Plastic Pipes Conference Association # 2010 Vancouver
M.Lamborn
Good resistance to Rapid Crack Propagation (RCP) is considered to be important to the field performance of polyethylene (PE) pipe. Even though RCP occurrences in PE pipe are very rare, it remains important to understand the RCP phenomenon to ensure that pipes are designed to avoid RCP events. The characterization of RCP performance depends on a variety of factors, such as the test conditions (temperature and pressure), pipe geometry (diameter and wall thickness), and choice of RCP test. Presented here are an accumulation of results from various experimental programs undertaken by us to develop a basic understanding of RCP in PE pipes and the test methods used to characterize RCP performance. Data are presented showing critical pressure critical temperature failure surfaces for MDPE, HDPE, and bimodal HDPE pipe, and their use in the selection of RCP resistant pipe based on specific service conditions is discussed. Data are presented to demonstrate the phenomenon of false arrest and to show how this can lead to misleading and incorrect interpretations of RCP performance from single-point S4 tests at excessively high pressures. The results of experimental work to assess the influence of pipe size on S4 test results are also presented. Analysis of these data, combined with consideration of the effects of shear lips and residual stress effects, indicates that an Irwin-Corten relationship can be employed to provide conservative estimates RCP performance for different size pipe, subject to specific restrictions on the relative geometries between pipes.
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