Abstract: A top entry ball valve comprises a housing having an interior cavity sufficiently large to receive a conventional ball and conventional seat rings through an opening in the housing. After the ball/seat package has been inserted into the cavity, a cam arrangement is used to axially load the seat rings. The cam arrangement comprises a pair of circular cams, each having an undulating annular surface, which are disposed in the housing cavity adjacent one of the seat rings with the respective undulating annular surfaces of the cams being in closely adjacent facing relation to one another. After assembly of the valve, one of the circular cams is rotated relative to the other cam to vary the rotational positions of the undulating annular surfaces relative to one another thereby to vary the axial positions of the circular cams relative to one another and relative to the ball and seat rings.

Abstract: A ball valve having improved inherent rangeability comprises a floating ball of conventional design that is rotatable through substantially 90.degree. between a pair of seats respectively located adjacent the upstream and downstream sides of the valve within a valve housing. At least one of the seats is a one-piece lubricant-impregnated metal seat configured to provide a concave central surface portion that makes full-face direct sealing contact with the ball, and which defines multiple spaced holes that extend through the seat to increase the fluid-to-metal contact of fluid passing through the seat thereby to reduce the pressure between the upstream and downstream sides of the valve. The pattern of holes may be such as to cause the valve to exhibit an equal percentage of flow characteristic for at least a portion of the ball rotation and/or a linear flow characteristic for at least a portion of the ball rotation.

Abstract: A valve seat for ball valves comprises a ring-shaped or annular body fabricated of sintered metal particles having interparticulate spaces which are substantially completely filled with graphite. The seat is fabricated by pumping a dispersion of colloidal graphite in a liquid carrier through the matrix of a preformed ring-shaped sintered metal body, thereafter heating the body to drive off any portion of the liquid carrier which remains in the interparticulate spaces of the body, and then coining the body to collapse any voids which remain in the body and to mechanically bind into the body the graphite which has been trapped in said interparticulate spaces during the pumping step.