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Microstructure and pitting corrosion resistance of UNS S32205 DSS weld were systematically studied, and its failure causes were analyzed carefully. The results showed the uneven metallographic microstructures with majority of austenite in the HAZ and then the significantly reduced pitting corrosion resistance of the weld. Furthermore, large potential difference between the both sides of the insulation joint and high salinity of the formation water in the pipeline make the leakage current preferably flow out from the weld and enter the transmission fluid, so localized corrosion happens at the inner surface of the weld and leads to the corrosion perforation eventually.

The present work primarily investigates the corrosion characterization of the common P110 steel and the anti-sulfide P110SS steel in CO 2 -containing solution with or without hydrosulfuric acid (H 2 S) at 70 °C. The electrochemical techniques such as potentiodynamic polarization sweep and electrochemical impedance spectroscopy (EIS) were used to disclose the differences of the corrosion mechanisms between both P110 and P110SS steels in CO 2 -containing solution with various additions of H 2 S.The EIS data fitted by ZsimpWin software were analyzed and discussed. The experimental results indicated that H 2 S could accelerate and also inhibit the corrosion attack according to the changes of corrosive environments.