Fluid controlling valves with rockable sealing means

Claim 1

A VALVE SEATING ARRANGEMENT INCLUDING A SEATING RING FOR EFFECTING A SEAL BETWEEM AN OBTURATING MEMBER WHICH SLIDES RELATIVELY TO THE RING, AND A VALVE CASING, THE RING ALSO BEING SEALED TO THE CASING AND PRESSED AXIALLY AGAINST THE OBTURATING MEMBER, IN WHICH THE RING INCLUDES IN ITS STRUCTURE AT A SUBSTANTIALLY DISTANCE BEHIND THE ACTUAL SEATING AREA A SUBSTANTIALLY RIGID ANNULAR RIB HAVING A CONVEX OUTER SURFACE WHICH FITS WITH NO MORE THAN WORKING CLEARANCE IN A BORE IN THE VALVE CASING, SAID BORE BEING CYLINDRICAL IN THIS REGION, WHILE TOWARDS THE REGION OF THE ACTUAL SEATING AREA THERE IS SUBSTANTIALLY GREATER CLEARANCE ROUND THE RING STRUCTURE CONTINUED FAR ENOUGH TO ENABLE THE RING STRUCTURE AS A WHOLE TO ROCK IN RELATION TO THE CASING ON ANY TRANSVERSE AXIS THROUGH THE RIB, THE RIB BEING RIGID WITH A THRUST RING AND THE SEATING AREA BEING PROVIDED ON A TUBULAR MEMBER SLIDABLE AXIALLY IN RELATION TO THE THRUST RING AND HAVING A SEALING CONNECTION WITH MEANS FOR SEALING THE RING TO THE VALVE CASING.