Corrosion rate of high CO2 pressure pipeline steel for carbon capture transport and storage

The paper deals with the effect of pressure, temperature and time on corrosion rate of pipeline steels in CO2 saturated water and in humid saturated CO2 gas in the range from 25 to 60° C and pressure from 20 to 145 bar, up to 400 hours of exposure. The results of weight loss tests show very high rates in the aqueous phase, one or two order of magnitude higher than the values obtained in CO2 saturated with water, but remaining in any case much lower than values extrapolated by De Waard and Milliams model at high partial pressure. Depending on temperature and rpessure, cementite and iron carbonate scales can grow on metallic surface reducing corrosion rate. SEM and metallographic analysis evidenced the evolution of scale from defective cementite-based layer to protective compact carbonate scale.