| 摘要 |
PURPOSE:To perform a strong connection of heat-retaining double pipes easily by a method wherein, after main pipes are mutually welded and equipped with heat insulating material, a specific outer pipe is welded on them. CONSTITUTION:Main pipes 1, 1 are mutually welded and heat insulating material 2, 2A is fixed on them. Then a short pipe 7 is shifted to the welded part of the main pipes 1, 1. Deformation takes place by means of a press jig 8 to make the outer diameters of both ends of the short pipe 7 equal to those of casing pipes 3, 3. After the deformation, the casing pipe 3 is welded to the short pipe 7. As the deformation is performed to an extent that the diameter of the short pipe 7 becomes equal to that of the casing pipe 3 and the welding is conducted only in the peripheral direction, the welding process is simplified and the strength is improved. |
