Abstract: A valve insertion method without stopping passage of fluid, wherein, first, a part of an already-installed pipe is enclosed air-tightly with a valve casing, a milling type cutting tool which has cutting edges on a free end surface and an outer circumferential surface thereof, and a gate being housed in the valve casing with the gate and the cutting tool fixed thereto. The gate and cutting tool are provided in positions spaced from each other in the axial direction of the already-installed pipe. A worker then feeds the cutting tool in the radial direction of the already-installed pipe as he has the cutting tool make cutting motions for cutting the pipe by the rotation of the cutting tool. The valve casing is then turned in the circumferential direction of the already-installed pipe as the cutting motions are kept made, whereby a cut groove cut in the direction of the range of the whole circumference of the pipe is formed.

Abstract: The present invention provides an improved gate valve system for cutting off a fluid flowing through a pipe. The gate valve system includes a gate valve and at least one member. The gate valve includes a seal member exhibiting an elastically deformable property for sealingly contacting the inner surface of the pipe, and a support member for receiving said seal member and movable in the perpendicular direction to the flowing direction of the fluid between the outside and inside of the pipe for timely bringing said seal member into a sealing contact with the inner surface of the pipe. The at least one expansion member is deformable, but is not substantially subjected to the volume variation even under pressure. The at least one expansion member is embedded in the seal member in such a manner as to expand the seal member laterally outwardly to the inner surface of the pipe upon receiving pressure effected by the sealing contact between the seal member and the inner surface of the pipe.

Abstract: A pipe coupling arrangement for coupling an end of a pipe section includes a coupling body having its open end, into which the end of the pipe section is inserted. An outer ring and a radially compressed inner ring are disposed in the open end of the coupling body. Inclined peripheries are respectively defined in the inner periphery of the outer ring and the outer periphery of the inner ring. These inclined peripheries are inclined so as to become smaller in diameter as they advances towards the open end of the coupling body. The inclined periphery of the outer ring and that of the inner ring are engaged by each other. A pressing means for pressing an outer periphery of the outer ring is provided such that the inner ring is tightly pressed against an outer periphery of the pipe section via the outer ring. A space is defined by the inclined surface of the outer ring and the outer periphery of the pipe section, into which the inner ring is inserted.