| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat-treatment method and a heat-treatment apparatus for accurately, uniformly and efficiently performing a heat-treatment on only the weld zone of the welded steel pipe over the whole regions thereof in accordance with the shape of the welded steel pipe. SOLUTION: The heat-treatment method is performed with the use of a heating apparatus which covers the whole region of the weld zone of the welded steel pipe and has a heating element divided into a plurality of portions in a longitudinal direction of the welded steel pipe, the heating element having interval holding legs for always holding the interval between the welded steel pipe and the heating element constant. The heat-treatment method is performed in such a way that only the whole regions of the weld zone of the welded steel pipe is heated concurrently to a temperature in the range of 100-500°C so that the difference between the maximum value and the minimum value of the heating temperature becomes 100°C or below. COPYRIGHT: (C)2009,JPO&INPIT |
