The Effect of H2S Pressure on the Formation of Multiple Corrosion Products on 316L Stainless Steel Surface.

M Shah,N K Othman,N Yaakob,M T M Ayob,R Rosdan,Z Embong

doi:10.1155/2020/3989563

Abstract

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.

Highlights

Southeast Asia is a rich source of natural gas and petroleum, especially Brunei, Vietnam, Malaysia, and Indonesia
A commercial austenitic stainless steel type 316L with a chemical composition listed in Table 1 was used. en, optical emission vacuum spectrometer analysis was performed on the stainless steel using the point-to-plane excitation technique, following ASTM E 1086 Standards [6]. e 316 L steel sample was machined into a dimension of 20 × 20 × 3 mm3, abraded with a series of silicon carbide papers, polished with a diamond spray, rinsed with distilled water, degreased with acetone, dried at room temperature, and stored in a desiccator
E corrosion rate increased by 90.1% from 0.07 mm/yr at 0 bar pH2S to 0.74 mm/yr at 3 bar pH2S due to aggressiveness of sulfide ions in test solution [1]. e data show that overall mass loss is symmetrical with H2S pressure, and sulfide ions play a significant role in determining the kind of corrosion scales and reducing the surface protection of 316L steel [1]

Summary

Introduction

Southeast Asia is a rich source of natural gas and petroleum, especially Brunei, Vietnam, Malaysia, and Indonesia. From GlobalData statistic, Malaysia and Indonesia will contribute around 80% and 70% of the Southeast Asia’s total crude oil and natural gas production from eight planned projects in 2025, respectively. In upstream oil and gas applications, the most desirable alloy should be made of a strong material with good localized corrosion resistance, low cost, and suitable mechanical characteristics. Austenitic stainless steel type 316L (UNS S31603) has excellent corrosion resistance to the electrochemical properties of the passive film that forms on its surface. Us, stainless steel alloys with a higher composition of Cr and Ni prevent the iron from rusting and provide heat resistant properties [1]. 316L steel is a low carbon alloy that contains molybdenum (Mo), which makes it more corrosion resistant, especially in highly sour conditions [1]

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Results

Conclusion