A flow-undisrupted process using a flow-undisrupted apparatus to which a boring machine including a cutter for boring a portion of a pipe wall of an existing pipe to form an opening in the pipe wall is attached, the flow-undisrupted apparatus allowing the boring machine to be removed therefrom after the opening is formed, the flow-undisrupted apparatus comprising:
- a sealing case including a plurality of separate cases separated from one another in a circumferential direction of the existing pipe for enclosing a portion of the existing pipe, and a branch-shaped branch pipe portion formed in a first separate case of the plurality of separate cases and having a branch hole extending in a radial direction of the existing pipe;
- and
- a rubber packing for sealing a gap between the sealing case and the existing pipe, wherein:
- the branch pipe portion of the first separate case is provided with a flange for allowing for attachment and removal of the boring machine;
- the sealing case is capable of reciprocating in a pipe axis direction of the existing pipe;
- and
- the rubber packing forms:
- a first sealed area surrounding a portion of the sealing case where the branch hole is provided for sealing a gap between the sealing case and the existing pipe around the branch hole;
- and
- a second sealed area for temporarily shutting the opening bored by the cutter, the second sealed area being adjacent to the first sealed area, sealed against the first sealed area, and displaced from the first sealed area in the pipe axis direction,
- the flow-undisrupted apparatus further comprising:
- a gate valve body being intruded into an inside of the existing pipe through the opening formed in the pipe wall so as to disrupt a flow of a fluid through the existing pipe;
- and
- a valve cover accommodating the gate valve body therein, the valve cover being coupled to the first separate case via the flange instead of the boring machine,
- the flow-undisrupted process comprising an assembly step, a boring step, a first movement step, a replacement step, and a second movement step, wherein:
- the assembly step is a step of airtightly enclosing the portion of the existing pipe by the sealing case and attaching the boring machine to the flange of the first separate case without providing an operation valve;
- the boring step is a step in which the cutter passes through the branch hole to form the opening in the portion of the existing pipe;
- the first movement step is a step of moving the sealing case in a first direction of the pipe axis direction after the boring step so that the second sealed area covers the opening without the first sealed area covering the opening;
- the replacement step is a step of removing the boring machine from the flange together with the cutter after the first movement step, and attaching the valve cover accommodating the gate valve body therein to the flange instead of the boring machine;
- and
- the second movement step is a step of moving the sealing case in a second direction, opposite to the first direction, after the replacement step to such a position that allows the gate valve body to be intruded into the opening.