GB2093568A - Ball valves - Google Patents

Abstract

A ball valve comprises a valve ball (2) which is hollow and defines an inlet (29) and an outlet (30). A piece of resilient sheet material (31) is coiled, inserted into the ball (2) and then allowed to spring out again so that its natural resilience urges it against the inside of the inlet (29) and outlet (30) of the ball (2) to provide a smooth connection from inlet (29) to outlet (30). This provides a lighter and less expensive ball valve. <IMAGE>

Description

SPECIFICATION Ball valves The present invention relates to ball valves.

In the construction of steel ball valves it is sometimes necessary to provide a clear full bore in order to reduce the pressure losses causes by the presence of the valve in the line, to reduce turbulence and to permit the passage of a product separation or line cleaning device.

In reduced bore valves it is permitted to offer shell type balls which are essentially hollow and thus do not provide a straight through bore. In full bore valves, however, it is necessary to provide a conduit bore through the ball so that an uninterrupted flow passage exists of approximately the same diameter as the pipe bore.

If the ball is made as a solid sphere with a straight hole through its centre it becomes extremely heavy and, especially where stainless steel is employed, very expensive. Various methods of producing straight through bores in lighter construction balls are employed but these involve either complicated casting cores or extensive fabrication by welding.

According to one aspect of the present invention there is provided a valve ball for a ball valve which is hollow and defines an inlet and an outlet in which a piece of resilient sheet material in coiled form extends between the inlet and the outlet to define a bore therebetween, the natural resilience of the material resulting in a tendency to uncoil so that the material is urged against the edges of the inlet and the outlet to hold it in position.

According to another aspect of the present invention, there is provided a ball valve comprising a valve housing defining a valve inlet and a valve outlet, a valve ball also defining an inlet and an outlet and rotatably disposed in the housing and means for rotating the ball relative to the housing to align respective inlets and respective outlets in the housing and the ball when the valve is in the fully open position orto disalign those inlets and outlets when the valve is in the partly open or closed position in which the ball is hollow and a piece of resilient sheet material in coiled form extends between the inlet and the outlet to define a bore therebetween, the natural resilience of the material resulting in a tendency to uncoil so that the material is urged against the edges of the inlet and the outlet to hold it in position.

A preferred form of the invention may comprise any one or more of the following advantageous features: (a) The ball and sheet are made of steel.

(b) The steel is stainless.

(c) The ball is formed at the inlet and outlet to accommodate the sheet material.

(d) The formation of (c) comprises rebates which accommodate opposite longitudinal ends of the sheet material.

(e) The coil has a single turn.

(f) Adjacent longitudinal edges of the sheet of (c) are tack welded.

(g) A drain/pressure equalising hole is provided in the sheet adjacent to the longitudinal edges.

In order that the invention may be more clearly understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a longitudinal section of a ball valve; Figure 2 is a section through part of the ball valve of Figure 1 along the section line A-A; Figure 3 is a cross-section through the ball of the valve of Figures 1 and 2 taken on the line B-B of Figure 4; and Figure 4 is a longitudinal section taken through the ball ofthe valve of Figures 1 and 2 taken on the line C-C of Figure 3.

Referring to Figures 1 and 2, the ball valve comprises a valve housing, indicated generally by the reference numeral 1, a valve ball 2, and a valve operating mechanism indicated generally by the reference numeral 3. The valve housing comprises two cast flanged parts 4 and 5 which are bolted together by means of a plurality of nuts and bolts 6 spaced radially around, and extending through, the flanges. Part 5 is rebated at 7 to accommodate a housing gasket 8 which serves as a seal between the two housing parts 4 and 5. Part 4 is formed with a shoulder 9 which is complementary to the rebate 7 on part 5. Valve seat rings 10 and 11 are accommodated in respective grooves 12 and 13 formed in respective housing parts 4 and 5.

The valve ball defines a recess 14 and the housing part5 a bore 15 to receive a stem 16 of the valve operating mechanism 3. The stem 16 is bored at its lower end and laterally somewhat disposed from the lower end to receive two stem plungers 17 and 18 with associated springs 19 and 20. These plungers in turn connect the valve ball 2 to the stem 16 and the stem 16 to the housing 1 in order to prevent the build-up of static electricity in the ball 2. A distance tube 21 having stem sealing rings 37 top and bottom is interposed between the wall of the bore 15 and the stem 16 and a spacer 22a is disposed around the stem 16 above the tube 21. The upper part of the stem 16 is screwthreaded and a stem stop plate 22 is placed onto this portion until it abuts the spacer 22a.

A spring washer 23 and tab washer 24 are placed over the stem 16 and a lock nut 25 is screwed on the stem 16 before a double ended wrench 26 is placed on to complete the mechanism and locked in position by means of a screw. The relative position of valve ball 2 and valve housing 1, and therefore, the degree of opening of the valve, is controlled by appropriately turning the wrench 26.

Housing part 4 of the valve defines the valve inlet 27 and housing part 5 defines the valve outlet 28 or vice versa. The ball 2 also defines an inlet 29 and an outlet 30 or vice versa and in Figure 1 the inlets 27 and 29 and the outlets 28 and 30 are shown aligned.

That is the valve is fully open. Referring more particularly to Figures 3 and 4, the ball is hollow and a piece of resilient sheet material 31 is coiled, inserted into the ball. 2 and then allowed to spring out again so that its natural resilience urges it against the inside of the inlet and outlet of the ball 2.

The thickness of the sheet of material is chosen in dependance upon the ability of the sheet to coil without buckling. The length of the material piece 31 is substantially the same as that of the recess between positions 34 on Figure 4 and the uncoiled width is substantially equal to the circumference of the inlet 29 and outlet 30. Opposite substantially circular edges of the piece are received in rebates 32 and 33 specially formed for that purpose in the ball 2.

Adjacent longitudinal edges of the coiled piece 31 are tack welded together in position at 34 although welding is not essential. Both the ball and the piece are made of stainless steel. In addition to the recess 14 in the top of the ball 2, the ball is bored at its bottom 35 to ensure that pressure equilibrium is maintained between the valve housing and the pipe-line. The edges of the ball defining the inlet 29 and the outlet 30 (or vice versa) are curved as shown in the inset diagram of Figure 4 to avoid damage being caused to valve seat rings 10 and 11 when operating the valve.

It will be appreciated that the above described arrangement provides a lighter and less expensive ball. The lightness is particularly important with the larger size, for example 6", valves. Hollow ball valves may be simply converted to parallel bore valves, that is having a conduit bore. It will also be appreciated that the above valve has been described by way of example only and that many variations are possible without departing from the invention.

Claims (11)

1. Avalve ball for a ball valve which is hollow and defines an inlet and an outlet in which a piece of resilient sheet material in coiled form extends between the inlet and the outlet to define a bore therebetween, the natural resilience of the material resulting in a tendency to uncoil so that the material is urged against the edges of the inlet and the outlet to hold it in position.

2. Avalve ball as claimed in Claim 1, in which the ball and piece of resilient sheet material are made of steel.

3. A valve ball as claimed in Claim 2, in which the steel is stainless.

4. Avalve ball as claimed in Claims 1,2 or 3, in which the ball is formed atthe inlet and outletto accommodate the sheet material.

5. Avalve ball as claimed in Claim 4, in which the ball formation comprises rebates which accommodate opposite longitudinal ends of the sheet material.

6. Avalve ball as claimed in any preceding claim in which the coil has a single turn.

7. Avalve ball as claimed in any preceding claim, in which adjacent longitudinal edges of the piece of sheet material are tack welded.

8. Avalve ball as claimed in any preceding claim, in which a drain/pressure equalising hole is provided in the piece of sheet material adjacent to the longitudinal edges.

9. Avalve ball substantially as hereinbefore described with reference to the accompanying drawings.

10. A ball valve incorporating a valve ball as claimed in any preceding claim.

11. A ball valve comprising a valve housing defining a valve inlet and a valve outlet, a valve ball also defining an inlet and an outlet and rotatably disposed in the housing and means for rotating the ball relative to the housing to align respective inlets and respective outlets in the housing and the ball when the valve is in the fully open position or to disalign those inlets and outlets when the valve is in the partly open or closed position in which the ball is hollow and a piece of resilient sheet material in coiled form extends between the inlet and the outlet to define a bore therebetween, the natural resilience of the material resulting in a tendency to uncoil so that the material is urged against the edges of the inlet and the outlet to hold it in position.