Patent ID: 12013072

Abstract:
A shut-off system of the present invention includes a straight pipe made of a polyolefin-based material, and a knife gate, wherein: a semicircular arc-shaped first cutting blade is formed on a distal end side of the knife gate to cut open the straight pipe to form a slit-shaped opening; an arc band-shaped sealing portion is formed on a proximal end side of the knife gate to be in contact with cut surfaces of the straight pipe; the knife gate includes a pair of side edge portions that connect the first cutting blade and the sealing portion; the first cutting blade and the side edge portions bite into an inner circumference surface of the straight pipe along the inner circumference surface; the knife gate is formed in a flat plate shape having a first surface and a second surface, extending from the first cutting blade to the sealing portion and between the pair of side edge portions; the opening extends in a circumferential direction on the straight pipe; and the sealing portion extends from one end of the opening to the other end thereof, and extends from the inner circumference surface to an outermost surface, which is on an outermost side, of the straight pipe.