Caltex Materials of Construction

7/25/2019 Caltex Materials of Construction

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SECTION 1SECTION 1

MATERIALS OFMATERIALS OFCONSTRUCTIONCONSTRUCTION


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2.2.7 Vinyl Paints.........................................................................................................................192.2.8 Chlorinated Rubber Paints..................................................................................................192.2.9 Latex Paints........................................................................................................................192.2.10 Epoxy-Coal Tar Paints.........................................................................................................202.2.11 Silicones..........................................................................................................................20

2.2.12 Polyurethane or Urethane Paints.....................................................................................202.2.13 Silicone Alkyd Paints........................................................................................................202.2.14 Vinyl Alkyd Paints............................................................................................................202.2.15 Acrylic Paints...................................................................................................................202.2.16 Wash Coat Pretreatment.................................................................................................212.2.17 Bituminous Paints............................................................................................................212.2.18 Mastics and Cements......................................................................................................212.2.19 Special Purpose Paints.....................................................................................................21

2.3 COATING SELECTION ................................................................................................................222.3.1 Service Exposures................................................................................................................222.3.2 Selection of Paints...............................................................................................................22

2.4 INSPECTION ..............................................................................................................................252.5 TYPES OF COATING PROBLEMS AND CAUSES............................................................................26

2.5.1 Lifting.................................................................................................................................262.5.2 Blushing..............................................................................................................................262.5.3 Orange Peeling...................................................................................................................262.5.4 Checking, Crazing ..............................................................................................................262.5.5 Fisheyes..............................................................................................................................272.5.6 Cracking.............................................................................................................................272.5.7 Embrittlement.....................................................................................................................272.5.8 Softening............................................................................................................................272.5.9 Chalking.............................................................................................................................272.5.10 Undercutting ..................................................................................................................272.5.11 Blistering.........................................................................................................................27

2.6 PAINT COST...............................................................................................................................282.7 TEMPORARY PROTECTION.........................................................................................................29

2.7.1 Grease Preventives..............................................................................................................292.7.2 Oil Preventives....................................................................................................................292.7.3 Solvent Cut Back Preventives...............................................................................................292.7.4 Strippable Plastics...............................................................................................................30

2.8 GALVANIZING............................................................................................................................30

3.03.0 PLASTICSPLASTICS ..............................................................................................................................................................................................................33333.1 THERMOPLASTICS.........................................................................................................................343.2 THERMOSETTERS..........................................................................................................................34

4.04.0 REFRACTORIESREFRACTORIES................................................................................................................................................................................................37374.1 MATERIAL CLASSIFICATION .......................................................................................................37

4.1.1 Castable and Gunning Mixes..............................................................................................374.1.2 Vibration Castable...............................................................................................................384.1.3 Plastics................................................................................................................................384.1.4 Ramming Mixes..................................................................................................................394.1.5 Chemical Setting Mixes......................................................................................................394.1.6 Fiber Linings.......................................................................................................................394.1.7 Bricks/Formed Shapes.........................................................................................................40

4.2 MATERIAL SPECIFICATIONS........................................................................................................404.2.1 Chemical Composition........................................................................................................40


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4.2.2 Bulk Density........................................................................................................................404.2.3 Cold Crushing.....................................................................................................................414.2.4 Permanent Liner Change....................................................................................................414.2.5 Thermal Conductivity.........................................................................................................414.2.6 Abrasion Resistant...............................................................................................................41

4.2.7 Temperature.......................................................................................................................414.2.8 Porosity ..............................................................................................................................41

4.3 MATERIAL TESTING....................................................................................................................434.4 DESIGN......................................................................................................................................434.5 ANCHORING SYSTEMS AND STEEL FIBERS.................................................................................444.6 INSTALLATION ...........................................................................................................................444.7 CURING AND DRYOUT ..............................................................................................................45

TABLE OF TABLESTABLE OF TABLES

Table 1-1a NOMINAL COMPOSITION ...................................................................................................7

Table 1-1b COMMON ASTM SPECIFICATIONS FOR FREQUENTLY USED ALLOYS....................................9Table 1-2 CLASSIFICATION OF COATINGS BY METHOD OF CURE......................................................16Table 1-3 OVERCOATING TIMES OF SELECTED PAINTS.......................................................................17Table 1-4 PRINCIPLE ADVANTAGES/DISADVANTAGES OF FREQUENTLYUSED INDUSTRIAL COATINGS23Table 1-5 RECOMMENDED COATING TYPES........................................................................................25Table 1-6 AVERAGE JOB BREAKDOWN..................................................................................................28Table 1-7GENERAL TYPES OF REFRACTORY MATERIAL FOR CHEMICAL PROCESS INDUSTRY (CPI) USE......................................................................42

Table 1-8 SELECTION OF REFRACTORIES FOR REFINERY USAGE............................................................42


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1.01.0 MATERIALS OF CONSTRUCTIONMATERIALS OF CONSTRUCTION

1.11.1 CARBON STEELCARBON STEEL

Carbon steel is the basic material used in refinery construction. It is selected based on cost,availability and suitability for general service. At higher temperatures above 800oF (427oC) and incorrosive environments, other materials are usually more economical. Carbon steel's strengthdecreases rapidly above 800oF (427oC) as well as its resistance to graphitization. Oxidationresistance above 1000oF (538oC) and sulfidation resistance above about 500oF (260oC) areproblems. Other problems include resistance to hydrogen attack in hydrogen environments attemperatures over about 450oF (232oC) and problems with environmental cracking in aqueoussulfide, caustic and amine solutions in welded equipment. Depending on chemistry and steelmaking practice, some carbon steels may be susceptible to brittle failure as high as 100oF (38oC)while others are satisfactory down to approximately -50oF (-46oC). As more alloying elements areadded, overall cost for all product forms goes up.

1.21.2 LOW ALLOY (CARBON - 0.5MO)LOW ALLOY (CARBON - 0.5MO)

Carbon-0.5Mo has better elevated temperature strength than carbon steel and was thought tohave increased resistance to hydrogen attack in hydrogen environments. Unless chemistry, steelmaking and fabrication procedures are strictly followed, carbon-0.5Mo steels can have very poornotch toughness (resistance to brittle failure) in thicker sections greater than 3/4 inch. Because ofvariable hydrogen attack resistance, carbon-0.5Mo has not been used for new construction,although a considerable amount of equipment is in service. "GPS A-9 Selection of M etallicM aterials" prohibits the use of carbon 0.5Mo steel.

1.31.3 LOW ALLOY (CR-MOLOW ALLOY (CR-MO ALLOYS) (1.25CR-0.5MO - 9CR-1MO)ALLOYS) (1.25CR-0.5MO - 9CR-1MO)

Increasing Cr content gives better high temperature strength than carbon steel, increasingoxidation resistance and hydrogen attack resistance. Sulfidation resistance in environments withno hydrogen is considerably improved over carbon steel. Notched toughness can be considerablyimproved over carbon steel with proper chemistry and heat treating controls. In service ductilityproblems leading to serious cracking can be reduced with chemistry and heat treating controls.

These alloys have good hardenability and must be pre and postweld heat treated to haveacceptable ductility for service. Many reactors and other heavier wall equipment greater than oneinch can have serious cracking and/or ductility problems after service above roughly 650oF(363oC). Chemistry and heat treating restrictions can minimize these potentially serious problemson new equipment. Special inspection and startup/shutdown handling procedures may berequired for existing susceptible equipment.

1.41.4 LOW ALLOY (AISILOW ALLOY (AISI 4140, 4340)4140, 4340)These alloys are hardenable by heat treatment and offer the high strength at temperatures up toabout 800oF (427oC) needed for bolting, compressor and pump shafts and sometimes impellers.

The alloys are weldable with special procedures and proper heat treatment. However, because ofthe high strength levels, they are very susceptible to sulfide stress corrosion cracking in wetsulfide environments. Special heat treatments can minimize the cracking potential.


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1.51.5 LOW ALLOY (2.5NLOW ALLOY (2.5NI, 3.5NI)I, 3.5NI)

The low nickel alloys are used because of their improved notch toughness at lower temperaturesif properly fabricated and heat treated. While certain carbon steels can be used down to -50oF(-46oC), 3.5Ni can develop good notch toughness down to -150oF (-101oC). Proper heattreatment is necessary to develop the desired properties. The low nickel alloys may require more

careful temperature control during postweld heat treatment/tempering than the Cr-Mo steels todevelop desired properties.

1.61.6 STAINLESS STEELSSTAINLESS STEELS

1.6.1 Ferritic/Martensitic

Chromium contents in the 11 to 18 percent range give these steels good resistance to sulfidecorrosion with or without hydrogen in the environment, good oxidation resistance and goodresistance to chloride stress corrosion cracking.

The ferritic stainless steels generally are not hardenable by heat treatment but can develop verylow ductility because of grain growth during welding. Type 430 is susceptible to sigma phaseformation at temperatures over 1050oF (566oC). However, it is rarely used at temperatures thishigh because of strength considerations . Types 405 and 409 are susceptible to service inducedductility problems at 650o - 1050oF (343 - 566oC). This is commonly referred to as "885oFembrittlement". The loss of ductility may show up as welding or tray straightening problems andcan generally be solved, at least temporarily, with an embrittlement erasing heat treatment at1100oF (593oC) to allow welding or straightening.

The ASTM A240 Grade 26-1 alloy has very good sulfide, oxidation and chloride stress corrosioncracking resistance. However, it has ductility problems as welded because of grain growth and isvulnerable to 885oF (474oC) and sigma phase embrittlement problems.

The martensitic stainless steels can be hardened by heat treatment and can reach hardness levels

(generally greater than 200 Brinell hardness) that make them susceptible to sulfide stresscorrosion cracking in wet sulfide environments. Welding requires preheat and postheat treatingto guarantee usable service properties. CA6NM is used for castings because it is easier to castthan the standard 12Cr (CA15) material. CA6NM requires a difficult double temper to minimizehigh hardness that would make it very susceptible to sulfide stress corrosion cracking. Carbon

and silicon must be limited to 0.3% and 0.05% respectively in order to meet HRC22 even after a

double temper. Type 410S has lower carbon and will generally be less susceptible to developinghigh hardness during welding.

All of these alloys may be vulnerable to pitting problems due to underdeposit or oxygenconcentration cells.

1.6.2 Austenitic

The austenitic stainless steels are nominally 18Cr - 10Ni with various other elements added forspecific reasons. They have good overall resistance to oxidation [up to about 1500oF (816oC)]and sulfidation in both hydrogen and hydrogen free environments. They have good elevatedtemperature strength [up to roughly 1400oF (760oC)]. The molybdenum bearing grades (types316 and 317) have good resistance to naphthenic acid corrosion with resistance increasing withhigher molybdenum content. Types 321 with titanium and 347 with niobium (columbium) arevery resistant to sensitization and intergranular polythionic acid cracking if properly heat treatedduring product form manufacture. The L or low carbon grades can usually be welded without


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sensitizing (forming grain boundary carbides) that makes the alloy susceptible to intergranularcracking. If service temperatures are low enough [below 750oF (399oC)], they will not sensitizeduring service.

The alloys in this group are all susceptible to chloride stress corrosion cracking in aqueous

conditions, although the molybdenum alloys have better pitting resistance. The nonstabilized(i.e. no titanium or niobium added) grades are susceptible to sensitization and intergranularcorrosion in many refinery environments after fabrication and/or service exposure above about750oF (399oC). The niobium stabilized grade type 347 is sensitive to hot short and other weldcracking problems in sections over about 3/4 inch thickness. Type 347 corrosion protectionoverlay often used on heavy wall reactors is susceptible to hot short and sigma phase formationproblems if the proper chemistry is not laid down. The titanium stabilized alloy, Type 321, hasshown poor stress rupture properties above about 1100oF (593oC) so type 347 has been used forheater tubes.

1.6.3 Duplex Ferritic/Austenitic

The duplex stainless steels have the good overall corrosion resistance of the austenitic stainless

steels but are not as susceptible to chloride stress corrosion cracking. The duplex stainless steelsare generally more resistant to pitting problems. They are not as easy to weld as the austeniticstainless steels and will embrittle above about 650oF (343oC) because of the extensive ferritephase present in the microstructure.

1.6.4 A286

A286 is an iron based Ni-G superalloy alloy used primarily for its high temperature strength andthermal expansion characteristics similar to austenitic stainless steels. Its ductility is verydependent on proper heat treatment and does not have much of a strength advantage over theaustenitic stainless steels over about 1300oF (704oC). It has been used for high temperaturebolting such as the internal bolting in FCCU slide valves.

1.71.7 NICKEL ALLOYSNICKEL ALLOYS

1.7.1 20Cb3 (Alloy 20)

20Cb3 is an Fe-Ni-Cr-Cu-Mo-Cb alloy that is used for resistance to sulfuric acid in alkylation units.It is also more resistant to chloride stress corrosion cracking than the 300 Series stainless steels. Itis difficult to weld (hot short) and can be difficult to cast without defects for pumps and valves.

1.7.2 Alloy 800

Alloy 800 is an Fe-Ni-Cr alloy that has generally good resistance to sulfidation, oxidation andbetter high temperature strength than the 300 Series stainless steels. Although not immune tochloride stress corrosion cracking, it has better resistance than the 300 Series stainless steels. It

will sensitize and be vulnerable to polythionic acid cracking when furnished coarse grained.Typical of nickel alloys, cleaning sulfide scales from the surface when repair welding is necessaryto prevent cracking due to formation of a low melting Ni sulfide phase in the grain boundaries.

1.7.3 Alloy 825

Alloy 825 is an Ni - Fe - Cr -Mo - Cu - Ti alloy similar to 20Cb3 except it has more nickel makingit very resistant to chloride stress corrosion cracking. Alloy 825 has very good general corrosionresistance and generally will not sensitize. Alloy 825 is sensitive to sulfide problems during repairwelding but is easily welded with proper precautions. Alloy 825 has good resistance to


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ammonium bisulfide corrosion and along with Alloy 800 is used for tubes in hydroprocessingreactor effluent air fan coolers.

1.7.4 Alloy 600

Alloy 600 is an Ni-Cr-Fe alloy with good high temperature strength. The high nickel content andlower chromium level makes the alloy vulnerable to sulfide corrosion above about 750o-800oF(399oC-427oC)) particularly in hydrogen environments. Alloy 600 has good oxidation resistancebut will sensitize and be vulnerable to intergranular cracking problems. Being a high nickel alloy,it is very sensitive to sulfur or sulfides when being repair welded and very strict cleaningprocedures are necessary to prevent intergranular cracking due to nickel sulfide formation.

1.7.5 Alloy 625

Alloy 625 is a Ni-Cr-Mo-Cb alloy that has good resistance to sulfide corrosion, oxidation, a highresistance to pitting and good high temperature strength. It has been used for expansion bellowson FCC units. Alloy 625 will embrittle at temperatures over about 1050oF (566oC) and loseconsiderable ductility. Alloy 625 is very resistant to chloride stress corrosion cracking. The high

Mo content makes the alloy very resistant to naphthenic acid corrosion.

1.7.6 Alloy B

Alloy B is a Ni -Mo alloy that has good high temperature strength but is best known for itscorrosion resistance to reducing acids such as HCl. It is resistant to chloride stress corrosioncracking but can be sensitized and is therefore vulnerable to intergranular corrosion problems.Alloy B-2 has a modified chemistry and will not sensitize. Both Alloy B and B-2 can suffercatastrophic corrosion when exposed to certain oxidizing species.

1.7.7 Monel 400

Monel 400 is a Ni-Cu alloy that has good resistance to caustic and HCl at low concentrations. Ithas been used as cladding for atmospheric column top section corrosion protection. Monel 400

is very sensitive to nickel sulfide formation during repair welding. Monel will stress corrosion crackin ammonium chloride. Monel is used in HF alkylation service because of its good corrosionresistance to HF.

In general, the nickel based or high nickel alloys offer much better corrosion and chloride stresscorrosion cracking resistance than the 300 Series stainless steels. They are considerably moreexpensive and may be vulnerable to some side issue degradation problems.

1.81.8 COPPER ALLOYSCOPPER ALLOYS

1.8.1 Admiralty Brass

Admiralty is a Cu-Zn-Sn alloy used as condenser and/or cooler tubes because of its goodresistance to brackish water. It has reasonable resistance to process side sulfide corrosion but willstress corrosion crack in solutions containing ammonia, and/or ammonium chloride and oxygen.It will dezincify in aggressive waters under deposits even though it has dezincification inhibitorsAs, Sb or P. Admiralty has marginal resistance to sea water corrosion but is the standard refinerycondenser material in fresh and/or brackish water. In some services, water wash ammoniumchloride deposits off of bundles before opening to the atmosphere to minimize stress corrosioncracking.


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1.8.2 Aluminum Brass

Aluminum brass is very similar to admiralty with the same good features and problems. It isbetter than admiralty in sea water.

1.8.3 Naval BrassNaval brass is a Cu-Zn alloy that is generally used for tubesheets in condensers and/or coolers. Asa high zinc copper alloy it is vulnerable to dezincification. The dezincification is usually not aserious problem for tubesheets because of their thick section size.

1.8.4 Copper-Nickel Alloys (70-30 and 90-10)

The two Cu-Ni alloys are generally very corrosion resistant in sea water as well as fresh andbrackish water. The lower nickel alloy does not have as good a resistance to sulfide on theprocess side as the 30 percent nickel alloy. Both alloys are susceptible to under-deposit attack buthandle higher velocity waters better than admiralty and aluminum brass. The Cu-Ni alloys arevery resistant to ammonium chloride stress corrosion cracking. The cost of these alloys is highand they have been replaced with titanium in some services. The Cu-Ni alloys are weldable.

1.8.5 Aluminum Bronze

This alloy is used in sea water for pumps and condenser/coolers for channels and floating heads.It can be furnished as plate or cast. Aluminum bronze is weldable with difficulty.

1.91.9 TITANIUMTITANIUM

Titanium, usually Grade 2, is used for exchanger, condenser and/or cooler tubing in sea water orbrackish water service. Titanium is very corrosion resistant in many refinery type services but isvulnerable to hydriding and crevice corrosion in chlorides. The thin wall titanium tubes needmore support than regular TEMA R design. Vibration can be a major tube bundle problem. Whenthe tube wall temperature exceeds about 170oF (77oC), Grade 2 will pit under sodium chloride

and/or ammonium chloride deposits or in crevices. Grade 12 has better chloride pittingresistance [up to about 350oF (177oC)].

Titanium is very susceptible to hydriding above 180oF (82oC). Temperature increases hydrogensolubility while stress decreases solubility. Hydriding by hydrogen pickup from service or by beingcathodic to most other metals will seriously embrittle titanium and cause very low ductility,making handling a problem.

The allowable stress drops off rapidly with temperature even at 100oF (38oC). It is important,therefore, to accurately specify the design temperature for a solid tubesheet where there is adifferential temperature.

Titanium is cathodic to most other materials so Cu-Zn alloy tubesheets will corrode with titanium

tubes. Aluminum bronze does better but may require coating to minimize corrosion. Thedisadvantage of coatings is that pinholes can accelerate attack (large cathode, small anode).

There is little driving force for galvanic corrosion with CuNi (70-30) or Monel with titaniumtubes. CuNi (90-10) has low strength as a tubesheet and will cause problems when rolling thestronger Grade 2 titanium tubes.

Titanium will salt plug with low velocities in sea water. Titanium is not as sensitive toimpingement problems as copper based alloys. Do not bell tube ends; titanium tends to split orpush out of the roll in the tubesheet. Titanium tubing needs to be treated to minimize biofouling.


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1.101.10 ALUMINUMALUMINUM

Aluminum has been used in refinery service particularly in sour water stripper units because it isvery resistant to wet hydrogen sulfide corrosion. However, aluminum is very vulnerable to heavy

metal ion pitting problems and will deteriorate very rapidly in a caustic environment. Aluminummelts at a low temperature [approximately 1100oF (593oC)] and is considered a hazard forpressure containment under fire conditions.

1.111.11 HARD FACING ALLOYSHARD FACING ALLOYS (STELLITE)(STELLITE)

These alloys are generally Co-Cr-W alloys with various other carbide formers present. Asdeposited they form hard wear resistant carbides. The principal use is for high temperature wearresistance for sliding surfaces on slide valves and stems. There are refractories available that offerbetter erosion resistance for large areas on slide valves such as discs and throats. These alloys arecrack prone and generally are accepted for service with minor cracking.


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Table 1-1a NOMINAL COMPOSITIONTable 1-1a NOMINAL COMPOSITIONPage 1

MaterialMaterial UNS NumberUNS Number FeFe CrCr NiNi MoMo CuCu ZnZn OTHEROTHER

Carbon Steel (A516-70) K02700 Base - - - - - -

Low AlloyLow Alloy

Carbon-0.5 Mo K12822 Base - - 0.5 - - -

1.25 Cr-0.5 Mo K11597 Base 1.25 - 0.5 - - -

2.25 Cr-1 Mo K21590 Base 2.25 - 1 - - -

5 Cr-0.5 Mo K41545 Base 5 - 0.5 - - -

9 Cr-1 Mo K90941 Base 9 - 1 - - -

AISI 4140 G41400 Base 1 - 0.25 - - 0.4C

4340 G43400 Base 1 2 0.25 - - 0.4C

Low Temperature Alloy SteelsLow Temperature Alloy Steels

2.5 Nickel K22103 Base - 2.5 - - - -

3.5 Nickel K32018 Base - 3.5 - - - -

Stainless Steel Ferritic/MartensiticStainless Steel Ferritic/Martensitic

Type 405 S40500 Base 13 - - - - 0.3AI

Type 409 S40900 Base 11 - - - - 0.5Ti

Type 410S S41008 Base 13 - - - - 0.08C

Type 410 S41000 Base 13 - - - - 0.15C

Type 430 S43000 Base 17 - - - - -

CA6NM S41500 Base 13 4 1 - - -

26-1 S44627 Base 26 - 1 - - 0.01C

Ferritic/AusteniticFerritic/Austenitic

18-5-3 S31500 Base 18 5 3 - - 0.03C

22-6-3 S31803 Base 22 6 3 - - 0.03 C

AusteniticAustenitic

Type 304 S30400 Base 18 10 - - - 0.08C

Type 304L S30403 Base 18 10 - - - 0.03C

Type 316 S31600 Base 17 12 2.5 - - 0.08 C

Type 316L S31603 Base 17 12 2.5 - - 0.03 C

Type 317 S31700 Base 19 13 3.5 - - 0.08 C

Type 317L S31703 Base 19 13 3.5 - - 0.03 C

Type 321 S32100 Base 18 10 - - - 0.5 Ti, 0.08C

Type 347 S34700 Base 18 10 - - - 1Cb, 0.08C

A286 S66286 Base 15 26 1.5 - - 2Ti, 0.3V,1Cb


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Table 1-1aTable 1-1aPage 2

MaterialMaterial UNSUNS

NumberNumber

FeFe CrCr NiNi MoMo CuCu ZnZn OtherOther

Nickel alloysNickel alloys

2 Cb 3 N08020 36 21 35 3 4 - 1Cb

800 N08800 46 21 33 - - - -

825 N08825 30 22 42 3 2 - 1Ti

600 N06600 8 16 76 - - - -

625 N06625 3 22 62 9 - - 4Cb

B N10001 2 1 69 38 - - -

400 N04400 2 - 68 - 30 - -

Nickel Welding Electrodes/WireNickel Welding Electrodes/Wire

182 W86182 8 16 67 - - - 7Mn, 1Ti, 2Cb

A W861133 8 15 70 2 - - 3Mn, 2Cb

112 W86112 4 22 61 9 - - 3.7Cb

82 N06082 3 20 70 - - - 3Mn,2.5Cb, 0.8Ti

625 W86625 5 22 60 9 - - 3.8Cb, 0.4Ti

Copper AlloysCopper Alloys

Admiralty C44300 - - - - 70 29 1Sn, As

C44400 - - - - 70 29 1Sn, Sb

C44500 - - - - 70 29 1Sn,P

Aluminum Brass C68700 - - - - 77 212AL

Naval Brass C46500 - - - - 62 37 1Sn

Copper Nickel(90-10)

C70600 1 - 10 - 89 - -

(70-30)C71500 1 - 30 - 69 - -

Aluminum Bronze C61400 2 - - - 91 -7AL

Titanium Grade 2 R50400 99 +Ti

Aluminum Alloy3003

A93003ALbase, 0.1Cu, 1.25Mn, 0.6Si

Hard Facing AlloysHard Facing Alloys

Stellite 1 (1) W73001 2.5C, 30Cr, 12W, 54Co

Stellite 6 (1) W73006 1C, 29 Cr, 4W, 66Co

Wallex 50 (2) 0.8C, 21Cr, 17Ni, 10W, 44Co, 3Si, 3.25B(1)Trademark Cabot(2)Trademark Wall Colmonoy


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Table 1-1b COMMON ASTM SPECIFICATIONS FOR FREQUENTLY USED ALLOYSTable 1-1b COMMON ASTM SPECIFICATIONS FOR FREQUENTLY USED ALLOYSPage 1

MaterialMaterial PlatePlate HeatHeat

ExchangerExchangerTubingTubing

Pipe/Pipe/

TubingTubing

FlangesFlanges FittingsFittings CastingsCastings BoltingBolting

StructuralCarbon Steel

A283 - A53 A307

PressureEquipmentCarbon Steel

A285

A515

A516

A214

A179

A53

A106

API 5LB

A105

A181

A2334

WPB

A216

WCB

A193 B7

A194 2H

LowTemperatureCarbon Steel

A516 A334

Gr1,6

A333

Gr1,6

A350

GrLF2

A420

GrWPL6

A352

LCB

A320

GrL7

Low AlloyLow Alloy

Carbon-0.5Mo A204 A209 A335P1

A161T1

A182F1

A336F1

A182F1

A234WP1

A217

WC1

A193-B7

A194 2H,7

1.25Cr-0.5Mo A387

Gr11

A199T11

A213T11

A335P11

A200T11

A182F11

A336F11

A182F11

A234WP11

A217

WC6

A193-B7

A194 2H,7

2.25Cr-1Mo A387

Gr22

A199T22

A213T22

A335P22

A200T22

A182F22

A336F22

A182F22

A234WP22

A217

WC9

A193-B7

A194 2H,7

5Cr-0.5Mo A387

Gr5

A199T5

A213T5

A335P5

A200T5

A182F5

A336F5

A182F5

A234WP5

A217

C5

A193-B7

A194 2H,7

9Cr-1Mo A387

Gr9

A199T9

A213T9

A335P9

A200T9

A182F9

A336F9

A182F9

A234WP9

A217

C9

A193-B7

A194 2H,7

AISI 4140 - - - - - - A193-B7

B16

A194-2H,7

Low Temperature Alloy SteelsLow Temperature Alloy Steels

2.5 Ni A203B A334 Gr7 A333 Gr7 A350-LF9 A420-WPL9 A352-LC2 A320-L7

3.5 Ni A203E A334 Gr3 A333 Gr3 A350-LF3 A420-WPL3 A352-LC3 A320-L7

Stainless SteelStainless Steel

Type 405 A240 - A268 - - - -

Type 410S A240 - - - - - -

Type 410 A240 A268 A268 A336

F6

A182

F6

A217

CA15

A193-B6

A194-Gr6

Type 430 - A268 - - - - -

CA6NM - - - A182

F6NM

A182

F6NM

A352 -

26-1 A240 A268 A731 A182

FXM27

A336

FXM27

A182

FXM27

Type 304 A240 A249 A312

A271

A182

A336

A182

A403

A351

CF8

A193-B8

A194, 8

Type 316 A240 A249 A312

A271

A182

A336

A182

A403

A351

CF8M

A193-B8M

A194-8M

Type 316L A240 A249 A312 A182

A336

A182

A403

A351

CF3M


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Table 1-1b COMMON ASTM SPECIFICATIONS FOR FREQUENTLY USED ALLOYSTable 1-1b COMMON ASTM SPECIFICATIONS FOR FREQUENTLY USED ALLOYSPage 2

MaterialMaterial PlatePlate HeatHeat

ExchangerExchangerTubingTubing

Pipe/TubePipe/Tube FlangesFlanges FittingsFittings CastingsCastings BoltingBolting

Type 317 A240 A249 A312 A182 A182

A403

A351

CG8M

Type 321 A240 A249 A312

A271

A182

A336

A182

A403

- A193-B8T

A194-8T

Type 347 A240 A249 A312

A271

A182

A336

A182

A403

A351

CF8C

A193--B8C

A194-8C

22-6-3 A240 A789 A790 A182-FS1 A182-FS1 -

A286 - - - A453

Gr660

Nickel AlloysNickel Alloys

20Cb3 B463 B468 B464 B462 B366 A351

CN7M

B473

800 B409 B163 B407 B564 B564 - B408

825 B424 B704

B163

B423 B564 B564 - B425

600 B168 B163 B167 B564 B564 A494

CY40

B166

625 B443 B704 B444 B564 B564 B446

B B333 - - B366 B366 A494

N12M

B467

B468

400 B127 B163 B165 B564

B366

B564

B366

A494

M35

B467

B468

Copper AlloysCopper Alloys

Admirality B171 B111 - - - - -

Aluminum Brass - B111 - - - - -

Copper Nickel B171 B111 B469

B466

- - - -

Naval Brass B171 - - - - - -

AluminumBronze

B171 - - - - B148 -

Titanium B265 B338 B337 B381 B363 B367

Aluminum B209

Alloy

3003

B234

Alloy

3003


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2.02.0 COATINGSCOATINGS

2.12.1 FUNDAMENTALS OFFUNDAMENTALS OF COATING TECHNOLOGYCOATING TECHNOLOGY

Paints have been used by man from the dawn of civilization. Painted, lacquered, and varnishedartifacts created by early man for decoration, religious expression, and teaching or storytelling areexhibited in museums around the world and are in remarkably good condition. They attest to theability of paints to protect as well as beautify.

Through the years, there have been greater demands for paints to provide protection in a varietyof conditions. The paint chemist has responded to these demands and has developed a widevariety of paint materials that can resist severe chemical environments. The World War II searchfor synthetics to replace the cut off natural rubber supply, led to the discovery of a number ofsynthetic resins, used today in coatings to impart chemical, abrasion, and moisture resistance topaints. With the development and use of these exotic paints, it is possible for an engineer tospecify lower cost structural materials, such as carbon steel and concrete, in environments that

otherwise would require more durable and expensive construction materials.

Paints continue to serve multiple functions in modern industrial and architectural applications.The sophistication of paint chemists has created formulations which make paints suitable for:

corrosion protection

anti-fouling chemical resistance

decoration/identification heat resistance

camouflage noise control

fire retardation

While paints serve these multiple functions, it is the ability of the cured paint film to act as abarrier between the substrate to which it is applied and the surrounding environment, therebyproviding corrosion/erosion control and preventing structural damage, that is of fundamentalimportance in selecting coating systems for industry.

The properties of paint which define its useful performance in service include:

Abrasion resistance

Chemical resistance

Moisture resistance

Hardness

Brittleness

Color retention

Chalking characteristics

Hiding power Gloss

Flow

Applicator requirements (e.g. temperature limitations, required surface preparation)

A review of the generic paints in common industrial use today with reference to these propertiesand service limitations, is the topic of this section.


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Paints vs. Coatings.The terms 'paint' and 'coating' are both widely used and often interchanged. In the most narrowsense, paint is used when referring to pigmented liquids such as wall paint, exterior architecturalpaint, traffic paint, and masonry paint. Other paint type products, such as sealers, varnish,lacquer, stains, and primers are commonly called coatings or finishing materials. Elastomeric

coatings, synthetic organic coatings, flame spray metal coatings (more recent additions to thepaint chemists' line) have expanded the use of the term coatings.

In general, paint is used to refer to the less chemically sophisticated materials of alkyds, enamels,and latexes; and, coatings to the more exotic high performance industrial products. The practiceof engineers and field applicators of employing the term coating or referring to a particulargeneric coating type will be adopted here.

2.1.1 Coating System Composition

PRIMER: Holds to the metal substrate and protects the substrate and the topcoat. Primers contain corrosion inhibitors

TOPCOAT: Protects the primer from the environment.

2.1.2 Coating Composition

The manufacturing of coatings is an important segment of the chemical industry. Technically, it isone of the most complex, employing more kinds of raw materials than any other division of theindustry. Paints incorporate almost the complete range of commercial organic polymersincluding the chemical counterparts for most types of plastics, rubbers, adhesives and syntheticfibers. A paint manufacturer may stock 500 to 600 different raw materials and intermediates inorder to produce a complete line of coatings.

Coatings have two basic components; the pigment and vehicle. The pigment, finely ground solid

material, is dispersed in the vehicle which is a liquid containing two parts, the solvent anddissolved resin or binder.

2.1.2.1 The PigmentPigment solids are used in coatings for a variety of purposes.

(i)

Protective Pigments - provide corrosion control or chemical resistance in three ways:

BarrierProtection

Laminar pigments reduce permeability, and help the binder to form

coating film which is impervious to water, oxygen, and salts that acceleratedeterioration.

Galvanic

Protection

Metallic zinc dust provides galvanic protection by combining with oxygen

in preference to the anodic steel substrate. The zinc is sacrificed forming azinc salt which appears as a white dust on the surface of the coated steel.

InhibitiveProtection

A large number of pigments exert a chemical physical effect which servesto protect steel from corrosion. Included here are red lead, zinc chromate,zinc phosphate, calcium plumbate, and metallic lead. The mechanism ofprotection is complex. While several theories exist, the mechanism is notwell understood.


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(ii)

Hiding Pigments - Sunlight has a marked degrading effect on the organic resins in acoating film. The ultraviolet and infrared ranges of the spectrum cause the film to loseelasticity. Hiding pigments shield the film from the sun's rays, and reflect much of the solarradiation. Aluminum flake and titanium dioxide, which is snow white in color, are typical ofhiding pigments.

(iii)

Tinting Pigments - Color is imparted to a coating by adding the appropriate tintingpigments. Iron oxide is used to obtain yellows, reds, and browns of subtle, dullish hue. Whitepaints contain large quantities of titanium dioxide, a very stable, non-reactive pigment, and,in addition to providing hiding and color, Ti02will offer good control over chalking. Carbon,or lampblack, is used to obtain black.

(iv)

Extender Pigments - These pigments are generally referred to as extenders or fillers becauseof their low cost and high bulking value. However, they may add valuable properties such asdecreased permeability and enhanced film build. Calcium carbonate (chalk), mica, and silicaquartz are common extender pigments.

2.1.2.2 The VehicleThe vehicle is the liquid medium in which the pigment is suspended and is comprised of thevolatile or solvent portion which totally evaporates as the film dries, and the non-volatile, vehiclesolids, resin or binder portion which remains on the surface of the substrate to form the filmencapsulating the pigment matrix.

The volatiles, or solvents, control consistency, dissolve the solids so that they can be applied, andpromote leveling. The non-volatile, or resin, is composed of one or more polymers orprepolymers that form the coating film, determine the method of cure, and to a large degreedefine the corrosion and chemical resistant properties of the coating. For these reasons, coatingsare generally classified by the type of resin used, for example, alkyd, vinyl, epoxy, coal tar,phenolic and urethane resin bearing coatings.

(i) Vehicle Volatiles - Solvents in the coating serve a variety of functions. The primary role of thesolvent is to permit easier application, or to dissolve the resin which will dry to form a film, afterthe coating has been applied and the solvent volatilizes. Solvents which are added to the coatingafter the can has been opened in the field are called thinners. Thinning solvents promote ease ofapplication and assist in the flow-out and leveling of the film. It is good practice to avoid thinningexcept as is necessary to achieve the desired workability when applying the coating. Sprayingusually necessitates a certain amount of thinning, and additional thinning may be necessary inwarm or windy weather.

The most frequently encountered solvents for identical coatings fall into the followinggeneral categorization:

aromatic hydrocarbons (toluene, xylene, benzene)

aliphatic hydrocarbons (mineral spirits)

Ketones (methyl ethyl ketone [MEK], methyl isobutyl ketone [MIBK])

esters and alcohols (ethylacetate, isopropanol)

Drying oils are a class of solvent obtained from plants and certain fish. They dry to form films byabsorbing oxygen and by polymerization. Drying oils may be used as the sole ingredient in thesolids portion of the vehicle or may be fortified with resins.


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Varnish, is a term used to describe the product resulting from cooking a drying oil with resin.Upon exposure to air, varnishes will dry to form a smooth, durable elastic film. The degree ofelasticity is affected by the types and proportions of oil and resin used and the cooking procedureused. Until relatively recently Lead-In-Oil paint, a lead pigmented raw linseed oil formulation, wasabout the only type of house paint sold. Linseed oil is the most commonly used drying oil in

paints. It makes an excellent vehicle for paints for wood and structural steel, especially under mildatmospheric conditions. Though its moisture penetration resistance is only fair, this quality can beenhanced by further processing the oil.

(ii) Vehicle Non-volatiles - The resin or binder is considered the heart of the coating, for it bindsthe pigment particles together and to the surface of the substrate forming a rough, durable film.In nonpigmented, or clear, coatings, the binder is the total film forming agent.

Resins exist in two broad classifications, natural and synthetic. Resins are solid or semisolid, waterinsoluble, organic substances, evidencing little tendency to crystallize. Resins are often added todrying oils to decrease their permeability. A dried resinous vehicle tends to be brittle, but thiseffect can be mitigated by combining the resin with drying oil. A natural resin is defined as a solidorganic substance, originating in the secretion of certain plants or insects and dissolves in certain

solvents, but not water (ASTM D16, Definitions Relating to Paint). Though there are many naturalresins available, most are not used in metal protective coatings. Rather, their main use is infurniture varnishes. Shellac is one of the most common natural resins.

Synthetic, or manmade, resins are manufactured by polymerizing organic chemical compoundsof many types, and form the backbone of the protective coating materials used in industry today.

Their types and classifications are many and varied, and seem to be increasing at an exponentialrate. Furthermore, resins are frequently chemically blended in combinations of two or more resinsto obtain a synergistic effect, i.e., to provide coating materials with qualities superior to thosewhich could be provided by any of the constituent resins used singularly.

While all the solvent is lost upon curing of a coating, the proportion of resin and pigmentremains the same. The ratio of pigment to resin is related to the gloss of the coating. Flat

coatings expose more pigment than high gloss coatings. Gloss is related to the fineness of grindof the pigment, the smaller the size of the pigment particle, the greater the gloss.

(iii) Additives - Other materials such as driers, plasticizers, ultraviolet light absorbers, emulsifiers,anti-skinning agents, anti-flocculation agents and anti-mildew agents are added to coatings toimpart special properties. Depending upon their solubility, they may be considered part of thevehicle or pigment component.

Driers are a particularly important coating additive. They fall into two general classes: chemicalcompounds, added to shorten the drying time, or catalysts.

Driers: Metallic soaps. Metallic soaps are formed by mixing metallic oxides with oils. Theseinsoluble soaps promote faster drying, act as thickening agents, and provide a flat hand-rubbedappearance for certain product finishes. Soaps of lead, cobalt, manganese, calcium, tin,zirconium, aluminum and zinc are common.

Lead promotes drying throughout the coating film, and is frequently used in combination withcobalt. Where environmental controls restrict the use of lead, zirconium is frequently substituted.

Tin, a fast drying agent, is usually used in combination with other metallic soaps for a morecontrolled reaction.


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(iv) Catalysts - Technically speaking, a catalyst is a substance which effects a reaction, but doesnot enter into, or become part of, the reacted material. In coatings, chemical catalysts are used tospeed up the cross-linking of molecules. Reactive urethanes, thermosetting polyesters, andamine, polyamide, and amine adduct-cured epoxies are frequently used as catalyzed, highperformance coatings.

2.1.3 Methods Of Cure

Coatings cure in three basic ways:

(i) Solvent evaporation

(ii) OxidationThe process by which oil or resin molecules combine with oxygen in the air to effect cure; Driersare used to initiate or accelerate this reaction.

(iii) PolymerizationThe linking of free molecules in the resin to form long chains of high molecular weight. Cross

linking may be activated by the presence of heat (e.g., baking enamel) chemically, by theaddition of a catalyst (e.g., reactive epoxy, urethane and polyester), or by exposure to radiation,gamma rays, x-rays, ultraviolet rays. (NOTE: Radiation cures are being experimented with forvarious types of product finishing, especially automobile exteriors. They have not yet found realcommercial acceptance.)

Complete curing of a coating is essential in order to obtain promised service life and may be acritical factor in the adhesion of a multicoat system.

Curing and drying, while often used interchangeably, are not synonymous. A dry film is onewhich is dry to touch. When the thumb is pressed with moderate pressure on a dry film androtated 90 degrees, the coating film will not distort, sag, or retain an imprint. A coating may bedry to touch, but may not be cured. Solvents may be trapped in the interior of the coating film

(i.e., only the surface has dried and the hard skin has entrapped solvents which may form blistersor cause lifting of the film, or oxidation or polymerization within the film may be incomplete).

The manufacturer's data sheet will indicate time to cure, but this is affected by ambientconditions, and time adjustments may need to be made for a particular job.

A classification of generic coating types by their method of cure is found in Table 1-2. Typicalovercoating times of commonly used paints are shown in Table 1-3.


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Table 1-2 -Table 1-2 - CLASSIFICATION OF COATINGS BY METHOD OF CURECLASSIFICATION OF COATINGS BY METHOD OF CURE

SOLVENT

EVAPORATIONwater thinned water soluble coatings "emulsion" coatings

solvent thinned shellaclacquers

solution vinyls

polyvinyl chloride

chlorinated rubber

T/P acrylics

OXIDATION oilphenolic varnish

oleo resinous varnish

alkyds

chlorinated alkyds

silicone alkyds

epoxy esters

acrylic enamels

urethanes (oil modified)

POLYMERIZATI heat conversion silicone (crosslinked with oil material)phenolics

aminos, urea and melarnine formaldehydes (crosslinked withalkyds, vinyls, or oils)

T/S acrylics

Polyurethane

chemical conversion"catalyzed"

reactive or "two-pack"

vinyl esters

furon linings

coal-tar epoxies

coal-tar urethane

polyurethanepolyester

epoxy, polyamide cured

epoxy, amine & amine adduct cured epoxy polyester

PVB (wash primer)

moisture conversion ethyl silicatezinc rich primer

urethene


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Table 1-3Table 1-3 OVERCOATING TIMES OF SELECTED PAINTSOVERCOATING TIMES OF SELECTED PAINTS

NAMENAME OVER COATING TIMEOVER COATING TIME COMMENTSCOMMENTS

Alkyd Resin Paints 12-48 hrs. if the interval greatly exceeds 48 hrs. there is risk of poor intercoatadhesion.

Chlorinated RubberPaints

2-4 hrs. (normal)

48-72 hrs.(high build

No upper limit for overcoating time drying of these paints. Leastlikely to be affected by low temperature. High build types bestfinished with normal types.

Vinyl Resin paints 1-2 hrs. (normal)

48 hrs (high build)

Epoxy Resin paints 4 hrs. Intervals greater than 24 hrs. incur risk increasing with delay, ofpoor intercoat adhesion. Curing time 7 days (for max. resistance).

Epoxy/Pitch paints

Polyurethane Resinpaints

4 hrs. Intervals greater than 24 hrs. incur risk, increasing with delay, ofpoor intercoat adhesion. -

Zinc Silicate 5-7 days Allow 4 hrs. before curing paints with acid wash and wash with(inorganic) water before recoating

Zinc Silicate

paints (organic)

1-2 days Cure is hastened by washing down after 2 hrs, using clean water.

2.22.2 PROPERTIES OF PAPROPERTIES OF PAINTSINTS

Specific properties of some types of paints have been mentioned, but general advantages anddisadvantages have not been discussed. Each type of paint has properties that make it suitable for

particular uses. Of course, there are large variations in properties within each type, and it isseldom possible to select a suitable paint by type alone.

2.2.1 Oil Paints

Oil paints have drying oil vehicles that cure by oxidation and polymerization. Raw and bodiedlinseed oil are the most commonly used drying oils. Raw linseed oil paints have excellent wettingability, but are slow drying. Bodied linseed oil paints are faster drying, have increased waterresistance and decreased permeability, but their wetting properties for rusted or dirty steel areinferior. A mixture of raw and bodied linseed oil is frequently used, especially for primer paints.

Oil paints are used extensively because of their excellent weathering characteristics. In normalatmospheric exposure, oil paints gradually erode by deterioration of the surface until the

undercoats are exposed. At that time, they should be recoated with a finish paint, priming anyrusted areas if necessary. Films of oil paints are elastic and flexible and have good adhesion.However, they have poor resistance to abrasion and conditions of high humidity and theirresistance to alkaline environments is very poor. Films of oil paints are too porous to be generallysatisfactory for underwater surfaces.


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2.2.2 Oleoresinous Paints

Oleoresinous paints are those that have both drying oils and resins in their vehicles. Naturalvarnish resins are sometimes used but synthetic resins are more commonly used in metalprotective paints. These paints are better than linseed oil paints for severe service conditionsbecause of their decreased permeability and increased chemical and abrasion resistance. Films of

these paints are more brittle than those of linseed oil paints, and they must be formulatedcarefully to avoid a brittle film that fails by checking and cracking. The most widely used classesof oleoresinous paints contain alkyd, phenolic or epoxy resins.

2.2.3 Alkyd Paints

Most alkyd paints formulated for painting structural steel are oleoresinous paints. The vehicles ofthese paints are referred to as oil-modified alkyds to indicate that the resin has been combinedwith a drying oil. Properties of the alkyd paints are controlled primarily by the amount and typeof oil incorporated in the resin. However, a limited variation in wetting and drying properties ispossible through the selection of alkyd resin. Long oil alkyd paints, which contain a highproportion of drying oil to alkyd resin, have good wetting and slow drying properties similar tothose of oil paints. Short oil alkyd paints, which contain only a small proportion of drying oil,

have properties approaching those of unmodified alkyds, that is, rapid drying, extreme hardness,good durability, relative insolubility in mineral spirits, and poor wetting of rusted or dirty steel.

The quick drying, unmodified alkyds have poor adhesion, and thorough blast cleaning isrecommended before application of these paints as primers. In general, alkyd paints are lesspermeable and have better chemical resistance than oil paints and, therefore, are better suited forsevere environments. However, they are too permeable to be satisfactory for continuousimmersion in water.

2.2.4 Phenolic Paints

Like the alkyds, most phenolic paints formulated for painting structural steel are oleoresinous.They contain oil soluble phenolic resins modified by the addition of drying oils. And theirproperties depend, to a large extent, on the amount and type of drying oil used. In general, oil

modified phenolic paints are quick drying and have low permeability, good water resistance, andgood chemical resistance. They are not, however, resistant to alkalis. Their adhesion is only fair,and blast cleaning is the recommended minimum surface preparation. Oil modified phenolicpaints are particularly suitable for fresh water immersion and atmospheric exposure in severeindustrial or marine atmospheres.

2.2.5 Epoxy Paints

Air drying epoxy paints are formulated with epoxy resins that have been esterified with a dryingoil acid. They are referred to as esterified epoxies, epoxy esters, or modified epoxies. As withother oil modified synthetic resin paints, the properties depend largely on the type of drying oilacid reacted with epoxy resin. In general, they are suitable for severe industrial and marineenvironments. Esterified epoxy paints are relatively quick drying and have low permeability, good

water resistance and good chemical resistance. In these respects, they are better than the alkydsand comparable to the air drying phenolics. They have excellent adhesion, and surfacepreparation is usually no problem, though blast cleaning is always recommended wherepractical.

Unmodified epoxies, or 100% epoxies, that require the addition of a catalyst just beforeapplication have excellent acid and alkali splash resistance. They are suitable for immersion inhydrocarbons, mild acids and alkalis, but blistering may be a problem in sea water, aqueousammonia and fertilizer solutions.


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2.2.6 Lacquer Type Paints

Lacquers are usually considered to be pigmented or unpigmented solutions of cellulose esters, orethers that cure to a solid film solely by solvent evaporation. In recent years, however, several

non-cellulosic, solvent drying resins have been developed, and these are used by themselves orcombined with cellulose derivatives to give coatings of improved properties. The term lacquertype paint can be used to distinguish cellulose lacquers (nitrocellulose automobile lacquers, forexample) from other classes of solvent drying resin paints such as the vinyl and chlorinatedrubber paints.

As previously mentioned, oleoresinous and oil paints cure by reaction with oxygen from the air,but lacquer type paints do not require oxygen. The resin that is in solution at the time ofapplication is deposited on the surface with the pigment and becomes a solid film when thesolvent evaporates. High molecular weight resins, suitable for this type of coating, are difficult toput into solution and high solvency power solvents are required. A low solids content paintgenerally results and the dry film thickness per coat of applied paint is low. Several coats may berequired to obtain desired film thicknesses. However, the use of hot spray processes permits a

high build per coat.

2.2.7 Vinyl Paints

Vinyl paints and lacquer type paints are formulated with vinyl resins in alcohol, ketone or estersolvents. The most common resins used are copolymers of vinyl chloride and vinyl acetate with asmall amount of another constituent, such as maleic anhydride, to improve adhesion. Pooradhesion is the principal disadvantage of these paints and the minimum surface preparationrequired is abrasive blasting to white metal. However, they have outstanding resistance to severeenvironments, particularly for submerged surfaces. Vinyl paints are quick drying because lowboiling solvents (for example, methyl ethyl ketone) and they must be sprayed. Using recentlydeveloped hot spray techniques, vinyls may be applied in film thicknesses comparable tooleoresinous or oil paints.

2.2.8 Chlorinated Rubber Paints

Chlorinated rubber paints are lacquer type paints containing, in addition to pigments,chlorinated rubber resin, plasticizers, stabilizers and aromatic solvents. A plasticizer is required todecrease the brittleness of the film. A stabilizer, usually an epoxide compound, is requiredbecause the resin has a tendency to liberate small quantities of hydrogen chloride. Chlorinatedrubber paints have outstanding resistance to acids and alkalis and are used extensively where acidfumes are present. Their adhesion is better than that of the vinyls, but their wetting ability fordirty or rusted steel surfaces is only fair and blast cleaning is recommended. The aromaticsolvents used (for example, toluene and xylene) provide relatively quick drying properties but areslower drying than the vinyls.

2.2.9 Latex Paints

Latex paints are usually based on aqueous emulsions of three basic types of polymers; polyvinylacetate, polyacrylic and polystyrene butadiene. They dry by evaporation of the water followed bycoalescence of the polymer particles to form tough, insoluble films. They have little odor, are easyto apply, and dry rapidly. Latex films are somewhat porous so that blistering due to moisturevapor is less of a problem than with solvent thinned paints. They do not adhere readily tochalked, dirty or glossy surfaces. Therefore, careful surface preparation is required.


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2.2.10 Epoxy-Coal Tar Paints

Coal tar is often added as an ingredient of epoxy paints, resulting in a significant decrease in costwith relatively minor effect on corrosion resistance. Color choice is limited because of the blackcolor of the coal tar. It is used primarily for interior and submerged surfaces.

2.2.11 Silicones

Silicones are used for water repellents and for heat resistant coatings.

(i) Water RepellentsDilute solutions (5% solids) are used to reduce water absorption on unpainted concrete ormasonry. They usually do not affect the color or appearance of the treated surface.

(ii) Heat Resistant CoatingsThese contain a high concentration of silicone resins. When properly formulated and applied,they can withstand temperatures as high as 1500oF. (816oC)

2.2.12 Polyurethane or Urethane PaintsThere are two general types of polyurethane coatings; oil modified and moisture curing.

(i) Oil ModifiedThese are similar to phenolic varnishes, although more expensive. They have better color andcolor retention, dry more rapidly, are harder, and have better abrasion resistance. They can beused as exterior spar varnishes or as floor finishes.

(ii) Moisture CuringThese are unique in having the performance and resistance properties of two componentfinishes, yet are packed in single containers. Moisture curing urethanes are used in a mannersimilar to other one-package coatings except that all containers must be kept full to excludemoisture during storage. If moisture enters or is in the container, they will gel.

2.2.13 Silicone Alkyd Paints

The combination of silicone and alkyd resins results in an expensive, but very durable, coating foruse on smooth metal.

2.2.14 Vinyl Alkyd Paints

The combination of vinyl and alkyd resins offers a compromise between the excellent durabilityand resistance of the vinyls with the lower cost, higher film build, ease of handling and adhesionof the alkyds. They can be applied by brush or spray and are widely used on structural steel inmoderately severe corrosive environments.

2.2.15 Acrylic Paints

Cross-linked acrylic resins with styrene and other materials provide a very durable and attractiveline of lacquer and enamel coatings used for automotive and appliance finishes. These coatingsrequire baking at temperatures of 300-400oF (149oC-204oC) after application. Water basedacrylic latex emulsion paints are used widely for wood, plaster, and masonry coatings.


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2.2.16 Wash Coat Pretreatment

The wash coat pretreatment, also called a wash primer treatment, is a surface preparation steprather than a paint because a chemical reaction with the surface is involved. However, a thin, 0.3to 0.5 mil, film is left on the surface. Essentially, the material is a two part composition thatconsists of an alcohol solution of polyvinyl butyral resin and phosphoric acid, pigmented with

zinc tetroxy chromate. When it is applied to a blast cleaned steel surface, an adherent film isformed by reaction with the steel. The film improves the bond between the steel and poorlyadherent paints, such as the vinyls. The wash coat pretreatment is used to improve adhesion ofpaints on such smooth metals as galvanized steel, stainless steel, magnesium and aluminum.

2.2.17 Bituminous Paints

Bituminous paints are solvent solutions of bituminous materials; that is, asphalt, coal tar, gilsoniteor vegetable pitch, with or without added fillers. These paints normally do not exhibit inhibitiveproperties and metal protection is derived from a mechanical barrier obtained by applying thickcoats of 1/8 inch or more. Film thickness per coat is increased by the addition of inert fillers, suchas calcium carbonate, mica, silica, asbestos and others. Solvents used, vary from aliphatichydrocarbons for asphalts to aromatic hydrocarbons for coal tar materials. Good protection is

obtained with these coatings if applied in sufficiently thick films. One of the disadvantages is thenumber of coats required to obtain the thickness desired. In severe exposures, a rust inhibitiveprime coat is recommended and this introduces the problem of lifting of the undercoat by thearomatic solvent in coal tar base paints. The bituminous paints are not resistant to longtermexposure to sunlight and weather and they must be protected when used outdoors. The use ofasbestos is not acceptable environmentally in many countries.

2.2.18 Mastics and Cements

As the result of surface tension effects on drying films, coatings are usually too thin on sharpedges, over rivet and bolt heads, etc., to prevent corrosion. These are the places coatingsbreakdown first. This, however, can be easily overcome when using vinyls or by applying vinylmastic on all sharp edges, rivets, bolt heads and nuts and in cracks where two or more members

are jointed. This will effectively prevent rapid coating failure. The mastic may be applied bytrowel, putty knife, brush or high pressure spray equipment.

2.2.19 Special Purpose Paints

Film forming materials other than oils and resins can be used for special coating requirements.Zinc dust is used in an inorganic vehicle containing sodium silicate to produce a paint thatrequires a chemical hardening agent. Portland cement and casein are used in water basecoatings. Water base paints consisting of water emulsions of many types of coating materials arebeing used for wood and masonry surfaces but they are seldom used in metal protective paints.Some water emulsions may be heavily pigmented and applied as very thick coats. These are theso-called mastics. Water emulsions of polyvinyl acetate or acrylic resins are used extensively forpainting masonry surfaces. They have greater tolerance for alkaline surfaces than previously used

oleoresinous paints. Water emulsion paints are gaining wide acceptance for interior paintsbecause they eliminate the odor of organic solvents indoors.


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2.32.3 COATING SELECTIOCOATING SELECTIONN

2.3.1 Service Exposures

In industrial maintenance coating, more than any other coating area, it is important to choosethat paint, of the many available types, whose resistance properties best coincide with the

demands of the service environment. A paint that performs perfectly well under one set ofconditions, may fail miserably under others. Or, a less resistant paint may be completelysatisfactory in areas where high performance coatings are sometimes used.

Table 1-4 shows the principle advantages/disadvantages of frequently used industrial coatings.

Table 1-5 shows the recommended type of coatings for refineries and terminals (inland andcoastal.)

2.3.2 Selection of Paints

The following criteria should be used in selecting a coating:

Abrasion resistance Adhesion

Impact resistance

Flexural qualities

Resistance to a given media

Resistance to sunlight

Temperature resistance

Drying time

Appearance

Wetting time

Applied cost

Antistick properties

The coating, or coatings, having the best properties for a given set of conditions should beselected, providing the cost is not prohibitive.

Top quality coatings should be compared generically. However, it is important to keep in mindthat identification, by generic name per se, is no guarantee of quality. Coatings should bepurchased on specifications from reliable coatings manufacturers. It is false economy to purchasea protective coating without knowing its solids content and the resin content of the solids.

Heavy bodied vinyls and other materials are now available that can be applied from 6 to 8 milsthick/coat with an ordinary spray gun. Where no large crevices are to be filled, this is superior tomastic because they can be applied much faster and with regular paint-spray equipment. Masticor heavy bodied vinyl and some of the other materials should be applied after the prime coat is

applied.

When coated structures have large numbers and lengths of cracks and crevices, especially whenthese are subject to fading action as is the case in bridges, priming preliminary caulking will notonly save time, but will insure a longer lasting job.

Vinyl and phenolic mastics have been tested with good results on steel pilings in sea water. Thereare epoxy compounded cements, which may be used in conjunction with epoxy coating systems

just as vinyl mastic is used with vinyl systems.


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Table 1-4 PRINCIPLE ADVANTAGES/DISADVANTAGES OF FREQUENTLYTable 1-4 PRINCIPLE ADVANTAGES/DISADVANTAGES OF FREQUENTLY

USED INDUSTRIAL COATINGSUSED INDUSTRIAL COATINGS

GENERIC TYPE ANDGENERIC TYPE ANDCURING MECHANISMCURING MECHANISM

PRINCIPAL ADVANTAGESPRINCIPAL ADVANTAGES PRINCIPAL DISADVANTAGESPRINCIPAL DISADVANTAGES

DRYING OILS

Oxidation

Very good application properties

Fair exterior durability

Outstanding wetting and penetration qualities

Excellent flexibility

Good film build per coat

Relatively inexpensive

Slow Drying Soft films - low abrasionresistance

Poor water resistance

Fair exterior gloss retention

Poor chemical and solvent resistance

ALKYDS

Oxidation

One-package coating

Fair exterior durability

Moderate cost


Excellent adhesion to most

surfaces, including poorly prepared surfaces

Easy to apply

Good gloss retention

Poor chemical and solvent resistance

Fair water resistance

Poor heat resistance

PHENOLICS

Oxidation

Excellent exterior durability

Good film build per coat

Very good chemical resistance

Excellent water resistance

Extremely hard film

Very brittle

Critical recoat intervals

Poorgloss retention

Yellows on aging

EPOXY ESTERS

Oxidation

One-package coating -unlimited pot life

Hard, durable film

Good chemical resistance

Good water resistance

High film build per coat

Moderate cost

Fair gloss retention

Not applicable over inorganic zinc

ACRYLICS

Evaporation

Rapid drying

Excellent durability, gloss and color retention

Good heat resistance

Moderate cost

Poor chemical resistance

Low film build per coat

Thermoplastic at elevated temperatures

Blasted surface desirable.

VINYLS

Evaporation

Rapid drying and recoating

Excellent chemical resistance


Excellent durability

Very good gloss retention

Applicable at low temperatures

Poor solvent resistance


Low film build per coat

Requires white metal blasted and primedsurface

CHLORINATED

RUBBERS

Rapid drying and recoating

Excellent chemical resistance



Good gloss retentionApplicable at low temperatures



Blasted surface desirable

questionable over inorganic zincs

EPOXIES

Polymerization

Excellent chemical and solvent resistance


Very good exterior durability

Hard, slick film

Two-Package coating -- limited pot life

Curing temperature must be above 50oF(10oC)

Poor gloss retention

Film chalks on aging

Sandblasted surface desirable

Topcoating may require blasting


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EPOXY

PHENOLICS

Polymerization

Excellent chemical and solvent resistance

Very good acid resistance


Good heat resistanceExtremely hard film

Excellent abrasion resistance


Not for exterior use

Critical recoat intervals

Required white metal sandblasting

Two-package coatings - limited pot life.

EPOXY

EMULSIONS

Evaporation

Polymerization

Very good chemical and solvent resistance

Hard, abrasion resistant film


Excellent adhesion - - particularly to aged, intact coatings

Easily topcoated after extended periods of time with avariety of coating types

May be applied directly to clean, dry concrete surfaces

Two-package coating -- limited pot life

Curing temperatures above 50oF (10oC)

Sensitive to early rain or dew

SILICONES

Polymerization

(Heat Required)

Excellent heat resistance

Good water resistance and water repellency

Must be heat cured

Very high cost


Requires blasted surface

SILICONE

ALKYDS

Excellent exterior durability

Good chemical resistance

Good heat resistance

Excellent adhesion to most surfaces

Excellent gloss and color retention


Very good moisture resistance


Relatively high cost

SILICONE

ACRYLICS

Excellent gloss or color retention at elevated temperatures

Excellent heat resistance



Moderate chemical resistance

High Cost

INORGANIC

ZINCEvaporation-Polymerization

Offers one coat protection under many service conditions

Excellent exterior durabilityExcellent heat resistance

Excellent abrasion resistance

Hydrocarbon insoluble

Provides "galvanic" protection properties

Provides "permanent" primer capability when used inconjunction with proper topcoats and/or maintenance

practices

Self-curing (some types)

Selected ability to accelerate cure - depending on typeused

High cost

Requires excellent surface preparation--relative to many other types of coatings

Spray application only-- skilled applicatorsrequired for successful job

Not suitable for acidic or caustic serviceunless properly topcoated

Requires careful selection of tie coats andtopcoats for service involved.

Selected temperature and humidity effects--depending on type used

POLYURETHANES

Polymerization

Excellent gloss retention (aliphatic types)

Can be applied at low temperatures

Excellent chemical and solvent resistanceHigh hardness



Regular to high film build recoatable

Gloss drop with high humidity

Limited pot life

High costGood clean, dry surface required

Two-component

Isocyanate sensitivity


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Table 1-5Table 1-5 RECOMMENDED COATING TYPESRECOMMENDED COATING TYPES

REFINERIES AND TERMINALS - INLANDREFINERIES AND TERMINALS - INLAND

TYPE OF UNITTYPE OF UNIT GOODGOOD BETTERBETTER BESTBEST

Tanks - Cone Roof Alkyd Epoxy Ester Acrylic

Tanks - External Floating Roof Shell: Alkyd

Roof: Zinc/Vinyl

Shell: Epoxy

Roof: Zinc/Vinyl

Shell: Acrylic

Roof: Zinc/Vinyl

Structural Steel Alkyd Epoxy Ester Amine Epoxy

Control Equipment Alkyd Alkyd Alkyd

Piping Alkyd Epoxy Ester P.A. Epoxy

Stacks and Breeching

to 500 oF (260oC)

to 1000 oF (538oC)

Zinc/ Silicone Acrylic

Silicone


Silicone


Silicone

REFINERIES AND TERMINALS - COASTAL INDUSTRIAL ENVIRONMENTREFINERIES AND TERMINALS - COASTAL INDUSTRIAL ENVIRONMENT

TYPE OF UNITTYPE OF UNIT GOODGOOD BETTERBETTER BESTBEST

Tanks - Cone Roof Alkyd Epoxy Ester Acrylic

Tanks - Shell and External

Floating Roof

Zinc High Build Zinc High Build Vinyl Zinc High Build Epoxy

Structural Steel Epoxy Ester Epoxy Ester Zinc High Build Epoxy

Control Equipment Alkyd Chlorinated Rubber P.A.Epoxy

Piping Alkyd Epoxy P.A. Epoxy

Stacks and Breeching

to 500 oF (260oC)

to 1000 oF (538oC)


Silicone


Silicone


Silicone

2.42.4 INSPECTIONINSPECTION

The tightest specifications and the most corrosion resistant coating systems are money wastedwithout competent inspection. Because maintenance painting is not critical for the immediateoperation of an existing plant, and because a good paint job is not necessary for starting up anew plant, their priority levels are very low. Maintenance foremen, maintenance engineers, andunit inspectors are in the field already; therefore, one of them is usually asked to "inspect"painting as part of his daily routine. Assistant project engineers or craft inspectors are assigned

the task on new construction. Though these men might be eminently qualified in their own field,often they are not familiar with the coatings, equipment, inspection tools, or specificationsnecessary for making the intelligent decisions required in a good inspection effort.

Equally important as the qualifications of the inspector are his methods of carrying out theprogram. An inspection procedure should be written and included in the specifications andcontracts. It is important for both the customer and contractor to have this in writing. It allowsthe contractor know exactly what to expect and protects the customer from complaints orharassment because the job is being held up.


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It is advisable to include the following steps in the procedure:

1. Surfaces to be inspected for oil, grease, or any other contaminant which will not permitproper surface preparation.

2. All surface preparation to be inspected and approved before any coatings are applied.

3. Each coat to be inspected and approved before ensuing coats are applied.

It is desirable to stipulate that areas be kept squared up as the work proceeds. This reduces thechances of the inspectors missing poorly cleaned areas or skippers in the paint.

The inspector must be careful that the contractor does not use him as a tool for his own benefit.An inspector who is not careful will find himself pointing out every little discrepancy and thenwaiting while it is repaired. This is the paint foreman's job, not the inspector's. When theinspector is called to approve an area, he should assume the paint foreman has already inspectedand corrected the deficiencies. If a significant number of deficiencies are found, the entire area

under consideration should be rejected and the inspector recalled when it is ready for approval.

Taking an engineering approach toward painting, using qualified people who can write concisespecifications, select appropriate coating systems and ensure proper application by diligentinspection, can reassure management that money spent on painting is not wasted money.

2.52.5 TYPES OF COATINGTYPES OF COATING PROBLEMS AND CAUSESPROBLEMS AND CAUSES

2.5.1 Lifting

Lifting is defined as softening of an undercoat by application of a topcoat. It can be recognizedby a swelling or rising of the wet coating film and occasionally a shriveled surface. Peeling occurs

as this film dries or cures. It is principally caused by incompatibility of the two coats - solventsattacking the previous coat.

2.5.2 Blushing

The appearance of blushing will be that of a mist of milky haze and loss of gloss on the surface. Itcan be caused by the condensation of moisture in the wet coating film due to the cooling effectproduced by evaporation of solvents or incompatible thinner. Blushing can be corrected byreducing humidity, using a retarder or slow/dry thinner, or proper thinners.

2.5.3 Orange Peeling

This condition is easy to identify as the surface will have a dimpled appearance resembling an

orange peel. It is caused by droplets of coating drying prematurely due to a solvent which is toofast, an improperly handled spray gun, or an air temperature which is too high.

2.5.4 Checking, Crazing

Checking has the appearance of a parallel pattern of cracks and checks. It is generally caused byexcessive film thickness. An irregular pattern of tiny splits, scales or cracks is referred to as'crazing' and can result from the solvents softening the previous coat. Extreme temperaturechanges can cause both problems.


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2.5.5 Fisheyes

When small openings, holes or deep depressions form in wet film exposing previous coating orsubstrate they are designated as fisheyes. This problem is traced to surface contaminants, such as

silicone, that repel the wet coating.

2.5.6 Cracking

Cracking is a splitting or disintegration of coating by breaks through film. This results fromexpansion and contraction when a heavily pigmented coating is applied over a more flexibleundercoating that has greater extensibility. Inorganic zinc coatings also may crack when appliedat excessive thicknesses. This is commonly referred to as 'mud-cracking'.

2.5.7 Embrittlement

As coatings cure, they become harder and generally more impervious. Certain coatings,particularly most epoxies, embrittle on aging. Exposure to sunlight or alkali environmentaccelerates this process. The coating, at some stage, is vulnerable to cracking and chippingshould the steel substrate flex or be subjected to physical abuse.

2.5.8 Softening

Softening results from two causes: (1) coating is not resistant to corrosive environment and isbeing attacked and (2) lack of cure caused by poor formulation, manufacturing or impropermixing of two component materials. When a coating softens, it often stains, indicating areaction with corrosives.

2.5.9 Chalking

Organic coatings deteriorate by oxidation resulting in wearing away of the film and continuesuntil the binder is completely destroyed. Heavy chalking tends to accelerate erosion Measuring

yearly film loss with a thickness gauge tells when recoating is necessary.

2.5.10 Undercutting

Undercutting results when a corrosive penetrates the coating film through the pinholes ordamaged areas. Corrosion proceeds under the film with a lifting force that separates the filmfrom the substrate. In many cases, undercutting cannot be detected without cutting intosuspected areas with a knife. Primers having good adhesive properties and chemical resistancewill prevent or retard subfilm corrosion. With inorganic zinc coatings, undercoating does notoccur; corrosion is localized, and damaged areas are easily repaired.

2.5.11 Blistering

Blistering is defined as 'bubbling' in dry or partially dry films. Water found under blisters indicatesthat the coating was applied over a moist surface. Application of topcoats before undercoatsolvents have been released will cause solvent blistering. Certain inorganic zinc coatings areprone to cause topcoat blistering because of water soluble alkali residues that remain in the filmand are dissolved out in a wet atmosphere.


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2.62.6 PAINT COSTPAINT COST

When talking to users or potential users of blast cleaning equipment, the universal question isalways asked, "What is it going to cost to clean a specific surface?"

There are six obvious reasons why no one can give an accurate answer to this type of question.

1.

The Type of Surface to be Cleaned - No one can look at a surface and determine what is onthat surface. It might be easy to see that a green coat of paint is facing you; however, youhave no knowledge of what is under the surface coat. There may be three or four mils, or3/16" of old paint that have been applied over the many years the surface has been standing.Beneath, may be the original rust and mill scale which caused the initial coating to fail. Thereis no visual way of determining these factors and, even if there were, they could varyconsiderably over different areas of the surface.

2.

The Type of Abrasives Being Used - The type, particle size, shape and hardness have a largeinfluence on both the rate and degree of cleaning. Another prime consideration is thedelivered cost of the abrasive. Prices on abrasives can range from a locally available sand at$4.oo per ton to products costing as high as $800.oo per ton for specially manufacturedmetallic types.

3.

What Is Clean? - The surface preparation required must be clearly specified, for obviously, awhite metal blasted surface requires a more thorough job than does a brush-off blastedsurface. If you have five inspectors in a room, you could probably secure five differentdecisions as to what constitutes a clean surface to match the particular specification.

4.

Air Pressure Available at Nozzle - The nozzle air pressure has a tremendous effect on jobefficiency and the rate of production can be seriously hampered if the nozzle pressure is toolow.

5.

Operator Efficiency - The ability for the operator to perform an efficient job is one of thelargest variables.

6.

The Type and Efficiency of the Blast Cleaning Equipment - Using properly balanced blastingequipment can increase production two- or three-fold and has a great reflection on reducedcosts.

Table 1-6 AVERAGE JOB BREAKDOWNTable 1-6 AVERAGE JOB BREAKDOWN

Cost % of TotalCosts

Surface Preparation 15-50

Coating Material Cost 15-20Application 30-60

Accessory Products 2-5

Clean Up 5-10


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2.72.7 TEMPORARY PROTECTEMPORARY PROTECTIONTION

Essential features of any temporary preventive include the following: It must be easy to apply andeven more important, easy to remove. While it is on the metal, it must resist the corrosive effectsof humidity, fumes, fingerprints, weathering and water. These coatings prevent mechanicaldamage, such as nicks and burs, and preserve the

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