| 摘要 |
PURPOSE:To join safely and thoroughly both inside and outside pipes irrespectively of the diameter and length of the pipes by heating both pipes and welding both pipes by diffusion joining with an insert metallic layer interposed therebetween by the stress generated by the difference in thermal expansion between both pipes. CONSTITUTION:The outside circumferential surface of an inside pipe 1 and the inside circumferential surface of an outside pipe 2 are worked to provide a clearance between both pipes 1 and 2. An insert metallic layer 3 is adhered by spot welding to the defatted outside circumferential surface of the pipe 1 and the pipe 1 is fitted into the pipe 2. Both pipes 1, 2 are put in a vacuum chamber and the end faces 4, 5 of the pipes 1, 2 are welded by an electron beam to seal the gap between both pipes 1 and 2. The pipes 1, 2 are then put in a heating furnace and are thus heated. Since the pipe 2 has the smaller coefft. of thermal expansion, the gap between the pipes is eliminated by the difference in the thermal expansion. The pipes 1, 2 are welded to each other by diffusion joining with the layer 3 interposed therebetween, on account of the stress generated by said difference, by which the clad steel pipe is produced. |
