EFFECT OF TEMPERATURE ON WET CO_2 CORROSION OF 3Cr PIPELINE STEEL

摘要

For their superior CO_2 corrosion resistance and relatively low cost, the new generation of low Cr (3 to 5%) bearing steels seem to be a good choice to meet the demand of preventing wet CO_2 corrosion of sub-sea wet gas pipelines. The data of extensive laboratory assessment and field experience have confirmed that low Cr bearing steels have an improved corrosion performance when immersed in CO_2 containing solutions, while the resistance to wet CO_2 corrosion has not been clarified. In this paper the effect of temperature on wet CO_2 corrosion of 3%Cr pipeline steel was investigated. Wet CO_2 corrosion environment in sub-sea wet gas pipelines was simulated in a high temperature and high pressure autoclave. Aseries of experiments were carried out at wet gas temperature of 30~90°C, while the cooling temperature was kept relatively low to provoke water condensation on the surface of coupons, ranging from 10°C to 30°C. The corrosion rate was determined by weight loss measurement. Scanning Electron Microscope (SEM) and Energy Dispersive Spectrum (EDS) were employed to analyze the corrosion scales.