Parametric Evaluation of Naphthenic Acid Corrosion and Sulfidation Under High Temperature High Velocity (HTHV) Conditions

Abstract Predicting the corrosivity of crude oil remains a critical challenging aspect of refinery operations, directly impacting feedstock purchase decisions, and the assessment of process equipment serviceability and planned maintenance. This paper covers certain results of a comprehensive Joint Industry Project designed to quantify the effects of crude oil chemistry on naphthenic acid corrosion (NAC) under realistic refinery conditions. Systematic high temperature, high velocity testing incorporated controlled variations in temperature, wall shear stress, total acid number, and active sulfur content. In this paper, the study investigated the interaction of naphthenic acid corrosion and sulfidation under high temperature, high velocity conditions, generating data at wall shear stresses (WSS) up to 1000 Pa, temperatures of 600–700 °F, and total acid numbers (TAN) of 1–5.5 mg KOH/g. Using the hot oil flow loop, tests were performed with naphthenic acid in mineral oil to replicate low, medium, and high H2S environments. Results revealed critical WSS thresholds for NAC and sulfidation, dependent on TAN, temperature, and alloy composition. NAC corrosion rates showed no WSS dependence below a critical limit, but above it, exhibited distinct behaviors at low vs. high TAN. Sulfidation exhibited breakaway behavior above a critical WSS, with some alloys showing reduced sensitivity.