Evaluation of cracking conditions for butt-welded joints of polyethylene pipes

Pipelines made of polyethylene are used to transport fluids and gases of low temperature (cold water, gaseous fuels) and various aggressive fluids as well as water of elevated temperature, used in technological processes. The work shows the results of calculations and analysis of critical-size defects in the forms of surface and internal fissures in the butt-welded joints. The initiation of cracking process in a pipeline can occur at the critical size of the fissure. The creep phenomenon of plastic at the temperature of 23°C was taken into account in the analysis. The critical fissure sizes were determined for nominal working pressure in pipelines. The paper is a continuation of an earlier research work published by the authors in the same journal in 2013 [6].