GB2347196A

GB2347196A - Ball valve spindle sealing

Info

Publication number: GB2347196A
Application number: GB9904499A
Authority: GB
Inventors: David Cornwell
Original assignee: OLIVER VALVES Ltd
Current assignee: OLIVER VALVES Ltd
Priority date: 1999-02-27
Filing date: 1999-02-27
Publication date: 2000-08-30
Also published as: GB9904499D0

Abstract

A ball valve assembly has a housing body in which is disposed a ball valve rotatable on a spindle 6 that is sealed to the housing body by means of a sealing arrangement. A first seal 17 is disposed adjacent to a pressure ring 19 which is designed to apply pressure to the first seal during rotation of the ball valve so as to deform the first sealing member into a sealing configuration. The pressure ring has a radially extending flange 25 of a diameter greater than that of the first sealing member so as to prevent extrusion of the seal past the pressure ring. Further sealing may be provided by an O-ring 13 and a graphite gland seal 15. The seal 17 is preferably a graphite gland seal. Preferably seal 17 is disposed in an annular groove 18 in a surface of the housing and the ring 19 is made of a rigid material.

Description

A BALL VALVE ASSEMBLY The present invention relates to a ball valve assembly.

Known high pressure ball valve assemblies comprise a valve ball that is rotatably mounted in a fluid passage such that it may be rotated between an open position in which an aperture through the ball valve is in register with the passage so as to permit fluid flow therethrough and a closed position in which the valve is rotated through ninety degrees so as move the aperture out of register and close the passage.

Rotation of the valve is effected by an actuating handle that is attached to a spindle extending upwardly from the ball valve. The spindle is disposed perpendicular to the passage and is sealed along part of its length in a bore in a surrounding housing member so as to prevent fluid leakage from the passage. The remainder of the spindle extends above the housing where it is retained on the handle by means of lock nuts.

In conventional ball valve assemblies the spindle is sealed by an arrangement that includes a primary 0-ring seal received in a circumferential groove of the spindle above the passage. The 0-ring seals the passage from the bore in which the spindle is rotatably received. Between the primary 0-ring seal and the handle there is provided in the bore a thrust ring generally manufactured from a polymeric material and upper and lower graphite-based gland seals. Above the bore the spindle supports a piston pressure ring, an anti-torque plate and two disc springs. After the components have been assembled on to the spindle, torque is applied to two lock nuts above the handle and the piston pressure ring is compressed against the upper gland seal so that it deforms to provide an effective seal against the spindle. A significant disadvantage of this arrangement is that the upper seal can be over-compressed such that it extrudes past the piston ring thereby compromising the efficiency of the sealing arrangement.

It is an object of the present invention to obviate or mitigate the aforesaid disadvantage.

According to the present invention there is provided a ball valve assembly comprising a valve housing body in which there is a flow passage therethrough, a ball valve disposed in said passage and rotatable between a first position in which it closes said passage and a second position in which an aperture through the ball valve is in register with the passage, the ball valve being rotatable on a spindle that is sealed to the housing body by means of a sealing arrangement comprising a first sealing member that is adjacent to a pressure member, the pressure member being designed to apply pressure to the first sealing member during rotation of the ball valve so as to deform the first sealing member into a sealing configuration, wherein the pressure member has a radially extending flange of a diameter greater than that of the first sealing member.

The flange prevents the first sealing member from extruding past the pressure member during its deformation and thereby ensures effective sealing.

The pressure member is preferably constructed of rigid material.

The first sealing member may be disposed in an annular groove in a surface of the housing body.

The pressure member is preferably radially outwardly stepped having a first diameter substantially equal to that of first sealing member and immediately adjacent thereto.

Preferably the spindle and valve ball are rotatable by an actuating handle There may be provided a second sealing member disposed on the spindle between the first sealing member and the fluid passage.

A specific embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a longitudinal sectional view of a ball valve assembly in accordance with the present invention; and Figure 2 is a longitudinal sectional view of a pressure member of the present invention.

Referring now to the drawings, the ball valve assembly comprises a housing body 1 (shown partially cut away) defining a horizontal fluid passage 2 and a valve chamber 3 within which is disposed a rotary valve ball 4. For clarity the valve seat is not shown.

The valve ball 4 has an aperture 5 therethrough and is rotatable between an open position (shown in figure 1) in which the aperture 5 is in register with the fluid passage 2 so as to permit fluid to pass therethrough and a closed position in which it is rotated through ninety degrees so as to close the passage 2. In order to effect rotation the valve ball 4 is mounted on the end of a spindle 6 that is received in a vertical bore 7 through the housing body 1 and which is rotatable by means of an actuating handle 8 disposed above the housing body 1.

A sealing arrangement is provided around the spindle 6 in the vertical bore 7 so as to prevent fluid leakage therethrough. The bore 7 has a lower portion 9 nearer the fluid passage 2 in which a wider portion 10 of the spindle 6 resides and an upper portion 11 in which a smaller diameter portion 12 of the spindle 6 is received. Starting at the lower portion 9 of the bore 7 and working upwards, the arrangement comprises an 0-ring seal 13 disposed in an annular circumferential groove 14 in the spindle 6.

Immediately above the wider portion 10 of the spindle 6 is a graphite-based gland seal 15 that is seated between offset transitional steps 16 that mark the change in diameters of the bore 7 and spindle 6. At the top of the housing body 1 a further graphite-based gland seal 17 is disposed in an annular groove 18 around the bore 7.

Immediately above the upper gland seal 17, between the bore 7 and the handle 8 there is, successively, a piston pressure ring 19, an anti-torque plate 20 and two opposed spring washers 21,22. The handle 8 is secured to the spindle 6 by two locking nuts 23,24.

The piston pressure ring 19 is constructed from a rigid material such as steel and is of"top-hat"configuration having an upper radially outward extending flange 25 of diameter greater that the bore 7 and the upper gland seal 17. The lower portion of the ring 19 is substantially the same diameter as the bore 7. The anti-torque plate 20 is designed to prevent torsional forces from the handle 8 being transmitted to the upper seal 17 as is well known in the field.

In use, the valve ball 4 is rotated between open and closed positions by actuation of the handle 8 to rotate the spindle 6 in the bore 7.

During assembly of the sealing arrangement torque is applied to lock nut 23.

This has the effect of compressing the spring washers 21,22 and the upper and lower gland seals 17,15 and forces the piston pressure ring 19 against the upper gland seal 17. The pressure ring 19 thus applies a compressive force such that the upper seal 17 deforms and applies an effective seal between the spindle 6 and bore 7. The flange 25 prevents the whole piston pressure ring 19 from entering the annular groove 19. In the event that excessive torque is applied to tighten lock nut 23, the flange 25 prevents the seal 17 from being forced out of the annular groove 18, over the pressure ring 18 and thereby compromising the effectiveness of the seal.

Once the lower lock nut 23 has been tightened sufficiently a second lock nut 24 is added (a lock washer may alternatively be used).

Claims

CLAIMS 1. A ball valve assembly comprising a valve housing body in which there is a flow passage therethrough, a ball valve disposed in said passage and rotatable between a first position in which it closes said passage and a second position in which an aperture through the ball valve is in register with the passage, the ball valve being rotatable on a spindle that is sealed to the housing body by means of a sealing arrangement comprising a first sealing member that is adjacent to a pressure member, the pressure member being designed to apply pressure to the first sealing member during rotation of the ball valve so as to deform the first sealing member into a sealing configuration, wherein the pressure member has a radially extending flange of a diameter greater than that of the first sealing member.
2. A ball valve assembly according to claim 1, wherein the pressure member is constructed of rigid material.
3. A ball valve assembly according to claim 1 or 2, wherein the first sealing member is disposed in an annular groove in a surface of the housing body.
4. A ball valve assembly according to claim 1,2 or 3, wherein the pressure member is preferably radially outwardly stepped having a first diameter substantially equal to that of first sealing member and immediately adjacent thereto.
5. A ball valve assembly according to any preceding claim, wherein the spindle and valve ball are rotatable by an actuating handle.
6. A ball valve assembly according to any preceding claim, wherein there is provided a second sealing member disposed on the spindle between the first sealing member and the fluid passage.
7. A ball valve assembly according to any preceding claim substantially as hereinbefore described with reference to the accompanying drawings.