# 1982 York
Long term failure of plastics pipes is governed by very slow crack propagation. Assessing pipe materials' resistance to this slow growth is time consuming and in the case of recent very tough medium density polyethylenes is difficult using constant load tests. It is shown that fatigue tests can achieve comparative results in an acceptable time scale and rank these materials in the same order as other longer term tests of real performance.
The fatigue method thus has potential for assessing very tough grades.