Uninterrupted flow device and uninterrupted flow construction method

摘要

The present invention is provided with: a sealed case having a branched opening extending in the radial direction of an existing tube and formed in a first split case; and a rubber gasket sealing between the sealed case and the existing tube. A flange for attaching/removing a piercing machine is provided to the first split case. The sealed case can move reciprocally in the axial direction of the tube. The rubber gasket is formed with: a first sealing region that encircles the position of the sealed case to which the branched opening is provided and that occludes the branched opening; and a second sealing region that is adjacent to the first sealing section and is sealed from the first seal region, is offset from the first sealing region in the axial direction of the tube, and has a size able to occlude the opening pierced by a cutter. An allowance space that is clearance for a second sealing ring is formed between a gasket device groove and the second sealing ring.