Janson
# 1992 Eindhoven
New research and development particularly concerning the long-term strain of modern PE resins have created a basis for a simple and adequate method for tightness testing of plastics pressure pipelines. Thus, it is shown that for plastics pipes subjected to constant internal hydraulic pressure, it is quite possible to predict the increase of the tensile strain in the pipe wall during the time of tightness testing solely based upon the initially observed strain increase. This is due to the fact taht the strain plotted in a lin strain versus log time-diagram follows a rectilinear course and consequently does also the water volume change in the pipeline.
