Effect of chloride concentration on carbon steel corrosion of boilers supplied with feed water in refineries

Abstract. Corrosion has a significant economic and environmental impact in most of the oil sector facilities. One of the most widely used materials in these facilities is carbon steel. The corrosion of carbon steel caused by dissolved carbon dioxide (CO2) has been recognized to pose a serious threat to the oil and gas industry. Numerous factors affect CO2 corrosion including temperature and water composition. Effects of temperature and Cl- concentration on the corrosion behavior of carbon steel in CO2-saturated environments were investigated for boiler used in refineries supplied with feed water of certain composition with different Cl- concentration. Corrosion rate was measured using electrochemical linear polarization method. The purpose of this study is to investigate the effect of chloride concentration on the final corrosion rate of refinery boiler made of carbon steel supplied with feed water at two different temperature. The study found that the corrosion rate decreased with the increase of Cl- concentration and that decrease was more significant at 30°C. At 30°C, initial corrosion rate was 1.18mm/yr., and was reduced to 0.041mm/yr. at Cl- concentration of 1000mg/l while at 45°C, initial corrosion rate was 0.885mm/yr., and was reduced to only 0.478 at Cl concentration of 1000mg/l. These results could be explained by the reduced penetration of CO2 gas caused by the higher Cl- concentration.