High pressure plug valve having particular sealing arrangement

Claim 1

A PLUG VALVE FOR CONTROLLING FLOW OF HIGH AND LOW TEMPERATURE FLUIDS, COMPRISING A RIGID BODY HAVING A CONTAINED PASSAGE FOR CONTINUOUS FLOW OF FLUID FROM AN INLET IN ONE WALL OF THE BODY TO AN OUTLET IN ANOTHER WALL THEREOF DISTANT FROM SAID INLET, A STEPPED RECESS INTERMEDIATE THE ENDS OF SAID BODY DISPOSED IN SUBSTANTIALLY PERPENDICULAR RELATION TO A PORTION OF SAID BODY PASSAGE AND INCLUDING A WIDER PORTION OPENING THROUGH A WALL OF THE BODY AND A NARROWER ADJOINING PORTION EXTENDING INWARDLY THEREFROM SUBSTANTIALLY BEYOND SAID PASSAGE AND TERMINATING WITHIN THE BODY, MEANS ON THE BODY FOR CONNECTING THE INLET OF THE PASSAGE IN A FLUID CONDUCTING LINE, MEANS ON THE BODY FOR CONNECTING THE PASSAGE OUTLET IN A FLUID CONDUCTING LINE, AN ANNULAR SEAT MEMBER FITTED IN THE INNER END OF THE RECESSED PORTION AND HAVING OPENINGS ALIGNED WITH UPSTREAM AND DOWNSTREAM PORTIONS RESPECTIVELY OF SAID VALVE PASSAGE, SAID SEAT MEMBER BEING FORMED OF A PLASTIC COMPOSITION POSSESSING COLD FLOW CHARACTERISTICS AND HAVING A TAPERING INTERNAL SURFACE, A TAPERED PLUG FITTED IN THE SEAT MEMBER AND FORMED OF A MATERIAL HARDER THAN SAID SEAT MEMBER, SAID PLUG HAVING A PASSAGE ADAPTED TO BE ALIGNED WITH SAID UPSTREAM AND DOWNSTREAM PORTIONS OF THE VALVE PASSAGE IN ONE POSITION OF ITS ROTATION, A STEAM ON THE PLUG EXTENDING OUTWARDLY THROUGH THE RECESSED PORTION BEYOND THE BODY FOR ROTATION OF THE PLUG WITHIN THE SEAT, A SEALING MEMBER OF A DIAMETER CORRESPONDING TO AND FITTED IN THE NARROWER RECESSED PORTION, CLOSURE MEANS FOR THE OPEN END OF SAID RECESS THROUGH WHICH SAID STEM EXTENDS CONSTRUCTED AND ARRANGED TO EXERT THRUST ON THE SEALING MEMBER AND FORCE THE PLUG AGAINST THE SEAT MEMBER SO THAT THE SEALING MEMBER AND SEAT MEMBER PROVIDE A DOUBLE-LAYER SEAL FOR SEALING THE PLUG PASSAGE FROM THE EXTERIOR OF THE BODY THROUGH THE NARROWER RECESS.