Failure Investigation of Superheater Through Investigate the Nearest Component

The failure of the superheater (SH) tube can cause the power plant to stop operating. A study was conducted to detect the cause of tube leak at the failure of the superheater in HRSG. This study investigated the mechanism of degradation and leak of SH HRSG by examining the SH tube adjacent to the failed SH tube. Because the failed sample was not found, this investigation was essential for the failure prevention of the recurring problem. This problem was analyzed through metallography examination, hardness test, Finite Element Method (FEM) simulation, SEM/EDS review, and tensile testing. The analysis showed that the cause of the superheater tube bending was the presence of a hotspot, which was assumed to happen when the lower flue gas flap was opened for a long time while the fluid circulation system in the superheater tube was not functioning perfectly. As a result, the thermal stress that occurs exceeds the yield strength