# 1985 York
Since 1980, samples of field failures in polyethylene pipe for gas distribution have been collected and analyzed at Battelle in a field failure library. The majority of these failures were found to occur from slow crack growth as a result of a secondary load. Most often, the location of these failures were at points of stress concentration at socket or saddle joints in the boundary between the pipe and the fitting, although other failures have been received which occurred due to rock impingement or bending in the absence of any joints, fittings, or obvious stress concentration.
Microscopic features of representative failures will be shown and discussed, including fractures at socket joints, saddle joints, and squeeze-off locations as well as at points of rock impingement and bending.
Author(s) : Lustiger, Markham
In developing optimum polyethylene resins for gas distribution piping, it is important to maximize resistance to slow crack growth (SCG) which is the most common mode of material-related field failure in this application. It is proposed that SCG resistance is related to both tie molecule concentration and the...
Author(s) : Lustiger, Markham, Cassady
The phenomenon of environmental stress cracking, which occurs when polyethylene is placed under stress until failure in a detergent environment, is beiag studied both as a means of quality control and for determining the relative resistance to sluw crack growth in polyethylene gas pipe. Two techniques used to measure...