Advancements in Localized Electrochemical Analysis of Weld Zone Corrosion

Material and environmental interactions are still not well understood in CO2 environments despite decades of research. This is especially true with bulk phase interactions of reactive impurities and increased propensity for dropping out of a secondary liquid phase. Aqueous phase separation in dense phase CO2 transportation is anticipated to be less like two phase flow and more like droplet condensation on the walls of pipelines and associated infrastructure. Thus the corrosion threat associated with the secondary phase will be localized in nature. This work focuses on advancing the capability of conducting localized electrochemical parameter analysis in a single droplet via a bespoke syringe cell setup. The initial focus of this work was to understand the discrete differences in resistance to carbonic acid corrosion across weld zones of pipe steel in a CO2-rich environment. The localized electrochemical cell was used to analyze instantaneous corrosion rate differences between pipe body, heat affected zone and weld seam. With the implementation of a newly designed test cell that allows for maintenance of high humidity environments for longer duration experimentation. Recent developments have assessed the influence of more complex compositions of CO2-rich environments to understand the evolving corrosive effects of impurities in CCUS environments.