Butterfly valve with radially shiftable and fluid pressure responsive seat

Claim 1

A VALVE FOR FLUID LINES COMPRISING A VALVE BODY WITH A THROUGH PASSAGE BETWEEN A HIGH PRESSURE FLUID INLET AND AN OUTLET, A BUTTERFLY VALVE DISK PIVOTALLY SECURED TO THE BODY WITHIN THE PASSAGE FOR MOVEMENTS BETWEEN FULL OPEN AND FULL CLOSED POSITIONS, A VALVE SEAT, AND RECESS MEANS IN SAID PASSAGE TO RETAIN THE VALVE SEAT WITHIN THE BODY FOR LIMITED SHIFTING ABOUT THE PASSAGE IN A PLANE TRANSVERSE TO THE AXIS OF THE PASSAGE, SAID VALVE SEAT HAVING A FIRST ARCUATE BODY PORTION IN FRICTIONAL POINT CONTACT WITH SAID RECESS MEANS AND A SECOND PORTION EXTENDING FIRST RADIALLY INWARD AND THEN GENERALLY AXIALLY OF THE PASSAGE AND IN A DIRECTION OPPOSED TO THE PRESSURE FLUID FLOW FROM THE INLET, SAID FRICTIONAL POINT CONTACT PROVIDING THE SOLE ATTACHMENT BETWEEN SAID SEAT AND SAID VALVE BODY, AND SAID VALVE DISK, WHEN MOVED TO A CLOSED POSITION, ENGAGING SAID SEAT AND SHIFTING THE SAME SUFFICIENTLY TO OBTAIN FULL CONTACT WITH THE SEAT AND SAID SEAT UPON CONTACT BY THE DISK BEING URGED BY THE PRESSURE FLUID INTO EFFECTIVE SEALING RELATIONSHIP THEREWITH.