ROLES OF HzS IN THE BEHAVIOR OF ENGINEERING ALLOYS: A REVIEW OF LITERATURE AND EXPERIENCE

Hydrogen sulfide (H$) has long been associated with the cause of corrosion damage and sulfide stress cracking (SSC) in high strength steels and high hardness weldments used in oil and gas production, petroleum refining, and petrochemical/chemical processing. Other applications where sulfide species have produced environmental cracking include heavy water production, electric power, marine applications and many others where sulfate reducing bacteria can flourish and oftentimes produce substantial amounts of HZS. H$S has also been associated with internal blistering, hydrogen induced cracking (HIC) and stress oriented hydrogen induced cracking (SOHIC) of carbon steels used in refinery vessels in wet H2S service and pipelines containing sour (HzS-containing) fluids. In recent years, new stainless alloys have been implemented in lieu of conventional steels in many applications where H# corrosion is particularly severe. These materials have been used along with chemical inhibitors to mitigate corrosion. These alloys, however, may in some cases also be susceptible to SSC, localized corrosion and anodic stress corrosion cracking (SCC) in sour environments. In this review, the behavior of carbon and low-alloy steels, stainless steels, and nickel alloys in sour environments is discussed. Emphasis is placed on the identification of the various types of HzS-related corrosion and environmental cracking that can occur, the origin and mechanisms, and the methods of control.