The causes of clamping tube leakage for rear platen superheater of a 2 045 t/h boiler in one power plant have been analysed by using methods of macroscopic inspection

crack analysis

chemical elements analysis

tensile strength analysis

microscopic hardness test

metallographic structure analysis

intergranular corrosion test

etc..The results show that the clamping tube leakage of rear platen superheater is caused by intergranular corrosion cracking on the steam side.Firstly the intergranular corrosion cracks happened at inner wall of middle profile in elow of the clamping tube

and then extended along grain in direction of the tube wall thickness untill penetration leakage.