Many times of cracking and leakage have occurred in socket weld joint on the third-stage extraction steam balancing pipe of dearator's head on units no.4 and no.5 in one power plant

and large amount of cracks existing on the inner wall of said dearator's barrel shell.The causes leading to said cracks have been analysed

results show that the main causes resulting in cracks on inner wall of the dearator's barrel shell are lack weld penetration in angle weld joint on the socket

and unreasonable structure of the trickling disc in the dearator's head.For this

corresponding repair and improvement measures have been put forward.