Corrosion studies in dense phase CO2 present significant experimental and analytical challenges, particularly due to long, multi-step procedures in which each stage can introduce potential sources of error. Such experiments are typically conducted using either batch impurity injection or continuous injection systems, each of which has distinct strengths and limitations. Batch systems allow the system to gradually approach steady state conditions if sufficient time is provided; however, starting impurity concentrations often change due to chemical reactions, leading to depletion during the experiment. In contrast, continuous injection via a flow-through system maintains constant impurity concentration throughout the experiment but never fully equilibrate, potentially causing discrepancies when experimental observations are compared with thermodynamic models that assume true steady state conditions. This work focuses on the batch autoclave methodology, including experimental configuration, impurity dosing strategies, and procedural safeguards necessary to ensure reproducible and reliable corrosion results. Practical modifications that enhance the reliability of batch testing are discussed, along with considerations for sample configuration, impurity introduction, and concentration monitoring to minimize uncertainties commonly associated with dense phase CO2 experiments. Experimental results are then presented in the context of deviation between thermodynamic model predictions (based solely on the chemical reactions in dense phase CO2) and observed corrosion behavior. Notably, the steel surface was found to act as a catalytic site, accelerating localized acid formation at the specimen surface even when the thermodynamic model predicted negligible acid formation. These findings highlight the complex interplay between surface-catalyzed reactions and bulk phase CO2 chemistry, emphasizing the need for integrated modeling frameworks that couple thermodynamics with surface-driven reaction kinetics. Such approaches are essential for accurately predicting corrosion risks in CO2 transport pipelines and for guiding the development of more reliable experimental methodologies.
