A ball valve is provided which comprises a valve body formed from a tubular member with a cylindrical hole extending therethrough, a stem having one end thereof projecting into the hole, and a ball fixed to an end of the stem. The ball has a circular bore extending diametrically therethrough, wherein the ball is spherical in shape with removed chordal segments corresponding to the bore. A seat carrier is inserted in the hole, the seat carrier having one end adjacent the ball, a connecting sleeve contacts the seat carrier at the other end thereof opposite the end adjacent the ball, and a union nut couples the connecting sleeve to the valve body. Diametrically opposed projections are provided on the inner surface of the valve body, the projections extending into the hole, recesses formed on the side of the seat carrier adjacent the one end thereof, and diametrically opposed grooves are formed in the side of the seat carrier adjacent the recesses. The grooves extend in the circumferential direction from the adjacent recesses. When the seat carrier is inserted into the valve body and rotated therein, the projections on the valve body engage the grooves in the seat carrier to thereby hold the seat carrier in the valve body. Further, a flange is formed on the other end of the seat carrier wherein one of the flange and valve body includes at least one projection and the other of the flange and valve body includes at least one cavity. The projection is engaged in the cavity to prevent the rotation of the seat carrier with respect to the valve body.
