| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for improving residual stress of piping, a method that can prevent stress corrosion cracking by reducing or compressing a tensile stress that actuates on the inner face of the piping in the proximity of a weld zone thereof during piping expansion using an internal pressure. SOLUTION: In the proximity 2 of a weld zone which includes the weld zone of piping 1A, 1B and which is a range with an inner face machined for the purpose of grooved face alignment for welding, the thickness of the proximity 2 of the weld zone of the piping is made thinner than in other areas. By making the thickness thinner in the proximity 2 of the weld zone, the deformation of the proximity 2 during piping expansion by an internal pressure becomes larger than the deformation in other areas. Then, the piping 1 is expanded until plastically deformed by the expansion, which improves residual stress of the piping. COPYRIGHT: (C)2009,JPO&INPIT
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