Abstract: A spaced apart pair of plates in a steam bypass conduit provide pressure reduction and desuperheating of the steam. The plates have holes, some of which are equipped with nozzles that discharge water axially at the nozzle exits or radially at the throats. The nozzles are formed by inserts that form annular spaces communicating with a network of water supply conduits in the plate. Water discharge jets communicate with the annular spaces.

Abstract: A fixture for testing and servicing a MSIV of a nuclear power generation plant includes a cover plate for bolting to the valve body and a support member extending from the plate for supporting the valve stem. A pressure cylinder attaches to the support member for loading the stem to conduct a leak rate test. Means are provided for pressurizing the valve body to perform a leakage test. Stem bearings spaced apart along the stem provide accurate stem alignment, and prevent bending of the stem under test loading. Seals between the fixture, the body and the stem permit pressurization of the valve body above the poppet, permitting a leak test of the MSIV without reassembly of the actuator structure. In another embodiment, a collar having an axially directed thrust face mounts on the stem and bears against a thrust bearing to permit rotation of the stem during assembly.

Abstract: A fluid operated valve in which the fluid from the line in which the valve is placed is used to aid in the opening and closing of said valve. A shuttle valve communicating with both the inlet and outlet chambers of the valve is operable to permit one of said chambers containing fluid under pressure to communicate with an auxiliary chamber in the valve to provide a closing force for the valve.

Abstract: A valve having a valve stem in the form of an actuating rod connected with a hydraulic piston in an hydraulic cylinder and an air piston in an air cylinder and which is closed by a spring has a system for assisting the spring in closing the valve and in maintaining it closed. As the actuating rod travels during the closing operation, a pressure differential across the air piston is exerted and thereafter the pressure differential across the hydraulic piston is exerted to assist the spring in closing the valve and to maintain it in a closed position.

Abstract: A shutoff valve in a line containing fluid under pressure which after being closed is held closed by another fluid under pressure. The other fluid is one such as air which is available at the valve.