Spherical plug valve having pressurized seats including body pressure relief means

Claim 1

A SPHERICAL PLUG VALVE COMPRISING: A. A BODY HAVING: (1) AN OPEN ENDED, CENTRALLY LOCATED VALVE CHAMBER, (2) A PAIR OF AXIALLY ALIGNED FLOW PASSAGES EXTENDING INTO AND COMMUNICATING WITH THE CENTRAL VALVE CHAMBER AND TERMINATING IN PARALLEL SPACED SEAT PADS, EACH OF SAID SEAT PADS HAVING A FLAT SURFACE DEFINING A PLANE NORMAL TO THE AXIS OF SAID FLOW PASSAGES; B. A ROTATABLE VALVE MEMBER TRUNNIONED IN SAID VALVE CHAMBER HAVING GENERALLY SPHERICAL SEALING SURFACES AND A PASSAGE WHICH IN THE OPEN POSITION IS ALIGNED WITH THE FLOW PASSAGES AND A STEM EXTENDING THROUGH AND PAST THE OPENING OF THE VALVE CHAMBER; C. A PAIR OF ANNULAR SEAT MEMBERS, ONE POSITIONED BETWEEN THE VALVE MEMBER AND EACH SEAT PAD, EACH SEAT MEMBER COMPRISED OF AN ANNULAR RETAINER RING ENCOMPASSING A PORTION OF THE SPHERICAL SEALING SURFACES OF THE VALVE MEMBER AND HAVING: (1) A FRUSTO CONICAL SURFACE FORMING THE FRONT FACE OPPOSING THE VALVE MEMBER, (2) AN ANNULAR GROOVE HAVING ITS AXIS PARALLEL WITH THE AXIS OF THE SEAT MEMBER IN THE FRUSTO CONICAL SURFACE, (3) PERIPHERAL WALLS OF SAID GROOVE PROVIDED WITH BUTTRESS TYPE THREAD SERRATIONS HAVING THE ANGULAR PORTIONS FACING OUTWARD TO ESTABLISH A BARBED EFFECT, (4) AN INSERT OF RESILIENT PLASTIC MATERIAL FILLING SAID SERRATIONS IN SAID GROVE AND EXTENDING ABOVE THE PLANE OF THE FRUSTO CONICAL SURFACE, (5) A FLAT SURFACE FORMING THE BACK FACE OF THE ANNULAR RETAINER RING OPPOSING THE SEAT PAD, AN ANNULAR GROOVE IN THE GENERALLY FLAT SURFACE, (6) A PRESSURE ACTUATED PISTON IN SAID BACK FACE GROOVE, (7) MEANS PERMITTING THE ENTRY OF PRESSURE BETWEEN THE BOTTOM OF THE BACK FACE GROOVE AND PISTON, (8) MEANS ESTABLISHING A SEAL BETWEEN SAID SEAT MEMBER AND THE SEAT PAD; (9) MEANS ESTABLISHING A SEAL BETWEEN SAID PISTON AND THE SIDE WALLS OF SAID BACK FACE GROOVE; D. A BONNET SECURED ABOUT THE OPENING OF THE VALVE CHAMBER, THE BONNET HAVING A SEALED PASSAGE THROUGH WHICH THE STEM EXTENDING THROUGH THE OPENING IS TRUNNIONED.