Abstract: A rotary plug valve is disclosed in a preferred embodiment that has two telescoping seat assemblies that fit into respective recesses provided in the valve body surrounding a passageway through the plug valve. A valve chamber is formed in the valve body into which the rotary plug may be positioned to control flow through the valve by rotation thereof. In a preferred embodiment, the telescoping seat assemblies provide an upstream and a downstream seal with the rotary plug. The telescoping seat assemblies preferably function differently when in the open and closed position so that both assemblies expand when in the open position whereas in the closed position one assembly expands and one is compressed A line pressure surface is provided to provide a force against the plug seal seat element. The plug seal seat element and plug mate with a curved surface and the contact stress varies depending on the location along the curved surface.

Abstract: A rotary plug valve is disclosed in a preferred embodiment that has two telescoping seat assemblies that fit into respective recesses provided in the valve body surrounding a passageway through the plug valve. A valve chamber is formed in the valve body into which the rotary plug may be positioned to control flow through the valve by rotation thereof. In a preferred embodiment, the telescoping seat assemblies provide an upstream and a downstream seal with the rotary plug. The telescoping seat assemblies preferably function differently when in the open and closed position so that both assemblies expand when in the open position whereas in the closed position one assembly expands and one is compressed A line pressure surface is provided to provide a force against the plug seal seat element. The plug seal seat element and plug mate with a curved surface and the contact stress varies depending on the location along the curved surface.

Abstract: A rotary plug valve is disclosed in a preferred embodiment that has two telescoping seat assemblies that fit into respective recesses provided in the valve body surrounding a passageway through the plug valve. A valve chamber is formed in the valve body into which the rotary plug may be positioned to control flow through the valve by rotation thereof. In a preferred embodiment, the telescoping seat assemblies provide an upstream and a downstream seal with the rotary plug. The telescoping seat assemblies preferably function differently when in the open and closed position so that both assemblies expand when in the open position whereas in the closed position one assembly expands and one is compressed. A line pressure surface is provided to provide a force against the plug seal seat element. The plug seal seat element and plug mate with a curved surface and the contact stress varies depending on the location along the curved surface.

Abstract: A gate valve is disclosed having a telescopingly interfitted seat assembly that fits into a recess in a gate chamber between the gate valve body and the gate. A sealing cavity is formed between two seat elements that form the telescopic connection. A preferably unidirectional seal is disposed therein having two lip seals. The unidirectional seal is preferably oriented to allow leakage for a pressure differential wherein the gate chamber has a higher pressure than the pressure on the opposite side of the seal from the gate chamber. The seal is preferably made of non-permeable material and the material is preferably flexible but non-elastic with little or no memory. Additional such seals may be used for sealing with the gate valve body. In one embodiment, an expansion member is provided for extending into an open end of the seal to expand the two lip seals.

Abstract: A pneumatic actuator and method for a gate valve are disclosed which provide for stepped guide connections between upper and lower cylinder plates for a pneumatic cylinder to thereby automatically centralize and locate the relatively heavy pneumatic cylinder and upper/lower plates with respect to each other to increase the speed and ease of the assembly of the pneumatic actuator. Each major metallic sliding component of the actuator is mounted on a wear ring that prevents metal-to-metal contact to thereby prevent friction wear and galling. A wear ring is provided in the operator stem packing assembly that provides for more reliable sealing due to lack of wear on the operator stem in the region of the stem packing wherein the operator stem reciprocates. A smaller diameter spring housing is provided to house that portion of the spring assembly that extends beyond the stroke of the piston to reduce cost of the larger diameter pneumatic cylinder.

Abstract: A subsea actuator and method is disclosed that includes a removable monolithic cap/hydraulic chamber that seals the actuator housing top with seals placed around the monolithic cap, defines a straight hydraulic line and port for control line hydraulic fluid, and provides for fasteners to secure the top of the subsea actuator. The monolithic cap/hydraulic chamber is so limited in metal and machine time that it can be a throw-away maintenance item. A preferably cup-shaped spring lifter is provided in telescoping relationship to the hydraulic chamber. Several short hydraulic fluid passageways are provided in the bottom cup portion of the spring lifter to permit assist hydraulic control fluid into the hydraulic chamber below the piston. The driving stem provides a removable connection to the hydraulic piston from the top of the actuator housing and a quick disconnect permits disconnection of the driving stem from the valve stem.