Material selection for hydrogen sulfide-containing media
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Among the common media, when should carbon steel be chosen? When should one choose stainless steel or even duplex stainless steel?
Could you be more specific? Could you give some examples? Thank you
It is generally believed that in a wet hydrogen sulfide environment, there are two main forms of degradation: (1) corrosion caused by FeS generated as a result of anodic reactions, leading to a uniform thinning of the metal wall thickness, as well as localized corrosion in the form of pitting and perforation. (2) The hydrogen atoms generated by the cathodic reaction can also penetrate and diffuse into the steel, causing damage such as hydrogen embrittlement, hydrogen-induced cracking, and sulfide stress corrosion cracking (SSC). SSC is a common form of failure; water in the transformed gas is a necessary condition for corrosion to occur. The presence of CO2 accelerates corrosion, while the presence of CN- facilitates the penetration of hydrogen into the steel. Based on this, grades with a carbon content reduced to below 0.03% by mass (such as 304L, 315L, etc.) can be used, or stable stainless steels can be chosen. And if it is more than 20°C above the gas dew point with no liquid water formed, then carbon steel can be considered suitable for use
Carbon steels that can be used for HIC testing are also those in which liquid water is present, right? Can all the carbon steels listed in SY/T 0599 be used?