Investigation on the influence of corrosion inhibitor concentrations on top-of-the-line corrosion

Purpose The purpose of this study is to investigate the influence mechanisms and performance effects of varying corrosion inhibitor concentrations on top-of-the-line corrosion. Design/methodology/approach A wire beam electrode (WBE) and electrochemical techniques were applied to investigate the effects of CORR-series corrosion inhibitor concentration on macro-cell current distribution and interfacial electrochemical processes, with morphological characterization further revealing the heterogeneity of the product film. Findings Although the CORR-series inhibitor could effectively reduce the anodic dissolution process, it suppresses the formation of protective corrosion product films beneath condensed liquid droplets under high-pressure CO2 environments. Excessive inhibitor dosage not only fails to enhance corrosion inhibition efficiency, but also amplifies corrosion risks by promoting macro-cell corrosion currents. Originality/value This study systematically investigated the nonmonotonic relationship between corrosion inhibitor concentration and protection efficiency through an integrated approach combining WBE technology with electrochemical methods. The findings could provide operational guidelines for concentration optimization of corrosion inhibitors in submarine oil/gas pipeline systems.