Electrochemical investigations on the corrosion behavior and corrosion natural inhibition of API-X100 pipeline steel in acetic acid and chloride-containing CO ₂-saturated media

The purpose of this experimental work was to investigate selected electrochemical aspects of the corrosion behavior of API-X100 in CO ₂-saturated, multivariable- controlled corrosion media. Utilizing potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), the corrosion rates, anodic dissolution, cathodic regimes, and free interfacial interactions were discussed. The tests were performed with respect to the environmental factors of 10, 20, 30, 40, 50, and 60 g L ^-1 chloride and of 10, 20, 30, 40, 50, and 60 mL L ^-1 acetic acid at 20 and 90 °C in the absence and presence of 10 vol% crude oil. The corrosion rates exhibited a peak value with respect to the chloride content while they increased continuously with the acetic acid content irrespectively from temperature. The corrosion behavior was nearly independent from chloride in the presence of acetic acid and oil demonstrated an effective inhibition in all conditions. EIS results showed an agreement with the polarization findings and indicated adsorption-controlled mechanisms.