Effect of CO in Stress Corrosion Cracking of Carbon Steel Pipelines in CCS Environments –part 2

Carbon capture and storage (CCS) is recognized as a proven technology to potentially mitigate emissions and meet net-zero objectives. Utilization of pipeline infrastructure for transporting CO₂ from capture and treatment sites to geological storage locations is a common method. It is necessary to understand the material integrity under CO₂ transportation pipeline operating condition and in the presence of impurities in the CO₂ stream, which can potentially cause corrosion, cracking, fracture and fatigue issues. In the previous publication (AMPP paper no. C2024-20647), it was reported that carbon steel X65 line pipe grade, both base and weld materials, exhibited pseudo-passivity with the additions of CO thus susceptible to stress corrosion cracking (SCC) under supercritical CO₂ conditions with water. The presence of oxygen weakened the pseudo-passivity of carbon steel with CO impurity, resulting in higher corrosion rate and enhanced SCC susceptibility. In this follow-up study (part 2), it further explored the safe limits of CO and O₂ partial pressures on SCC and acquired the key results. Additionally, this study investigated the impact of CO and O₂ on fatigue behavior of carbon steels in dense phase CO₂ saturated with water.