Patent ID: 7850143

Claim:
A ball valve assembly for controlling flow of a mixture through bores in two flanges, the mixture comprising at least one fluid and a plurality of solid particles, the ball valve assembly comprising: a body to which said flanges are mountable, the body comprising a cavity therein and at least one engagement surface proximal to the cavity; a ball positioned in the cavity and comprising a passage therethrough between an inlet end and an outlet end thereof, the passage being positionable to be in fluid communication with the bores when the flanges are mounted to the body; a low-pressure valve seat comprising an opening therein, the low-pressure valve seat additionally comprising an inner side adapted for engagement with the ball and an outer side positioned opposite to the inner side, the low-pressure valve seat being at least partially engageable with said at least one engagement surface to locate the low-pressure valve seat in a first predetermined position relative to the ball; a high-pressure valve seat comprising an opening therein, the high-pressure valve seat additionally comprising an inner side adapted for engagement with the ball and an outer side positioned opposite to the inner side, the high-pressure valve seat being at least partially engageable with said at least one engagement surface to locate the high-pressure valve seat in a second predetermined position relative to the ball; the valve seats being positioned for locating the ball therebetween, the ball being movable between an open position, in which each of the inlet and the outlet ends is at least partially aligned with one of the openings in the low-pressure and high-pressure valve seats respectively to permit flow of the mixture in a flow direction from the inlet end to the outlet end, and a closed position, in which flow of the mixture through the ball is substantially prevented; the high-pressure valve seat being adapted to withstand pressure to which the mixture is subjected when the ball is in the closed position; the low-pressure valve seat comprising at least one scallop formed to permit movement of at least a portion of the mixture past the low-pressure valve seat when the ball is in the open position; the low-pressure valve seat comprising an edge portion adapted for at least partial engagement with said at least one engagement surface of the body, for locating the low-pressure valve seat in the first predetermined position; said at least one scallop comprising a first channel wall positioned in the edge portion of the low-pressure valve seat to define at least one aperture between the first channel wall and the engagement surface, said at least one aperture being adapted to permit movement of the particles therethrough; and said at least one scallop additionally comprising a second channel in the outer side of the low-pressure valve seat, the second channel being at least partially aligned with said at least one aperture.