| 摘要 |
PURPOSE:To improve a characteristic of stress corrosion crack resistance, corrosion fatigue resistance, fragility destruction resistance, etc. in a corner part, by generating a temperature difference between an outer and an inner surface of a nozzle part and compression residual stress in the internal surface corner part of the nozzle part. CONSTITUTION:A pressure vessel nozzle part, generating a temparature difference between an outer surface (a) and an inner surface (b) of a corner part, forms a predetermined temperature distribution (c). That is, the outer surface (a), being compression plastic yielded by heating, generates tensile residual stress in a condition of the surface that its temperature returns to a room temperature after being heated. While the inner surface (b) generates compression residual stress reversely to the above. Here a pair of split type heating devices 1, 2, being connected with a gas source 3, 4 of acetylene and oxygen and providing a gas hole in the internal surface, is set so as to hold a nozzle B from a pipe side A, heating the outer surface of said corner part. In this way, a characteristic of stress corrosion crack resistance, corrosion fatigure resistace and fragility destruction resistance or the like in the corner part can be improved. |
