Impact of Water Excursions on Carbon Steel Corrosion of Pipelines Transporting Supercritical CO2

RIP2025-00147: Considerable work in the industry has focused on defining specifications to ensure safe transport and storage of CO2 without imposing unnecessary burden to the CCUS projects. Additional work is required to understand corrosion risk related to potential water excursions. Even if a water excursion is promptly identified and solved, water that has entered the pipe can produce significant damage until it eventually evaporates or dissolves into the nominally dry CO2. Also, the impacts of the corrosion products left behind and risk of subsequent water upsets in the same area have not been evaluated.

An experimental approach was implemented to evaluate the impact of a successive small ingress of water on supercritical CO2 (sCO2) systems maintained at low water saturation levels. The kinetics of water dissolution into the sCO2 as well as changes in the corrosion rates with time were determined based on electrochemical impedance data. Results confirmed that water dissolution into sCO2 is a very slow process, and that corrosion rates tend to decrease with time due to precipitation of an iron carbonate. In addition, it was found that the corrosion products left behind after water evaporation can have a significant impact in subsequent corrosion processes.