Comparison of corrosion behaviour for X-65 carbon steel in supercritical CO2-saturated water and water-saturated/unsaturated supercritical CO2

The corrosion behaviour of X65 carbon steel was evaluated in supercritical carbon dioxide (SC-CO2)-saturated water, water-saturated SC-CO2 and under-saturated SC-CO2 conditions at 80 bar and 50 °C to simulate conditions of CO2 transportation in carbon capture and storage applications. A detailed assessment of localised corrosion and corrosion product film morphology/chemistry was conducted. Localised corrosion is shown to be a fundamental consideration in all environments, particularly in water-containing CO2 systems. Corrosion was shown to occur when under-saturated water was present in the system, however, no dissolution of the steel was observed at water contents below 1600 ppm at the conditions considered.