US 4,572,239 A · High pressure ball valve

Abstract

A ball valve designed for high pressure shut-off at fluid pressures approaching the ultimate compressive stress of plastic annular seat rings which are employed. The ball member is trunnion mounted in order to carry the total force of the shut-off pressure and the seat rings are disposed in seat ring carriers. Each seat ring includes a spherical ball engaging surface having a radius slightly smaller than the radius of the ball. Each carrier is continuously urged toward the ball by a plurality of disc springs in order that the seat ring engaging surfaces will be in continuous sealing engagement with the ball surface. The seat ring engaging surfaces are configured so that at least the areas thereof located adjacent the outer diameters will be first to sealingly engage the ball. The valve components are configured and dimensioned to limit the effective area on which fluid pressure may act in urging the seat rings into ball contact for thus controlling compressive stresses which may be exerted on the plastic seat ring material. Also, fluid pressure urges the seat rings toward the ball to enhance sealing engagement with the ball regardless of the position of each seat ring upstream or downstream of the ball from the source of fluid pressure and also with the valve in the open position. The inventive concept involved may advantageously be employed in a variety of valve bodies to accommodate a plurality of fluid shut-off applications.

A high pressure ball valve comprising:

a valve body having a cylindrical first flow passageway and a cylindrical central passageway extending therethrough in a generally normal relative relationship and in communication with each other, the opposite ends of said first passageway defining a pair of valve body branches;
a valve closure member received in said central passageway and being selectively rotatable about the central passageway axis, said closure member having a spherical ball portion disposed in said first passageway and a pair of cylindrical trunnions disposed on opposite sides of said ball portion in said central passageway, said ball portion including a fluid passage therethrough and one of said trunnions including means for connecting said closure member to control means, that portion of said central passageway receiving the other of said trunnions defining a third valve body branch;
control means in operative communication with said valve closure member connecting means for allowing selective rotation of said closure member to move said fluid passage in said ball portion between valve open and closed conditions;
a pair of radially inward extending annular shoulders in said first passageway located generally equal distances from said ball portion, each said shoulder being circumferentially continuous and having a surface normal to the axis of said first passageway facing said ball portion;
a pair of seat ring carriers disposed in said first passageway with one of said carriers positioned at each area of communication of said first passageway with said central passageway, each carrier including an axial fluid flow opening therethrough and a radially outward extending annular face compatible with and facing the said surface of an associated one of said shoulders, said carriers each further including an annular seat ring receiving groove facing said ball portion and a cylindrical tail portion extending axially of said first passageway away from said ball portion in a radially inwardly spaced relation to said first flow passageway to form a cylindrical seal chamber;
a plurality of partially stressed disc springs interposed between each shoulder surface and the annular face of the associated carrier for urging said carriers axially of said first passageway toward said ball portion, each disc spring having a central opening and in its unstressed condition having a truncated conical shape, said disc springs being positioned so that the smaller diameter ends of alternating ones thereof face in opposite directions;
a deformable annular seat ring closely received in the seat ring receiving groove of each carrier with said seat rings each including a continuous engaging surface facing said ball portion and wherein said engaging surface has a spherical conformation in its unstressed condition of a radius less than the radius of said ball portion, said seat ring engaging surfaces being urged into sealing contact so that said surfaces first contact with said ball portion at about the outer diameter of said surfaces during assembly and such contact widening from the outer diameter radially inwardly toward the inner diameter of said surfaces under the influence of said disc springs and fluid pressure loads, said sealing contact occurring at least at a diameter across the engaging surface of each seat ring which is smaller than the diameter across the associated seal chamber, said seat rings locating said closure member ball portion in said first passageway and retaining said closure member in said central passageway;
seal means interposed between each carrier tail portion and the valve body, in the associated seal chamber, and said seal means each including at least one annular seal ring adapted to be axially shifted between defined limits in response to fluid pressure exerted thereagainst;
and,
said third branch comprising an upstream branch and said pair of seat rings comprising downstream seat rings with fluid pressure contacting either of said carriers adapted to further urge the associated seat ring toward engagement with said ball portion, the area which provides the net force of fluid pressure for such further urging being limited to a predetermined annular area defined between the outside diameter of the engaging band on each seat ring and the outside diameter of the associated carrier tail portion for preventing the application of destructive compressive loads to the seat rings.

7 more elements

High pressure ball valve

Life of this patent

High pressure ball valve

Life of this patent

Abstract

Claims17