| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an induction heating stress improvement method clarifying the dimension or the like of a crack to which the induction heating stress improvement method is applicable so as to apply the induction heating stress improvement method even to a weld joint part of a crack-bearing pipe. <P>SOLUTION: In order to improve the residual stress in the inner surface of the weld joint part 2 formed by TIG welding of an austenitic stainless steel-made pipe 1, the induction heating stress improvement method arranges high frequency induction coils at the predetermined width on the outer circumference of the weld joint part 2 centered on the weld joint part 2, and causes the high frequency current to flow in the high frequency induction coils to heat the weld joint part while causing cooling water to flow in the pipe 1. Ultrasonic flaw detection test checks whether or not any crack is present in the inner surface of the pipe. If the ultrasonic flaw detection test shows that there is a crack in the inner surface of the pipe, the depth of the crack is ≤3/8 time the thickness t where t denotes the thickness of the pipe, and that the length of the crack is equal to or smaller than the length of the entire circumference of the pipe, the induction heating stress improvement method is performed. <P>COPYRIGHT: (C)2012,JPO&INPIT |
