1. PIPING DRAWINGS
C H A P T E R T W E N T Y- O N E

2. OBJECTIVES
1. Identify cast iron, brass, copper, and thermoplastic pipe and
tubing fittings.
2. Draw and label common pipe joints using ANSI/ASME standard
designations.
3. Draw a multiview or pictorial piping drawings using standard
schematic symbols.
4. Draw the schematic symbols for valves and identify flow
direction.

3. Steel and Wrought-Iron Pipe
Steel or wrought-iron pipe is commonly used for water, steam, oil, and gas
Steel pipe is available as:
Black pipe for natural gas
Galvanized pipe for water distribution

4. Cast-Iron Pipe
Cast-iron (C.I.) pipe is used for water or gas service and as soil pipe
Generally water and gas pipes are connected with bell and spigot joints or flanged joints
Cast-iron pipe is brittle and settling can cause fracture unless the joints are sufficiently flexible

5. SEAMLESS BRASS AND COPPER PIPE
It is used in plumbing for supply, soil, waste drain, and vent lines. It is also particularly suitable for process work where formation of scale or oxidation in steel pipe would be troublesome. Brass pipe and copper pipe are available in straight lengths up to 12'.
Brass pipe, generally known as red brass pipe, is an alloy of approximately 85% copper and 15% zinc. Copper pipe is practically pure copper with less than 0.1% of alloying elements.
Brass pipe and copper pipe should be joined with fittings of copper-base
alloy to avoid galvanic action resulting in corrosion.

6. PLASTIC AND SPECIALTY PIPES
A wide variety of plastic pipe, both rigid and flexible, is used in construction.
Plastic pipe is lightweight, corrosion proof, resistant to many chemicals, and has a smooth inner surface which offers low flow resistance.
PVC (polyvinyl chloride)
CPVC (chlorinated polyvinyl chloride)
HDPE (high-density polyethylene)

7. PIPE JOINTS
screwed
flanged
welded
Completed Weld
soldered

8. Cast-Iron Pipe Joints

9. Pipe Fittings Pipe fittings are used to: Join lengths of pipe
Provide changes of direction
Provide branch connections at different angles
Effect a change in size

10. Screwed Fittings

11. Flange Pipe Fittings

12. Solder Fittings

13. VALVES
Valves are used to stop or regulate the flow of fluids in a pipeline.
Common types are:
Single-Line Valve Drawing
Double-Line Valve Drawing
Gate valves
Globe valves
Check valves
Pressure-reducing valves
Safety valves

14. Piping Drawings

15. UNDERSTANDING PIPING DRAWINGS
CAD systems have standard symbols available, and templates for drawing piping symbols are a convenient timesaver when you are sketching piping.
Standard Piping Symbols

16. Pipe Fittings

17. Single and Double Line PIPING DRAWINGS
Piping Symbols Used in a Double-Line Drawing and a Single-Line Drawing
(Courtesy of Softdesk, Inc.)
Single-Line Drawing
Double-Line Drawing

18. Types of Drawings
Piping may also be shown in a dimetric drawing or in orthographic projection
In a developed piping drawing, vertical pipes are revolved into the horizontal plane or horizontal pipes revolved into the vertical plane so the entire installation can be shown on one plane

19. Types of Drawings

20. Dimensioning Piping Drawings
In dimensioning piping drawings, give distances from:
Center to center,
Center to end, or
End to end of fittings or valves
Give the lengths of all straight runs
Show the size of each pipe

21. STEEL AND WROUGHT IRON PIPE
Steel or wrought iron pipe is used for water, steam, oil, and gas.
The American National Standards
Institute/American Society of Mechanical Engineers (ANSI/ASME) has developed dimensions for 10 different schedules of pipe

22. CAST IRON PIPE
Cast Iron Pipe, Thicknesses and Weights—American National Standard
Cast Iron Pipe Flanges and Fittings