Characterization of the effect of hydrogen sulfide on the corrosion of X80 pipeline steel in saline solution

• The sulfide film transformation at the initial immersion stages.
• The effects of the sulfide film on electrochemical corrosion behavior.
• Galvanic effect between fresh steel and sulfide-film-covered steel electrodes.

The corrosion products and electrochemical corrosion behavior of X80 pipeline steel in saline solution with saturated H2S at 50 °C were evaluated. The results showed that mackinawite and cubic FeS were the primary and secondary crystalline phases observed and that a series of changes in the size, shape, thickness, and chemical composition occurred as the immersion stages developed. Electrochemical results showed that the sulfide film hindered pitting and enhanced the corrosion resistance definitely. Zero-resistance ammeter measurements showed that the sulfide film repaired itself when local failure occurred.