Ball valve impedance seat

摘要

The present invention relates to a ball valve, comprising
a ball (76) mounted in a housing and having a flow bore termed therethrough, wherein the ball (76) is rotatable between a closed position and an open position;
an impedance seat assembly disposed in a flow port of the housing comprising an impedance seat (102) having a radius for metal-to-metal sealing with the ball (76) by rotation thereof circumscribing a concave surface comprising a plurality of flow passages (18, 22) disposed therethrough;
a seat platform comprising a plurality of flow passages (22) disposed therethrough, and comprising an integral seat ring having an outer profile matching a seat ring retention profile of the housing; and
a plurality of stacked plates, each comprising a plurality of flow passages (18) disposed therethrough, and arranged within the flow port between the impedance seat and the seat platform to form a plurality of tortuous flow passages through the flow port;
wherein fluid communication between the flow bore of the ball (76) and the plurality of tortuous flow passages is selectively blocked by rotating the ball from a partially closed position toward the fully closed position to advance a trailing edge of the flow bore past openings of the tortuous flow passage and provided by rotating the ball from a fully closed position toward the partially open position to advance a leading edge of the flow bore past the openings of the tortuous flow passages. The invention also resides in a method of retrofitting a ball valve comprising:
disposing an impedance seat assembly in a flow port of a housing of the ball valve to form a metal-to-metal seal against a correspondingly spherical surface of a ball element of the ball valve;
the impedance seat assembly comprising an integral seat housing having a peripheral seat flange comprising a radius for metal-to-metal sealing with the ball by rotation thereof circumscribing a concave inlet surface comprising a plurality of flow paths disposed therethrough; and
an outlet surface comprising a central planer surface circumscribed by a chamfered section dimensioned to allow the impedance seat assembly to fit into the ball valve.