High pressure valve assembly

In a valve assembly adapted to receive a slurry at relatively low pressure and discharge the slurry to a system at relatively high pressure and comprising a housing having a low pressure slurry inlet and outlet means on opposite sides of said housing, a high pressure fluid inlet and slurry outlet means on opposite sides of said housing separated from said low pressure slurry inlet and outlet means, and a tapered valve plug having a plurality of offset ports therein defining the openings of a valve chamber between corresponding pairs of inlet and outlet offset ports, said valve plug being rotatably supported in said housing at one end by bearings and a drive shaft passing through a first end cover and at the other end of said housing by a laterally adjustable means passing through a second end cover, said valve plug ports being in registry with said housing inlets and outlets in a predetermined sequence during rotation of said valve plug, the improvement comprising means defining at least one annular groove contained in exposed communication between the radially separated relatively rotating surfaces of said valve plug and said housing at a selected longitudinal location corresponding to a location of potential banding wear therebetween, conduit means adapted continuously to supply fluid of the character of that being transferred from the low pressure side to the high pressure side from a source to said at least one groove and control means operative to control fluid flow in said conduit means so that upon rotation of said valve plug fluid in said conduit means is provided to said groove to establish a continuous lubricating/flushing flow between said housing and said valve plug surfaces thereat.