| 摘要 |
PROBLEM TO BE SOLVED: To minimize a residual stress generated in a weld zone on an inner side and restrain the occurrence of stress corrosion cracking by forming a groove on inner and outer sides of a pair of tube body edge part and making a groove angle of the tube body outer side smaller than that of the inner side. SOLUTION: Edge parts of the first tube body 1 and the second tube body 2, on which an X-shape groove 13 is formed, are butted. Since the relation ship between an angleθi of a groove 13a on the inner side and an angleθo of a groove 13b on the outer side of the groove 13 isθi>θo, width dimension of a welding 4b on the outer side is smaller than that of a welding 4a on the inner side. After the welding 4a on the inner side is completed, the welding 4b on the outer side is carried out. Therefore, when the metal of the welding 4b is solidified, shrinkage force generated in the tube bodies 1, 2 in an axial direction becomes smaller in a case that the width dimension of the outer side welding 4b is made smaller than that of the inside welding 4a in comparison with shrinkage force generated wherein width dimension of the outer side welding 4b is not made smaller than the welding 4a.
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