GB1221989A - Stem construction for rising stem-gate valve - Google Patents

Abstract

1,221,989. Valves. R. S. YOLPIN. 8 Aug., 1968, No. 37991/68. Heading F2V. In a gate valve having a main housing 10 and a bonnet 17, actuation of the gate 23 is effected by a shaft 26 which is non-rotatably reciprocable by an actuator 29, 32, the shaft having slidably mounted thereon a seal piston 46 which serves to isolate the actuator from line pressure and furthermore, to define within the bonnet a lubricant chamber 18a, 52, 51, 30, 53, 19a to which lubricant may be supplied through a fitting 56 and from which the same may be released via a vent 58. The piston 46 attains a position within the bonnet at which the fluid forces acting on its opposite faces and due to line pressure and to the lubricant are equal. The actuator has a bearing 43, 44 which is disposed, with slight clearance, within a gap defined by two bonnet shoulders 40, 41. The gate is formed with a notch 65 which, when the gate is in its lowered, valve closed position, serves to bring into communication annular seat grooves 63, 64 and corresponding passages 61, 62, the passages leading from reservoirs 59 60 which contain lubricant sealant and pistons 67, 68, which like piston 46, are responsive to line pressure, such pressure being applied to the pistons by virtue of leakage at the upstream side of the gate when the latter is in the closed position.