| 摘要 |
PURPOSE:To make it possible to shield a welding section of the heat exchanger from the atmosphere by a method wherein in the heat exchanger made of a titanium type material, a tapered section is formed at the outer end of a heat transfer pipe fitting hole and the top end of the heat transfer pipe is positioned in the vicinity of the boundary of the tapered section and the heat transfer pipe fitting hole. CONSTITUTION:The heat transfer pipe fitting hole 4 is drilled through a titanium type pipe plate and the outwardly widened tapered section 11 which is inclined at an angle of about 15-45 deg.C and which has a length of from several to several tens times the thickness of the wall of the heat transfer pipe 1. Then a titanium pipe as the heat transfer pipe is inserted into the fitting hole 4 in such a manner that the top end of the pipe 1 coincides with the boundary of the tapered section and the fitting hole and is welded to the pipe plate 2 as at 3. The welding is performed in such a manner that a torch 6 is made to confront the top end of the pipe 1 and an inert gas retaining area (a) is formed between the pipe and the tapered section 11 so that the welding section is completely shielded from the atmosphere to thereby prevent pollution due to an activated gas. Further, the tapered section 11 is made bell-mouthed so that no vortex of the cooling water generates when the cooling water enters the heat transfer pipe and the adhesion of organisms to the surface of the pipe plate is prevented. |
