Effect of temperature on corrosion behaviour of X70 steel in high pressure CO2/SO2/O2/H2O environments

The corrosion study of the pipeline steel is extremely important for the safety of CO2 pipeline. The present work studied the effect of temperature on the corrosion behaviour of X70 steel in high pressure CO2/SO2/O-2/H2O mixtures. Weight loss method was utilised to measure the corrosion rate. Environmental scanning electron microscopy and focused ion beam technology were employed to observe the morphology of product scales. X-ray diffraction was used to analyse the composition of product scales. The porosity of product scales was measured, and the exhaust gas was detected by gas chromatography. Results showed that the corrosion rate increased with the increasing temperature and then started to decline with temperature with the peak corrosion rate at 348 K. Results also showed that there was hydrogen that existed in the exhausted gas, indicating that the hydrogen evolution reaction was contained in the corrosion cathodic process.