Based on an investigation of the Small Scale Steady State (S4) test, an integrated computational/ experimental approach has been developed in order to assess the fracture behaviour of polyethylene (PE) gas distribution pipe material during rapid crack propagation (RCP). This paper describes the use of the results obtained from the S4 test and program modified from PFRAC (Pipeline Fracture Analysis Code) to evaluate the fracture toughness of the material, G(d), which could not be directly obtained from the test, and to predict critical pressure, p(c), for RCP in a full scale PE pipe. The contact algorithms are developed to consider the opening pipe wall impact against a series of containment rings and the capabilities of PFRAC are also extended. Since G(d) is evaluated, the investigations are made on it to the effect of temperature and wall thickness. In addition, procedures to evaluate the critical pressure for the S4 test pipe are also discussed.