Users' Guide on Bending Limits for Polyethylene Gas Pipes. Volume 1. Topical Report, January 1988-January 1992.

摘要

Polyethylene (PE) gas distribution pipe can be easily bent during installation because it is flexible. As a result, PE pipe systems may not require elbows to achieve the desired layout. Furthermore, PE pipe can be coiled. This makes the pipe easier to handle and transport, and depending on the length of pipe within the coil, numerous butt joints may not be required. The report contains guidelines for the safe bending of PE gas pipes during installation. In the research investigation, suggested guidelines for bending PE pipe were based on laboratory test data and a service life analysis. For the analysis, it was assumed that the pipe contained a sharp flaw prior to bending; the time for the flaw to grow and propagate through the pipe wall was then determined. The analysis incorporated the following installation and service parameters: material, pipe size and standard diameter ratio, presence or absence of socket fittings, bend radius, time required to make the bend, installation temperature, mean operating pressure and temperature, and initial flaw dimensions. Volume 1 presents bending limits guidelines in graphical form consisting of several plots giving life expectancy as a function of bend radius for several parameters such as pipe size, temperature, etc. Volume 2 presents details of the analysis used to predict service life.