Influence of Gas Partial Pressure Ratio on Corrosion of 20# Pipeline Steel in H2S/CO2 Environment

The corrosion behavior of 20# pipeline steel in H2S/CO2 environments at normal temperature as well as high pressure was studied by weight loss measurement, and the surface analysis of the steel was performed by SEM and EDS. The results show that the general corrosion along with slight localized corrosion occurred in this system. At the low gas partial pressure ratio, the corrosion rate increased first, then decreased and increased again at last. According to the corrosion law, the range of low gas partial pressure can be divided into two areas. In these two corrosion areas, the percentage variations of corrosion product elements were similar, corrosion produts were mainly FeS and FeCO3.