ME444 ENGINEERING PIPING SYSTEM DESIGN

CHAPTER 2 : PIPING MATERIALS

LAST SESSION

1. INTRODUCTION 2. STANDARDS3. BASIC UNITS4. BASIC FLOW IN PIPE5. QUICK LOOK AT PIPE DRAWINGS

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CONTENTS

1. PIPES2. VALVES3. ACCESSORIES4. PUMPS

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1. PIPES

PIPE SELECTION:• MATERIAL • SIZE• THICKNESS

CONSIDERATIONProperties of the fluid° Corrosive or scale-forming properties ° Unusual characteristics, for example, viscosity or sludgesService conditions° Pressure (including surges and transients)° Corrosive environment for exposed piping or buried piping° Soil loads, bearing capacity and settlement, external load

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PIPE SIZES

NPS = NOMINAL PIPE SIZE (INCHES)DN = DIAMETER NOMINAL (mm.)

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STANDARD SIZES

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STANDARD SIZES (CONT’D)

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STEEL PIPE THICKNESS

A schedule number indicates the approximate value of the expression

1000 P/S,whereP is the service pressure and S is the allowable stress.

Higher schedule number means the thicker pipe.

[SEE TABLE E2.1 IN PIPING HANDBOOK]8

STEEL PIPE TABLE

[SEE APPENDIX ข.8] 9

STANDARD DIMENSION RATIO

SDR = Outside diameter / Thickness

SDR is used mostly in plastic pipes .

For comparison; a DN100 sch.40 steel pipe SDR = 114.3/6.02 = 19

Examples

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PVC PIPE SIZES

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PRESSURE RATING

Class – PSIGPN – BARS

Actual allowable working pressures depend on MATERIAL and TEMPERATURE

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PRESSURE RATING

Temperature (Celcius)

Allo

wab

le W

orki

ng P

ress

ure

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PIPE MATERIALS

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CARBON STEEL PIPES

TYPES:SEAM/SEAMLESSBLACK/GALVANIZED

JOINTS:THREADEDWELDEDFLANGED

APPLICATIONS:GENERAL PRESSURE PIPING

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STAINLESS STEEL PIPESStainless steel pipes have Cr, Ni and Mo content.

1.Ferric type: resist corrosion, magnitic response, cannot be harden: ASTM 430

2.Austenitic: corroded under chloride, non-magnetic response: ASTM 304 – Most popular, ASTM 316, general purpose: food-drug, chemical, etc.

3.Superaustenitic: high corrosion resistance4.Martensitic: high temperature applications,

magnitic response: ASTM 4105.Duplex (1+2)

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CAST IRON PIPES

TYPES:CAST IRON/DUCTILE CAST IRONPLAIN/COATED

JOINTS:CAULKED

APPLICATIONSSOIL, WASTE, DRAIN

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COPPER PIPES

TYPES:HARD (ANNEALED) / SOFT (DRAWN)THICKNESS: K (THICK), L, M (THIN)

JOINTS:SOLDEREDFLAREDFLANGED

APPLICATIONS:COMPRESSED GAS, MEDICAL GAS

Copper pipes don’t like ammonia18

OTHER METAL PIPES

ALUMINUM – Light weight, low thermal inertia

BRASS (Cu+Zn) – General sanitary pipe, valves.

LEAD – Radioactive waste

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PLASTIC PIPESADVANTAGES1. Resistance to a very wide range of sanitary and chemical effluents2. Resistance to aggressive soils3. Availability in long lengths4. Light weight5. Low resistance to fluid flow6. Generally low initial cost

DISADVANTAGES1. Poor structural stability requiring additional support2. Susceptibility of some types of plastics to physical changes resulting from exposureto sunlight3. Generally low resistance to solvents4. Poor fire resistance

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MAJOR TYPES

PVC, CPVCPP, PP-RPE, HDPE, PB

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OTHER PIPE MATERIALSCONCRETE

NON-REINFORCE/REINFORCE CLASS I TO 5GENERAL WASTE AND DRAIN

GLASSFOR CORROSIVE LIQUIDS i.e. ACIDS.

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JOINTS

CAULKED JOINT FOR CAST IRON PIPES

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JOINTS FOR STEEL PIPES

FLANGED WELDED24

FLANGES

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JOINTS FOR COPPER TUBES

SOLDERED OR BRAZEDFLARED

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OTHER TYPES

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JOINTS FOR PLASTIC PIPES

HEAT-FUSED JOINT

SOLVENT CEMENT JOINT

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FITTINGS

WYE TEE ELBOW

BEND

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FITTINGS (FOR WELDING)

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2. VALVES

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GATE VALVES

Advantages1. Good shutoff characteristics.2. Bidirectional.3. LOW pressure loss

Disadvantages1. Not quick opening or closing valves. 2. Require large space3. High-fluid velocities when near-fully-closed

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GATE VALVES

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Advantages 1. Good shutoff capability2. Good throttling capability3. Shorter stroke4. Available in tee, wye, and angle patterns, 5. Easy to resurface the seats

Disadvantages 1. Higher pressure drop 2. Requires greater force or a larger actuator to seat the valve (with pressure underthe seat)

ApplicationsFlow regulation

GLOBE VALVES

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GLOBE VALVES

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BALL VALVESAdvantages1. Provides bubble-tight service.2. Quick to open and close.3. Smaller in size than a gate valve.4. Multiport design offers versatility5. Required less actuated force

Disadvantages1. Not suitable for sustained throttling applications.2. Suspended particles can settle causing failure.3. Small size

Applications1. Air, gaseous, and liquid applications requiring bubble-tight service2. Low-point drains and high-point vents 3. Instrument root valves4. Cooling water and feedwater systems5. Steam service

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BALL VALVES

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BUTTERFLY VALVES

Advantages1. Compact and light weight.2. Quick acting (quarter-turn) 3. Available in large sizes: NPS 11⁄₂ (DN 40) to over NPS 200(DN 5000).4. Low-pressure drop

Disadvantages1. Limited throttling (low differential pressure)2. Must avoid turbulent:

- Locate 4 to 6D downstream from turbulent source- Orient valve stem carefully…How?

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BUTTERFLY VALVES

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ORIENTATION OF VALVE STEM

CORRECT INCORRECT40

VALVE ACTUATORS

• Pneumatic• Electric

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VALVE PRESSURE DROP

PQCv ∆

=

Q IN GPM∆P IN PSI

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CHECK VALVES

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CHECK VALVES

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RELEIF VALVES

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AIR RELEASE VALVES

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PRESSURE REDUCING VALVESPRV, pressure regulator, pressure regulating valve, pressure control valve

Direct acting

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PRESSURE REDUCING VALVESPRV, pressure regulator, pressure regulating valve

Pilot operated

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OTHER VALVES

DIAPHRAGM VALVESPLUG VALVESNEEDLE VALVES

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3. ACCESSORIES

Water hammer arrestersStrainerPressure guagesFlow metersPIPE HANGERSEtc.

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STRAINERS

WYE STRAINER BUCKET STRAINER

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Y - STRAINERS

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PRESSURE GUAGE

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TEMPERATURE GUAGE

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FLUID FLOW METER

Rotameter

Propeller/turbineDifferential head-Pitot tubeDeflectionVariable area (rotameter)MagneticUltrasonicEtc.

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TURBINE FLOW METER

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ORIFICE FLOW METER

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WATER TANK ACCESSORY

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PIPE HANGERS

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HANGING INSULATED PIPES

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4. PUMPS

DISPLACEMENT PUMPS DYNAMICS PUMPS

CENTIFUGRALTURBINERECIPROCATING ROTARY

High head High flow61

TYPES

Lobe/gearPiston Diaphragm

Positive displacement Dynamics

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RANGE

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CHARACTERISTICS

Dynamics

PositiveDisplacement

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PISTON PUMP

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FLOW FLUCTUATION

Install receiver tank to reduce fluctuation66

DIAPHARGM PUMP

Avoid contact between fluid and pump mechanism67

ROTARY GEAR PUMP

For high viscosity fluid68

ROTARY SCREW PUMP

For very high viscosity fluid69

CENTRIFUGAL PUMP

End suction Split-case70

CENTRIFUGAL PUMP CONSTRUCTION

End suction pump71

IMPELLERS

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LEAKAGE JOINTS

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INSTALLATION

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NEXT SESSION

• Pipe drawing. Symbols. • Cost estimation. • Theory of flow in pipes. • Calculation of pressure drop in pipes. • Energy balance in fluid flow.

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HOMEWORK 21) Design a check valve that can be built easily.

2) Find the weight per meter of a DN150 sch40 steel pipe filled with water.

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