Patent attributes
A valve is disclosed having a telescoping seat assembly that fits into a pocket or enlargement of a flow passageway through the valve body. An outer seat element seals with the pocket utilizing a plurality of seal assemblies to seal with the pocket whereby pressure may become trapped between the seal assemblies during valve operation under certain unusual conditions. A groove with a tapering or angled surface is provided in the outer seat. A seal ring is disposed in the groove whereby pressure from one side of the seal ring moves the seal along the tapering or angled surface to wedge the seal into contact with the wall of the pocket. Pressure from the other side of the seal ring moves the seal ring along the tapering surface and away from the wall of the pocket so as to be out of sealing engagement thereby permitting bleeding off of the pressure or de-energizing of the seal assemblies.
