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. Corrosion perforation causes of UNS S32205 DSS weld in a gas transportation pipeline were analyzed carefully. Excess austenite was found in the HAZ, and then the pitting corrosion resistance was lowered significantly. In the condition with large potential difference between the both sides of the insulation joint and high salinity of the formation water in the pipeline, leakage current caused the preferable dissolution of weld and then the corrosion perforation.