Guidance for Selecting SCC Direct Assessment Locations and Estimation of Re-Inspection Intervals

Abstract

A significant amount of research and development has been carried out on the mechanism of the stress corrosion cracking of underground pipelines. This paper describes the results of a study, co-funded by PRCI, the US DOT, and pipelines companies, to bring together the results of these various studies in the form of a set of guidelines that will assist companies in identifying the most likely SCC locations on their systems and in predicting how frequently inspection or other mitigation is required. The guidelines have been developed along mechanistic lines, and are divided into four “steps” representing: susceptibility to SCC, crack initiation, early-stage growth and dormancy, and crack growth to failure. For each step, a series of Research Guidelines has been derived from the results of individual research papers or studies. These Research Guidelines may or may not be easily validated against field data. The SCC Guidelines were then developed based on one or more Research Guidelines. Wherever possible, the SCC Guidelines have been validated against field data, but in some cases currently un-testable SCC Guidelines were defined because they offer a potentially unique opportunity to identify where and when SCC might occur.