Review of naphthenic acid corrosion in oilrefining

Naphthenic acid corrosion is a major concern for the oil refinery business. While much is now known about the phenomenon, it is still not completely understood because of the complex influences on corrosion of the type of acid and other constituents in the crude oil and the effects of both temperature and fluid flow. A review of this form of corrosion has been undertaken with respect to the role of crude oil composition, temperature, fluid velocity, physical state (vapour or liquid), pressure, and materials of construction. Simple measures of corrosivity based on the total acid or neutralisation number are insufficient. The sulphur content of the crude is important but the extent to which the various sulphur containing compounds act as inhibitors or corrodents is not understood. There is little knowledge also of the nature of films formed on the steel surfaces under operating conditions and the role of natural inhibitors that may be present in crudes requires more attention.