HEAT TREATMENT METHOD FOR BRANCH PIPE WELDED PORTION

摘要

In a heat treatment method, using a bonded joint (31) for bonding a small bore pipe (12) having a diameter of 200 mm or less and a thickness of 15 mm or less to a larger bore pipe (10), after the small bore pipe (12) and the bonded joint (31) are welded to each other and then the vicinity of the welded portion is heated, the pipe inner surface is cooled by a refrigerant. The heat treatment method is characterized in that the distance between a heating range and the large bore pipe (10) is 70 mm or more. This provides a heat treatment method capable of reducing tensile residual stress caused by welding or processing of a pipe.