Abstract: The reasons for leakage of the low temperature superheater pipe SA210C in subcritical units for a thermal power plant were analyzed and the relevant improvement was given to avoid the similar failure. The results show mechanical damages caused in the process of pipe bending evolved into the microcracks after flame correction and hammering. These microcracks propagated under the combining effects of external environment and internal stress, resulting in the failure of pipe. A fatigue characteristic could be found in fracture morphology. In process of pipe bending the contact surface should keep neat and the processes of flame correction and hammer for the bended pipe were reasonable, the ultrasonic guided wave inspection technology was suggested to apply before this type pipe were used.