Root Cause Analysis of Premature Failure in Reheater Bend Tube of a 700 MW Thermal Power Plant

The root cause for the premature failure of a reheater tube bend of a 700 MW supercritical boiler after 15000 hrs of service was investigated. The chemical composition, mechanical properties, and microstructural degradation have been studied both on the failed and virgin tube material. The mechanisms involved in the failure process have been identified and the methodology to be followed for preventing recurrence of the incidence has been brought out. Keywords: Boiler tube, reheater, sensitization, carbide precipitation, austenitic steels