Ball Valves and is especially advantageous in ball valves in which the valve ball "floats" in the sense that it is subject to displacement by the force of differential fluid pressure on the ball. The invention is directed more specifically to ball valves of the type in which the valve is tightened by moving the valve ball and coacting seat structure in a transverse direction in relation to the flow passages opening into the valve chamber containing the valve ball.

In a Ball Valves of the character to which this invention relates, the valve seat is required to form a seal between the valve ball and the body structure encircling a flow passage to the valve without imposing undue resistance to rotation of the ball and without causing wear on the ball. If the seat is disposed on the downstream side of a valve ball which is free to move against the downstream seat, the full force of differential fluid pressure on the ball as applied by the ball to the downstream seat can have a destructive effect on the valve.

In prior valves, seat structures capable of forming good seals between a valve ball and the body structure encircling a fluid passage have been subject to abuse by temperatures and pressures exceeding the limitations that are normal for such valves. BALL VALVESMany such valves are subject to complete failure upon exposure to excessive heat, as in the event of a fire, even though the valve temperatures reached are not sufficient to destroy metal components of the valves. Valves less vulnerable to damage have generally been less effective in precluding the leakage of fluid through the valves.

One form of ball valve to which the present invention relates is illustrated in U.S. Pat. No. 3,168,279. In this particular type of valve, the planes containing the annular seat-supporting surfaces are such that they converge, contrary to the prior art embodiments which generally utilize parallel supporting surfaces. Further, biasing means is employed to engage the ball and force it as well as the seats inwardly in a direction corresponding to that of the convergence of said seat support surfaces. Thus, this valve construction is self adjusting, the converging nature of the support surfaces tending to force the seats into firm sealing contact with the ball.

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