Electrochemical evaluation of chemical treatment effect on corrosion process of carbon steel in oil atmospheric distillation environments

The effect of chemical treatment composed of mono ethanol amine and a commercial imidazoline based corrosion inhibitor on corrosion process of carbon steel in an acid sour solution typically found in oil atmospheric distillation plants was studied. Electrochemical impedance spectroscopy characterization showed the aggressiveness of the sour media alone. A protective behaviour is evidenced at different pH values, which is enhanced when inhibitor is added. The better corrosion control is attained at pH 6.5 and 30 mgL^-1 of inhibitor. This behaviour is explained on the basis of the formation of a mixed corrosion film composed of inorganic - organic compounds. SEM characterization supports these results.