Enhancements in Susceptibility of Stress Corrosion Cracking (SCC) on Liquid and Gas Pipelines

Abstract Saudi Aramco is a fully integrated, global petroleum enterprise and a world leader in exploration, production, refining, transportation, distribution, shipping and marketing. The company runs a vast network of vintage pipelines from pre-1979 period to transport oil, gas and refined products all over the Kingdom of Saudi Arabia. Saudi Aramco initiated the inspection of these vintage liquid and gas 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). Following the inspection, Saudi Aramco has discovered SCC on both liquid and gas pipelines. Saudi Aramco built on the hybrid criteria for identifying SCC susceptible segments using ASME B31.8S [1], CEPA [2], and TTO8 [3] criteria to prioritize its network for conducting inspections on SCC. The criteria were based on pipeline design and operating parameters, environment, age and condition. A total of 43 pipelines (both liquid and gas) were inspected for SCC, where, 21 pipelines exhibited SCC which was also verified through direct examination. This paper discusses in more detail how Saudi Aramco capitalized on the existing industry literature to enhance the SCC susceptibility criteria, prioritized pipelines for SCC inspection, and the major findings and highlights realized from this activity. The study team from Saudi Aramco used logistic regressions [4] to identify factors that increase or decrease the likelihood that cracking is present. The findings were used to identify liquid and gas pipelines susceptible to cracking to include in the future ILI run.