| 摘要 |
PROBLEM TO BE SOLVED: To perform work after a branch pipe part is completely stopped with a gate valve completely removed. SOLUTION: After the branch pipe 2a is completely stopped by a cut-off rubber 20, a fixing plate 30 of a two-split structure is fitted to an open end. After slip-off of the cut-off rubber 20 is prevented, an advance and retreat rod 15 and a moving rod 16 are detached from a receiving plate 19 and a pressing tray 25, and the gate valve 3 detached in the preceding process is completely removed.
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