CO₂ Corrosion Behavior of X70 Steel under Typical Gas–Liquid Intermittent Flow

Abstract

Gas–liquid intermittent flow is a kind of flow pattern that distinguishes itself from the conventional flow by the apparent non-steady feature, which causes serious corrosion issues, including localized corrosion. Although it widely exists in wet gas pipelines, how the gas–liquid intermittent flow influences CO2 corrosion of pipeline steels remains a problem to be clarified. In this work, a testing device that enables good simulation of gas–liquid intermittent flow in wet gas pipelines under various conditions was developed and used to perform experimental studies, combining electrochemical tests and corrosion morphology observations. The result shows that flow velocity and gas–liquid ratio act together to affect the CO2 corrosion behavior of X70 steel in typical intermittent flow conditions. The flow velocity has a more profound effect on the corrosion rate, while the gas–liquid ratio is associated with the occurrence of localized corrosion. The effect of the gas–liquid ratio on corrosion behavior was discussed.

Keywords

• CO₂ corrosion
• X70 steel
• intermittent flow
• gas–liquid ratio
• wet gas pipeline