Summary of the study
The presence of dissolved hydrogen sulfide in upstream or refining fluids is known to encourage corrosion and hydrogen-induced mechanical failures of carbon or low alloy steel. The extent of the hydrogen uptake/permeation response of steel is an important parameter that dictates its sulfide stress cracking (SSC) susceptibility, alongside the material microstructure, tensile strength, and applied mechanical stress state. Historically, the solution pH and the gaseous partial pressure of H2S (PH2S, bar) are used to evaluate an aqueous environment’s severity during materials corrosion cracking qualification tests. However, in recent years, reports in the literature from steel cracking tests have made clear that the H2S fugacity (fH2S) and actual dissolved H2S concentration ([H2S]aq) rather than the actual PH2S ought to be used to more closely judge or predict a material cracking performance. The particular aim of this project was to generate data and knowledge on the hydrogen uptake and permeation response in different steel grades as a function of the different corrosive environments’ H2S fugacity. The parameter of fH2S is different to PH2S as the former is more representative of the non-ideality and severity found in high pressure environments.
This first JIP was conducted between 2019 and 2021. The work was continued between 2023 and 2026 in a second project phase to gather more data on this topic