| 摘要 |
<P>PROBLEM TO BE SOLVED: To perform a connection construction for replacing an old main branch pipe of an existing supply pipe with a new main branch pipe. <P>SOLUTION: First and second branch joints 6, 7 are fitted to two positions in a mid-way of the existing supply pipe 3 and then first and second switching devices 11, 12 are fitted to each of internal and external branch openings 9, 10 of the joints. A bypass pipe is connected between the switching devices 12, 12 to make the second switching device 12 "open". A bag type in-pipe blocking device is fitted to the switching devices 11 to block a gas flow inside the existing supply pipe. A first branch joint 6 and second branch joint 7 of the existing supply pipes 3 are cut. The new main branch pipe 4 and the cut portion of the second branch joint of the existing supply pipe 3 are connected by the new supply pipe 26. The first and second switching devices 11, 12 are made to close and the bypass pipe 22 is removed from the second switching device 12. Temporary plugs are attached to the first and second switching devices 11, 12 to remove the switching devices 11, 12. Actual plugs are attached to the branch openings 9, 10 of the second branch joint 6 to implement actual closing plugging. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
