Machinery's Handbook, 31st Edition
Metal Pipe 2767 pipe. A swivel ring fits over the hub for the purpose of bolting the joint together. The swivel ring flange facilitates flange alignment. There are a number of compact flange designs that include tapered sections or proprietary designs. Always comply with the manufacturer’s specifications when using this type of flange connection. Flanges are specified using the nominal pipe size, type and facing, pressure class, mate rial, schedule, and applicable standard. Since surface condition is critical to flange seal - ing, all surfaces must be carefully inspected before use, and all scratches, rust, and burrs removed. Gasket selection must be done with consideration of temperature, internal pres sure, cycling conditions, vibration, material compatibility, erosive/corrosive potential of the media, and potential to leach substances into the fluid. Gaskets may be ring-type, spi - ral wound, or sheet. They must be inspected carefully before use for damage, and should never be trimmed or re-used. Bolts must be of the proper material and grade for the joint, and tightened gradually according to standard procedure. Lubricant of the proper type should be used if recommended, and a torque wrench should be employed upon final tightening to ensure proper compression. Welded and soldered pipe connections should be made according to applicable stan- dards and safety precautions. Steel pipe is often welded, while copper pipe is typically joined by soldering. In soldered pipe joints, capillary fittings are used. Expansion with Temperature: Metal pipe expands and contracts with temperature by an amount dependent on both temperature change and material. This must be considered when designing pipe systems where temperature will change between installation and operation, or when the fluids pumped will be above or below installation temperature. Use the factors in the following table to calculate length increase or decrease for each pipe run. Linear Expansion and Contraction Factors per 100 Feet of Pipe Temperature Change, ° F Pipe Material Steel Copper PVC FRP PP & PVDF 0 0 0 0 0 0 20 0.15 0.25 0.62 0.26 2.00 40 0.30 0.45 1.30 0.52 4.00 60 0.46 0.65 2.20 0.78 6.00 80 0.61 0.87 2.80 1.05 8.00 100 0.77 1.10 3.50 1.31 10.00 120 0.92 1.35 4.25 1.57 12.00 140 1.08 1.57 4.80 1.83 14.00 160 1.24 1.77 5.50 2.09 16.00 180 1.40 2.00 6.30 2.35 18.00 200 1.57 2.25 7.12 2.62 20.00 Multiply length of pipe by the table factor and divide by 100 for the increase or decrease in length. Plastic Pipe.— Plastic pipe is lighter and less expensive than metal pipe, and can be more chemically inert. It is generally non-conductive and thermally insulative. Due to its smooth inner surfaces, it can offer better flow characteristics than metal pipe. However, plastic pipe can be affected by ultraviolet radiation and extreme temperatures. The most common plastic pipe is suitable for nonflammable liquids up to 150 psi (1000 kPa) and temperatures up to 140°F (60°C). Plastic pipe expands with temperature much more than metal pipe. Materials: Many types of plastics are available as plastic pipe. Polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS), and polyethylene (PE) are the most common in the United States. Crosslinked polyethylene (PEX) is common in Europe and gaining pop ularity in the United States.
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