Corrosion of X80 steel in a wet gas pipeline under the top-of-the-line environment

Abstract

• The electrochemical corrosion behavior in top-of-the-line conditions was studied. • Compare the corrosion products in thin liquid layer and immersion conditions. • The three stages of the surface in the top-of-the-line environment were discussed. Top-of-the-line corrosion (TLC) is a challenging failure topic in natural gas pipelines. The electrochemical behavior of TLC under wet-gas transmission was studied by electrochemical testing and corrosion product analysis and compared with the electrochemical corrosion behavior under the immersion environment. The results showed that TLC is more severe than corrosion under the immersion environment. The β-FeOOH in the rust layer of TLC led to more corrosive ions contacting the steel, causing severe corrosion. The denseness of the rust layer under the immersion condition is denser than that of the TLC environment, which is inseparable from the protective properties of α-FeOOH and Fe 3 O 4 .