External pressure testing of 4-in-dia high-density polyethylene pipe

Many of the investigations dealing with the determination of the time-to-fa ilure of high-density, polyethylene (HDPE) pipes involve internal pressure tests. HDPE pipe, however, can also be subjected to external pressure such as from underwater laying, vacuum, or burial. For the particular case of un iform external pressure, only, a small amount of data detailing the time-to -failure of such pipes is available, and no definitive testing procedure ex ists. Here, an experimental apparatus and corresponding testing procedure a re developed to explore remedies for this situation. On the basis of the da ta thus obtained, a three-coefficient equation relating time, temperature, and pressure is generated. The failure predictions from this design basis e quation are in good agreement with the available data existing in the liter ature.