Abstract: A screw gland assembly that comprises a body having threads formed on an outer surface of the body. A piston retainer coupled to the body, and a piston disposed within the body. A biasing member disposed between the piston retainer and the piston such that the piston is moveable relative to the body against a bias force of the biasing member.

Abstract: A screw gland assembly that comprises a body having threads formed on an outer surface of the body. A piston retainer coupled to the body, and a piston disposed within the body. A biasing member disposed between the piston retainer and the piston such that the piston is moveable relative to the body against a bias force of the biasing member.

Abstract: An improved gate valve for high fluid pressure applications has a housing with aligned inlet and outlet passages and a well intercepting those passages. A piston-type gate is slidably positioned in the well and movable by conventional means between an open position wherein it does not intercept the inlet and outlet passages and a closed position wherein it blocks those passages and seats against the bottom of the well. The gate is fitted with a special seal which includes a circular section seated in a circumferential groove in the gate located above the inlet and outlet passages and a pair of lengthwise sections extending from diametrically opposite locations on the circular section toward the end of the gate at opposite sides thereof, those sections being located transversely with respect to the valve inlet and outlet passages.