Induction heating method and apparatus for relieving residual stress in welded joints in pipe line

摘要

A heating method and apparatus for effecting the residual- stress- relief treatment of a welded joint in a pipe line. A welded joint between main pipes, between a main pipe and a branch pipe, between a main pipe and a pipe base or between a branch pipe and a pipe seat and a portion adjacent to the welded point are uniformly or substantially uniformly heated by an inductor which can be varied into configurations according to the performance of the welded joint. The problems encountered in the conventional residual-stress-relief treatment can be substantially overcome.