Abstract: A valve operable to control flow between two adjacent pipe sections and having a system for relieving pressure from an enclosed cavity within the valve. The valve includes a first pressure port, a second pressure port, and a seal. When the valve is closed, the first pressure port is in fluid communication with one pipe section and the second pressure port in fluid communication with the enclosed cavity. The seal isolates the second pressure port from the first pressure port when fluid pressure within the enclosed cavity is less than a pre-selected valve and is displaceable to enable fluid communication between the second pressure port and the first pressure port when fluid pressure in the enclosed cavity is equal to or greater than the pre-selected value.

Abstract: A valve operable to control flow between two adjacent pipe sections and having a system for relieving pressure from an enclosed cavity within the valve. The valve includes a first pressure port, a second pressure port, and a seal. When the valve is closed, the first pressure port is in fluid communication with one pipe section and the second pressure port in fluid communication with the enclosed cavity. The seal isolates the second pressure port from the first pressure port when fluid pressure within the enclosed cavity is less than a pre-selected valve and is displaceable to enable fluid communication between the second pressure port and the first pressure port when fluid pressure in the enclosed cavity is equal to or greater than the pre-selected value.

Abstract: In some embodiments, a valve may include a plug that is pivotable relative to a portion of a stem so that the plug is capable of aligning itself to the seat liner. In such circumstances, the valve may be manufactured to provide close guidance of the plug proximal to the control surfaces and so as to reduce the sway of the plug relative to the seat liner.

Abstract: Certain embodiments of a fluid control valve include one or more ceramic components that operate substantially free of tensile stress concentrations along the control surfaces. In some embodiments, a fluid control valve includes a ceramic plug having a set of longitudinal grooves milled in the cylindrical surface of the plug to define control surfaces. The plug is disposed in an internal longitudinal cavity of the valve body such that the fluid flows over the plug's control surfaces in a direction substantially parallel to the control surfaces. The ceramic plug and other ceramic components may be manufactured using relatively simple machining techniques to reduce the overall production costs.

Abstract: A ball valve has a valve body defining an inner seat and having a fluid inlet and fluid outlet and a control ball element rotatably mounted in the inner seat. The control ball element has a partially spherical outer surface, a flow passage having a leading edge, a first inner control surface abutting the leading edge, and a second inner control surface abutting the leading edge at an angle oblique to the first inner control surface.

Abstract: A ball has a valve body defining an inner cavity and a fluid inlet and fluid outlet, a control ball element rotatably mounted in the inner cavity, and having a segment defining a ball face, and a flexible valve seat positioned in the valve body. The seat comprises a base portion, a cantilevered portion with a sealing face disposed toward the ball face, and a connecting portion between the base portion and the cantilevered portion that is lesser in width than are the base portion and the cantilevered portion.