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H2S gas when exposed to metal can be responsible for both general and localized corrosion, which depend on several parameters such as H2S concentration and the corrosion product layer formed. Therefore, the formation of passive film on 316L steel when exposed to H2S environment was investigated using several analysis methods such as FESEM and STEM/EDS analyses, which identified a sulfur species underneath the porous structure of the passive film. X-ray photoelectron spectroscopy analysis demonstrated that the first layer of CrO3 and Cr2O3 was dissolved, accelerated by the presence of H2S-Cl-. An FeS2 layer was formed by incorporation of Fe and sulfide; then, passivation by Mo took place by forming a MoO2 layer. NiO, Ni(OH)2, and NiS barriers are formed as final protection for 316L steel. Therefore, Ni and Mo play an important role as a dual barrier to maintain the stability of 316L steel in high pH2S environments. For safety concern, this paper is aimed to point out a few challenges dealing with high partial pressure of H2S and limitation of 316L steel under highly sour condition for the oil and gas production system.

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H2S corrosion of equipment and pipeline system failures in oil and gas industry is a major concern of researchers as it involves high maintenance costs. Therefore, this study discusses the effect of H2S partial pressure at 0, 3 and 15 bar towards the corrosion behaviour of 316L austenitic stainless steel in chloride environments. The 316L steel exposed to 0 bar pH2S was slightly corroded due to the presence of Cr element which has increased the corrosion resistance of the 316L steel. However, pit penetration rate of 316L steel was increased by 90.1% from 0.07 mm/year at 0 bar pH2S to 0.74 mm/year at 3 bar pH2S and decreased by 83.2% at 15 bar pH2S due to the saturated sulfide content in the test solution. Therefore, 316L steel at 3 bar shows highest corrosion effect due to the dissolution of Cr element at 316L steels surface, thus enhanced passive film breakdown.