Patent ID: 8061381

Claim:
A seat assembly for use in a ball valve comprising: a seat for seating the ball of the ball valve, the seat having: a flat outer wall; a flat top surface; a top curved shoulder surface positioned between the outer wall and the top surface, the top curved shoulder surface beginning at the top surface and continuing to the outer wall, the top curved shoulder surface comprising a circular radius; a flat bottom surface that is the mirror image of the top surface; and a bottom curved shoulder surface positioned between the outer wall and the bottom surface that is the mirror image of the top curved shoulder surface; and a seat rest configured to receive the seat in either a top surface up or a bottom surface up orientation, the seat rest having a matching surface corresponding to one of the top surface and bottom surface of the seat and having a curved corner surface so that when the seat is assembled with the seat rest the seat and seat rest are in substantial contact at all points from one of the top curved shoulder surface to the top surface and the bottom curved shoulder surface to the bottom surface, on the one hand, and from the curved corner surface to the matching surface, on the other.