Effect of H2S concentrations on corrosion failure of L245NS steel in CO2-O2-H2S system

The corrosion behavior of L245NS steel with different gas environments and H 2 S concentrations in CO 2 -O 2 -H 2 S environment were studied by weight-loss test and surface characterization techniques. It was found that in the CO 2 -O 2 -H 2 S environment, the H 2 S, CO 2 , and O 2 reacted successively, and the deposition and hydrolysis acidification of elemental sulfur aggravated the occurrence of localized corrosion. When H 2 S changed in the low concentration range (1000 – 5000 ppmv), the reaction was dominated by the gradual development of the dense inner film, which decreased the corrosion degree. At 10,000 ppmv, the solution pH value would decrease. More H 2 S was involved in hydrogen evolution corrosion and enhanced the synergistic effect with O 2 to accelerate the corrosion.