Analysis of Leakage Causes of 6ADG011VR Branch Pipe in a Power Plant

The socket-welded branch pipes of a power plant leaked and failed in the ADG System. To find the cause of the failure, this paper analyzed the failure reasons of the socket-welded branch pipes through macroscopic inspection, chemical composition analysis, mechanical performance test, metallographic inspection, and fracture microscopic analysis. The results show that the failure mode leading to leakage in socket-welded pipelines is fatigue cracking, which initiated at the weld toe on the outer wall and propagated inward. The vibration generated by the system environment is the main cause of fatigue cracking of socket-welded branch pipes.