Chapter 22 Industrial Process Piping

Learning Objectives After completing this chapter, you will –Describe different types of pipe and their respective uses –Define methods of connecting pipes –Identify pipe fittings and valves –Identify symbology associated with industrial process piping

Part I Definitions

Piping –Any kind of conduit used in a wide range of applications Plumbing –Small diameter pipes that carry liquids, solids, or gases Water Natural gas Waste

Definitions Process piping –Transport of fluids between storage tanks and process equipment Transportation piping –Carry products hundreds of miles Petroleum products Gases Coal slurries

Definitions Pipe drafting –Visualization of pipes and fittings in various orthographic and pictorial views Double line Single line –Most visualization problems for beginners Isometric Flow diagram –Schematic, non-scale diagram of system layout

Double- and Single-Line Drawings

Definitions Piping drawing –Most complex Scale drawing Provides several views –Plan –Elevation –Section All equipment, dimensions, and notes shown Drawn from flow diagrams, manufacturer specifications, and mechanical drawings

Definitions Piping isometric –Pictorial drawing –Illustrates pipe run in three dimensions –Information from piping drawings Spool drawing –Drawn orthographically –Shows all pipe and fittings used to assemble a segment –Usually non-scale

Part II Types of Pipe

Cast Iron and Steel Most common –Commercial –Industrial Carbon steel –Strong –Relatively durable –Can be welded and machined –Not as expensive as copper

Copper Manufactured by hot piercing and rolling Corrosion resistant Good heat transfer properties Expensive Applications –Instrument lines –Food processing –Residential water lines

Plastic PVC –Applications Acids Salt solutions Alcohols Crude oil

Plastic Polyethylene –Temperature resistant to 150°F –Applications Water Vent piping of corrosive and acidic gases Conduit –Electrical and phone lines –Water lines –Farm sprinkler systems –Chemical waste lines

Clay Corrosion proof Applications –Sanitary and industrial sewers –Chemical waste, except hydrofluoric acid

Glass Chemical resistant Transparent Clean Applications –Chemical plants –Food and beverage industries –Pharmaceuticals

Wood Continuous stave wood pipe –Used in Pacific Northwest Redwood and Douglas fir Transport of water

Steel Tubing Small diameter Flexible Applications –Boilers –Superheaters –Hydraulic lines Automotive Aircraft

Pipe Sizes Availability –1/8” to 44” diameter Process piping –1/2” to 24” diameter Instrument lines –1/8” to 1/2” diameter

Pipe Sizes Nominal pipe size (NPS) –1/8” to 12” diameter Inside diameter (ID) –14” diameter and greater Outside diameter (OD) Inside diameter –(Outside diameter) – 2*(Wall thickness)

Part III Pipe Connection Methods

Pipe Connections Welded –Butt-welded –Socket-welded –Solvent-welded Screwed Flanged Soldered Bell and spigot

Pipe Connections Mechanical unit Flaring

Pipe Fittings Enable pipe to change direction and size Provide for branches and connections Types –Welded –Screwed

Welded Fittings

Screwed Fittings Union –Connection in a straight run of pipe Coupling –Attaches two lengths of pipe Half coupling –Used for instrument connections

Screwed Fittings Street elbow –90-degree elbow –Can be attached directly to a fitting Bushing –Reducing fitting Plug –Seals the screw-end of a fitting

Screwed Fittings

Flanges Creates a bolted connection point Circular piece of steel –Contains center bore equal to pipe ID –Several bolt holes spaced evenly around center bore

Flanges Types –Slip on –Weld neck –Blind –Stub end –Reducing and expander –Orifice

Flanges

Valves Purpose –Provide on/off service –Control and regulate fluids –Maintain constant pressure –Prevent pressure buildup –Prevent backflow

On/Off Valves Gate –Exclusively provide on/off service –Fluid flows with minimal friction and pressure loss Plug –Cock valve –Requires ¼ turn to open and close –Low throttling ability –Used on small diameter lines

Regulating Valves Globe –Regulates pressure –Fluid flows in “S” pattern Angle –Special type of globe valve –Creates 90-degree direction change Butterfly –Regulates pressure in low-pressure situations

Backflow Valves Check –Prevent backflow Swing check –Similar to gate valve in design –Operates by gravity –Best for low-velocity liquids

Safety Valves Keep pressures at or below a given point –Pop safety Used for steam, air, and gas lines –Relief Used for liquids

Control Instantaneous control and adjustment –Flow –Pressure –Temperature Contains a controller, or actuator Operation –Electric motor –Air or hydraulic cylinder

Part IV Pipe Drawings

Piping Drawings Requirements Pipe length dimensions Dimension locations Location of fittings and valves Elevation location of all pipe direction changes in section views

Piping Drawings Requirements Size and type of valves and fittings Pipe diameter, contents, and identification number Pipe flow arrows Equipment names and numbers

Piping Details Special pipe connections or fittings Special valve arrangements Small diameter pipe and fitting assemblies Special pipe support arrangements

Piping Details Tank attachment details Minor structural alterations Operating and installation procedures

Piping Details

Piping Isometric

Summary Piping drawings are used in both commercial and residential applications Piping drawings may be orthographic or axonometric Selection of pipe and fittings are application specific