Naphthenic acids combat naphthenic acid corrosion

The aim of this work is to study corrosiveness of fractions of naphthenic acids (NA) distilled every 10°C from commercial NA mixtures of four suppliers "F", "A", "M", and "K" towards carbon steel UNS G10100 (C1010) at their boiling points and at 195°C, and examination of inhibitive properties of NA distillation residues of the four commercial NA for low temperature (∼200°C) naphthenic acid corrosion (NAC). Corrosiveness of NA is a function of their molecular weight (boiling point), and temperature. Corrosiveness of different fractions of NA distilled every 10°C from industrial NA mixtures of four suppliers "F", "A", "M", and "K" was examined at their boiling points and at 195°C. The corrosiveness depends on temperature and is significantly higher at boiling points of fractions than at 195°C. The corrosiveness of the fractions from "F", "A", and "M" showed a maximum at ∼ 300°C, and "K" at ∼ 320 to 330°C. The fractions of NA "K" are two-threefold more corrosive than fractions of NA "F", "A", and "M". It was shown that NA distillation residues (high molecular weight NA) inhibit low temperature (∼200°C) NAC of carbon steel. Their efficiency depends on their concentration, varying from 81 to 94% at concentrations of 25 to 200 ppm of the NA distillation residues and does not depend on type of carbon steel.