Plug valve construction

Claim 1

IN A VALVE CONSTRUCTION HAVING A VALVE SEAT PROVIDED WITH A PAIR OF RELATIVELY SPACED PORTS; A VALVE PLUG ROTATABLY MOUNTABLE WITHIN SUCH VALVE SEAT, SAID PLUG COMPRISING A ROTATABLE CORE HAVING TAPERED SIDE WALLS, A PASSAGEWAY FORMED IN SAID CORE AND HAVING THE OPPOSITE ENDS OF SAID PASSAGEWAY TERMINATING AT SPACED LOCATIONS ON SAID TAPERED SIDE WALLS AND BEING REGISTRABLE WITH THE PORTS OF SUCH VALVE SEAT WHEN SAID CORE IS IN ONE POSITION OF ROTATABLE ADJUSTMENT, AND AN END FACE PROVIDED WITH AN AXIALLY DISPOSED BOSS AND A RECESSED PORTION HAVING THE INNER PERIPHERY THEREOF SPACED FROM SAID BOSS; THE SEGMENT OF SAID END FACE INTERMEDIATE SAID BOSS AND THE INNER PERIPHERY OF SAID RECESSED PORTION FORMING A SUPPORTING SURFACE; A RESILIENT MOLDABLE COATING HAVING A PREDETERMINED SHRINKAGE PROPERTY, OVERLYING CONTINUOUSLY THE SIDE WALLS, THE INTERIOR SURFACES OF THE PASSAGEWAY, AND ALL OF SAID END FACE OF SAID CORE EXCEPT FOR SAID END FACE BOSS AND SUPPORTING SURFACE; THE DEPTH OF RECESS OF SAID RECESSED PORTION RELATIVE TO THE PLANE OF SAID SUPPORTING SURFACE BEING GREATEST ADJACENT THE INNER PERIPHERY OF SAID RECESSED PORTION, GRADUALLY DIMINISHING TOWARD THE OUTER PERIPHERY, AND BEING SUCH AS TO PROVIDE A RELIEVED EXPOSED COATING SURFACE; AND A REMOVABLE END PIECE MOUNTED ON SAID END FACE AND HAVING A PLANAR SURFACE ENGAGING SAID END FACE SUPPORTING SURFACE AND OVERLYING THE EXPOSED SURFACE OF SAID END FACE COATING; THE OUTER PERIPHERY OF SAID END PIECE PLANAR SURFACE COMPRESSIVELY ENGAGING THE END FACE COATING OVERLYING SAID END FACE OUTER PERIPHERY; THE THICKNESS OF SAID END FACE COATING BEING GREATEST AT SAID RECESSED PORTION INNER PERIPHERY AND BEING GREATER THAN THE SPACING BETWEEN THE OUTER PERIPHERY OF SAID END PIECE PLANNER SURFACE AND THE OUTER PERIPHERY OF SAID CORE END FACE WHEREBY THE COMPRESSIBILITY OF THE PORTION OF SAID END FACE COATING ADJACENT SAID RECESSED PORTION INNER PERIPHERY IS SUCH THAT SUCH END FACE COATING PORTION IS IMPASSABLE RELATIVE TO SAID SPACING, SAID END PIECE EFFECTING PROGRESSIVELY GREATER COMPRESSION FORCES AGAINST SAID END FACE SURFACE COATING AS THE OUTER PERIPHERY OF SAID CORE END FACE IS APPROACHED.