# 1995 Edinburgh
One of the main design criteria for limiting the operational pressures of polyethylene (PE) gas pipes is its resistance to rapid crack propagation (RCP). Below a critical pressure the crack arrests but above the whole pipeline may be fractured. The paper discusses the critical pressures measured during European and USA round robin test programmes to evaluate the new Small Scale Steady State (S4) laboratory test methid.
These critical pressures are compared with the results on the same pipes using the full-scale test method so as to try and establish a correlation factor between them. Once established, it is intended that the relatively inexpensive S4 method will replace full-scale testing.