Abstract

Within a carbon capture utilization and storage (CCUS) process, pipeline transportation of supercritical CO₂ (s-CO₂) is recognized for its efficiency and cost-effectiveness. However, corrosion concerns necessitate a comprehensive understanding for effective integration into reliability and safety assessments. A s-CO₂ pipeline typically consists of at least 90% CO₂, with the remaining composition comprising impurities. Among these impurities, water content is a crucial one, as it can cause in-situ formation of corrosive carbonic acid, posing a threat to pipeline integrity. Simultaneously, the role of microstructure in the adherence and protectiveness of corrosion product films is noteworthy. The presence and morphology of iron carbide is often correlated with the film’s adherence, emphasizing the microstructure’s impact on corrosion performance. While identifiable trends in performance may exist, the challenge is not yet fully comprehended and anticipated, primarily due to various variables such as the existence of impurities. The present study aims to investigate the influence of various monolithic microstructures, including pearlite, martensite, and bainite on corrosion in simulated acidic aqueous phases expected from water condensation in s-CO₂. Corrosion testing is being carried out in bulk surrogates of the aqueous phase Carbonic acid (25 °C), produced using a commercial (SodaStream™) apparatus (dissolving pressurized CO₂ in water), will serve as the baseline solution on corrosion of steel. The effect of acid gas impurity (NO₂) will be evaluated through the addition of soluble sodium salts. Samples of 1080 (pearlitic) steel will undergo heat treatment to produce additional monolithic phases of bainite and martensite. Corrosion susceptibility, as interpreted by the kinetics of the controlling anode and/or cathode process involved, will be evaluated using potentiodynamic polarization measurement . Surface composition and structure characterization will be conducted using plan-view imaging using both light optical microscopy (LOM) and scanning electron microscopy (SEM), and surface composition depth profiling using X-ray photoelectron spectroscopy (XPS). The paper will present and discuss the results acquired to date.