffected

by overheat temperatures, but do experience problems at the lower temperature

ranges. Since the natural draft of a chimney is a function of the temperature

of the gas conveyed, the decreased temperatures of scrubbed gas systems re-

sult in less available natural draft. When subtracted from the sum of all the in-

ternal pressure losses of the chimney, such decreased buoyancy is insufficient to

provide selfdrafting and the lining is subjected to positive pressure. Under this

condition, brick liners require supplementary design considerations. Aside from

leaking at breeching entries and normally occurring cracks, they also experience

exfiltration of flue gas through their mortar joints. As the flue gases reach either

the concrete outer shell or brick wall, they tend to cool and condense. This can

result in acid attack to nonresistant materials within the annular space or the

structural column, itself. Feasible solutions to this problem include the use of

acid resistant coatings or materials for the column and internal appurtenances as

well as the use of fans at the chimney base for the purpose of pressurizing the

annular space between the liner and concrete column. This solution has becomequite popular since the inclusion of pressurizing fans results in a fairly small

initial price increase to the chimney. A typical installation would entail the

following.

Sealing the annulus-This is generally accomplished by spanning the gap

between the tops of the brick liner and concrete shell with a hood system which

restricts the outflow of induced pressurization air while allowing for differential

growths and lateral deflections of the outer and inner shells. It is typically con-

structed of alloy steel or FRP because of the relatively severe corrosive action at

the flue gas exit. Sealing details vary, but the majority consist of flexible belt

arrangements, similar to expansion joint details. At minor openings, such as the



Chimneys 645

gaps between the entry ducts and the shell or liner, various combinations of

flashing, gasketing, packing and caulking are employed to prevent uncontrolled

leakage. Doors and vents are also designed to resist pressure and leakage.

Controlling the induced airflow-Through various combinations of fan

capacity and controlled venting areas, a balance point can be reached at which

the pressure within the annulus is equal to or slightly greater than the pressure

within the lining. Under the condition, the assumption is that most of the flue

gas exfiltration will be prevented because of the balance of forces. However,

owing to certain unknowns, such as osmotic pressures or the degree of future

leakage due to cracking or deterioration of seals, it is advisable to provide a

combination of excess pressure within the annulus (generally 0.5 to 1 .O in. water

column) along with the ability to adjust the pressurization system. This can be

accomplished through the use of variable venting devices, backdraft dampers,inlet vanes, and other system controls. It is recommended that the control

system be kept relatively simple, so that constant maintenance is not required,

and that backup fans be installed. While acid penetration and attack does not

occur instantaneously upon fan failure, an extended duration of operation of the

liner under unbalanced pressure conditions can lead to problems. For this

reason, most specifications call for two 100% capacity fans set up in such a

manner that upon failure of the primary fan, the other is automatically acti-

vated and a warning signal is transmitted to the operator’s control panel. Other

recommendations are as follows.

Install start/stop switches at each door location in the outer shell to allow

depressurization of the annulus prior to opening the door-The usual internal

pressure on a chimney man door approximates a gale force wind, potentially

hazardous to personnel entering and exiting. Switches on both the inside and

outside of doors will allow the pressurization system to continue operation

while personnel are in the annulus, an important feature for ventilation purposes

during extended maintenance work.

Design drain systems for the lining and annulus to account for pressureconditions-For example, a common drain system servicing both the annulus and

liner would not be advisable unless traps or other pressure stops were installed.

Any difference in pressure could result in either the pumping of flue gas into the

annulus or pressurization air into the liner. Similarly, any termination points for

such drains should also provide for pressure conditions.

PRESENT AND FUTURE ASPECTS

Recent Problems Due to Wet Gas Conditions

Within the last few years, there have been several instances in which inde-

pendent brick liners have experienced problems in resisting the effects of wet

flue gases. In certain instances the problems have been due to actual deteriora-

tion of mortar and/or brick which were subjected to chemical attack by certain

constituents of either the flue gas itself or “carry over” reagents from the flue

gas desulfurization system. In general, the commonly used silicate mortars for

chimneys are quite resistant to a wide range of acids and actually thrive in a wet

acid environment. However, certain acids, such as hydrofluoric acid, and most




strong basic reagents can be severely harmful to the commonly specified acid

resistant brick masonry. The strong alkalies and HF tend to dissolve the silica

structure of the mortar and brick itself, and in some cases, the formulation of

certain types of mortar can cause it to be severely affected by sulfation. Else-

where within this handbook, the limitations and strengths of each componentof acid resistant masonry are discussed at length. For the purposes of this

chapter, the author simply recommends direct consultation with each product

manufacturer to determine it’s suitability for the intended operational con-

ditions.

Aside from the chemical degradation problems discussed above, another

effect has recently surfaced which can cause major problems with masonry

liners conveying wet gas, that of irreversible moisture expansion of the brick

itself.In the past, even with a completely dry liner subjected to heat alone, it has

been noted that many independent brick liners tended to take on a “banana

like” deflected shape after startup of a boiler. This phenomenon is attributed

to differential vertical growth of parallel wall elements subjected to a thermal

gradient across the diameter of the brick liner. In viewing Figure 48-10, it is

evident that flue gas entering the brick chamber will directly impinge on a

LEANING LINER

THEORY

Direct impingement area exposed to

higher temperatures and greater mois-

ture deposition.

Stagnated flow area not subjected to

direct flow remains cooler and dryer.

Differential growth of parallel wall ele-

ments causes incremental rotations and

resultant deflection of liner.

RESULTS

1 Small rotation over great height yields

large lateral deflections.

2 Deflections are:

Empirically predictable for dry heat.

Unpredictable for moisture expansion.

Greatly exaggerated for the combined

effect.

Figure 48-10: Chimney with full height independent brick liner.



Chimneys 647

fairly large area of the liner wall opposite the breeching entry. As the gas turns

upward toward the top of the chimney, it gradually mixes and eventually con-

forms its flow path to the full extent of the liner cross section. However, de-

pending upon the geometry of the entry and other factors affecting the flow

characteristics of the gas, the overall effect is that the direct impingement sideof the liner will be measurably hotter than the stagnated flow area immediately

above the breeching entry. When this occurs, each wall element about the cir-

cumference will expand at a different rate, causing, a gradual rotation of the

horizontal plane passing through a given “cool position” elevation of the parallel

axial elements. At that point where the gas has completely mixed and the ther-

mal gradient ceases to exist, the rotation is at its maximum value and the masonry

cylinder above will generally expand uniformly at a predictable rate along its

true axis. It follows mathematically that from this point, due to the slope of thehorizontal axis, each projected vertical increment of the liner will have a hori-

zontal displacement component. It is obvious that even a slight rotation in

combination with a large vertical projection will yield a fairly substantial lateral

deflection at the top of a chimney. For this reason, the general design approach

has been to allow additional clearance between the inside of the windshield and

the outside of the liner to accommodate the liner displacement. Quite often, due

to the inelastic characteristics of the masonry, a large portion of the lateral de-

flection remains permanent even after the liner is cooled to its original tempera-

ture. This condition is generally attributed to lateral slippage in the horizontal

bed joints of the masonry, much as one would see in an unaligned stack of poker

chips. In general, though, the deflected shape of brick cylinders subjected to

thermal gradients alone is empirically predictable and has not limited the use of

such design.

Nowadays, the bending effects on brick liners are on the one hand lessened

because of the cooler gases, but are also worsened by the less predictable growth

effects attributable to moisture expansion of the masonry units themselves. Con-

sidering the probability that all acid resistant masonry units previously andpresently manufactured and used in chimneys throughout the U.S. have the

potential for moisture growth (some exhibiting volumetric growth rates as high

as 0.4% of their original volume). Proper analysis and design measures take on

great importance in a wet gas chimney.

Similar to the pattern of heat transmission as previously described, the

tendency for moisture deposition to be greater on the direct impingement area of

the liner is a cause for concern. The designer needs to consider possible solutions

to the problems associated with unequal moisture growth just as he addresses

the thermal bending effects. If a brick is determined to be a “high grower” as

previously described, a nonuniform expansion rate could cause a chimney liner

to deform drastically, to the point at which large lateral movements at the top

of the liner could cause the liner to lean into the shell. This, of course, is un-

desirable in that the masonry would then be subjected to induced stresses from

the superimposed wind and solar deflections of the outer shell. Ideally, to

eliminate the problem, sources of potential liner brick should be categorized as

to their growth characteristics or possibly their material formulations could be

altered to provide a lesser susceptibility toward such expansion. At present,however, there are no growth criteria included within the ASTM C-980 specifi-




cations for acid resistant masonry units and little is known about the issue

within the industry. However, an ASTM Task Force has been formed to study

the issue, and it is expected that eventually similar criteria to those of other

cognizant nations will be included. For the present, it is suggested that measures

be taken to diminish these effects so that the economy and versatility of theindependent brick liner is not lost for lack of confidence in the constituent

materials. To that end, the following proposed solutions are offered.

Preconditioning of Brick

Since, according to the commentary of certain other sources of brick speci-

fications, as much as 80% of potential moisture growth takes place within most

masonry units if they are exposed to ambient conditions for about a year, it

seems that some simple measures could be taken to lessen the problem. Forexample, the brick for a given chimney could be purchased a year ahead of

construction and “aged” before placement within the liner. Possibly even an

artificial environment could be created to enhance the process. The resultant

decrease in latent moisture growth characteristics would then reduce the degree

of subsequent expansion to a point where it could be accommodated. This, of

course, may not be practical for the majority of construction projects, but it

may be worth consideration for some.

Moisture/Heat Shielding

In this instance, the use of target walls or baffles is introduced to provide a

protective sacrificial surface which lessens the degree of heat and moisture dep-

osition on the primary wall of a brick liner. They are typically designed as partial

height cylindrical sleeves extending through the target zones or else flat walls

which shield impingement areas by diverting gas flow. The usual design calls for

a veneer layer of acid resistant masonry and/or a composite membrane/boro-

silicate block surface applied directly to the liner as if it were glued.

Flow Diversion Arrangements

Rather than allowing nonuniform flow characteristics and curing the symp-

toms as suggested above, this concept is based upon eliminating or reducing the

“direct impingement versus stagnated flow” relationship. In the past, many

A/E’s often specified turning vanes within the brick chamber to achieve better

flow characteristics. The practice has become rare in recent years, however,

because of the great amount of corrosion related maintenance required for metal

turning devices within the flue gas stream. It may be necessary to return to the

practice, using exotic alloys or other acid resistant materials. Another recently

specified concept which may offer the best solution as far as flow, corrosion,

and overall design is that of the bottom entry elbow arrangement as shown in

Figure 48-l 1.

Using this configuration, it is anticipated that the gas will achieve a much

better mix as it enters the brick chamber, a factor which should greatly reduce

the effects of unequal temperature and moisture distribution. It also eliminates

the need for turning vanes and baffle walls, although the use of this system may

be augmented by either some minor “swirling” vanes or a short section of target



Chimneys 649

wall just above the elevated floor. An additional benefit is that the brick cylinder

itself will be uninterrupted by any major openings and the banding systems will

be completely intact resulting in very simple installation and maintenance.

-

I

ll

PROPOSED

MODIFICATION

There is no direct impingement area on

masonry.

Stagnant flow areasare better distributed.

Growth due to thermal and/or moisture

expansion should be considerably more

uniform resulting in unrestrained upward

movement onlv.

Masonry wails and reinforcing corset area

now uninterrupted by major openings.

New requirements:

Concrete pedestal and slab.

Acid resistant detail at floor pene-

tration.

Ductwork must be well protected and

have allowances for future maintenance.

Figure 48-11: Chimney with partial height independent brick liner on concrete pedestal.

In specifying a brick lined chimney for a wet gas environment, the engineer

should consider all of the above recommendations with an eye toward com-

bining those which can apply to his particular case.



49

Coatings for Nuclear Power Generating Stations

Edmond W. Jarret

ConKhem, Inc.

Furlong, Pennsylvania

Protective coatings play a significant role in the safe and efficient opera-

tion of nuclear power plants. The manufacturing, application and documenta-

tion of coating materials used at these facilities are subject to rigid specifications

and procedures to assure a high level of performance. While this chapter will

include a discussion of surfacing cements and paints, materials may be referred

to as coatings for the purpose of brevity.

Nuclear power plants can be divided into three areas for identification pur-poses. Class 1 areas include interior surfaces of Primary Containment; Class 2

areas include those surfaces outside of Primary Containment that are subject to

exposure by radioactivity with traffic conditions, and chemical spills. Class 3

signifies “non-nuclear” areas.

OPERATING CONDITIONS

Two types of reactors are used to power these facilities. They are pressur-

ized water reactors (PWRs) and boiling water reactors (BWRs).

Within Primary Containment, the environment created by the two types of

reactors is similar and will vary according to the method of construction and the

operation of the particular reactor. Under normal conditions, coatings within

Primary Containment are subjected to a variety of conditions that are outlined

in Table 49-l.

Some localized areas may receive higher than average doses of radiation,

however. Examples would be fuel storage canals and areas adjacent to pipeassemblies. Table 49-2 outlines some typical areas.

650



Coatings for Nuclear Power Generating Stations 651

Figure 49-l: PWR pressure containment system. Chart by ANSI-see Reference 1.

Figure 49-2: BWR Mark II over and under pressure suppression containment system. Chart

by ANSI-see Reference 1.

Table 49-I: Typical Design Exposure Conditions of Coatings for Normal

Operation of Pressurized Water Reactors (PWRs) and Boiling Water

Reactors (BWRs)

Relative Pressure Accumulated Radiation

Reactor Humidity Tempfrature (mm Exposure During 40 yr

Tvw Atmosphere (XI ( I=) Hd Life (rads)

PWR Air or nitrogen 100 120 760” 5 x 106-3 x 109

BWR Air or nitrogen 100 135-150 760 5 x 106-3 x 109

“1 atmosphere.

From table by ANSI--see Reference 1.




Table 49-Z: Radiation Exposure Guide of Coatings for Normal Operation of

Pressurized Water Reactors (PWRs) and Boiling Water Reactors (BWRsj

General Level of Exposure During 40 yr* Life

Nuclear Containment Facility . . . . . . . . . . . . (rads). . . . . . . . . . . . .or Area Floor Wall Ceiling

(a) Containment structures 1 x10* 1 x10* 1 x10*

(b) Canals for fuel storage, 2 x 109-7 x 109 2 x 109-7 x 109 _

examination, and handling

(cl Ductwork and filtration system 0.5 x IO’-1 x IO’ 0.5 x 109 0.5 x 109

*It is not intended that a coating system initially applied to a reactor containment

facility last for forty years without appropriate maintenance or overcoating.

From table by ANSI-see Reference 1.

In the event of a malfunction of the reactor or safety related equipment, a

condition known as a Loss of Coolant Accident (LOCA) may occur within the

Primary Containment Structure. Should this happen, the environment would be-

come dramatically altered in a matter of seconds and result in the escalation of

temperature and pressure to dangerous levels. To counteract this condition, large

quantities of water with chemical additives are automatically directed onto all

surfaces by means of high pressure spray systems.

A LOCA condition could severely damage conventional paint systems,

causing them to disbond, combine with the spray solutions and clog the pump

suction spray screens; thus jeopardizing the safe operation of the plant.

Qualified coatings, on the other hand, are formulated to resist these condi-

tions and not peel or flake off in any sufficient quantity to affect the engineered

safety systems.

Typical time/temperature/pressure LOCA curves are pictured below in Fig-

ures 49-3 and 49-4.

60

Figure 49-3: Typical curve for PWR containment facilities showing temperature and pres-

sure vs time. Chart by ANSI-see Reference 1.




60

,,,.,E AFTER RUPTURE INITIATING ACCIDENT SEOUENCE, (secl

Figure 49-4: Typical curve for BWR containment facilities showing temperature and pres-

sure vs time. Chart by ANSI-see Reference 1.

Coatings in Class 2 areas are subjected to a variety of conditions which in-

clude abrasion and impact from fuel handling and other traffic operations,

radioactive exposure, chemical attack and demineralized water immersion. Since

personnel regularly service Class 2 areas, the coating systems must resist these

conditions and be easily decontaminated to safe levels.

Coatings in Class 3 areas are formulated for architectural and wear proper-

ties. Conventional paint systems are generally used in these areas.

QUALIFICATION REQUIREMENTS

In order to qualify coatings for use in nuclear power plants, suppliers must

prepare test specimens of the candidate systems and submit them to test agen-

cies having equipment that can simulate Class 1 and 2 conditions. The Oak Ridge

National Laboratories in Oak Ridge, Tennessee is one agency used by most

suppliers.

Coating suppliers, contractors, equipment manufacturers, and inspectionagencies wishing to do business in Class 1 and 2 areas must submit to thorough

audits by the A/E firm in charge of the project or the owner. Personnel, equip-

ment and Q/A programs are screened to see that they meet the requirements as

set forth by the specification.Failure to comply is grounds for rejection.

In order to assure that the most qualified personnel are available for nuclear

coating work, a program has been established to certify Registered Professional

Engineers and nonregistered engineers, technicians and other personnel. This

program was developed by, and is administered by, the National Board of Regis-

tration for Nuclear Safety Related Coating Engineers and Specialists, Box 1999,

Sun City, Arizona 85372.




Several engineering societies play an instrumental role in developing stand-

ards, specifications and in dispensing useful information with regard to nuclear

coating work. Typical are:

American National Standards Institute

American Society for Testing and Materials

Steel Structures Painting Council

National Association of Corrosion Engineers

COATING VARIETIES AND APPLICATION

Nuclear coatings are formulated to seal and protect concrete, concrete block

and steel surfaces. The most commonly used coating types are the amine and

polyamide cured epoxy systems. The solids, by volume, can vary from 50 to

100% with fillers or reinforcement fibers usually added so that the coating can

perform a wide variety of functions. Reasons for their wide use are that they

bond tenaciously to a variety of substrates; they cure to a hard smooth finish

which results in superior decontamination qualities; and, most importantly, they

perform satisfactorily in Class 1 and 2 service.

Inorganic zinc coating systems have been used quite frequently in certain

defined areas such as structural steel, primary containment steel (i.e., Wetwell,

Torus, exterior surfaces of pressure pipe, and some exterior steel equipment).

One coat is all that is usually necessary, although some specifications call for

two coats. Their main advantages are that they resist abrasion and provide

cathodic protection for long term and superior resistance to weathering, espe-

cially along ocean coasts. They finish to a somewhat rough and porous surface

and are occasionally topcoated with epoxies or urethanes, depending on the

ultimate service conditions.A class of coatings known as strippable coatings has been successfully used

in Class 2 areas. These polymer materials are airless sprayed onto surfaces to pro-

vide a temporary barrier against radioactive contamination of the substrate.

When saturated with contamination, the flexible material is pulled off of the

surface by workmen and safely disposed of in 55 gallon drums. A new coat can

then be applied.

Salt water intake tunnels, particularly along the southern coast, are sub-

jected to biofouling. A class of toxic coatings known as organotins utilizes com-

pounds of tin oxides and fluorides to retard the formation of barnacles, algae,

etc. These coatings look quite promising.

Waterborne epoxy formulations have been used quite extensively in some

nuclear facilities with good success. They have not yet met the requirements of

Class 1 testing, but perform well in certain areas such as radwaste handling areas.

As is the case in all critical coating applications, strict environmental con-

trols are required to permit the coating to bond and cure properly. Many specifi-

cations limit the temperature ranges from 50” to IOO’F, and the surface and sur-

rounding air temperatures to at least 5’F above the temperature where conden-sation will form (dew point). One exception to these restrictions would be the




inorganic zinc coatings that cure by hydrolysis. In this case condensation on the

surface (dew) is desirable during the cure cycle.

In Class 3 areas, several types of coatings are used. They include alkyds,

acrylic latexes, enamels, urethanes, and chlorinated rubbers.Steel surfaces do not provide any unusual difficulties during coating opera-

tions, as long as the steel is of high quality and the environmental conditions are

strictly controlled. Specifications usually call for an abrasive blast that meets

Steel Structures Painting Council (SSPC) Spec. #5 ("white metal") finish; al-

though steel to be used in non-nuclear areas usually receives an SSPC #10 ("near

white") finish or an SSPC #6 ("commercial") finish. Areas that require special

attention are welds, seams, edges, channels, etc.

Concrete, on the other hand, offers a variety of problems. In the pouring

and placement of concrete walls, the formation of blowholes or voids is inevi-table. These imperfections vary in size and quantity by the way the concrete is

placed and compacted. If the immersion vibrators are kept just below the sur-

face of the concrete during the pour and raised at the same rate as the concrete,

the formation of blowholes is kept under reasonable control. In actual practice,

this procedure is difficult to control; thus causing a variety of patterns and

textures to appear from one pour to the next. Figure 49.5 shows a variety of

blowhole patterns.

Figure 49-5: Blowhole patterns. Photo by Concrete Society-see Reference 5

Other contributing factors to the quality of the concrete finish are the types

of forms and the release agents used; the type of mix and aggregates used and

the ambient temperature. The improper placement of forms can result in signifi-

cant offsets of 1/2 o 1" or more as well as fins and projections.

Since Class 1 and 2 surfaces must be easily decontaminated to safe levels,

these imperfections must be corrected. The offsets, fins and projections areusually repaired by masons using stones and grinding wheels. The blowholes are

corrected by application of the coating materials.




Fi~re 49-6: A coating applicator is shown spraying epoxy coatings on Class 2 walls and

floors. Photos by Con/Chem, Inc.

Some coating suppliers have responded by increasing the volume solids to

90% or higher and adding fillers and/or fibers to arrive at a family of materials

commonly referred to as surfacing cements.Applicators apply these products by one or more methods including spray-

ing, rolling, troweling, squeegeeing and brushing. The materials can be made to

partially fill the blowholes; however, in fact, they actually bridge rather than fill

these voids. It is important to note that no applicator can guarantee a 100%

void-free surface without considerable expense and delays; therefore the pru-

dent and realistic specifying engineer will use such words as "essentially" void-

free and include some specific statement on the maximum number and size of

permissable voids in the finished film per area (50, 100, or 150 sq. ft., etc.).In order to minimize surface preparation, concrete surfaces are usually

water cured for 28 days; however, the use of curing agents cannot be altogether

avoided; so special care must be taken to assure the selected agent is compatible

with the coating used .

When selecting form release agents, the lacquer or epoxy types are usually

used as they remain on the forms when the forms are pulled and do not con-

taminate the concrete. (Under most circumstances, oils are not used as they will

detrimentally affect the bonding characteristics of the coating to the substrate;

however, some suppliers claim their oils degrade with time and leave a clean

surface.)

Hard troweled floor surfaces are usually broom finished to provide a surface

profile and to eliminate costly abrasive blasting. Some abrasive blasting will be

required on the typical job; however. The use of muriatic acid etching is pro-

hibited on nuclear sites due to the adverse effect of chlorides on stainless steel.




all coatings work. This practice is designed to assure the utility owner that the

coating system was appl ied in accordance with the provisions of the specification .

Items such as material storage, handling and application, surface prepara-

tion, mil thickness tests, environmental conditions, surface defects in the coating

film and coating adhesion are all checked and recorded. Inspectors have the

authority to halt work not being performed properly, and they can reject com-

pleted work that does not meet the requirements of the specification.

The importance of an effective inspection program cannot be over empha-

sized as the ultimate beneficiary of a safe and efficient operating nuclear power

plant is the general public.

Figure 49.7: (a) Steel surface profile monitoring equipment; (b) Dew point monitoring

equipment; (c) Wet film thickness gauge; (d) Elcometer adhesion tester. Photos by Metal-

weld, Inc.

INSPECTION

Highly trained and qualified inspectors are required to monitor and record




REFERENCES

1. Protective Coatings (Paint) for Light Water Nuclear Reactor Containment Facilities,

American National Standards Institute, New York, NY (1972).

2. Manual of Coating Work for Light Water Nuclear Power Plant, Primary Containmentand Other Safety Related Facilities, American Society for Testing and Materials,

Philadelphia, PA, Edition 1 (1979).

3. Fiittenhouse, R.C., Protective Coatings for Power Plants, Power Engineering, pp. 3038

(December 1982).

4. Berger, Dean, M., Gilbert Associates, Inc., Reading, PA, Preparing and Painting Verti-

cal Concrete Surfaces of Buildings, a Paper for a Symposium in Finland (August

1977).

5. Thompson, M.S., Blowholes in Concrete Surfaces, Concrete, The Journal of the Con-

crete Society, Great Britain, Vol. 3 (February 1969).

6. Conversations with: B.W. Chandler and S.J. Oechsle of Metalweld, Inc., Philadelphia,

PA and C.H. Hall, KTA-Tator, Inc., Houston,TX.



51

Pulp and Paper Industry Use of

Corrosion Resistant Masonry Construction

Larry C. Stephans

Rochester, New York

The pulp and paper industry experiences a wide range of corrosive condi-

tions involving highly aggressive chemicals frequently at high temperatures and

pressures. The most severe corrosion occurs in the digester area and the bleach

plant area of the pulp mill. Therefore, corrosion resistant masonry construction

is commonly used in these areas. Conditions are less severe in the paper mill,

in the peripheral equipment used in the recovery and disposal processes, and inthe buildings housing these processes. Corrosion resistant masonry construction,

however, is still used to advantage in these areas.

MATERIALS OF CONSTRUCTION

The masonry units used in the pulp and paper industry include fireclay,

shale, and carbon brick, structural glazed tile and portland cement/aggregate

brick. Structural glazed tile and portland cement/aggregate brick are relatively

unique to this industry and have not been widely used outside of it.

Mortars used in the past have primarily been composed of portland cement,

silicates, and litharge and glycerine. Except for portland cement, these traditional

materials have generally been replaced by resin mortars utilizing epoxy, poly-

ester, vinyl ester and furan resins.

The membrane material used in the past, if a membrane were used at all,

was lead. Today membrane materials include rubber, urethanes, fiberglass rein-

forced thermoset resins, and aggregate filled thermoset resins. The fiberglassreinforced and aggregate filled resins have also found use as linings without brick

or tile.

669




The physical properties and chemical resistance of brick, tile, mortars, and

membrane materials are discussed separately in other chapters of this book.

HISTORY OF BRICK AND TILE CONSTRUCTION IN THE PULP AND PAPERINDUSTRY

A single course brick sheathing was originally installed in a pulp digester to

hold the traditional loose lead digester lining in place and to reduce the amount

of maintenance on the lead. As the more corrosive sulfite pulping became more

widely practiced and pulping technology advanced, so did acid brick technology.

The observations of lining performance lead to the optimization of brick proper-

ties and establishment of lining design criteria.’ The advances in brick composi-

tion, manufacturing techniques, design and installation methods have greatly

improved lining life over that of early installations. Today’s acid brick are denser

than those early brick and are composed of clays selected to impart particular

properties to the brick. Lining design calculations now take into account brick

growth, mortar joint shrinkage and/or growth, and other physical properties of

the lining components.2

Another masonry product, structural glazed tile, found its first use in the

pulp and paper industry in the early 1930s. A number of different configura-

tions of these tile are shown in Figure 51-1.

Structural tile can be used as a lining in a metal vessel similar to a brick

lining, as shown in Figure 51-2, but is more commonly used to build relatively

Blocks Plates

Figure 51-1: Tile shapes.

inexpensive reinforced concrete structures with corrosion resistant interior and

exterior surfaces.3 Two different types of wall construction are shown in Figures

513 and 514. In Figure 51-3 the tile are used in their block form. The wallthickness is obviously limited by the width of the block. In Figure 514, the

tile is split to construct a wall of any practical thickness.

The method of construction of the structural tile walls shown in Figures

51-3 and 514 involves setting the steel reinforcing bars as in the construction of

a reinforced concrete wall. The tile is then set with portland cement or resin

mortar joints to form the inner and outer wall surfaces and the concrete is

placed to form the core of the tile wall. This process is repeated in vertical steps

a few feet at a time until the unit is complete. The backs of the tiles contain pro-

jecting lugs which tie into the concrete as it is placed, thus solidly incorporating

the tile as an integral part of the structural wall.



Pulp and Paper Industry Use

671

F i g u r e 5 1 . 2 : Tile lining in steel.

Figure 51-3: Block tile wall.

Figure 514: Split tile wall.




Tile construction is not used to any great extent for very aggressive liquid

corrosives because the tile and the mortar joints are relatively thin (approxi-

mately l/2 in. deep) and are somewhat porous. These structures, therefore, have

a tendency to weep or leak. Other factors which contribute to this tendency are

the lack of a membrane and the susceptibility of the portland cement core toattack by acidic media. Also, because the tiles are essentially the forms for the

concrete and are not removed after the concrete cures, controlling the quality

of the concrete wall by visually identifying stone pockets, pour lines, etc., is

impossible. Structural tile vessels are, therefore, used in stock tanks, pulp storage

tanks, washers, etc., where some leakage can be tolerated or the solids in the

contained media will plug leaks.

ACID SULFITE DIGESTERS

The relatively severe conditions in an acid sulfite digester dictate the use of

a multiple layer acid brick lining. The lining must be carefully selected and

specified since these units operate at elevated temperatures and pressures with

very acidic chemicals. Improper selection, design, specification, or installation

can result in an unacceptably short lining life, lining failure, or vessel failure.

The typical lining in an acid sulfite digester consists of two layers of acid

brick set in a resin mortar with a portland cement grout between the steel shell

and the back layer of brick. Litharge cement/glycerine mortars were used prior

to the development of resin mortars; however, with the increased severity of

digester conditions and the improvement of furan mortars, furan mortar is now

generally used. This lining is, therefore, relatively substantial, consisting of two

layers of brick bonded with furan mortar and a layer of portland cement grout

between the brick and the vessel wall forming a lining up to 7.5 in. thick.

In addition to being properly selected, designed and installed, these linings

must be properly cured and prepared for service. The lining is cured and growthof the brick and mortar initiated by a carefully programmed procedure involving

exposure of the lining to an acidic media, increasing the temperature of the

media to a specified maximum, then holding these conditions for a period of

time. The curing acid concentration, rate of temperature rise, maximum tem-

perature and time are critical to the proper curing and initial growth of the

lining. This procedure thus puts the lining in compression preparing it for a

long service life. If proper care were not used in preparing the lining for service

it could require substantial maintenance over its life and early failure could

result.

The layer of brick directly exposed to the digester operations, the face

course, is obviously exposed to the most severe conditions. The face course

experiences the greatest amount of chemical deterioration, thermal degrada-

tion, mechanical abuse, and wear and thus must be replaced occasionally.

Proper repair and timely replacement of the face course can prevent deteriora-

tion of the intermediate layer, the backing course, of brick and the portland

cement grout backing. The inspection and expeditious repair of the face course

and of the entire lining is important to achieving suitable service life.Periodic inspection of a lining will detect receded mortar joints, spalled

brick, excessively worn brick, cracks, and hollow areas behind the lining.



Pulp and Paper industry Use 673

Mortar joints between the brick will recede due to wear and adverse chemi-

cal and thermal effects. This is normally a relatively slow, progressive phenom-

enon. The condition is remedied by raking any loose or deteriorated mortar

from the joint and repointing with furan mortar. This is a maintenance pro-

cedure which will be done many times during the lining life.Brick spalling is the condition wherein ‘/4 to % in. of the brick face breaks

away. This is not of concern if it occurs in a few brick in isolated locations

since this would probably be a result of individual brick characteristics. How-

ever, if the condition occurs in a concentrated area involving a significant num-

ber of adjacent brick, there is cause for concern and a specialist should be

contacted to analyze the problem. Spalling problems can be caused by thermal

shock, excessive compression, receded mortar joints, exposed brick edges, or

perhaps other factors.

Obviously worn areas in the lining are usually a result of chemical softening

and subsequent erosion due to impingement of digester contents on the area.

The magnitude of the problem may be reduced by reducing the flow velocities

to which the lining is exposed.

Lining cracks are a cause for significant concern since they normally indi-

cate a lining which has, at some time, gone into tension. Brick linings are not

sufficiently strong in tension to resist being virtually pulled apart if tensile

stresses occur. One of the major objectives of lining selection, design, specifica-

tion, installation and curing is to create a lining which is always in compression.

Cracks may result from an error in any one of these procedures or perhaps from

a failure in the vessel shell itself. The cause of cracking should definitely be

determined before repairs are made and the vessel put into service. Cracks can

be repaired by sawing them open to permit pointing with a furan mortar and

then pumping catalyzed furan resin behind the mortar to fill any void which

may exist.

Hollow areas in a lining can frequently be detected by tapping the lining

with a hammer. A solid lining will give a solid sounding ring when tapped. Ahollow area in a lining will give a resonant hollow sound. A hollow area can be

a result of disbonding of the various layers of the lining, chemical attack within

the lining, or improper installation. Narrow paths or runbacks may lead from

voids in the lining as a result of chemicals collecting in the void and selectively

corroding pathways. Runbacks occur particularly in the portland cement back-

ing grout if digester acid penetrates back to the grout. Voids and runbacks must

be repaired to prevent progressive lining deterioration. This can be accomplished

in some cases by drilling a small hole in the lining to access the hollow area then

pumping appropriate material such as a catalyzed resin into the void. The access

hole is then closed with mortar. In more severe cases, a section of the lining may

need to be removed and replaced.

Because of the severity and cyclic nature of acid sulfite digester operating

conditions it is imperative that inspection and repair take place on a routine

basis. The face course obviously will receive the most attention but no oppor-

tunity to inspect and repair the intermediate layer of brick, such as during face

course replacement, should be missed. The steel digester shell should also be in-

spected for integrity and thickness whenever the opportunity is available.Occasionally maintenance requirements can be reduced by the installation




of carbon brick where rapid ceramic brick deterioration is caused by chemical

attack, thermal cycling, or high velocities. This type of installation has success-

fully reduced maintenance in areas around the strainer, bottom outlet, collector

ring, and circulation fittings. Since carbon brick linings are more expensive than

ceramic brick linings, the cost versus performance relationship must be con-

sidered.

PERIPHERAL EQUIPMENT IN THE DIGESTER AREA

The equipment surrounding acid sulfite digesters is also frequently brick

lined, although, since conditions are not as severe as in the digester itself, single

layer linings are normally adequate. These linings consist of a single layer of acidbrick set in a resin mortar with portland cement grout placed between the steel

shell and the brick lining. The equipment in which this type of construction is

used includes blow pits, dump tanks, acid storage tanks, and accumulators.

The same routine inspection and repair procedures as practiced in maintain-

ing digester linings should also be used in this associated equipment. Similar

lining problems can occur in this equipment and the remedies are the same as

in the digester.

KRAFT AND NEUTRAL SULFITE DIGESTERS

The operating conditions in these digesters do not always dictate the need

for a lining. The operating conditions of the original kraft process permitted the

use of unlined steel vessels. As kraft pulping technology developed and a variety

of more severe operating conditions were adopted, corrosion of the steel shell

did become a problem. Acid brick linings were not suitable for the high tempera-

ture alkaline conditions of operation, therefore, carbon brick linings were used.4These linings are normally 3.5 to 5 in. thick and consist of a single layer of

carbon brick set in portland cement mortar with portland cement grout between

the steel shell and the brick lining. The portland cement mortar used to set the

brick will have a longer service life if alkali resistant aggregate are used in the

mortar mix. A furan mortar may be used but the added expense is seldom justi-

fied. Proper design and installation are, again, required to avoid serious problems.

Routine lining inspection and maintenance procedures must be followed to

obtain suitable lining life. Maintenance procedures described for acid sulfite di-

gesters apply here with one addition, replacement of brick “fall-outs.” This

problem can be caused by movements of the lining and the steel shell, low com-

pression in the lining, and the low bond strength between the portland cement

mortar and the carbon brick. Proper design considerations will normally reduce

or eliminate this problem.

KRAFT LIQUOR SYSTEMS

As in the kraft digester, the vessels in the kraft liquor system can be brick

lined to prolong their useful life. Carbon brick linings are normally not used be-



Pulp and Paper Industry Use 675

cause of the cost, but a relatively inexpensive portland cement based brick can

and has been successfully used. This brick is composed of portland cement and

alkali resistant aggregate and is manufactured to achieve maximum density. The

brick is set in a portland cement mortar and a portland cement grout is placed

between the vessel shell and the brick lining. Vessels in which this lining has

been successfully used include the lime slaker, green and white liquor storage

tanks, causticizer, smelt tank, and clarifier.

PULP STORAGE VESSELS

Structural glazed tile tanks make excellent pulp storage tanks. Chemical

resistance is generally not a major requirement in these vessels although somechemical addition may take place in the dilution zone where the chemical re-

sistance of the glazed tile is quite adequate. These large vessels are economically

constructed, as described previously, with structural glazed tile set in portland

cement mortar forming the interior and exterior walls and reinforced concrete

forming the structural core. The glazed tile interior surface affords a smooth

nonporous surface which will not contaminate the pulp, does not permit pulp

buildup on the interior wall, and is easily cleaned.

Occasional repointing of the mortar joints is normally the only maintenance

required. In the dilution zone, where attack of the portland cement mortar may

occur, repointing with a polyester or vinyl ester mortar will usually solve the

problem. If voids are detected in the wall, these can be filled by pumping a port-

land cement mix or a catalyzed resin into the wall by the technique described

for filling voids in a digester lining. The service and maintenance history of these

vessels has generally been excellent.

CHLORINE DIOXIDE VESSELS

In the bleach plant the corrosion problems are somewhat different than in

the digester area but they are no less severe. One of the most corrosive and un-

stable chemicals in the bleach plant is chlorine dioxide. The decomposition

products of chlorine dioxide can be even more corrosive than chlorine dioxide

itself. Acid brick is thus typically used in much of the equipment handling

chlorine dioxide.

The normal lining construction consists of a membrane on the steel shelland one layer of acid brick in a resin mortar. The membrane materials used have

been a silica filled latex rubber or, more recently, a silica filled urethane. Either

of these membranes is installed by troweling it onto the steel shell. The mortars

used have been polyester or vinyl ester based and are used in the back joints, bed

joints, and side joints. That is, the brick are completely surrounded by the mor-

tar, except, of course, for the face. The equipment in which this type of con-

struction is used includes the chlorine dioxide storage tank, the chlorine dioxide

generator spent acid tank, and the chlorine dioxide bleach tower.

This equipment does not experience temperatures as high as those in di-

gesters and is not cycled as frequently as a digester, therefore, fewer maintenance

problems occur. However, routine inspection and sound preventive maintenance




practices should be followed to detect and repair receding joints, voids behind

the lining, and worn, softened or spalled brick. The remedies for these problems

are the same as described previously.

CHLORINATION, HYPOCHLORITE, PEROXIDE, AND CAUSTIC EXTRAC-TION TOWERS

In these bleach plant units the conditions are not as severe as in the chlorine

dioxide units. Thus, a tile lining is normally used; the more expensive acid brick

not being required. The lining is installed by setting the tile in a resin mortar or

portland cement mortar inside the steel shell. A few vertical courses of tile are

set around the circumference of the tower leaving a space between the vessel

wall and the back of the tile. A portland cement grout is then placed in this

space. The grout forms around the lugs on the back of the tile and holds the

tile firmly in place. The installation of the lining proceeds up the tower a few

courses at a time to completion.

The chlorination tower lining is tile set in a polyester or vinyl ester mortar

with a portland cement grout backing. The hypochlorite and peroxide units do

not need the resistance of the resin mortar, therefore, portland cement mortarcan be used. Caustic extraction towers are occasionally lined with tile set in

portland cement mortar even though the alkaline operating conditions may

soften the tile. To minimize the softening effect, the tile should have an ex-

tremely tight, well fired body.

Lined steel vessels have also been used in the manufacture and storage of

these bleach plant chemicals, however, today more and more of this equipment

is being constructed of fiberglass or thermoplastic lined fiberglass.

The tile linings in the bleach towers and other associated bleach plant equip-

ment should be inspected as often as possible to detect receding joints, excessively

worn tile, and voids behind the lining. Early detection of lining problems in

these units is important since the tile linings are relatively thin. Worn tile or re-

ceded joints exposing the backing grout can lead to chemical penetration behind

the tile I ning and rapid I n ing deterioration .

WASHERS AND SEAL PITS

Structural tile construction is commonly used in these units. The wall of

the unit is thus a concrete wall with tile faces. The tile has traditionally been set

with portland cement mortar but modern bleach plant operations with closed

loop recycl ing of chemicals has resulted in the increased use of resin mortars

with their broader chemical resistance.

Maintenance again involves routine inspection and repointing of receded

mortar joints and the filling of any voids in the wall structure.



677ulp and Paper Industry Use

used in the paper mill to handle the pulp and to handle the paper mill chemi-

cals. The tile affords a relatively smooth surface, it will not contaminate thepulp, and is resistant to chemical corrosion. The tile can be set in portland ce-

ment mortar, however, a resin mortar is frequently preferred since it will be

more resistant to a broader range of chemicals. Resin cements also have greater

strength and are somewhat more resistant to erosion.

Equipment in which this type of construction is used includes pulp storage

tanks, stock chests, machine chests, and wire pits.

TALL OIL REACTORS

These vessels are operated under extreme chemical and high temperature

conditions. They are, therefore, usually brick lined. The lining consists of a poly-

vinyl chloride sheet membrane applied to the steel shell with an acid brick I ining

set in furan mortar installed over the membrane. The vessel is occasionally ex-

posed to a caustic solution for cleaning and, therefore, a partial carbon brick

lining may be installed in the lower wall area and floor. These lower areas of the

vessel are normally where the most maintenance is required. Eroded mortar

joints may need repointing and softened and eroded brick may need to be

replaced.

TALL OIL SPENT ACID TANKS

These vessels are lined the same as the tall oil reactor since conditions are

similar to those in the reactor. The precautions rn exposing the lining to causticsolutions are also the same.

FLOORS

Concrete floor areas in a pulp and paper mill are frequently lined to prevent

deterioration of the concrete. These linings can consist of red shale brick, quarry

tile, or an aggregate filled resin (referred to as a monolithic floor lining), Floor

linings are primarily used in areas exposed to very aggressive chemicals such as in

the bleach plant and paper mill.

A red shale brick or quarry tile floor is usually installed over a hot or cold

applied mastic membrane. The mastic is applied to the concrete floor then the

brick or tile are set with a resin cement. The resin cement can be a furan, a poly-

ester or an epoxy depending on the anticipated exposure conditions. If high

temperatures and constant exposure to aggressive chemicals are anticipated, the

brick or tile will be bedded in the mortar as well as having mortar joints.

Aggregate filled resin floor linings or monolithic floor linings have seen anincreasing use as this technology has developed and improved. This type of lining

is installed by first applying a resin primer over a concrete floor surface prepared

by acid washing. The filled resin mix is then trowel applied. To meet particular

service requirements, this type of floor lining may be applied in several trowel

PAPER MILL

Structural tile construction and tile lined steel construction are commonly




coats and may be reinforced with a layer of glass cloth. Glass cloth reinforcing

is used to give some dimensional stability to a floor which may be subjected to

a hot water wash or hot chemicals. This type of lining is less expensive than a

brick or tile lining and gives at least equivalent chemical resistance. It is not

normally used where there is exposure to severe thermal shock or heavy me-

chanical abuse.

Selection, design, specification, and proper installation are as important to

the success of a floor lining as they are to the success of a vessel lining. Proper

curing of the concrete floor prior to the installation of the floor lining and the

proper preparation of the concrete floor will determine if the floor lining bonds

adequately to the concrete substrate. The location of expansion joints on the

floor and around building columns, along walls, and at machinery mounting

pads is particularly important.Maintenance of a floor lining usually involves repointing of deteriorated

and receded joints, replacement of broken brick or tile, and removal and re-

placement of loose or disbonded brick or tile or monolithic. If proper main-

tenance procedures are not followed, the lining can be severely undercut and

disbonded and the concrete substrate attacked.

SUMMARY

Corrosion resistant masonry construction is extensively used in the pulp

and paper industry to handle the wide variety of corrosive conditions present.

Considerable experience with this type of construction has resulted in the de-

velopment of materials and procedures which, when properly applied, results

in equipment that satisfactorily performs for many years. Continued experience

and the accumulation of information and data will undoubtedly lead to further

performance improvements and the reduction in installation and operating

costs.

REFERENCES

1. Tucker, E.F., Modern sulfite digester linings-recent technical developments, Paper

Trade Journal (October 1957).

2. Thomas, B., Designing brick linings to resist hot chemicals, Chemical Engineering 75:

111-116 (1969).

3. Thomas, B., Tile linings and process vessels in the deinking plant, TAPPl 47: 184A-

188A (1964).

4. Thomas, B., Carbon brick linings in alkaline pulp digesters, TAPPl 37: 174-176 (1954).



Section XIV

Inspection and Failure Analysis

679



Inspection and Failure Analysis


C.C. R.M., incorporated


Few municipalities, states, and certainly not the federal government, would

ever consider letting a construction contract to a contractor without assigning

the project to a government inspector to follow from beginning to end. Nor

would private investors be willing to put money into any construction project

that they knew had been built without continuing inspection by someone inde-

pendent of the contractor or other financially interested party, to be sure thatno shortcuts were taken, no inferior materials were used, nor incompetent cheap

labor employed. It is always possible that an inspector can be bought, just as

there are venal people in any business, but failure to inspect at all is obviously

not in the best interest of the principal party.

Until the last fifteen years, most major chemical companies retained per-

sonnel just to follow up the construction work they contracted to be sure that

the standards and specifications that were part of the contract were followed

completely and without exception. In the last decade, however, boards of di-

rectors looking for places to save money and to reduce payrolls, have unwisely

greatly reduced, or in some cases even eliminated, such jobs. The result is that

today employees of the general contractor are usually assigned to inspect the

work of their subcontractors-more often than not to follow specialty work

such as “acid” resistant brickwork or monolithic surfacings, of which they have

neither experience nor knowledge. In one instance, this writer observed an in-

spector at work who obviously had never before seen a quarry tile floor laid

with acid-resistant resin joints installed in a kitchen. The only thing he seemed

to understand in the specification was that the joints between the tile were tobe % in. wide. The specification writer obviously meant “nominal ‘/I” since,

680



inspection and Failure Analysis 681

unless the tile are ground, there cannot be an exactly uniform size joint due to

dimensional tolerances of the tile. The inspector, however, treated this dimen-

sion as absolute. He did not bother to see that mixing instructions for the resin

grout were followed, nor check to determine that the surface of the slab con-formed to the specification, nor check the mixing of the adhesive bed, or the

placement of the tile. Nor did he verify the uniformity of the top surface of the

finished floor. The only thing he did do was to take out a steel rule and circle

in white chalk as unacceptable any area where he found the joint to be not ex-

actly ‘14 in. wide-and this was more than half of the floor. Replacing this in-

spector and obtaining one who checked the important parts of the specifications

was difficult due to his personal relationship with the project manager, but this

was eventually done, and the work was accepted.

On another contract, in this case the principal was a university, all the in-

spection was to be handled by the general contractor, including that of the

laying of “dairy brick” pavers. The specification was absolutely clear, including

a requirement that the brick be laid in a furan resin bed a minimum of %I in.

thick, placed over a hot asphalt membrane. The finished floor was to have no

greater variation in elevation between adjacent brick than ‘/a2 in. This was a tight

specification, and one that would require slow and careful work to follow-but

one that would assure a beautiful showplace floor.

When the bids were tabulated, it was noted that the low bidder-and he wastoo low-was under his competition by the exact cost of the ‘/a in. resin bed

joint. Inasmuch as this bed was essential to accommodate the variations in thick-

ness of the adjacent pavers if the floor was to be smooth, the architect was

warned of the need for close inspection to be sure that the contractor did indeed

install the l/s in. resin bed. The architect said that that was up to the contractor.

His contract with the university did not include any site work. The contractor

said that he did not intend to inspect the work in progress because that would

cost him money. He trusted the subcontractor to do his job. If he did not, he

would catch it on the final inspection.

The work was thus not inspected until completed in mid-August when the

architect was advised that the floor was very rough (just as he had been warned

that it would be). He telephoned the resin manufacturer to complain. The resin

manufacturer pointed out that it was up to the contractor to deliver in accord-

ance with specification. The architect said that the contractor stated no one

could comply with that tight tolerance. The resin manufacturer said he could

name ten firms who had no trouble meeting the specifications, and asked if the

present contractor had taken exception to the specification when he bid. (He

had not.) Then he was told the floor should be taken out and put it in correctly!

The architect said there was not enough time to redo the floor-the building had

to be delivered by the time college opened-early September. (Of course, this was

what the contractor counted on.) The contractor offered to grind the floor to

make the surface smooth and meet specifications. The resin manufacturer

warned the architect that grinding takes off the hard-burned surface, exposing

softer interior. These brick will wear faster than the rest of the floor, and will

have a different color. The result will be short life and early replacement of thefloor.

Because he was unwilling to deliver the building late, the architect approved




the grinding. The contractor thus was able, by this change in the specifications,

to save the difference between $6600 that the furan resin bed, ‘18 in. thick,

would have cost him and $750 that grinding the floor cost him, so that he was

able to come out with a good profit. The floor had to be replaced three years

later-well after the usual one-year warranty expired. This type of sharp practice

is quite common, and only careful inspection can prevent it. The principal who

relies on others to do his inspecting for him is taking a chance.

If the contractor plans to cut corners or to evade the correction of errors,

he will often try to keep working quickly over and beyond the error, hoping to

proceed far beyond the substandard work. It would then be buried so deeply

that to correct it could be very costly in time and material, and so delay the job

completion that the client would let it go rather than tear out everything to get

to it. This procedure usually works unless the inspector is given the authority toshut the job down as soon as he sees a violation of the specifications, and to

keep it shut down until the substandard work is removed and the matter cor-

rected. Such authority, therefore, should be given to the inspector. If the con-

tractor disagrees with the inspector, he can appeal the decision before making

the correction, but there will be less lost time and material than if he continues

to work before making the correction and if the customer insists on the correc-

tion being made. If the inspector has this authority, the customer will not be

under pressure to let it go, rather than take out sufficient material to reach thesubstandard work. Further, if the contractor is told that the inspector has this

authority, he will be more careful in his construction work.

INSPECTION

Preliminaries

The procedure of inspection for the end user, as it applies to chemically-resistant masonry, starts with the drawings and specifications as received from

the designers. The very first thing for the end user to remember is that anyone-

any designer-can make mistakes, and under Murphy’s Law, someone probably

will, whether it be on the drawings or in the specifications. Therefore, the user

should do the following.

(1) Examine the drawings first, then carefully read the specifications to

see whether as prepared the details and the specifications will produce the end

product that is desired. Is everything absolutely clear? Can anything be inter-

preted in more than one way? Can there be any misunderstanding? If there is,mark that item for clarification.

(2) Examine the drawings and read the specifications a second time care-

fully, keeping in mind all the design limitations and rules from the appropriate

section of this book. Is there anything on drawings or in specifications that

violate these rules or limitations-anything that cannot be done as described?

If there is, mark that item for review.

(3) If any exceptions are found in (1) or (2), this is the time to correct

them. Bring in the designer, go over the items with him, and make changes toresolve the matter, changes which both you and the designer can agree upon.

Only after such matters are settled should the construction be put out for bids.



Inspection and Failure Analysis 683

(4) It is important that you (if your company is the end user of the cor-

rosion-resistant masonry equipment or structure) follow the construction

carefully. If this is only a part of a larger contract, the general contractor will

be expecting to follow this himself. Whether he does so or not, and whether or

not he has handled such subcontractors before, you would be well advised to

keep your finger on it yourself. Any contractor is more careful if he knows he

is being observed. But the general contractor may have planned to make a profit

on this subcontract by squeezing it-and only by following it carefully yourself

can you be sure that there will be no shortcuts taken. If this is a separate con-

tract, of course you will have an easier time following it.

Often, the general contractor will plan on installing all concrete substrates

himself. To save some of his costs, he may plan to cut corners on the contouring

of concrete walls (if these are specified), to provide rough slabs; ignoring the

specifications for the concrete finish specified, or otherwise furnish a concrete

that does not, as delivered by him to the subcontractor, meet the specifications

as written, leaving it to be the subcontractor who is to install the membrane and

brick, or tile, to provide any finish required to meet the specifications. It may

not be possible for the subcontractor to make up such deficiencies, nor will the

subcontractor have included in his costs this additional work. Consequently, he

will be unable to do an acceptable job. The subcontractor will almost certainly

have had his materials delivered to the site, ready to install when the concrete isfinished. If he refuses to accept the concrete in such condition, he may be told

by the general contractor that, if he does not agree to apply his materials and

finish the work, the general contractor will terminate his subcontract, force him

to remove his materials at his expense, and refuse to let him bid future work.

Fearing to alienate the general contractor, he may reluctantly proceed. This

author has, on several occasions, observed the unacceptable results of this situa-

tion. In all cases, he told the owner that the work was unacceptable, that all

materials had to be removed, the concrete corrected, then new membrane, brick

and tile re-laid. Failure to force this issue will result in both unsightly appearance

and short life expectancy for the contruction. Of course, there will also be con-

siderable delay on the completion of the contract.

It is, therefore, vital that the principal’s inspector catch such improper acts

as they occur, so that they can be corrected without excessive lost time. If one

error is permitted to pass, others will follow.

(5) Before accepting any bid from any contractor, be sure that the con-

tractor submits experience data, showing the satisfactory (to the customer)

completion of at least three contracts of similar nature and involving the same orequivalent materials, within the last two years. In addition, he must guarantee

that if awarded the contract, at the very least the lead craftsman to whom this

job will be assigned will be the one who handled one or more of these reference

jobs. If he is unable or unwilling to use craftsmen and supervisors experienced in

this work, he should not be permitted to bid.

(6) Regardless of the outcome of the bidding on this subcontract (if such it

is), demand to review the bids. Note any differences in the bids between those

received and all exceptions taken by all bidders, whether or not these exceptions

were taken by the lowest bidder. Is the low bidder close to the others? If he is

,nuch lower, examine the bid carefully to find out why. Has he included every-




thing? Is he planning on using alternate materials? Does he meet the experience

clause? Has he included (a) weather protection at site? (b) Storage and handling

costs for materials? (c) Heat in cold weather, ice or other cooling materials for

hot weather? (d) Will he see that site and materials are protected over weekends,

(at correct temperature) over holidays and at night? (e) Check out the references

for past work carefully with the operators and maintenance people at site, not

with Purchasing, for any comments they may wish to make about workmanship

or materials. Only those using or maintaining the floors or equipment really

know if everything is satisfactory. Don’t let anyone sign up the low bidder just

because he is cheaper. You may have cause to regret it. If you are overruled by

Purchasing, put your disapproval in writing so that it is recorded.

(7) You can’t be everywhere yourself. If you can’t get your company to

give you some help, talk to those working in the vicinity of the construction and

tell them you will be grateful for their comments if they see something unusual

going on. Tell the receiving desk to check in carefully everything brought in or

shipped to the contractor, and note where all of it is being stored. Check his

records every day and inspect the shipments. Examine all markings on packages

and compare with the shipping documents and with the specifications to con-

firm that all materials are those named in the specifications. Examine the storage

facilities to be sure that everything is kept clean and dry, and that perishable

items-those with limited shelf life-are stored exactly in accordance with themanufacturer’s recommendations, including storage temperatures. Check all

equipment brought onto the site by the contractor to be certain that no specifi-

cally prohibited equipment (such as mops to apply asphalt membranes, serrated

trowels to apply mortar bed under tile, motor-driven mixing equipment for

mortars or monolithics with mixer speeds greater than 350 rpm) have been

brought onto the site, and that the site is clean and kept clean and dry.

(8) Get the names of the experienced men whom the contractor has agreed

to bring on the site, and be sure that they really worked on the project you have

checked out. Contractors often shift men from one job to another. It is im-

portant that you check regularly to be sure that the experienced men are not

taken from your site for other work until the contract is completed to your

satisfaction.

(9) Before the work starts, sit down with the job foreman and go over the

drawings and specifications with him. If the specifications cite manufacturers’

literature and/or instructions, go over that too. Be sure that you and he are in

absolute agreement about all aspects of the job. If you find any disagreement

on the design, or how the materials are to be assembled, make sure that theforeman and you discuss the matter carefully with the designer to be absolutely

sure what is wanted and to be fully in agreement. If you find disagreement on

the installation or mixing procedures, get the materials manufacturer to send his

technical representative to meet with you, both to settle the differences, and to

be certain that what is done meets the specifications. Verify that adequate re-

inforcing has been designed with all concrete, and that the specifications cover

the welding (continuous) and surface (free of all weld splatter, holes, protru-

sions, internal angles, etc.) of all steel that may require lining. Take minutes of

the meeting covering all points discussed, get them typed up, and then signed

“approved” or “agreed” by the contractor, the designer and the materials manu-

facturer to be certain that there is no misunderstanding.




(10) If the work is outofdoors, make sure that if weather forecasts indicate

rain, high winds or temperatures outside the acceptable range (60’ to 85’F), (a)

cover is provided to prevent rain from falling in thework area, (b) dikes or barriers

are in place to prevent the intrusion of ground water, and well points provided,

if appropriate, (c) wind breaks are in place, (d) shade is provided if temperatures

are near 85’F or (e) heat is provided if temperatures are near 60°F. (f) check all

materials to be certain that they have been storedfor48hoursprior to installation

in the acceptable thermal range-the higher range in cold weather, the lower in

hot, (g) check and record the temperature of the substrate in several areas. It

is substrate temperature, not air temperature, that is the limiting factor. Check

the humidity to determine the dew point. No installation can be permitted when

air temperatures fall within 5OF of the dew point. Some manufacturers may in-

dicate an acceptable working range as low as 5O’F. Exept for materials that cure

at 35’F. do not accept this low a temperature for material storage. If something

should happen to the heating system and the temperature drops below 50°F, you

are left with no safety allowance and work will have to be stopped not only

until heat is restored, but until a// materials have been brought back to the

minimum surface temperature-probably 48 hours. (h) If there is any possi-

bility that there is water in or under the substrate, test the substrate by the

mat test (see under Design) to be sure that it is dry.

Concrete

If new concrete is to be installed, go to the bulk plant where the mix is to

be loaded, taking with you the formula for the mix, and verify it-not with the

plant superintendent, but with the workman at the chute who is loading the

truck. If there is anything in the mix that he is loading-air entrainment agent,

water reducer, additive of any kind, that is not in the approved formula that

was ordered, stop the shipment now and order the truck to be emptied, and stay

with the workmen until you are satisfied that the mix is exact/y as ordered.Don’t let anyone tell you that an additive in the mix that is in addition to what

is called for in the formula will “improve” it. It can have exactly the opposite

effect.

When the concrete gets to the site, before it is placed, demand to see a

slump test. If it is greater than 4 in., unless a higher slump is specifically ap-

proved by the materials manufacturer, stop the job and tell the contractor to

remove the concrete from the site as unacceptable.

After the concrete has been placed, be sure that the finishing and the curing

procedures exact/y follow the designer’s instructions, and that the full curing

time specified is permitted. At the conclusion of the specified curing time the

mat test for moisture (cited above) should be run, at the locations last poured

or where you feel there is the greatest likelihood of finding dampness. If a mono-

lithic topping is to be applied at this time, you should also run compressive

strength tests with a Schmidt (or Swiss) Hammer and a bond tensile test (El-

cometer) using as the adhesive for the coupons the monolithic that is to be

applied. The bond must register 300 psi minimum, and the coupon must pull

concrete (including aggregate) over the entire surface of the coupon.It is customary for the concrete strength to be verified by making cylinder

samples at each day’s pour of concrete, from the same mix used in placing the




new concrete. These cylinder molds are poured at the same time that the con-

crete is placed. Be sure that such samples are made from each truckload used,

and poured at the identical time that the rest of the load is placed. See that these

molds are placed in a warm and secure spot where they will not be bumped or

otherwise disturbed for at least 24 hours and at the same temperature as that of

the recently placed concrete. Do not allow anyone to remove the samples before

the concrete at the site is hard and can support traffic. If jolted or subjected to

conditions different from that of the placed concrete, you cannot expect tests

run on these samples to be representative of the concrete that has been placed.

If the concrete is to be formed-a vessel, pit, trench, etc.-make sure that if

release agents are to be used on the forms, they are ones that are acceptable to

the membrane manufacturer and installer. Verify that bracing is firm and strong

so that the weight of the concrete, as it is poured, will not move or deflect theforms, and that forms fit neatly and the formed surface will be uniform and

smooth.

Observe the pours to assure that the concrete is adequately, but not ex-

cessively, vibrated to produce uniformity and freedom from voids, honey-

combing and air pockets. When wet to wet pours cannot be made, make sure

that continuous water stops are placed and that before the next pour is made,

the preceding hardened surface is coated within the proper time limit with an

acceptable concrete bonding agent.When the forms are stripped, make sure that all surface laitance and form

marks are removed. All the wires must be cut back well below the concrete sur-

face. Check and sound the surface for holidays, honeycombing and stone pockets,

breaking surface crusts open to expose any that may be hidden under a thin

skin. These (and the wire holes) must all be hand-filled (packed) carefully with

a stiff and strong sand/cement mix and packed tightly. Over troweling is not

permitted. This brings laitance to the top and creates a weak surface.

All floor surfaces must be smooth and sloped enough so when flooded drain

completely without any standing puddles. If they do not, they are unacceptableand the contractor should be required to cut out sufficient surface material in

the low areas to install patches and bring the surface to uniformity with the

surrounding area.

All tools used to finish the concrete must be clean. No release agents may be

coated on the tools. (Release agents may wear off and leave remnants on the

concrete surface, affecting the bond of membrane system.) And no sealing or

curing agents may be used on the concrete surface that have not been accepted

in writing by the manufacturer and installer of the membrane material. If oil orgrease lubricants are found to have been used on the forms, the contact surfaces

must be brush sandblasted to remove all traces of the lubricants.

Check carefully (especially close to the form bottoms) to be certain that

the formed concrete is all dead straight or uniform/y curved as specified. If there

is even the slightest deviation from the design contour, that section must be cut

out and ground smooth.

All concrete pits, vessels and deep trenches should be checked for water

tightness. This is done by (1) plugging all outlets, (2) filling to the top with

water, and allowing to stand, covered, for no less than 48 hours. (3) After at

least 48 hours, add water to replace any loss by evaporation or soaking into




the concrete. (4) At a marked point, measure the depth accurately, take the

temperature of the water and cover tightly. (5) After 24 hours, uncover and

measure depth and temperature at the mark. Adjust depth for any difference in

temperature (coefficient of expansion of water and thermal change). If the levelis more than 1 in. lower, there is a leak somewhere that must be located and

stopped before the vessel can be lined.

Prior to application of membrane or monolithic check to be sure the con-

crete is sufficiently dry, by applying a rubber or plastic mat or sheet flatly to

the concrete surface, taping the edges. After 24 hours, if any moisture collects

under the mat, the concrete is too damp and must be dried.

Brick

Of all the materials brought to the site for the contract, brick are the most

likely to vary in quality. The specification will have identified them by type and,

if they are “acid brick,” by ASTM Specifications, most probably C279, which

classifies them primarily by fluid absorption and loss in weight in an acid boil

test. The manufacturer is expected to ensure uniformity in physical and chemical

properties, and that they are within dimensional tolerances by testing random

samples taken in accordance with ASTM C67, and he should certifiy that these

tests have been run, and that the brick shipped comply with the specifications.

However, if this is a large contract involving large numbers of brick, it is stilladvisable for the inspector to visit the manufacturers’ plant and inspect the

facilities, the brick and the records, and observe at least some of the sampling

and testing. It should be noted that although the specification is quite clear on

the limits of acceptable physical and chemical properties of all brick furnished,

the dimensional tolerances indicated apply only within each individual shipment,

so if there are a number of shipments required to complete the order, it will be

up to the end customer and his inspector to assure acceptable overall dimen-

sional tolerances for the duration of the contract.Unless the inspector monitors the brick shipments carefully, it is entirely

possible that at least some shipments will be made in inclement weather, in open

body trucks, and without cover, so that brick arriving wet and/or in dirty condi-

tion may not be noted. Even on tightly strapped stacked pallets, this author

has found brick in the center of the pallet coated with road dirt. While the

brick, if they otherwise meet the specifications, are acceptable,they should not

be taken to the job site and used until they have been cleaned and dried. It is

most important that the inspector also monitor the storage area, make sure that

it is covered, and, in cold weather, heated, and that all pallets are stored off

ground, at high enough elevation so that they will remain dry and free of surface

water should there be heavy rains and surface flooding. All brick in each ship-

ment should be stored together so as to reduce any problem that may result

from dimensional variations.

At least 48 hours before use, all pallets must be broken down, and the brick

stacked in open checker fashion in a space that is maintained at a temperature in

the range of 60” to 85’F. If there is dirt on the brick inside the pallets, they

must be removed, cleaned and restacked in open checker manner 48 hours be-fore use so that they can dry and come up to temperature.




Mortars

Some mortars are heat sensitive. The speed of set of furan mortars in par-

ticular, is much accelerated by heat, so that “open time” can be reduced to 10

minutes at 85’ to 9O’F. The effects of temperature on setting speeds of otherresins are less extreme, but the contractor will have more time to use up his mix

at a 60’ to 7O’F material temperature. Phenolic mortars must be stored prior to

use at temperatures of 6O’F or lower. If they are left in areas where they may be

overheated, they can be ruined in a short time or so badly affected as to be un-

usable. There is a case on record of phenolic mortars being delivered to a site in

Texas late on Friday, and left on the loading dock, resulting in materials which

were totally unusable by 7 A.M. on Monday morning when the construction

crew arrived. On the other hand, no serious damage will result if the components

of resin mortars are subjected to temperatures below freezing.

Silicate mortars, however, will not be injured by storage in warm locations,

with the possible exception of a few with limited shelf life, where it is possible

that shelf life may be shortened. But if the liquid component (sodium or potas-

sium silicate) is frozen, the fluid mixture (a colloid) will “break” and the silicate

will come out of solution and coat itself on the inside of the metal containers.

If this happens, the mortar will not function until the silicate is redissolved-

mixed back with solutions using a power-stirring device such as a “Lightning

Mixer .‘IThe liquid component of a silica mortar, if frozen, can never be reclaimed

and must be discarded.

A sulfur mortar, which is normally shipped in blocks or chips, is unaffected

by atmospheric thermal changes from below freezing up to 1 O’F or higher. Nor

is it subject to water damage from weather or flooding, so long as it is dried off

before putting the mortar in the melting pots.

Epoxy mortars, although susceptible to damage from water, are not seri-

ously affected by thermal effects in the ambient upper ranges, and as long as thematerials are kept covered, little difficulty is usually experienced.

Polyesters and vinyl esters are the most water-sensitive of all the resin mor-

tars. Although they are somewhat affected by higher ambient temperatures, they

can usually be installed without too much trouble even in the 90° to IOO’F

range. However, if water gets into the mix or comes in contact with resin, pow-

der or mortar before setting takes place, the cure may well be permanently

inhibited, and the mortar will probably have to be removed and discarded. There

is a case on record of a shipment of carbon-filled polyester floor surfacing ma-

terial which failed to cure, although the control sample retained at the factory

was perfectly normal. After a lengthy investigation, it was found that the pow-

der bags had been punctured-small holes-by the forklift operator. The air was

close to 100% humidity and the carbon filler had absorbed moisture from it-

enough to add 10% to its weight-although the powder appeared to be com-

pletely dry to the touch. After replacement of this powder, the mortar set

perfectly.

From the above summary, the inspector should see the importance of deter-

mining the condition of all containers shipped onto the site, and that the storageconditions-completely dry, off the ground, ventilated, and in the correct tem-

perature range-have been met by the contractor.




It may be a requirement in a chimney lining contract that mortar samples be

taken at regular, perhaps unannounced, intervals and 1 in. by 1 in. right cylinder

test units be made for compressive strength determination under the provisions

of ASTM C579 to verify the quality of the mortar mix. If such a provision

appears in the specification, it is important that the mortar be packed in the

sample molds at the same time that the mix is carried to the masons who are in-

stalling the brick, and that the molds be placed on a shelf in a cabinet in the base

of the stack, or in an enclosed space or room as close to it as possible, under

identical conditions of temperature and humidity, and permitted to cure there

for the exact period of time specified both before demolding and after demold-

ing. At the exact expiration of the aging time specified, the sample cylinders

should be taken to the testing machine and tested at that time. (They may NOT

be tested at the convenience of the laboratory technicians at some other time.

The test is meaningless and the results can not be correlated if the time span

between the mix and testing and the environmental exposure are not identical

for all samples tested.) The inspector must, therefore, make provisions for veri-

fication, and for the elimination of all variables.

Membranes and Expansion Joint Materials

Sheet membrane linings are usually shipped in rolls. Exceptions include

plasticized-unplasticized vinyl laminates, specially compounded asphalt and

asphalt and rubber compounded sheets, usually shipped flat in cartons or boxes.

These are applied to properly prepared surfaces with an adhesive that may be

air-cured or heatcured. At all events, so far as storage is concerned, temperatures

above freezing and under IOO’F are usually not matters of concern, unless the

manufacturer or applicator so advises. Water and dirt, however, damage these

materials so they should be stored in a clean storage area, off the ground and

under cover.

Fluid-applied membranes require similar storage, and unless the manufac-turer advises to the contrary, the component materials may be stored in the

same manner and under the same conditions as the sheet materials. However, all

latex emulsions, and some few other materials, can be damaged by freezing, and

it is unlikely that such damaged material can be reconstituted at the site. In any

case, if freezing occurs, the manufacturer should be notified on the chance that

he may want the material returned rather than discarded.

Examine carefully all liquid components received, and the shipping docu-

ments, and if delivered in cold weather in open body trucks, especially if they

were more than a very short time en route, check the contents for freezing.

The manufacturers should also be advised of any packages damaged in transit,

requesting advice as to use or disposition.

INSTALLATION

No work should be started until you are assured of the following.

(1) All materials have now been brought to the site. Each item has

been checked and double checked to be certain that it is (1) the exact




material specified or an approved (by the designer) equal, (2) that it is

clean, dry, free of any contamination, and in the specified thermal

range, and (3) that the packages are undamaged, no seals broken.

(2) All surfaces to be coated/protected meet prescribed surface prepa-ration requirements, including finish, and are clean, dry, in the correct

thermal range, and sloped in accordance with the specifications.

(3) The contractor’s crew at the site includes the experienced and

trained individuals, whose names have been given to you.

(4) No proscribed tools or equipment are on site.

(5) Cover, weather and wind protection should be as specified and in

place. If a spill occurs or water intrudes, all work should be stopped

until the area is once more clean and dry.

Membrane

If the substrate is concrete, the most frequently employed membrane is hot

asphalt.

(1) Observe the application of the primer. This must be scrubbed on using

a stiff bristle brush or broom. It may not be sprayed, or applied with a paint

roller or a soft paint brush, nor poured on and allowed to puddle. If the color

fades as it dries, so that the concrete surface merely looks dirty, another applica-

tion must be made, until the surface remains completely black.

(2) While the primer is being applied, the asphalt kettle is set up. Make sure

the kettle is empty, dry and clean. If this is a roofing kettle, be sure that any

remnants of asphalt have been scraped out of it before the kettle is heated and

before any asphalt membrane material is put into it.

The cover (if detached) should be placed next to it in case of need. The heat

should be brought up slowly to prevent smoking and foaming. Observe the open-

ing of the containers, removal of container exteriors and the loading to be sure

that no foreign matter enters the kettle with the asphalt. The hot asphalt pour-

ing (using) range must be within the thermal limits given by the supplier of the

materials. Before application is permitted, be sure that the liquid in the kettle is

smooth, thin, and free from foaming, bubbles and excessive smoking.

The contractor should have a man assigned to stay with the kettle to keep it

stirred, to fill the containers in which melted materials are carried to site, to

keep the heat adjusted so as to maintain the contents in the proper pouring

range, to keep the kettle full, recharging it as required, and to prevent anyone

from taking liquid out of it as long as there remains unmelted material in it. He

should prevent smoking in the vicinity of the kettle and, should the contents

catch fire, close the cover at once, or if it is detached, put it in place and seal off

any air leaks around the edges of the cover with wet burlap sacking. Under no

circumstances should anyone be allowed to turn a fire hose on it or to use chem-

ical fire extinguishers on it.

During breaks and lunch, someone should remain with the kettle atalltimes,

stirring it occasionally, and making sure that it neither cools off nor overheats.

At the end of the day, the heat source is removed and the kettle is covered. The

following day, the first one on the job will be the kettle man since it will take an

hour or more to get it ready to use.




(3) Application may start only after all solvent has evaporated out of the

primer, but the surface is still clean and tacky.

(4) Application of the hot asphalt on a floor (or other horizontal flat sur-

face) is by pouring the material on the surface and spreading it with a squeegee-

usually wood, and approximately 18 in. long. Observe workmanship carefully to

be certain the mechanic is providing a glassy, smooth and pinhole and bubble

(or blister) free surface. If there are bubbles or blisters in the membrane, the job

must be stopped until they have been removed and the membrane repaired. (See

the section on Asphalt for procedure.)

(5) Application to walls or other vertical or irregular upright surfaces is

made in the same manner, starting at the bottom and working from the bottom

to the top. (See the section on Hot Asphalt for full instructions.)

(6) The reinforcing is applied carefully using a roller or some other meansto flatten it out, remove all wrinkles, and press it into the asphalt already ap-

plied. Here is where one frequently finds carelessness. Beforethe fabric is applied,

the asphalt layer should be a smooth, glossy, uniform l/s in. thick, free of bare

spots, holes or bubbles. The thickness should be verified using a mechanical

thickness gauge, such as a large nail with distances marked on it from the point

in l/s in. increments. A piece of chalk should be carried to mark every point

where the membrane has been punctured to verify the thickness. The mechanic’s

repair and sealing of these holes should be checked to be sure they are liquid-tight. In like manner, the thickness of each increment in the membrane should

be verified,

If other types of membranes are used, and/or if surfaces other than concrete

are to be membrane protected, read carefully the specifications and the manu-

facturer’s literature on each and the section in this volume on that type, and

verify surface preparation and thickness, uniformity and continuity of mem-

brane. Make sure that not only the finished surface, but each intermediate one is

free of dirt, blisters and voids. Where the substrate is metal, and the membrane

is suitable for such testing, supervise spark testing to be sure that the voltage is

adequate to provide liquid-tightness, but not so high as to burn holes in the

membrane.

Monolithics

Troweled surfacing materials (monolithics) sometimes are used as mem-

branes, where there may be a load on the surface beyond the capability of a

membrane to support. In such cases, there may be adjacent areas of membrane

and monolithic. If the system is to be continuous and void-free, the monolithicmust be overlapped at all edges by the membrane, or the two surfaces continu-

ously mated or flashed together. The inspector should examine this section very

carefully for voids and discontinuities. In addition, he observes the following in-

spection procedure on the application:

(1) He checks the surface of the substrate carefully for proper surface

preparation, and verifies the compressive strength with a Schmidt (Swiss) Ham-

mer, and the surface bond strength with an Elcometer, using the monolithic

material itself as the bonding agent for the coupons. If a primer is used, then useit in bonding the coupons. The Elcometer test run in this manner also verifies

the compatibility of the concrete surface and the monolithic. To be considered




satisfactory, the coupon must pull concrete and bits of aggregate over the entire

surface.

(2) Verify the proportions of the components in the mix to be sure they

are those specified by the manufacturer, and measured as specified by weight,

and that the mix is properly trowelable-neither too “soupy” nor too “stiff.” Do

not rely on or accept the assurances of the mechanics for this. Do not permit the

addition of any unauthorized material to the mix. Verify that speed of all power

mixers is not more than 350 rpm.

(3) Observe the application of the primer. All surfaces must be adequately

covered, with no bare spots and free of puddling.

(4) The application should be uniform in thickness, smooth and compact,

without “tears,” cracks, blisters or holes. Any such irregularities should be re-

moved and repaired while the material is still soft. At the end of the day, and be-fore any work breaks, make sure that all ragged edges, etc., are removed, so that

a clean, tight juncture of new to old can be accomplished when work is resumed.

(5) Watch the mortar pallets carefully to see that no material is used after it

has passed its work life-become too stiff-and that any such material is dis-

carded and not mixed into a subsequent batch.

(6) Verify that expansion joints are cut or formed over a// points of move-

ment in the substrate: expansion joints, control joints, cold seams, working

cracks, etc.

Brickwork and Expansion Joint

(1) Before bricklaying starts, check the substrate (and/or membrane) and

the brick as they are brought to site, for cleanliness. Verify with a surface ther-

mometer that they are in the correct thermal range, and make sure everything

is dry.

(2) Check the tools and the mortar box to be sure that they are clean and

dry, and that no prohibited tools (such as serrated trowels) are brought on site.

(3) Observe the mortar being mixed. If a power mixer is used, make sure

the mixer speed is under 350 rpm. Check the measurement by weight of the

proportions and see that the person measuring the proportions marks the meas-

uring containers correctly after weighing, so that future measurements can be by

volume.

(4) Make sure that the mixing is carried to complete uniformity of the

mortar. Observe the way mortar handles on the trowel. It should have sufficient

body so that it clings and does not fail off when the trowel is turned so that its

face is vertical.(5) Observe the masons’ “pallets” to be sure that all the mortar is smooth

and creamy-free of lumps.

(6) Watch the way the masons handle the trowel and butter the brick. Are

the mating surfaces completely and uniformly covered with mortar? (If the mor-

tar is “runny,” it can run out of the joints and should be discarded. “Dipping”

brick into mortar is absolute/y prohibited. If there are any voids or bare spots,

more mortar must be applied.)

(7) Watch the brick being laid, pressed down onto the membrane or thebrick below it, and slid into place next to the adjacent brick. Mortar should be

extruded at all joints as the brick is pressed and tapped into place.




(8) The excess (extruded) mortar should be cut off with the trowel by the

mason, leaving the surface smooth. If the joint is cut while the mortar is still

within worklife, it will smear. This will not make any difference if a wall (or a

chimney liner) is being built. However, if a floor is being laid and minimum

smearing is desired, the mortar should be allowed to cure undisturbed until the

worklife has elapsed (usually about 3/4 hours) and then cut. The mortar will then

be stiff enough to cut cleanly without smearing. Obviously the mortar so re-

moved must be discarded, not reworked.

(9) Make sure that all brick cutting is done with a saw unless the designer

has agreed to accept hammercut brick. The cutting must be done away from the

installation to prevent dust and chips from getting into the work or the mortar

mix. Make sure that all spaces are filled with single units-whole brick or squarely

cut brick-not with chips or small pieces.

(10) Observe the layout of all expansion joints carefully to be certain that:

(a) Only whole brick (or if cut brick, no brick of less than half the longest di-

mension) is used as a side of the expansion joint. If cut brick are needed, place

them back a whole brick from the edge of the joint. (b) No mortar, pieces of

brick, rubbish, or other hard material intrudes into the expansion joint. (c) The

width and depth of the expansion joint are uniform for its full length and the

sides perfectly straight. (d) The sides of the joints are smooth, truly vertical,

and planar-that there are no ragged or sloping edges or broken corners. (e) Theexpansion joint terminates in another expansion joint, the outside of the struc-

ture, or a sliding plane, so that it is not immobilized.

(11) If you discover any violations of these guidelines-even the smallest

violation-stop the work at once and do not permit it to proceed until the viola-

tion is corrected.

(I 2) Make sure the brickwork is undisturbed and kept in the proper thermal

range until cure is complete. (See manufacturer’s literature to determine neces-

sary time interval .)

(13) If sulfur mortar is to be used, read the section in this book on sulfur

mortar, noting carefully all warnings and instructions. Verify cleanliness and

dryness of the melting pot and all handling equipment. See that all safety pre-

cautions are observed, that no work whatsoever is done if substrates, brick or

other materials that may be in contact with the hot sulfur are wet. See that the

pot is stirred thoroughly at least once every few minutes, and kept stirred and

covered, with heat removed when not in use. Handle fires in the same manner as

asphalt fires (above).

(14) Measure the width of expansion joints and the distances between them,and walk the area to be sure that all points of no movement are isolated by ex-

pansion joints-and placed midway between them. If any are omitted, are the

wrong dimensions, in the wrong place, or terminate in an anchor so that they

cannot function, have them corrected before permitting the work to proceed.

(15) Verify that all expansion joint materials brought to the site meet the

specifications. Observe the installation and if there is any deviation from the

manufacturer’s instructions or the specifications, stop the work at once and re-

move all material that has been installed which does not meet the exact stand-ards and specifications.

(16) In placing cellular material in the bottom of expansion joints, make




sure that it is slightly compressed as it is installed so that it presses firmly against

the joint sides. If the joint is packed with loose fibers, make sure that the pack-

ing is loose enough to permit the joint to close 25 to 50% more, compressing the

joint that much further. If it is packed too tightly, the joint cannot function.

(17) The sealant used to finish filling the joint should end flush with the

surface. If there is any “overpour, ” it should be left until cured, then cut off

with a razor blade, trimming it down to the plane of the floor surface. There

should be no air bubbles, nor voids. If any appear, they should be opened up

and repaired in the manner recommended by the manufacturer of the material.

(18) It is permissible to broadcast fine, clean silica sand, or small amounts

of the powder component of the mortar over the surface of an asphalt mem-

brane to prevent workmen’s shoes from sticking to the membrane and tearing

it. Do not allow other materials to be so used without the authority of thedesign engineer.

Final Inspection

After the work has been completed, spot checks should be made at intervals

to make sure that the area and work are kept dry and clean, at the correct curing

temperature, and free of traffic, until the cure is complete (see the manufac-

turer’s literature for anticipated time interval).

Also check all curing areas (brick joints, monolithics, etc.) for the appear-ance of bubbles or blisters. An occasional blister is to be expected. If there are

many, the matter should be brought at once to the attention of the designer for

a decision on action to be taken.

After the third day, test all curing surfaces with the point of a trowel. If

cure is delayed beyond the cure time shown in the literature, draw the matter to

the attention of the designer.

Make sure that the contracting officer or purchasing agent does not make

final payment on the contract until it is cleared by you.

FAILURE ANALYSIS

When a failure occurs in an alloy vessel containing chemicals, the owner

starts to investigate to learn if the correct alloy was used, if the designer mal-

designed it, or if the fabricator made some error in assembling it. However,

when a failure occurs in an “acid brick”-or other chemically resistant masonry-

structure, the customer often abandons the concept without investigation, with

a comment such as “we tried it and it didn’t work.” There is always a reason for

a failure and if you are able to analyze the failure so as to learn the source of the

trouble, there is no reason why such failure cannot be prevented in the future.

Just as with the alloy vessel, failure may be initiated at any of three stages:

design, selection and specification, and installation. When a failure occurs, first

check the design. It is always possible that the design includes a detail that can-

not be satisfactorily handled with chemically resistant masonry-that is a detail

that should have been modified to make it suitable for these materials. Reviewthe section on design to see whether all the factors mentioned there have been

taken into account.

Next, check the service conditions. Has any change in the environment




occurred since the unit was designed? Is there a change in the maximum or

minimum service temperature? When the unit is out of service, is it subject to

below zero cold or desert heat, while the original design data included only

indoor ambient temperatures when idle? Is there a change in the cleaning cycle?

Has higher heat or live steam been used when only hot water was originally

mentioned? Is a new or different cleaner or chemical being used? Has the process

changed with different chemicals and thermal levels, or have either high pres-

sures or vacuum conditions been introduced? Is the unit held at high pressures

for extended periods, then dropped to atmospheric pressure in less than a

second by opening a valve?

If there are any changes, whether those mentioned above or not, compare

these changes with the resistance tables of the materials manufacturers, and

study the section of this book on each material involved in the failure in order

to confirm that the selection made is the correct or best one for all the condi-

tions to which it is exposed.

Finally, consider the installation. If a competent inspector in your employ

was present at installation, review his reports. Look for any violations of ma-

terial selection, standards or installation techniques that he may have reported,

even if the report states that they were corrected. If a wall has fallen down,

check the supporting wall for bulges by using a string and/or straight edges. If

lack of adhesion is noted between two components that should be bonded toeach other, check the area of disbondment for foreign material-dust, dirt or

water. Do not assume that nothing is there because you cannot see it. It may

take a powerful glass or a chemical wash to find a contaminant. Do not assume

that because you find a semisoft or a softened area of mortar, while all other

areas are hard, that some chemical has damaged it. Maybe this is the case. But

it is also possible that the mortar in that spot never hardened after it was in-

stalled. Perhaps the contractor did not mix his mortar thoroughly, and this small

area was troweled with mortar containing too little hardening agent. Or perhaps

this area was wet when installed or subject to drops of dew or water from

another source after installation.

Some examples of such problems: a major manufacturer of spaghetti sauce

installed a very large brick floor laid with furan resin mortar over an asphalt

membrane during July. During installation, the weather was hot and the humid-

ity was at 100%. The unit was completed on a Friday afternoon, the weather

changed and the temperature dropped 15” to ZO’F. The plant was closed for a

week with only a watchman on duty, and all doors and windows were shut. By

the time the plant reopened, the temperature was back in the 90’s. Two weekslater, inspection of the floor showed that the mortar was somewhat rubbery

on the surface, but had hardened at the bottom of the joint-a sure indication

of surface water. A check with the watchman disclosed that during the cold

snap, enough water had condensed on the walls to run down over the floor and

puddle all over it. By the time the plant reopened, it was all dried up and so

had not been noticed. The floor had to be taken out and relaid.

In a Houston plant, temperature-sensitive paint warned of overheating near

the base of a CSs reactor which had only been in service for two months. After

the packing was removed, a large number of voids were found in the silicate

mortar joints in the insulating brick lining, many running all the way through to

the shell. Under magnification, these voids were shown to be circular and almost




certainly the result of water which had flashed to steam-passing out through the

brickwork, presumably when the unit was placed in service and heated up.

Where did the water come from? A check of the plant personnel disclosed that

the contractor had stacked the brick next to the vessel before and during the

lining of the equipment. The brick were not covered, but were open to the

weather. It was learned from the Weather Bureau that there was heavy rain

during the construction period. Insulating brick have a high absorption. If wet

brick had been used, the failure was explained. The contractor removed and

replaced the lining with dry brick, and no further problems were experienced.

An experienced brick contractor obtained the order to install a brick lining

inside a large waste collection tank-roughly 50 ft. x 20 ft. x 12 ft. deep-at an

Army Ordnance plant. He completed the installation in mid-November, and the

tank stood idle until the following March. When the operators prepared to put

it into service, they discovered one long wall had fallen into the tank. The con-

tractor asked for guidance from the manufacturer of the brick mortar. A tech-

nician was sent in. The technician, as instructed, snapped a string along the base

of the wall and found that the concrete contractor had not braced the forms

well enough, and the weight of the concrete, as it was poured, caused the wall to

bulge inward at the bottom. After the bulge was chipped away and the concrete

resurfaced, the brick was replaced and the problem was ended.

A waste collection pit of about the same size was built for a major oil com-pany in the Houston area. The vessel was to contain a waste which might include

various petroleum solvents, dilute acids and dilute alkalis. The consulting engi-

neers designed it of concrete block cemented together, lined with a furan resin

membrane reinforced with glass cloth, and then inner lined with two courses of

acid brick and furan mortar. When the tank was completed, it was water-tested

and found to have numerous leaks. The bricks were removed at those points;

cracks in the membrane were repaired and the brick replaced. As soon as one

repair was made, another leak started elsewhere. When the technical staff of the

mortar manufacturer was consulted in a conference call including the contractor,

the oil company project engineer and the engineering firm that designed the

tank, the mortar manufacturer learned for the first time of the structural design

of the vessel, and that (of course) it had not been tested liquid-tight before lining

it. When the mortar manufacturer was asked how to make it tight, he told them

that they were wasting their money. The vessel could never be made tight, be-

cause the walls would always move under load, and the membrane would rup-

ture somewhere else. At first, they did not believe this, but several months-and

many dollars-later, the vessel was abandoned. A replacement vessel was laterbuilt of sound, reinforced concrete, with the walls and bottom contoured, and

a furan resin/glass fabric membrane installed in the manner described in this

book, followed by two courses of brick and furan mortar. It has served satis-

factorily for well over a decade.

In the late 194Os, a major chemical company designed a reaction vessel,

about 3 ft. 6 in. in diameter and 16 ft. high, to handle a mixture of HCI and

organic solvents. The process involved charging the unit, closing it, heating the

process materials (with an internal heater) to 22O”F, and at the same time build-

ing up pressure in the unit to 200 psi. The unit was to be held at that tempera-

ture and pressure for 3% hours, then brought down to atmospheric temperature

and pressure, emptied and recharged to make a new batch. This was one of the



inspection and Failure Analysis 697

first process vessels ever to receive a furan resin/glass fabric membrane, and it

was inner-lined with 9 in. of the highest quality fireclay acid brick and furan

mortar. The unit was in service only a month when the customer complained

that the exposed surfaces of all the brick in the face course of the lining werebeing “eaten away” so that the mortar joints all stood out boldly-yielding a

pattern resembling a waffle iron. The brick and mortar manufacturers both sent

men down to examine the vessel. The brick technician stated that there had to

be acid fluorides contaminating the process liquids as the only thing that could

cause this damage. (The mortar had a carbon filler and so would not be damaged

by acid fluorides.) However, chemical analysis proved this to be untrue. There

were no fluorides, but the brick were certainly being destroyed from the face

back, a little more brick loss with each batch. The technician from the mortar

manufacturer stayed on to watch the unit being operated. All went as expected

as the vessel was charged, heated, and the pressure brought up to 200 psi and

held for 3l/s hours. But, when it came time to bring it down to atmospheric con-

ditions, the operator simply cut the valve open and the drop in pressure from

200 psi to atmospheric took place in a tiny fraction of a second-far faster than

the brick, which were saturated and stabilized for hours at 200 psi, could relieve

the pressure built up in them. This internal pressure trying to leave the dense

brick so rapidly was causing the surface to spall off. The trouble was mechanical,

not chemical. It was resolved by facing the existing lining with 2?2 in. of carbonbrick joined with the same furan mortar. The carbon brick was much more

absorbent-porous-and it could bleed out the pressure more rapidly, while it

acted as a buffer to protect the surface of the fireclay brick. Since that time,

the same company has built many other, much larger process vessels of the

same type-all with this inner 2 ‘!z in. of carbon brick to prevent the fireclay

from spalling-and all functioning satisfactorily.

From these experiences, and many others like them, it is usually possible to

track down and identify the sources of failures of chemically resistant masonry.

Just as no alloy-no metallic structure-of any fixed design and composition-is

suitable for all exposures, but will provide long and satisfactory life if properly

employed, so will chemically resistant masonry.

If a failure occurs, analyze it carefully. Look first at the points covered

above, and note any discrepancies in design, material selection and construction.

Then look for any environmental changes, or perhaps the presence of something

of which you were not previously informed. When you have completed this,

turn to the following tabulations. Note which items of failure you observe.

There may be several. Now read carefully the list of those causes that can lead

to each observed problem. Make a list of everything on each list and underline

those that appear on two or more lists.

Now carefully check out what you see against the underlined causes. There

is a high probability that you will be able to identify the source or sources of

the trouble and correct it.

First, let us consider constructions of masonry units (as acid brick) and

mortar.

The following material is from “Spotting and avoiding problems with acidresistant brick.” Reprinted by special permission from Chemical Engineering,

May 3,19820 1982 by McGraw-Hill, Inc., New York.




The boldface numbers mean the following:

I is noted where the cause of the failure can clearly be

assigned to the designer.

2 indicates the fault is that of the applicator.

3 means tberc are two or more individuals who may

be at fault.

4 indicates the materials manufacturer is responsible.

5 shows the fault probably lies with the operator.

I-Leaks through acid brick lining or floor. (Detected

by “holing” of steel tank, or wet spots, dixoloration, or

CollPpsc of concrete.)

1. Wrong mortar/membrane for chemicals and/or

temperature. (I)

2. Wrong mortar/membrane substituted for that speci-

fied. (2)

3. Sheet membrane material had pinholes in it. (4)

4. Mortar/membrane materials were off-spec. (4)

5. Membrane applied improperly. (2)

6. Hot-asphalt membrane froze, then cracked, after

application to concrete. (3)

7. Multicomponent membrane/mortar impmperly

proportioned or mixed. (2)

8. Mortar/membrane mixed with foreign material,

such as wind-blown dust, or sand. (2)

9. Material applied after it passed beyond its worklife

or outside of specified temperatures. (2)

IO. Mortar/membrane not thick enough or in continu-

ous layers; failure to install full-bed joints under or

behind brick. (2)

Il. Damage to membrane during bricklaying. (2)

12. Carbon brick and/or carbon-filled mortar in direct

contact with lead or stainless steel caused holing of

the lead or pitting of the steel. (1)

13. Concrete degraded. Anchon in the brickwork, or

other penetrations through membrane into concrete,

allowed Ilow of chemicals. (3)

14. If a vessel, it was not liquid-tight before being

lined. (2)

II-Brick wall lining (rectangular tank, or gutter or

trench) falls in. (Wall may or may not carr y membrane

with it.)

1. Brick lining tw thin for height and width. Brick lin-

ing must be independent of substrate. (I)

2. Concrete wall may have inward bulge at some

point. (2)

3. Failure to properly install expansion joints at correct

locations, or failure t” make them large enough. (3)

4. Use of improper joint filler, or improper installation

of tiller. (3)

5. Dirt or mortar in expansion joints, preventing func-

tioning. (2)

6. See also I, nos. 3, 5, 9, 10 and II.

7. Dirt or moisture on brick and/or membrane that pre-

vented m”rtar from bonding properly. Or mortar im-

properly mixed and applied. (2)

III-Damage or loss of mortar joints.

Sulfur mor1nr:

1. Loss or crumbling can be due to overheating. Check

recording thermometer, especially for cleaning cy-

cles. Absolute top service temperature for sulfur is

203’F. Manufacturers ray stay under 19OO’F. 5)

2. Empty joints due to poor installation procedures. (2)

3. Loss or damage can be caused by chemicals. Look

for unnoted trace chemicals or cleaners. Perhaps

operating conditions have been changed since design

was done. (I) (5) (Heat damage usually leaves joint

full, but crumbly. Chemical damage involving sol-

vents usually removes some or all material from the

joints.)

4. Receding or etched joints usually indicate chemical

damage. (I) (5)

5. Joint damage can also result from putting brickwork

into service before c”re of the m”rtar is complete. (2)

(Overheating may char or crack joint. It rarely

shows up as joint loss.)

6. Soft, receding joints result from exposure to steam

jets or to neutral or alkaline water. Receding joints

cao also be caused by HF or acid fluorides. (I) (5)

7. Neutral waterr or washdowns, before cure WOLFom-

plete, caused loss of mortar. (2)

OIl<rlll:

8. Bricks dirty, so mortar did not stick to them and

joints fell out. (2)

9. Mason never filled joint, laid brick dry. (2)

10. Mortar used past work-life, so had no adhesion (2)

I I. Unauthorized material mixed iota mortar. (2)

IV-Damage to shale-tire&y brick in the lining.

1. Fairly uniform surface damage, etching or spalling is

almost certainly chemical damage. (I) (5)

2. Acid fluorides dissolve off the brick face, leaving an

etched surface. (I) (5)

In either of these above exposures, carbon brick is the

material of choice.

3. Spalling at edges of brick (at joints), but fairly sound

at the middle of the brick. If joints recede (I) (5), or

were not full to start with (2), expanding brick are not

supported at edges, and corners spall off the brickedges.

4. Spalling of surface in selected areas. This can be

due to:

a. Local overheating from steam impingement. (5)

b. Local exothennic reaction. (5)

c. Usz of soft (or undertired) brick. (4)

V-Sags or runs in mortar joints, usually accompanied

by voids.

Soupy mortar is almost always the fault of the in-

staller. (2)

Such joints can be identified by rounded, smooth,

bulging horizontal joints in the brickwork, often glassy,

accompanied by pinholes or voids near their tops.

VI-H eaving upward of brick floors and tank bottoms.

1. Expansion joints improperly designed, in wrong

placa, or wrong size or wrong expansion-joint tiller.

(I) (See also II, 3. 4. 5.)

lRubhnrh in expansion joint prevents it from functioning.

iadded by author)]

2. Brick underfired or of a clay with excessive, irreversi-

blc growth. (4)

3. Failure to lay brick void-free. (2) (Air voids ““dcr




brick will pick up liquids, in which crystals can form,

causing growth and upward pressure on brick.)

4. Voids or holes in the membrane permit corrosives to

reach substrate. (2)

5. For epoxy adhesive bed, heaving is due I” dirt, dust or

faulty application. (2)

T& botlomr (/7d bottoms):

Items I through 4 apply.

6. Bottom flat, not ventilated, tank hot. (I)

VII-Cracking of brick linings of steel tanks.

I. Lining too thin to provide adequate insulation at the

operating temperature. (I)

2. For lead sheet, or sheet elastomer or plastic, welds (or

laps) not padded, brick not notched. (2)

3. Seizing of brickwork on scams causea cracking. (See

I, 11.) -94. ‘Jacking” of brickwork can cause cracks. (2)

5. Failure to provide for expansion at inlets, outlets and

other shell penetrations. (I)

6. Cure shrinkage of mortar: Strongly banding mortars,

as they shrink on curing, can pull brickwork apart.

(I) (4)

VIII-Voids in mortar joints.

I. Pinholes and other tiny holes in mortar joints result

from air beaten in by a high-speed mixer in the mor-

tar box. (2)

2. Pinholes and tiny voids rrsult from insufficient mor-

tar on the tmwcl. (2)

Now consider monolithic surfacings. (Although not identical, polymer con-

crete constructions will be found to be quite similar.)

The following material is from “Failure analysis of chemically resistant

monolithic surfacings.” Reprinted by special permission from Chemical Engineer-

ing, July 23, 1984 0 by McGraw-Hill, Inc., New York.

I Failure t” cure-material either remains soft or hardens

only partiaIIy; &matively, there may be both bard andsoft spots

I. hluirture (e.g.. mitt. spillAge) or other liquid has icttlrd

“tt the surface. This may be due to inadequate weather

protection, flooding of the surface from one or m”re sides,

cooling of the air below its dewpoint on the substrate. or

cold-air drafts over the surface (from external doors. etc.).

2. Surface was wet or chemically contaminated when the

surfacing was applied. Cause may be inadequate cleaning,

drying or neutralization.

3. Concrete mix contained an admixture (such as an air-

entrainment agent, water reducer or curing agent) that

either reacted with and de&ted the hardener in the surface

material or inhibited the cure of the surfacing.

4. Concrete may have contained to” much water (i.e., it did

not dry enough). so that when the topping was applied,

water collected under it to inhibit curing. (Thin sections

may fail to cure completely.)

5. Resin and hardener were not mixed in correct propor-

tions, or not mixed uniformly. (If cure is sp”tty, incomplete

mixing is often the cause.)

6. Substrate or materials were to” cold to cure properly, or

the temperature of the substrate was allowed to fall below

the curing temperature after IIS pkcement.

7. Overheating beyond their thermal limits will soften some

monolithic toppings. Ifso, these toppings may appear to he

partly cured, and show marks and indentations. They will

usually re-harden when they are cooled. (See also Item II-

II and Item VI-Y.)

8. The material was exposed to intense sunlight.

II Disbondmenl-material separates from the substrate

or does not adhere

1. Surface was madequately cleaned and dried. The bond is

to dirt on the surface. (If dirt is on the surface, it can often

be seen adhering to the underside of the delaminated

surldcing material.)

2. For new concrete. the c”nttact”r may have used a curing

agent or sealer that acted as a bond breaker.

3. For new concrete. cement finishers may have dipped

trowels in, or wtped them with, a silicone cleaner.

4. See also Item I-1.

5. Where the day-to-night thermal gradient is ? 50’F, water

under-not in-the slab may have been dtawn up under thetotminr from as far as I5 ft down. If this ha”oens. atmlv the

m;;t”lshic on the 4 p.m. to midnight shift.‘Fhe &‘will be

advanced enough to prevent such a problem by the time the

temperature rises in the morning.

ti. 011s. other release agents, or foams were used, and these

left residues on concrete surfaces.

7. Concrete has inadequate surface strength. This can be

the result of: (I) inadequate design specifications; (2) failure

of the bulk plant to follow design instructions; (3) too much

water in the mix: (4) excessive troweling in finishing the

concrete; (5) failure to clean tltr surface or remove “lai-

lance” (fine particles of lime or portland cement that come

to rite surtace upon hmshing). The surface of the concrete

may be clcrord by brush blartmg or by etchirtg with hydro-

chloric acid. Proper desagn strength calls for a compressive

strength of 3,000 psi at the time of applntion and a bond

strength of 300 psi, using the specified surfacing material as

a banding agent.

8. Either the resin and the hardener were mixed to ittcorrcct

proportions or mixing was incomplete.

9. Substrate was to” cold for adequate cure, but air tem-

perature was high enougtt to cure surface.

10. Materials were used that were partly set.

I I. Top temperature was exceeded. Topping has a higher

coefficient of expansion than does the concrete. When thebond strength is exceeded, the topping will dishond. bulge,

then crack. Cleaning by boiling water or steam can produce

this. (See also, Item I-7 and Item VI-Y.)

III Cracking

I. Topping was applied over an expansion joint, consttu~-

tion joint, or other point of movement in the substrate. (Att

exp&iort joint in the topping is required in such areas.)

2. The distance between expansion ioints or stress-relief

joints was too great. (Cure sininkagiesults in accumula-

tion of stresses in the topping. When these exceed the bond

strength, the topping disbonds and cracks.)

3. For larger sections of concrete substnte, stress-relief

jotnts were not placed at 20-ft or smaller intervals. (See

comment under No. 2.)




4. Materials were improperly proportioned or incomplaely

mixed.

5. Materials were applied after working life had erpircd.

G. Note that if disbanding occurs. cracking due to stresses

from cure shrinkage will almost certainly follow.

7. If ovcrhcating happens, disbandment will take place. If

the topping is hard and does not soften appreciably at

higher temperatures, it will crack.

8. Area had been frozen at particularly low tempctatures.

The material becomes more brittle and develops excessive

shrinkage strcsscs at very low temprratures.

9. During cure, materials were exposed to intense sun-

Ii&~-this is especially seen in rpolty xeas.

IV Penetration

All resinous. siliceous or sulfur cements. toppings and

monobthics arc porous to some dcgrce. Diiusion through

these surfacings is faster for small molecules. Expect evcn-

tual penetration in continuously wet conditions (e.g., pud-dling, retaining sumps and trenches in continual use). All

areas surfdced with such ccmemr, toppings and monolithicr

should be sloped to prevent puddling.

Pcnetratton will result successively in: (I) disbandment if

the penrtrant IS a chemical that attacks the subsuate at all

rapidly: (2) cracking of the topping; and (3) curling upward

of the edges of the crack. After disbandment and cracking

occur, the substrate will show signs of chemical attack. To

verify this, peel off an adjacent topping that appears sound,

and rheck the substrate’s surfxe with pH paper.

V Chemical attack

Evidence of chemical attack can be: (I) surface softening;(‘2) surface discoloration that canna be removed by clean-

ing; and (3) surf~c etching, by either dcsrruction or remov-

al of the aggregate (e.g., silica aggregate removed by HF

exposure). For etching, the surface can remain hard and

porous or become powdery and crumbly. Discoloration is

followed by deterioration. Other signs arc softening and

swelling.

VI Blisters or bubbles

Part A. Appearing after application and while the mnteri-

al is still soft and before it has hardened Bubbles or

blisters are small; some may break, leaving small

indentations1. Materials have been mired with a high-speed mixer,

entrapping air in the resin. After the surface has been

troweled in place and finished. air bleeds out as blisters or

tiny bubbles. A paddle mixer moving at more than 350 ‘pm

can cause this.

2. A breeze over 10 mph can cause this.

3. A highly alkaline surface (pH > IO) can result in “gas-

smg” and subsequent blisten.

4. Application on porous concrete: Air in the pores expands

as the daytime temperature rises, and pushes through the

topping, resulting in blisters. This can be avoided by apply-

ing the monolithic after 4 p.m.

5. Application “vcr~oncrctc that has moisture in it or below

it. The etTcct is the same as in No. 4, but here the undersideof the topping also fails to cure properly. (See ala” Item II-

5.)

6. Exposure to varying intense sunlight, heat or cold during

installation and cure.

Part B. Appearing weeks a&r cure has taken place.

Bubbles or blisters are thick-skbmed and usually rather

large

I. Possible dill&ion of corrosives through topping attacked

the suhstntc al the bond amface and caused gassing or

concrete “growth.” with resulting delamination.

2. Possible chemical attack from underneath. Corrosives

may have entered the substrate elsewhere and traveledalong the rcban.

3. Overheating may have caused disbanding and bulging,

similiar to blistering, if the topping softened when “verheat-

ed. (See also Item II-2 and Item I-7.)

VII Expansion joint failure

I, Lossf bond to sider ofjoint. This can be due to: (I) poor

design-edges of joint were not at tight angles to the

surface; (2) sealant bonded to bottom of joint-joint

opened and material was dragged offits sides: (3) sides of

joint were dirty or specified primer was not used when joint

was filled; (4) low-level chemical attack occurred-usually

caused bv a solvent: (5) elastic limit of the sealant wasexceeded: (6) sealant was heated beyond its thermal limit:

(7) subfreezing of the smface took place: and (8) material

suffered thermal shock, resulting in too-rapid movement of

adjacent surfaces.

2. Swelling ofjoint. The causes can be: (1) rhemical attark.

which results in swelling or gassing-this is detectable by

presence of cmmbling. a porous condition. or spongy

cavitation and loss of strength; and (2) failure to use a

compatible matrrial under the sealant-as joint closed,

noncompressible material below it extruded upward. push-

ing the sealant out of the joint.

3. Breakup ofjoint filler, usually due to either (I) excessive

movement &y”nd the elastic limit5 of the sealant, (2)chemical attack, or (3) crress hardcncr in mix.

4. Briltleness. hardness, crumbling and loss of elasticity,

due to (I) chemical attack or (2) overheating beyond the

maximum service tempcramre.

5. Uneven cure. This is usually due to (I) exposure to

moisture during curt. but can also be due to (2) wind

blowing over the surface, (3) excessive sunlight. or (4)

nonuniform mixing of the ingredients.

Procedures for failure analysis of expansion joints will be found in “Ex-

pansion joints for chemically resistant masonry,” by this author, in ChemicalEngineering, August 19,1985,vol 92, no. 17, pages 79-81.




Figure 52-1: Acid brick lining in throat of a scrubber in a large power plant. Smeared sur-

face is an immediate indication to the inspector that the mason has covered up voids and

pinholes in the joints.

Figure 52-2: A pinhole still visible in the lining. A thin wire was inserted 4 inches into thishole. The inspector demanded removal of the lining, which, as expected, proved to be fullof voids, with as much as 1/8 nch of the backs of some of the brick bare.




Figure 52-3: More unacceptable workmanship. Dirty, sloppy workmanship, irregular joints

in brickwork and expansion joints.




Figure 52-4: Note the unacceptable variation in the width of expansion joints and poor

selection and placement of joint filler .




Figure 52-5: Note badly laid brick, irregular width of expansionjoint,rough surface of mem-brane, and apparently flooded asphalt surface instead of surface smoothed with squeegee.

Figure 52-6: Note rough surface. Blisters indicate either wet surface or water in the sub-strate, drawn up by the heat of the hot asphalt. The interior of the kettle may have beenwet, or rain water may have fallen into the kettle before or while the kettle was beingheated.



705nspection and Failure Analysis

Figure 52-7: Careless, incompetent brick cutting and inadequate mortaring of bed joints

under the brick. Note the sloppy finished surface.




Figure 52-8: Brick surface not fully covered with mortar will result in voids in the bed andthe joint. Note roughness of the surface. Membranes should be applied smoothly. BrickI nes and cutting of brick should be absolutely straight.



707nspection and Failure Analysis

Figure 52-9: Sloppy, unacceptable brickwork with open voids. There is insufficient mortarin the bed joint, and the bottom of the brick are not fully covered.




Figure 52-10: Examples of totally incompetent and unacceptable brickwork. Note dirt,

voids and even an open joint in the curb, lower right corner of (b).




Fi~r952-11: Acid brick shipped in an open-bodied truck in bad weather picks up a greatdeal of road dirt, which can get all the way to the center of the pallet. These brick must be

washed and dried before use if the work is to be satisfactory .




Fi~re 52-12: Three different work areas, same day and time, on a platform at the 780 footlevel of a brick lining in a chimney, showing the surface of the work at the end of the shift

by three different masons. All three left voids in joints, used too little mortar, and did notsufficiently cover the brick surface. Note shadows in center circumferential joint wheremortar has subsided into a void below.




Figure 52-13: Showing the effect of trace amounts of acid fluorides in the acid washing theinside of the tower; in this case, 750 parts per million. This damage occurred in less than6 months. (a) Top picture shows loss of silicate mortar. (b) Underside of a brick on thefloor. Center of the picture di~plays original texture of the surface (protected by mortar).(c) Right-hand picture shows surface exposed to scrubbing liquid containing the fluorides.




Figure 52-14: A brick removed from the top 8 feet of the brick lining of a chimney erectedonly 1 Y2years before. Note the clean separation of the mortar from the adjacent brick and

the air voids in the joint, showing that the masons had applied the mortar to the brick eitherclose to the end of its work life (too dry to wet the surface, or to wet brick, to which it

would not bond) , and that they used too little mortar to fill the joint.




Figure 52.15: Cracks in substrate mirrored in surface topping.

Figure 52-16: Use of too tightly woven, hard, reinforcing glass cloth, possibly with in-correct surface treatment. The resin in the surfacing has failed to wet it, causing delamina-

tion, then cracking due to cure shrinkage.




Figure 52-17: Mal-design of concrete floor in thicker bottom. Note areas where expansionjoints merge at small, acute angles. It is very difficult to create or maintain such joints, andthe surfacing over such pointed areas.

Figure 52-18: Close up of same concrete floor. Cure was inhibited by subsurface waterdrawn upward under topping, shortly after application, by big thermal changes, night to

day, causing poor cure, delamination and cracking up.




BIBLIOGRAPHY

1. Sheppard, Walter Lee, Jr., Chemically Resistant Masonry, 2nd Ed, Marcel Dekker, NY

(1982).

2. Sheppard, Walter Lee, Jr., Inspecting chemically resistant masonry,P/anr Engineering,

(March 19 and April 16,1981).

3. Sheppard, Walter Lee, Jr., Spotting and avoiding problems with acid-resistant brick,

Chemical Engineering (May 3,1982j.

4. Sheppard, Walter Lee, Jr., Failure analysis of chemically resistant monolithic sur-

facings:, Chemical Engineering (June 1984).

5. Sheppard, Walter Lee, Jr., Obtaining sound chemically resistant masonry, The Con-

srrucrion Specifier (December 1981 and March 1982).

6. Sheppard, Walter Lee, Jr., Trouble shooting chemically resistant masonry, Civil Engi-

neering, pp 68-71 (May 1982).

7. Sheppard, Walter Lee, Jr., Expansion joints for chemically resistant masonry, Chemical

Engineering, pp 79-81 (August 19,1985).



Index

Absorption - 543

Accelerators - 272

Acid brick - 9-l 1, 15-17, 144-

150, 155, 165,672, 674,

675

Acid brick lining - 677Acid-proof brick - 46, 267, 270

Acid resistant masonry - 636

Acrylic polymer concretes - 280-

292

application - 291

Acrylic polymer monolithics - 280-

292

application - 291

Acrylic polymer mortars - 280-292,

365,367,368

application - 2 9 1

Acrylics - 363, 364, 366, 376, 538

Additives - 273, 274, 483

Aggregate filled thermoset resins -

669

Aggregates - 399, 420

Alumina - 14Aluminum silicate - 13, 15, 17

Anchor points - 549, 550

Annulus pressurization - 644

Armoring - 609

Asphalt, cold - 1 1 8

Asphalt, hot - 22, 1 1 1 - 1 2 2

chemical resistance - 119- 12 1

Asphaltics - 23, 25

Asphalt putties - 118

Asphalt sheet - 88,89

Asphalt-urethane adhesive/mem-

brane - 9

Backfill - 601, 602

Baffles - 568, 569, 573

Banding system - 641

Barytes - 8

Basalt brick - 10, 183-l 87

Bentonite - 101

Binders - 284

Borosilicate glass - 17, 166, 220,

540

Bottom support - 570

Brick - 7-9, 13, 22, 23, 31, 35,

40,42,45, 50, 51, 54, 196,

197,270,687,698,699

Brick growth - 543, 579, 586, 587

Brick lining - 29, 47

repair - 249

Brick shells - 631Brickwork and expansion joints -

692,693

Brittleness - 543

Calcium aluminate - 12, 14

Calcium silicate - 13, 17

Capping - 572



Index 7 1 7

Carbon brick - 7-l 1, 42, 155-l 59,

669,674,677

Carbon fibers - 503, 511-513

Carbon steel - 17, 28, 29

Carbon sulfur - 25Castables - 13

Cast cement - 14

Cast liners - 638

Cements - 24, 58,60, 271

Ceramic fibers - 503, 505-507

Ceramic sleeve - 47

Ceramic tile - 7, 10, 11, 24, 198-

209

mosaic - 198, 199,201

Channel pipe - 559,606,607

Channel tile - 23,24

Chemical resistant brick - 7

Chemical resistant tile - 7

Chimneys - 626-649

Chlorinated polyethylene (CPE) -

9 1

Chlorinated polyvinyl chloride -538

Clay pipe - 594-601,608

Cleaning - 274

Closed cell borosilicate glass

block - 13, 86, 494

foamed - 160-169, 177, 574,

648

Closed cell sponge rubber - 503Coatings for nuclear power - 650-

658

Concrete - 22, 57, 58, 60-62, 64-

73,282,685

Concrete substrate - 14, 24

Contouring - 545-548

Corbel supported brick - 627, 628

Covers - 572-574

CRM materials - 5

uses - 544

Curbs - 581,582

Curing - 285, 286

Curing agent - 420

Cylindrical vessels - 43

horizontal - 44

“Dairy” brick - 200Designing with CRM - 542-592

basic principles - 543

Design limitations - 5

Difference between mortar and

grout - 243

Dished or conical bottoms - 43

Divider wall - 565, 566, 568

Drains - 562, 563

Dynamic wind - 634

Elastomeric linings - 16

Epoxy coatings - 258, 333, 654,

656

Epoxy concrete - 377, 378, 380,418,419-424

Epoxy grouts - 252,4 17-433

Epoxy monolithics - 257-263,440-

457,677

diluents - 258

Epoxy mortar - 12, 13, 25, 246,

252-266

Epoxy phenolics - 139-141

air dried - 139

bake - 139

monolithics - 473-475

Epoxy primers - 261

Epoxy resins - 1 1 , 14, 22-25, 46,

100,252-266,376,669,677

application - 261

catalysts - 255

chemical resistance - 464-466curing - 255-258

hardening - 255

hardening agents - 464-466

Epoxy surfacing application - 462

Ethylene-chlorotrifluoroethylene

copolymer - 539

Expansion joints - 5, 13, 24, 25,47,

514,515,551-558, 561-563,

572,575,577,578,692

components - 498-504

materials - 689

prefabricated - 516-518

Failure analysis - 694-699

Felt - 503

Fiberglass reinforced linings - 268

Fiberglass reinforced thermosetresins - 669




Fibers - 662 674,677

Fillers - 101, 244,261, 262,273,

274, 283, 284, 399,467,482,

483,662

application - 245, 247

high bond - 241

repair - 249

barytes - 12, 100,242, 243,273carbon - 12, 100,242, 243,273

carbon fibers - 100

glass fibers - 100

glass flakes - 100

graphite - 100

nylon - 100

Furan polymer concrete - 244,434,435

Furan resins - 11, 240-251, 669, 677

catalyst - 243

curing agent - 243

quartz silica - 273

resinous - 100

silica - 12, 100, 242, 273, 420

textile fibers - 100

Fireclay - 7-9, 16,42, 144-150,

155-l 57, 165,669

Fired glass and porcelain - 123-

126

Galvanic corrosion from lead/carbon

couple - 584-586

Glass fabric reinforced furan mem-

branes - 134-I 38

Glazed tile - 7, 10, 11, 198, 201

Granite - 10, 192-196

Granulated blast furnace slag - 299,

300

Flake glass coating - 268

Flat bottoms - 43

“Flexibilized” epoxy - 25

Floors - 576, 577, 579,580

Floor thickness - 580, 581

Flow diversion arrangements - 648

Fluid-applied membranes - 98-108

application - 103, 104

chemical resistances - 105-107

Fluorinated ethylene-propylene

copolymer - 539Fluorocarbons - 97, 100, 514, 515

Fluorochemical fibers - 503

Fluoroplastics - 539

Flyash - 12, 300

Foamed borosilicate glass block - 7,

9

Grout - 5, 7, 11, 13, 243, 270, 271,

282

Gunite liners - 638

Gunned cement - 15

Gunned hydraulic monolithics - 478-

489

application - 484-487

equipment - 479-481

Gunned linings - 13

Gunned monolithic silicate - 9

Gunned potassium silicate mono-

lithic - 491-496application - 493

Gunned sodium silicate monolithic -

489,490

Foamed glass - 42

FRP liners - 637, 641

Fumed silica - 101, 369-372

Furan coating - 242

Furan grout - 242-244,246, 251,

435

Half-round pipe - 559

Hardeners - 272

High alumina and insulating brick -

7,9, 14


water cleanable - 248

Furan joint - 24

Furan monolithics - 249, 250

Furan mortars - 8-10, 12, 25, 100,240,243-246,250,251,672

High alumina cement - 340-363

alkaline hydrolysis - 354, 355

application - 350, 358-362

composition - 340-343,356

curing - 345,346

deterioration - 350-356

failure analysis - 356-358

hydration - 344

inspection - 356-358permeability - 347



index 719

High alumina cement (cont’d)

properties - 347

uses - 348, 349, 358-362

Horizontal fiber brick - 23

Hydration - 302

Hydraulic cement - 15, 17, 196,

197

Hydraulic mortar - 10, 12

Hypalon - 89,91

Independent brick - 628,629

Inhibitors - 273

Inlets and outlets - 47, 563, 570,571

Inspection

final - 694

preliminary - 682

Inspection and failure analysis -

680-7 15

Inspection and repairs - 608

Installation - 689-694Insulating firebrick - 165, 170-179

Internal repair - 610

Latent hydraulic materials - 300,

301

Latex - 13

Latex-modified concrete - 376, 377

Latex-modified monolithics - 363-

369

Latex-modified mortars - 363-369,

377

Latex-Portland cement - 246

Lead - 127-133, 669

Liner plate - 23, 24

Litharge glycerine mortars - 240

Loose liners - 91

Lumnite - 12

Manholes - 602-604,608

Masonry lining - 28

Masonry units - 4, 6-8, 22, 23

Mastic - 16, 677

Membranes - 4-l 0, 13, 15, 22, 23,

25, 28, 31,40,47-49, 54, 55,

98, 157, 185,675,689-691

impermeable - 246, 248

nonrigid - 6

rigid - 6

semi-6

true - 6

Methyl methacrylate - 383

Moisture/heat shielding - 648

Monolithics - 5, 13, 14, 17, 46, 267,

268,543,576-579,677,691,

692,699

Mortars - 5, 8, 10-14, 22, 24, 31,

27 1,273,282,688,698,699

Neoprene - 16,89,91,364

Nonmetallic CRM in waste handling -

594-6 11

Nozzles - 47, 54, 570, 571

Organic fibers - 508-510

Oxidized asphalt - 248

Packing house tile - 200

Pavers - 200, 201Penetrations - 562, 563

Perfluoroalkoxy resin - 539

Phenolic monolith’ics - 473-475

Phenolic mortars - 10, 11, 12, 25,

100,230-239,240

catalyst - 232, 233

curing agent - 232,233

fillers - 234

shrinkage - 236, 237

Phenolic resins - 11, 230-239

Pipe joints - 596, 598-601

Piping - 594

Plasticizer - 224

Plasticizer and modifier for sulfur -

225

Plastics - 85, 86, 503

Polybutylene terephthalate - 539Polychlorotrifluoroethylene - 539

Polyester cement - 274-276

Polyester grout - 267, 274-276

Polyester monolithics - 440-457

Polyester mortar - 10, 12, 25, 267,

274-276,675,676

Polyester resins - 11, 249, 267-279,

669,677

Polyester/vinyl ester grouts - 423-

425




Polyethylene - 13, 526-528

Polyethylene terephthalate - 539

Polymer concretes - 5, 13, 270,

287,337,376,392-438,

699

Polymer-impregnated concrete -

383-391

Polymer portland cement concrete -

376-382

Polymethyl methacrylate - 538

Polyphenylene oxide - 539

Polypropylene - 13, 91, 528-534

Polystyrene homopolymers-

538,

539

Polytetrafluoroethylene - 539

Polyvinyl acetate - 363, 364, 376

Polyvinyl chloride (PVC) - 13, 89-

91,533-538

Polyviny lidene fluor ide - 539

Porcelain brick - 8, 180-182

Porosity - 543

plasticized - 248

Polyviny l chlor ide sheet membrane -

677

Portland cement - 12, 57-73,293-

340,669

blended - 298, 299

chemical resistance - 293

compos ition - 294-303

deterioration - 303-337Portland cement/aggregate brick -

669

Portland cement based brick - 675

Portland cement mortar - 674-677

Potassium hydroxide - 219

Potassium silicate - 8, 9, 14-17, 212-

218

Pozzolans - 299-302

Preconditioning of brick - 648

Preformed liners - 559

Press-molded hydraulic bonded

brick - 7, 10

Prestressed brickwork - 614-623

Prestressing - 574, 575

Primer - 276

Pulp and paper indust ry - 669-678

Quarry tile - 7, 10, 11, 24, 198,

201,677

Raw material suppliers - 277-279

Rectangular vessels - 44

Red shale - 7,8,42, 144-150,677

Refractory firebri ck - 170-179

Refractory liners - 638-640

Reinforced concrete shells - 632

Reinforcing - 577

Resin mortar - 11, 25,672

Rice hull ash (RHA) - 12,369-372

Rigid nonmetallic membranes - 109,

110

Rigid plastic - 13Rigid thermoplastic fabrications -

520-540

natural - 16, 89, 90, 248, 363,

376

nitrile - 91

Nordel - 91

polyi sobutylene - 91

sponge - 503

Rubber - 88,503,669,675

butyl - 89, 90

chlorobutyl - 16, 89, 90

hard natural - 90

isobu tylene, isoprene polymer -

90

Saran - 89

Scrubbers - 608Sealants

acrylic - 501

asphalt -urethane - 499

butyl - 501

epoxy - 498,499, 502, 503

Hypalon - 501

mastics and thermoplastics -

500-503

Neoprene putty - 501

polysulf ide - 499, 500, 502, 503

silicone - 500, 502, 503

urethane - 499, 502, 503

Seismic loads - 635

Shale - 155-l 57,669

Sheet lin ings - 88-97

Shell, metallic - 28

Shell supported steel - 629

Side effects - 584



Index 727

Silica brick - 7, 9, IO, 150-154

Silica mortars - 11, 218-221

Silica sol - 220

Silicate castables - 374, 375

Silicate grouts - 212-217, 374, 375

Silicate mortars - 1 1 , 35, 212-217,

241

Silicon carbide - 15, 187-192

Silicon carbide brick - 7, 10, 14

Silicones - 25

Slag cement - 2 9 9

Sleeve - 47, 54

Sliding joints - 549, 550Armalon - 503

Hypalon - 503

impregnated felt - 503

Kynar - 503

Neoprene - 503

polyethylene - 503

Teflon - 503

uncured rubber _503

vinyl - 503

Sloped bottoms - 560, 561, 567

Sodium hydroxide - 219

Sodium silicate - 11, 14, 17, 212-

218,240,374,375

Specialty brick - 9

Specialty tile - 670-678

Sponges - 501,503

Spray applied epoxy monolithic -458-472

Square vessels - 44

Stability - 548, 549

Steel - 30-37, 39-45,47-55

Steel decking - 46

Steel liners - 637

Steel shells - 631

Steel substrate-

15Strength - 543

Sulfur cement - 24,395-398

Sulfur concrete - 392-417

Sulfur mortars - 1 0 , 1 1 , 2 2 2 - 2 2 9 ,

240,24 1,246


Sulfur spray coatings - 659-668

Superplasticized portland cement

concrete - 436, 437

Support for waste lines - 601

Supporting structure - 17

Surface preparation - 48, 265

Surfacer (see Monolithics)

Synthetic rubber - 248

Tank bottoms - 567, 568

Tanks - 607

Thixotropy - 258

Thrust b l o c k s - 5 5 6 , 5 5 7

Tile - 7,8, 10, 11, 15, 23, 24, 578,

582,583

Trenches - 556-563,604-607

covers - 557, 558

gratings - 557, 558

walls - 551

Unlined independent concrete

liners - 641

Urethanes - 13, 669, 675

Urethane modified acrylics - 281

Urethane monolithics - 473, 476,

477

Vertical fiber brick - 23

Vessels - 565-575

Vinyl ester cement - 274-276

Vinyl ester grout - 267, 274-276,

417

Vinyl ester monolithics - 440-457

Corrosion and Chemical Resistant Masonry Mtls Hbk (PARTIAL) - W. Sheppard (Noyes, 1986) WW

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Transcript of Corrosion and Chemical Resistant Masonry Mtls Hbk (PARTIAL) - W. Sheppard (Noyes, 1986) WW