Ball valve for cold fluids

Abstract

A ball valve including upstream and downstream seats and a ball having a flow opening disposed between the upstream and downstream seats. A flow path is defined through the valve only when the ball is disposed in an open position. In one embodiment, when the ball is disposed in a closed position the upstream seat may intermittently disengage from the ball to relieve hydrostatic expansion of a liquid within the ball resulting an increased pressure that is greater than a pressure within a body cavity of the valve outside the ball. In another embodiment, a distance between the upstream and downstream seats is greater than an outer diameter of the ball and the ball engages only one of the upstream and downstream seats when disposed in the closed position and a pressure differential is defined between the upstream and downstream seats. The upstream and downstream seats may each include a partially spherical sealing surface that may have a crenulate configuration.

Dependencies are inferred from the claim text.