| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize a gas bag insert jig, simplify gas shut-off work and cut down earth work cost. SOLUTION: Opening parts 2, 2a and side walls 3, 3a are formed toward the right and the left at the lower part of a vertical gas bag insert pipe 1, and gas bags 5, 5a inserted by a guide pipe 8 are respectively expanded from the opening parts 2, 2a toward the inside of a gas conduit A. As a result, the gas bags 5, 5a are correctly controlled in the attitude and expanded in a position close to an insert hole B so as to adhere closely to the pipe to shut off gas. With this constitution, the length of air force-feed pipes 6, 6a can be minimized, so that a jig can be miniaturized. Workability is improved by miniaturization of the jig, and a work ditch can be made small so as to cut down earth work cost. |
