Abstract
Literature information concerning the effect of liquid hydrocarbons on flow-induced sweet (FIS) corrosion is limited and most of the currently available prediction models exclude the roles of liquid hydrocarbons in FIS corrosion. Results of an innovative test method, employing a rotating cylinder electrode tester and liquid hydrocarbon-brine two-phase fluids, successfully isolated the roles of hydrocarbons in FIS corrosion. It was found that the concurrent presence of liquid hydrocarbon and water phases, which were flowing but distinctively separated, promoted localized (interfacial) corrosion at the hydrocarbon/brine interface. Evidently formation of passive carbonate films was severely hampered at the liquid hydrocarbon/water interface. When both phases were in either a quiescent condition or severely mixed, however, the interfacial corrosion did not occur. The severity of the interfacial corrosion was sensitive to rotating speed, temperature, and liquid hydrocarbon type. Influencing the chemi-sorption crystallization process of protective iron carbonate films, the liquid hydrocarbon phase appears to destabilize the formation of passive iron carbonate films on a carbon steel surface under FIS corrosion environments.
