Valve seat for ball valves

A ball valve structure comprising:

• a valve body having a valve chamber therein, fluid flow passages through the valve body in communication with the valve chamber, and an annular seat pocket formed at the juncture of at least one of the fluid flow passages and the valve chamber and having a valve seat supporting abutment therein;
• a ball valve member positioned in the valve chamber movable between open and closed positions relative to the fluid flow passages;
• an annular valve seat assembly positioned in the seat pocket and having inner and outer concentric seat rings of generally cylindrical form wherein the outer seat ring is arranged in juxtaposed relation to a portion of the inner seating with a sealing ring mounted therebetween, the outer seat ring having an inside peripheral surface facing the inner concentric seat ring, and a sealing ring mounting groove around the inside peripheral surface at one end portion thereof the receive and mount the sealing ring, the inner seat ring having a first outer peripheral surface adjacent the outer seat ring inside surface, and an outer peripheral frusto-conical portion adjacent the end facing the ball valve member whereby upon sliding engagement of the concentric inner and outer seat rings the frusto-conical portion of the inner seat ring engages and deforms the sealing ring positioned in the outer seat ring mounting groove to provide a protruded annular sealing portion extending beyond the ends of the inner and outer seat rings to sealingly contact the exterior surface of the ball valve member;
• and
• spring means positioned in the seat pocket, one end of which contacts the valve seat supporting abutment and the other end contacts the end of the outer seat ring remote from the ball valve member to urge the valve seat assembly and protruded annular sealing portion of the sealing ring toward and into fluid-tight sealing contact with the ball valve member.