Development of Guidelines for the Identification of SCC Sites and the Prediction of Reinspection Intervals for SCC DA

A significant amount of research and development (R&D) has been carried out on the mechanism of the stress corrosion cracking (SCC) of underground pipelines since the phenomenon was first recognized in the 1960’s.  This R&D has taken the form of both laboratory-based experimental investigations and the correlation of measurements and observations on operating pipeline systems to the occurrence and severity of SCC in the field.  An effort is underway, 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 e companies to not only locate SCC on their systems but also predict how frequently inspection or other mitigation is required.

The guidelines are being developed along mechanistic lines, and are broken down into four “steps” or “modules” representing: susceptibility to SCC, crack initiation, early-stage growth and dormancy, and crack growth to failure.  The paper will highlight the guidelines that have been developed from the R&D literature from the past 40 years and their validation against field data.  Eventually, the guidelines could be incorporated into future revisions of the NACE SCC Direct Assessment Recommended Practice RP0204.