L51609 A Modified Criterion for Evaluating the Remaining Strength of Corroded Pipe

From its inception, the B31G criterion was intended to embody a large factor of safety to protect pipelines from failure. Experience has shown that the amount of conservatism embodied in the criterion is excessive, resulting in the removal or repair of more pipe than is necessary to maintain adequate integrity. Therefore, it is desirable to have a modified criterion that will still preserve adequate pipeline integrity but will result in less removal of pipe. A modified criterion that meets this requirement is described in this report.

A new and improved criterion was desired because of the known excess conservatism in the original B31G method. Even though the use of the B31G criterion has undoubtedly helped pipeline operators to avoid many unnecessary cut outs, the excess conservatism continues to cause some unnecessary cut outs that could be avoided without compromising safety. Thus, this project was undertaken to-devise a modified criterion that, while still assuring adequate pipeline integrity, would eliminate as much as possible the excess conservatism embodied in the existing criterion.