Ball valve and seal

Claim 1

A ball valve of the type having a body; a ball chamber in the body; inlet and outlet passages in the body; the inlet passage leading to, and the outlet passage leading from, the ball chamber; a diametrically apertured ball in the ball chamber; means for rotating the ball to open or close the way from the inlet passage to the outlet passage; a pair of sealing rings engaging the ball about the inlet and outlet passages; an annular insert threadedly engaged in the outlet passage and adapted to be screwed into the outlet passage towards the ball to force the sealing ring in said outlet passage into firm engagement with the ball, said annular insert being substantially cylindrical and engaged in a cylindrical threaded inner part of the outlet passage, the outer part of the outlet passage being formed with an internal tapered thread tapering towards the said cylindrical threaded inner part of the outlet passage; a peripheral annular rebate at the axially inner end of the annular insert, the rear face of said rebate forming a radially extending contact surface; an annular groove formed in said body about the inner part of said outlet passage; and a deformable ring positioned partly in said peripheral rebate and partly in said annular groove, the front face of said deformable ring, when said annular insert is in an assembled position, contacting the front face of said groove and the outer peripheral edge of the rear face of said sealing ring in said outlet passage, and the rear face of said deformable ring contacting the radial rear face of said rebate thereby to provide solid line contact at both the front and rear faces of said deformable ring to provide a fluid tight seal.