| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a heat treatment method of a piping system whereby the residual stress in a welded metal zone and a heat affected zone on the inside surface is converted into compressive stress; and a heat treatment apparatus used therefor. <P>SOLUTION: After a piping system is constructed, a heating coil is wound at least twice around the outer surface of a pipeline 1a, and a cooling fluid is caused to flow through the pipeline with a cooling water circulation device 19. A high-frequency heating device equipped with the heating coil, an electric source 17, and a transformer 16 causes the temperature difference between the inner surface and outer surface of the pipeline. Based on the temperature of a heated zone detected by a thermocouple 22, a control unit 18 controls the temperature distributions in the peripheral and axial directions of the pipeline. <P>COPYRIGHT: (C)2004,JPO&NCIPI</p> |
