This paper first presents a brief description of naphthcnic acid corrosion and the main factors which influence its onset and severity. After a brief discussion of traditional control methods, it proceeds to a discussion of chemical inhibition, which is a relatively new control technique. Chemical inhibitors can be divided into two broad classifications: phosphorus-based and non-phosphorus-based. Three types of phosphorus-based inhibitors have been reported: amine-neutralized phosphate esters, alkaline earth phosphonate phenate sulfide plus trialkyl phosphate, and thiazolines plus di- and trialkyl phosphates. Non-phosphorus based inhibitors include: thiazolines, organic polysulfides, and sulfonated akyl phenols. A description of each inhibitor and its effectiveness in the laboratory and field is presented.
Keywords: naphthenic acid, corrosive liquids, high temperature corrosion, inhibitors, phosphates, phosphites, phosphonate phenate sulfides, thiazolines, organic polysuifides sulfonated alkyl phenols