Abstract: A method of forming a valve seat having a resilient plastic insert received in a serrated groove of the seat. The insert is inserted into the groove and is pressed therein with a power driven ram to effect cold flowing of the insert into serrations in the sides of the groove. The insert is then subjected to hydraulic fluid at a relatively high pressure level to completely bottom the insert against the bottom of the groove prior to machining of a protruding sealing surface of the insert. The invention is directed additionally to another method which includes the step of swaging a lip into the insert to secure it in a non-serrated groove of a valve seat. Hydraulic fluid pressure is then applied to the insert to completely bottom it in the groove prior to installation of the seat in a valve body.

Abstract: A ball or spherical plug valve has a pair of annular seal rings with outer peripheral portions thereof mounted in contact with the valve chamber end walls and inner annular edge portions thereof in sealing contact with the ball member and in a spaced relation to the end walls when the ball member has not been displaced by fluid pressure. Each seal ring has a substantially sharp inner edge portion contacting the ball member in substantially a line contact with the ball member when the ball member has not been displaced by fluid pressure. Each seal ring has a substantially flat inner side portion adjacent to the substantially sharp edge portion and the ball member.