Effect of carbon dioxide on corrosion of tubular steel in high hydrogen sulfide and carbon dioxide environments

Purpose - The present work primarily aims to study the corrosion characterization of tubular steel API-P110 in high H2S containing solution with or without CO2. Design/methodology/approach - Corrosion behaviors of steel in buffered solutions containing 50 percent H2S and various levels of CO2 concentration were investigated via weight-loss method, SEM and EDS. The effects of CO2 on corrosion occurred on the metal were analyzed by electrochemical techniques. Findings - Corrosion rates of steel decreased as the CO2 content in H2S/CO2 solution increased. It was observed for the tubular steel to experience an increase in corrosion rate at concentrations 17 percent CO2 or 34 percent CO2 in 50 percent H2S while when further increasing concentration of CO2 to 50 percent the corrosion rate decreases. Increased CO2 content in H2S/CO2 led to fewer anions desorbing and fewer reactants adsorbing, e.g. H +, H2CO3. As a result, cathodic reaction rate decreased and the amount of hydrogen absorbed decreased. Originality/value - The experimental results showed that corrosion alleviated when increasing CO2 content in high H2S and CO2 containing environment.