Addition of water impurity for dense phase CO₂ corrosion experiments (C2026-00124)

Kushal Singla, Xi Wang, Zahed Ghelichkhah, PRIYANKA ADAPALA, Yoon-Seok Choi

The presence of trace amounts of water in dense phase CO₂ transport pipelines can pose significant corrosion risks, especially when combined with other impurities such as SOₓ, NOₓ, and H₂S, which can lead to the formation of highly corrosive acids. Laboratory experiments under these conditions require precise control over water concentration, particularly at very low levels (ppm range). This work presents a comparative analysis of three distinct methods (based on direct addition of deoxygenated liquid water; based on equilibrium relative humidity of saturated salts; and based on solubility of water in supercritical CO₂ at set temperature and pressure) for introducing water as an impurity in batch autoclave systems designed for dense phase CO₂ corrosion testing. Each method is evaluated based on its practicality, accuracy, and compatibility with specific autoclave volumes and target water concentrations. The strengths and limitations of each approach are discussed, with emphasis on reproducibility and experimental control. Water concentrations achieved through each method are quantitatively validated using a gas analyzer, and the resulting data are presented to support method selection for future corrosion studies in CO₂-rich environments.