Stress Corrosion Cracking (SCC) Direct Assessment in accordance with the guidance set out in NACE SP0204 is an accepted method for assessing the threat of SCC in High Consequence Areas in the US, as prescribed for gas transmission pipelines by CFR 192 Sub-part O. Although operators have used excavations as part of their integrity management strategies for SCC for many years, the formalized method for gathering, interpretation and application of information that is set out in NACE SP0204 has only been applied for less than ten years.
During a recent Joint Industry Project involving eight major North American natural gas transmission operators, the current status and application of SCC Direct Assessment has been reviewed. Several of these operators have developed in-house procedures incorporating the relevant guidance from NACE, CEPA and ASME, and over 160 SCC Direct Assessment excavations in accordance with the requirements of NACE SP0204 have been undertaken during the last five years. This paper reviews the development of the procedures, their in-field application and the use of the interpreted data to further refine the SCC Direct Assessment processes.