CORROSION RATE OF CARBON STEEL IN CONDENSED WATER AND HUMID GAS AT HIGH CO2 PRESSURE

The paper is devoted to the study of the corrosion rate of pipeline steels in CO2-Saturated Water and in Water-Saturated CO2 as a function of pressure, temperature and exposure time. Tests were carried out at temperature ranging from 25 to 60°C and at CO2 and pressure ranging from 20 to 145 bar at different exposure time from 48 up to 400 hours. The results were discussed in order to understand the effect of corrosion product scales on the corrosion rate. The corrosion rate in every conditions tends to decrease with the exposure time. Corrosion rates in the aqueous phase were one or two order of magnitude higher than the values obtained in CO2 saturated with water. Scales morphology was assessed by means of SEM and metallographic analysis. The layer formed by corrosion products was composed by cementite, cementite and iron carbonate or iron carbonate depending on experimental conditions.