Stress Corrosion Cracking (SCC) Management Program for Onshore Pipelines

Abstract Stress Corrosion Cracking (SCC) on buried pipelines results from simultaneous presence of tensile stress, corrosive environment, and material that is susceptible to SCC. In-Line-Inspection (ILI) using smart tools have been effective in the industry for locating and sizing SCC on pipelines. However, there are some inherent limitations in ILI tools, therefore pipeline operators must develop a comprehensive SCC Integrity Management plan. Saudi Aramco operates a combined pipeline network of approximately 26,000 kilometers in length. A significant number of Saudi Aramco pipelines were built prior to 1980 with tape coated pipelines, thereby increasing the pipeline network susceptibility to SCC. Saudi Aramco initiated the inspection of these vintage pipelines using Ultrasonic Crack Detection In-Line-Inspection (UTCD ILI) tools and Electromagnetic Acoustic Transducer ILI (EMAT ILI) tools respectively to detect the presence of Stress Corrosion Cracking (SCC). In-Line-Inspection (ILI) results from a total of 21 pipelines showed presence of SCC. These cracks were later verified through direct assessment results. ASME B31.8S provides a criterion for gauging the severity of SCC by comparing the ratio between failure pressure and maximum allowable operating pressure (MAOP). This paper will cover details of the SCC integrity management planning including but not limited to the pre-validation SCC control and mitigation measures and post-inspection SCC mitigation measure.