New method corrects criterion for evaluating corroded pipe

Abstract

An improved method for evaluating the remaining strength of corroded pipes has been developed. The method is based on the original B31G method but reduces the method's inherent over conservatism. The modified criterion permits metal-loss anomalies of greater size to remain in service at the current maximum operating pressure. And, for anomalies which exceed the newly recommended allowable size, it will require less pressure reduction for maintenance of an adequate margin of safety. This article outlines how the original criterion was developed and its shortcomings.