| 摘要 |
PURPOSE: A tandem overlay welding apparatus is provided to increase productivity of overlay welding and to supply cooling for multi layer welding to be possible. CONSTITUTION: A tandem overlay welding apparatus comprises a pipe rotating unit and a welding unit. The pipe rotating unit rotates a pipe. The welding unit performs overlay welding of the inner side of the pipe from the inside of the pipe. The welding unit is equipped with booms (410,420) whose end parts are installed with welding torches and with a main body (450) which moves the booms. The multiple welding torches which are installed on the booms are with a fixed space from each other in the length direction of the pipe. The multiple welding torches includes a first welding torch (430) which performs overlay welding on the pipe, and a second welding torch (440) which performs overlay welding on a welded layer which is overlay-welded by the first welding torch.
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