Crevice Corrosion of Duplex Stainless Steel in Simulated Sour Gas Environments

Abstract

The crevice corrosion behavior of 22% Cr duplex stainless steel (SS), which has become widely used because of its high strength and stress corrosion cracking (SCC) resistance, was investigated in simulated sour gas conditions. The crevice corrosion is accelerated with increasing partial pressure of H2S and temperature, decreasing pH of the test solution, and the addition of sulfur. The duplex SS was more resistant to the crevice corrosion than AIS1^1) 316 SS in the H2S-Cl-environment.A simple model of the crevice corrosion, in which the initiation process and the mode of crevice corrosion were discussed, was proposed. The crevice corrosion incubation time based on this model was calculated, and the effect of the crevice gap and the partial pressure of H2S was clarified. The mode of the crevice corrosion changed with the partial pressure of H2S, which was explained by the stability of the NiS film and the depassivation pH in the crevice.

Influence of Aging on Intergranular Corrosion of a 25% Chromium-5% Nickel Duplex Stainless Steel

“…They have higher strength, better corrosion resistance, and better stress corrosion cracking resistance than austenitic SS. [1][2][3][4][5][6] Because of these properties, duplex SS are used increasingly in petroleum refineries, petrochemical industries, and marine applications. Duplex SS have been available commercially for many years, but they were not used widely before development of the highalloy duplex SS because of problems in hot workability and their susceptibility to intergranular corrosion (IGC) after welding and heat treatment.…”

Crevice Corrosion of Corrosion-Resistant Alloys in Simulated Sour Gas Environments

“…12 Figure 12 shows the effect of the partial pressure of H 2 S on the pH d of the 40%Ni-20%Cr-3%Mo alloy together with the result on 5%Ni-22°roCr-3%Mo duplex SS. 10 The pH d value of the high-Ni CRA decreased with increasing partial pressure of H 2 S, which is opposite of the tendency of the duplex SS. This difference in the pH d comes from the difference in Ni content between those alloys.…”

“…The crevice corrosion in a H 2 S-CIenvironment is thought to be basically similar to that in an 02-C1 environment 10 :…”

“…As mentioned in the previous work, consideration of the chemical equilibrium in the crevice is useful for discussing crevice corrosion in H 2 S-CIenvironment. 10 In narrow crevice, dissolved H 2 S is spent by the reaction with Ni t ion to form Ni-S compound because the diffusion of chemical species is restricted. As a result, the crevice solution shows a decrease in the H 2 S concentration when it is compared with the bulk solution.…”

“…e ' 9 In our previous work, the crevice corrosion of duplex SSs was investigated in H2S-CL environments and the effects of environmental variables were clarified. 10 In this paper, the crevice corrosion behavior of CRAs with various contents of Ni, Cr, and Mo is investigated and the roles of those elements on the crevice corrosion are discussed.…”