Combination steel and teflon seat

Claim 1

In combination with a ball valve including a body having two longitudinally aligned fluid passages and a lateral opening communicating with a central space; a rotatable ball, positioned within said central space, having an opening therethrough communicable with said fluid passages; seat rings, of wedge shape cross section, positioned against and clampingly securing said ball therebetween; seat ring retainer means having flow openings aligned with said fluid passages, said seat ring retainer means further having side walls inclined downwardly and inwardly towards each other, said ball and said seat rings being wedgeably received between said side walls; bonnet means releasably secured to said body so as to selectively apply pressure to an upper portion of said seat rings and thereby compress said seat rings to said ball and seat ring retainer means side walls; and a rotatable valve stem, projecting through said lateral opening and said bonnet means, connected to said ball to rotate the ball between positions of permitting and preventing the passage of fluid therethrough; an improved seat ring comprising: a. an outer ring, formed from a metallic material substantially immune to circumferential and radial expansion, having a rear inclined surface positioned to contact said seat ring retainer means side walls; b. said rear surface of said outer ring having an annular recess formed therein for receipt of an O-ring for causing a seal between said outer ring and said seat ring retainer means side walls; c. an inner ring, formed of a yieldable polymeric material, received in an annular recess in a front surface of said outer ring and positioned to form a seal with said ball; d. said later recess having an outer diameter less than the outer dimension of said outer ring and said inner ring having a thickness slightly greater than the depth of said recess; and e. said outer ring having a section removed from an upper portion thereof extending across the entire thickness of said outer ring so as to define a top surface of reduced area to more evenly distribute the pressure applied thereto by the bonnet means and thereby control the compression of said seat rings to said ball and seat ring retainer means side wall.