CUT-OFF VALVE Russian patent published in 2000 - IPC

FIELD: pipeline cut-off fixtures. SUBSTANCE: cut-off valve relates to cut-off equipment with drive used in production lines of pipeline with liquid corrosive media, steam, gas, at high temperature (T < 600C) and pressure (P < 400_atm.abs). Cut-off valve has body, seat arranged in it, cut-off member with sealed rod, and ball-screw transmission, nut of which is coupled to flywheel. Transmission is provided with device by-passing of balls from extreme actuated screw turn to the other one. Seat and cut-off member are provided with tapered sealing surface. Transmission nut is coupled to rod of cut-off member. Screw is positioned concentrically with rod for its centering and creating of force on rod sealing. The above-indicated device is made as bushing with recess mounted on nut for by-passing of balls. Valve is provided with flexible element acting on bushing at end of closing for separation of its recess from transmission turns. EFFECT: enhanced sealing. 1 dwg