Abstract: A plug valve is disclosed having a valve chamber with inlet and outlet flow passages in fluid communication therewith, at least one of the flow passages having a generally cylindrical seat recess formed therein about the flow passage and an axially movable seat assembly disposed therein. The valve includes improved means for biasing the sealing assembly against the plug member and cleaning the space between the sealing assembly and the valve body, namely a plurality of conduits extending from the interior surface of a flow passage to a shoulder surface of its associated seat recess and providing for fluid communication between those surfaces.In the preferred embodiment of this invention, wherein the plug is spherical and rotatably mounted on upper and lower trunnions, the lower end of the lower trunnion is mounted in a trunnion cap, and a limit stop is incorporated therein comprising trunnion.