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

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.

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

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

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.

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)

PIPE JOINTS screwed flanged welded Completed Weld soldered

Cast-Iron Pipe Joints

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

Screwed Fittings

Flange Pipe Fittings

Solder Fittings

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

Piping Drawings

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

Pipe Fittings

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

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

Types of Drawings

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

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

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