Polyethylene pipe can be made in diameters ranging from 1/2 inch to 63 inches in diameter. It is most commonly found in 3/4-inch, 1-inch and 1 1/4-inch sizes. Because polyethylene pipe is manufactured in a continuous extrusion process, it is also available in almost any length. Polyethylene pipe can be purchased in rolls hundreds of feet long.
Water Pipe Standards
The American Water Works Association has issued standards for polyethylene pipes used to carry water and waste-water in homes and businesses. AWWA standard C-901-08 applies when the pipe has a diameter of ½ inches to 3 inches. AWWA standard C-906-07 applies to large-diameter polyethylene pipe with diameters from 4 inches to 63 inches. These standards define how polyethylene water and waste-water pipes must be labeled, the pressure ratings they must endure, and test methods to ensure that they do not corrode in the presence of water or leech chemicals into the water. Both of these AWWA standards have also been adopted by the American National Standards Institute (ANSI).
Polyethylene pipe can be used to encase iron pipe to protect it from corrosion. These polyethylene-encased pipes range from 3 inches to 63 inches in diameter. ANSI standard C105 applies to this type of PE pipe. The International Standards Organization (ISO) has developed standard ISO 8180 for PE-encased pipe. These standards define the corrosion resistance the protective polyethylene pipe must demonstrate, testing methods for determining pipe quality and installation methods.
The Standard Dimensional Ratio or SDR is a measure of pipe wall thickness. In the "Facility Piping Systems Handbook," author Michael Frankel says, "the SDR is found by dividing the average outside diameter of the pipe by the wall thickness ... It is possible for a pipe of have different SDRs depending on whether the I.D. (internal diameter) or O.D. (outer diameter) is the controlling factor." The American Society for Testing and Materials also has standards regarding SDR of PE pipes. SDR is used to determine pressure ratings and bursting pressure for polyethylene pipe.