Abstract: A two-stage hydraulic solenoid valve for controlling the application or release of hydraulic pressure to components of a steam turbine control system. The valve includes a primary hydraulic circuit in which a floating poppet operates between first and second valving positions to connect the valve's outlet port to either an inlet port or a drain port so that the connected control system components receive full hydraulic pressure or are provided with a pressure release path. A secondary hydraulic circuit controls the poppet position through a solenoid actuatable ball and valve seating arrangement wherein a ball is alternatively positioned between a pair of valve seats to switch fluid connections to poppet actuation chambers, one such chamber being located at each end of the poppet. The ball is positioned in sealing contact with one valve seat by the solenoid and is returned to the other seat by fluid pressure upon deactivating the solenoid.

Abstract: A butterfly valve comprises a valve disc mounted on and rotatable with a shaft disposed across the inner diameter of a cylindrical valve casing, said shaft being rotatably supported at each end by a bearing within the valve casing. Fluid flow through the valve casing is controlled by rotating the valve disc from a fully open position through a fully closed position. A shaft seal and bearing is disclosed which prevents leakage of the controlled fluid out of the valve casing axially along the valve disc shaft even under conditions of shaft flexure. Moreover, the shaft seals adjust to the shaft flexure to obviate binding between the shaft and shaft seals.

Abstract: A combined stop and intercept valve is provided for controlling steam flow from a high-pressure steam turbine to a low-pressure steam turbine and comprises a substantially cylindrical casing having two identical butterfly discs fixed to rotatable shafts and disposed within the casing one immediately downstream of the other. Under normal operating conditions, both the stop (upstream) and intercept (downstream) valves are opened providing a relatively unrestricted passage for the flow of steam. During a turbine overspeed condition when the turbine speed reaches 103% of rated speed, the intercept valve closes substantially all the way. The stop valve backs up the intercept valve. Should the turbine speed reach 108% of rated speed, the stop valve closes completely shutting off the flow of steam to the low-pressure turbine. When opened, the discs partially overlie each other so that any wakes in the steam flow produced by the stop disc will not cause the intercept disc to flutter.