| 摘要 |
PURPOSE:To prevent generation of defects such as blisters, pinholes, undercuts and the like in weld zones by fitting an end plug having a small through-hole into one end prt of a pipe, evacuating the pipe inside through the small hole and welding the pipe and the end plug. CONSTITUTION:End plugs 19 are fitted into both end parts of a coated pipe 1 and the pipe 1 is inserted into a rotary holding mechanism 17. It is inserted into a welding chamber 12 until the plug 19 abuts on a stopper 23. The small through-hole 20 of the plug 19 and the communicating hole 29 of the stopper 23 are communicated by this. When a vacuum pump 30 is operated, the inside of the pipe 1 is evacuated. Then, an electrode 22 for welding is controlled of its movement and an inert gas is injected through the electrode 22 and is filled in the chamber 12. The pipe 1 and the stopper 23 are rotated by the mechanism 17. Electric current is flowed to the electrode 22 to weld the butted part of the plug 19 and the pipe 1. After the welding, an inert gas is filled by pressure through the hole 20 into the pipe 1 to seal the hole 20 part. |
