Experience with Naphthenic Acid Corrosion in Low TAN Crudes

Abstract

Abstract Over the past few years, it has become evident that naphthenic acid corrosion can occur at much lower TAN levels than the previously reported crude TAN level of 0.5. Experience with naphthenic acid corrosion at low TAN levels is most often associated with sweet crudes (less than 0.5% Sulfur). This paper details the corrosion damage caused by sweet, low TAN crudes in a Crude/Vacuum unit designed for sour crude service. The crudes were primarily from West Africa. The various metallurgical upgrades used to improve plant reliability including furnace repairs, clad vacuum furnace headers and transfer lines, and vacuum tower cladding and internals work are described.