An electrochemical investigation on the effect of the chloride content on CO2 corrosion of API-X100 steel

This research argues that the corrosion rate for high strength steel in CO2-saturated solutions reaches a maximum at a threshold chloride content. At 20 °C, the corrosion rates increased from 60 μA/cm2 in 5 g/L solutions to a maximum of 185 μA/cm2 in 15 g/L solutions, and then became less in the more concentrated solutions. The anodic dissolution accelerated at 90 °C and the cathodic reactions decelerated with adding 10 vol.% oil where the chloride content effect remained relatively the same. Some EIS experiments demonstrated an agreement with the polarization results without confirming that threshold effect of chloride on charge transfer.

► Corrosion rates increased up to a threshold chloride content and then decreased.
► Anodic reactions accelerated at 90 °C and cathodic reactions decelerated by oil.
► Adsorption governed the interfacial corrosion interactions in OCP conditions.