| 摘要 |
PROBLEM TO BE SOLVED: To improve the workability in a back shield device and a back shield method of a pipeline welding part and a support member for a seal gas pipe.SOLUTION: A back shield device is provided with: a seal member 12 (an on-off valve 106) which seals a predetermined region in a pipeline 101 and thereby may form a sealed space A; a seal gas pipe 11 which may feed a seal gas to the sealed space A; and support members 13, 14 for the seal gas pipe which may support the seal gas pipe 11 at an upper position in the pipeline 101. |
