Insights into the corrosion perforation of UNS S32205 duplex stainless steel weld in gas transportation pipelines

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.