Abstract: With hi-grade steel welded linepipes both construction and operation costs of the pipe line will be reduced,and the transport pressure and transport efficiency thereof enhanced.This is why hi-grade steel linepipes are increasingly sought after and used.However as it is known that the higher the steel grade,the lower the weld-ability of the steel,weld repair of the welded joint of the pipe has to be used when manufacturing the pipe.In this case actions as necessary should be employed including proper weld repair process,preheating and inter-layer temperature control to ensure good property of the pipe welded joint.