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

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

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