Ball valve seat

Claim 1

IN A SPHERICAL PLUG VALVE COMPRISING A VALVE BODY HAVING A VALVE CHAMBER FORMED THEREIN AND FLOW PASSAGES IN COMMUNICATION WITH THE VALVE CHAMBER, A ROTATABLE PLUG MEMBER OF GENERALLY SPHEROID FORM DISPOSED WITHIN SAID VALVE CHAMBER AND HAVING A PASSAGE FORMED THEREIN FOR REGISTRY WITH SAID FLOW PASSAGES IN THE OPEN POSITION OF SAID VALVE, MEANS FOR IMPARTING ROTATION TO SAID PLUG MEMBER, A PAIR OF OPPOSED SEAT POCKETS FORMED IN SAID VALVE BODY AND EACH HAVING A PAIR OF RADIALLY SPACED CYLINDRICAL WALLS FORMED CONCENTRICALLY WITH THE FLOW PASSAGE AND A PLANAR BOTTOM WALL DISPOSED IN NORMAL RELATION WITH THE FLOW PASSAGE, A SEAT MEMBER DISPOSED IN EACH OF SAID POCKETS, EACH OF SAID SEAT MEMBERS IN THE FREE CONDITION THEREOF HAVING A CYLINDRICAL INNER WALL DEFINING THE INTERNAL PERIPHERY THEREOF AND A FRUSTO-CONICAL SEALING FACE INTERSECTING SAID CYLINDRICAL INNER WALL, THE INCLUDED ANGLE OF SAID FRUSTO-CONICAL SEALING SURFACE BEING SUCH RELATIVE TO THE DIMENSION OF SAID PLUG THAT INITIAL ENGAGEMENT BETWEEN THE PLUG AND SAID FRUSTO-CONICAL SURFACE WILL OCCUR AT THE RADIALLY OUTER PORTION OF THE FRUSTOCONICAL SURFACE, EACH OF SAID SEAT MEMBERS HAVING A BACK WALL HAVING AN INNER PERIPHERAL PORTION THEREOF IN ENGAGEMENT WITH SAID BOTTOM WALL OF SAID SEAT POCKET AND OUTER PERIPHERAL PORTION THEREOF IN RADIALLY OUTWARDLY DIVERGING RELATION WITH SAID BOTTOM WALL, SAID SEAT MEMBERS EACH HAVING AN OUTER WALL THEREOF IN DIVERGING RELATION WITH THE OUTER WALL OF SAID SEAT POCKET.