A Corrosion and Cracking Testing of Stainless Steels and Nickel Alloy under Dense Phase CO2 Transport Conditions

Abstract Carbon Capture and Sequestration (CCS) is an important part of the global greenhouse CO2 gas emission reduction through decarbonization of different industries (i.e., cement, steel, power plants, etc.). CCS also enables low-carbon hydrogen production. CO2 transport via pipelines and injection in underground reservoirs requires a good understanding of materials corrosion and cracking performance under dense phase CO2 transport and injection conditions especially when there are different impurities in the CO2 such as H2O, SO2, NO2, O2, and H2S. This work explores corrosion and cracking performance of 316L stainless steel, 22Cr stainless steel, 6Mo, 625 Nickel alloy, and S13Cr-110 stainless steel under dense phase CO2 pipeline transport conditions at 75°C, 218bara CO2, 200ppm chloride containing brine, and different impurities (i.e., SO2, NO2, O2, and H2S). Materials were tested in the water phase, CO2 phase, and water/CO2 interface. Four-point bend cracking and pitting corrosion testing showed 316L stainless steel pitting and cracking. Presence of O2 is an important cause of 316L stainless steel materials cracking under the conditions tested in this work. Water/CO2 interface was found to be the most corrosive part of the system mainly because of fast replenishment of water with O2 coming from the CO2 phase. S13Cr-110 showed significant corrosion damage under the conditions tested in this work but Nickel alloys, 6Mo, and 22Cr performed well and showed good corrosion and cracking resistance.