Discussion of the CO2 corrosion mechanism between low partial pressure and supercritical condition

The corrosion behaviour of X65 pipeline steel at various temperatures for different immersion time under low CO2 partial pressure and supercritical CO2 condition were investigated by weight loss measurements and surface analysis techniques. By comparing the characteristics of CO2 corrosion product scale formed under experimental conditions and the variation rule of corrosion rate with temperature, the CO2 corrosion mechanism under low partial pressure and supercritical condition was studied. To explain the big difference of corrosion rate between low CO2 partial pressure and supercritical CO2 condition, thermodynamic calculation of the solubility of CO2 in H2O were discussed. (C) 2012 Elsevier Ltd. All rights reserved.