Effect of Carbon Dioxide and Hydrogen Sulfide on the Localized Corrosion of Carbon Steels and Corrosion Resistant Alloys

摘要

Carbon steels, low alloy steels (LAS) and corrosion resistant alloys (CRA) used in the upstream oil and gas industry may be susceptible to localized corrosion. Several variables control the occurrence of localized corrosion, including alloy composition, heat treatment, and environmental effects such as temperature, and concentration of chloride, oxygen and other species. Regarding carbon and LAS, it is recognized that even small concentrations of hydrogen sulfide (H_2S) can have an important effect on general corrosion rate when compared to environments where carbon dioxide (CO_2) controlled the corrosion phenomenon. However, there are still several unknowns about the effect of H_2S on pitting, which is the most common mode of sour service failure. Regarding CRA, there is contradictory information on the effect of H_2S and CO_2 in the environment and how it affects pitting corrosion initiation and propagation. The purpose of this review is to discuss the environmental effects, especially H_2S and CO_2 on pitting susceptibility of LAS and CRAs.