Leakage Analysis of 15CrMo Cladding Wall Pipe Used in 660MW Supercritical Unit

Abstract

The cause of leakage of the 15CrMo steel cladding wall tube of a 660MW supercritical unit of a power plant is analyzed by macro analysis, hardness measurement, and metallographic organization observation. The results show that the two sides of the weld are the original old pipe and the new pipe. The old pipe side, after the long-term operation and re-welding of the organization of the aging, is serious after analysis of the first leakage point is located in the old pipe fusion line; the first leakage point is located in the old pipe fusion line, the existence of multiple cracks in the inner wall of the pipe and the presence of oxide skin inside the cracks indicate that the cracks have existed for a long time, and at the same time, due to the severe aging of the old pipe organization, the ability to withstand external forces becomes weaker, which contributes to the expansion of the cracks in the process of operation, which leads to the leakage of the pipe. As a result, the wall cladding pipe was pulled apart after being subjected to external forces