Removable head and seat ball valve construction

Claim 1

A VALVE COMPRISING A CASING WITH AN INLET AND OUTLET AND A SUBSTANTIALLY FRUSTO-CONICAL VALVE CHAMBER THEREBETWEEN HAVING INNER END SURFACE LIMIT DEFINED BY A CURVED SURFACE OF SPHEROIDAL CONFIGURATION; (A) A ONE-PIECE HOLLOW FLEXIBLE PORTED FRUSTO-CONICAL SEAT MEMBER WITH AN INNER ROUNDED IMPERFORATE WALL PORTION OF THE SAME CONFIGURATION AS THE SAID VALVE CHAMBER INNER SURFACE LIMIT AND BEING NONROTATABLY MOUNTED IN SAID CASING TO SUBSTANTIALLY COVER THE WALL SURFACES DEFINING THE SAID VALVE CHAMBER; (B) A SPHEROIDAL PORTED VALVE CLOSURE MEMBER FITTED CLOSELY WITHIN SAID SEAT MEMBER AND BEING ROTATABLE THERETO IN OPENING AND CLOSING THE VALVE; (C) THE SAID IMPERFORATED WALL PORTION BEING OF UNIFORM THICKNESS TO FILL A UNIFORM SPACE BETWEEN THE SAID SPHEROIDAL CLOSURE MEMBER AND THE CURVED SURFACE END PORTION OF THE VALVE CHAMBER WHEREBY TO EFFECT UNIFORM DISTRIBUTION OF THE COMPRESSION LOAD BETWEEN THE CURVED SURFACE END LIMIT OF THE CASING CHAMBER AND THE SAID SPHEROIDAL CLOSURE MEMBER; (D) AND MEANS COOPERATING WITH AN UPPER PORTION OF THE CASING TO BEAR AGAINST AN UPPER OUTER SURFACE PORTION OF THE SAID FLEXIBLE SEAT MEMBER TO EFFECT INCREASED COMPRESSION LOAD BY THE SAID SEAT MEMBER APPLIED RESPECTIVELY BETWEEN THE SAID CLOSURE MEMBER; (E) THE INNER ROUNDED IMPERFORATE WALL PORTION OF THE SAID SEAT MEMBER AND THE SAID FRUSTO-CONICAL WALL SURFACES DEFINING THE SAID VALVE CHAMBER.