Abstract: The Sshaped deformation of high temperature reheater tube in No.1 boiler of Minquan Power Generation Corporation Limited of China Guodian Corporation was occurred during trial operation. The macroscopic detection and related data measurement were carried out for the deformed tubes. The analysis showed that the deformation reason of reheater tubes bundle is the expansion coefficient difference of tubes materials and the inner stress of the tubes material. Some measures were adopted such as replace certain tubes sections, tracing and supervisory, comprehensive treatment, etc. so the safety and stable operation of the high temperature reheater tubes bundle had been ensured.

Key words: high temperature reheater tube, S-shaped deformation, reason analysis, treatment