Effect of interaction between corrosion film and H₂S/CO₂ partial pressure ratio on the hydrogen permeation in X80 pipeline steel

Abstract

The hydrogen permeation behaviour of X80 pipeline steel exposed to corrosion environments with different H2S/CO2 partial pressure ratios at room temperature was investigated through the high-pressure electrochemical hydrogen permeation test. Both CO2 and H2S have a hydrogen permeation promoting effect; however, CO2 hydrogen permeation promoting effect is much weaker than H2S. The hydrogen permeation curves have the rising, falling then stable stage. When at a total pressure of 1 MPa, as the H2S partial pressure decreases, the hydrogen permeation promoting effect weakens, but the peak current of hydrogen permeation gradually increases. The main reason is that the role of corrosion products has changed from promoting hydrogen permeation to hindering hydrogen permeation during the reaction.