Machinery's Handbook, 31st Edition
Plastic Pipe 2769 (NPS) is given, along with the schedule or IPS designation to indicate the full dimensional characteristics of the pipe. Sizes: Plastic pipe size designations are often tied to the outside diameter, as they are for steel pipe according to the NPS system. PVC has its own ASTM pipe sizing standard, while CPVC is available in either ASTM standard sizing or CPVC-CTS (Copper Tube Standard). Dimensions for schedule 40, 80, and 120 PVC pipe are given in Table 12. Alter native sizing methods are the Standard Inside Dimension Ratio (SIDR) method and the Standard Dimension Ratio (SDR) method. The SDR method uses OD and wall thickness, and SIDR uses ID and wall thickness. The SIDR method is useful when designing flow- critical applications. The SDR method is useful when pressure rating is of primary con cern. PEX is most commonly sized as tube, which is covered in the section Plastic Tube starting on page 2773. Table 12. PVC Pipe Dimensions, Schedule 40, 80, and 120, Sizes Up To 12 ″ PVC Pipe Size, inch Outside Diameter, inch Inside Diameter, inch SCH 40 SCH 80 SCH 120 1 ⁄ 8 0.405 0.249 0.195 … 1 ⁄ 4 0.54 0.344 0.282 … 3 ⁄ 8 0.675 0.473 0.403 … 1 ⁄ 2 0.84 0.602 0.526 0.48 3 ⁄ 4 1.05 0.804 0.722 0.69 1 1.315 1.029 0.936 0.891 1 1 ⁄ 4 1.66 1.36 1.255 1.204 1 1 ⁄ 2 1.9 1.59 1.476 1.423 2 2.375 2.047 1.913 1.845 2 1 ⁄ 2 2.875 2.445 2.29 2.239 3 3.5 3.042 2.864 2.758 3 1 ⁄ 2 4 3.521 3.326 … 4 4.5 3.998 3.786 3.574 5 5.563 5.016 4.768 … 6 6.625 6.031 5.709 5.434 8 8.625 7.942 7.565 7.189 10 10.75 9.976 9.493 … 12 12.75 11.889 11.294 … Pressure Ratings: Pressure rating of plastic pipe is highly dependent on material, as well as wall thickness. Most commercially available plastic pipe will be rated by the manufac turer. PEX pressure ratings are 160 psi at 74°F and 100 psi at 180°F. Pressure ratings for polyethylene pipes depend on the material formulation. Pressure ratings of standard sizes of PVC pipe are given in Table 13. Pressure ratings must be derated with elevated temperature. Derating factors for PVC pipe are given in Table 14. Further derating must be done to account for water hammer, and this is often 20 percent. Connections: Some plastic pipe is threaded for use with threaded fittings. Threading normally follows the NPT standard. If the pipe is not threaded, a variety of other connec- tion methods may be used. PVC pipe is usually bonded into socket fittings using solvent cement. PE pipe can be joined using heat fusion and electrofusion. In some cases, tube fittings may be used to connect plastic pipe. Expansion with Temperature: Plastic pipe expands and contracts with temperature by an amount dependent on both temperature change and material. This must be considered
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