Effect of CO₂ partial pressure and different CO₂ phases on carbon steel corrosion

Carbon capture and storage (CCS) is the recent promising technology aimed at reducing greenhouse gas emission. Like many other developed technologies, CCS is faced with great challenges such as pipeline transportation failure due to corrosion. There are many factors contributing to steel corrosion during the pipeline transportation of carbon dioxide (CO₂). This study focuses on CO₂ partial pressure and different phases of CO₂ as some of the factors contributing to steel corrosion. Carbon steel was used as a testing specimen. High pressure reactor was used in this study to compress CO₂ from low to high pressures ultimately changing the CO₂ from gaseous phase to gas/liquid phase (subcritical) and to dense phase (supercritical). Weight loss method was employed to determine the corrosion rate while scanning electron microscopy (SEM) and X-Ray diffraction (XRD) were used to study the carbon steel morphology and phase analysis. Using low magnification digital camera, the type of corrosion that took place on the carbon steel surface was identified.