Determination of critical pressure for full scale PE gas pipe using small scale test results

The Small Scale Steady State (S4) test has been recently developed in order to assess the fracture behaviour of polyethylene (PE) gas distribution pipe material during rapid axial crack propagation. Based on an investigation of the S4 test, a simulation model of S4 test has been developed. This paper describes the use of the results obtained from the S4 test to evaluate the fracture toughness of the material, G_d, and to predict critical pressure, p_c, for rapid crack propagation (RCP) in a full-scale pipe. If p_c has been determined, then crack propagation can be prevented. This will ensure that a crack will arrest shortly after initiation, thus limiting the damage. In addition, procedures to evaluate the critical pressure for the S4 test pipe are given and the relationship between the critical pressures in the S4 test and that in the full-scale pipe is also discussed.