Optimisation of Carbon Steels for Sour Service

Abstract

Abstract Failures in sour environments are a major concern to oil producing companies because these failures do not usually involve material loss (wall thinning). These time – dependent failures can release toxic gas (hydrogen sulphide) to the environment. Of major concern is the exposure of facilities designed for sweet service to wet hydrogen. Hence, this paper reviews the theory of HIC. For new production facilities such as Pipelines, free-water knock out ( FWKO) drum and flare stack, material selection using the well-known immersion test NACE TM0177/ NACE TM02 84 is highlighted. Structure – property relationship is of paramount importance in design, hence regression equations were used to establish the effect of chemistry and microstructure on mechanical properties. Recommendations were made for repair of equipment / facilities that failed during the transition from sweet to sour services. Eventually, a rule based form of expert (knowledge based) system was used to formalize a number of relationships. These rules are in the form of IF -THEN relationships. A brief explanation of the expert system is given as the basis of rule format.