Single seal pipeline tapping fixture having secure valve

Abstract

A piercing valve comprises upper and lower blocks having, respectively, lower and upper mating surfaces. Each mating surface has a positionally corresponding generally linear groove extending thereacross. The upper block has a cylindrical bore extending vertically therethrough and intersecting the grooved lower surface thereof. An upper bore section is adapted for receiving screw threads, with the topmost section of the bore having a diameter less than that of the threaded upper section thereof; the lower section of the bore is of a diameter larger than that of the upper section. The upper block further has an access port extending therethrough and intersecting the bore along the lower section thereof, a cylindrical piercing needle, and a cylindrical unitary seal. The piercing needle has an upper threaded portion having a radial diameter suitable for engaging the threads of the bore, a coaxial central portion having a decreasing radial diameter, and a coaxial lower portion having means for tapping an access hole. A cylindrical seal having a gas or liquid communication there through so as to permit the communication of the gas or liquid from a point external to the mated upper and lower portions of the block into the region defined by the grooves thereof is coaxially interposed between the valve and the inner bore surface of the upper fixtures. The seal further extends above the intersection point of the access port with the bore and is of a length to make sealing contact with the surface of the pipeline being pierced.