| 摘要 |
PURPOSE:To generate thermal stress in the inside and outside surface of a pipe wall and to improve the residual stress in the weld zone by passing cooling water into a pipe body having a double pipe part and subjecting adequately the pipe body to a heat treatment while the stagnating water is allowed to remain in the annular hollow part of the double pipe part. CONSTITUTION:A pipe body provided connectively with a double pipe part equipped with a thermal sleeve 6 and a single pipe part is welded 9 while an annular hollow part 5 is interposed to the nozzle 4 of a vessel 3 and thereafter cooling water is passed in the pipe body in an arrow direction and at the same time the stagnating water is allowed to exist in said hollow part 5. The pipe body is subjected to a heat treatment by heating in this state to generate compressive stress against the residual tensile stress in the weld zone 9, etc., thereby preventing generation of stress corrosion cracking. The heating for the above-mentioned treatment is accomplished by the method of heating first inductively the single pipe part by a coil X to apply the temp. difference to generate the thermal stress exceeding the yield point in different directions at the points C, D near the inside and outside surfaces of the pipe wall, then heating the double pipe part by a coil 7 for short time to apply a required temp. difference between A and B and thereafter stopping the heating in the single pipe part after a time lag.
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