Material Science RCP # 2006 Washington DC
The small scale steady state (S4) test is a convenient and relatively inexpensive means of measuring the critical pressure (Pc) for rapid crack propagation in plastic pipes. The critical pressure measured in the S4 test is not the same as the critical pressure measured in a full scale test, which more directly reflects the field service performance. A well known gas dynamics theory based correlation function exists to relate S4 and full scale results for polyethylene pipes, but the universality of the correlation coefficient used in the function is not certain, especially when considering pipes made of tough engineering plastics like polyamide-11. Full scale and S4 rapid crack propagation testing was carried out on the same lot of 4-inch IPS SDR-11 pipe made of polyamide-11 (PA-11). A correlation coefficient was established that is quite different from that accepted for polyethylene (PE).