Assessment of organic acid–induced corrosion behavior in carbon steel heat exchanger tubes of natural gas refineries

Purpose One significant risk threatening reliable and continuous flow of gas from refineries to end users, both residential and industrial, is the corrosion in refinery facilities as a result of thermal decomposition of monoethylene glycol (MEG) in the heat exchangers of the MEG recovery unit, which is used as an inhibitor to prevent hydrate formation in offshore and onshore transmission lines. The purpose of this research is to investigate the effect of the accumulation of weak acidic ions generated from the thermal decomposition of MEG on the corrosion of equipment and process pipelines. Design/methodology/approach This study examines the effects of acetic, formic and oxalic acids on the corrosion behavior of SA179 carbon steel using a Box–Behnken experimental design. The corrosion rate in the different concentration of weak acids obtained from the potentiodynamic polarization test, expressed in millimeters per year (mmpy). Findings The results indicate that acetate is the principal corrosive species, markedly elevating corrosion rates, whereas formate induces only a modest increase and oxalate shows negligible or slightly inhibitory effects. Statistical modeling verified a robust linear correlation between acid concentration and corrosion rate, with corrosion intensifying as pH decreases. The optimal conditions for minimizing corrosion arise at the lowest concentrations of acetate and formate. Originality/value The findings highlight that corrosion control in MEG regeneration systems should focus primarily on limiting acetate and formate accumulation.