Pipe and vessel failure probability

This generalised approach to the estimation of failure probability is based on a pragmatic and scientific analysis of actual service failure statistics. Approximation strategies have been devised in order to estimate failure probability at the leakage level Psub(L) and for rupture Psub(C). Psub(L) is estimated from global statistics for leakage failure by using an observed correlation that a geometric proportionality measure of size and shape and weldments gives a direct measure of failure probability. This is the most powerful single influence of all in the determination of Psub(L), but the influence of plant age is also worth considering. The estimate may then be scaled for other factors if their influence is known. Psub(C) may be estimated given a Psub(L) estimate, partly by using a fracture mechanics model which gives a carpet of Psub(C)/Psub(L) curves. Observed statistics are also used. (author)