An overview of naphthenic acid corrosion in a vacuum distillation plant

After 5 years processing about 6500 m3/day of reduced crude oil with an average total acid number of 1.2 mg KOH/g and total sulfur content of 0.8 wt%, a vacuum distillation plant had its operations interrupted to suffer maintenance and inspection. Following theoretical considerations, this work shows the inspection outcome and tries to stress the several morphologies resulting from the naphthenic acid attack as well as different types of action by which the naphthenic acid corrosion occurs in a vacuum distillation plant.