GATE VALVE WITH HYDRAULIC ACTUATOR

摘要

A hydraulic actuator for controlling the operation of a safety valve actuates automatically upon loss of control pressure. The hydraulic chamber of the actuator is sealed by static annular seals which bear against polished external surfaces of an indicator stem and a cylindrical piston, respectively. The piston is connected by a threaded coupling to the valve stem to accommodate assembly and drift alignment of the gate bore with the safety valve bore. A threaded rod is pinned to the valve stem and is received within an axial pocket of the piston. The piston is movably coupled to the threaded rod by a collar which has inside diameter threads and outside diameter threads. The valve stem static seal is retained within a smooth counterbore formed on the coupling bonnet by a packing collar. The packing collar also serves as a seating stop for the piston and is axially adjustable within the coupling bonnet during assembly onto a safety valve for establishing smooth bore alignment of the gate bore with the safety valve bore.