ZA200903036B - Valve - Google Patents

Description

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VALVE

FIELD OF THE INVENTION

This invention relates to a valve, and in particular to a valve suitable for controlling slurry flow.

BACKGROUND TO THE INVENTION

The problem of effectively sealing a valve for controlling slurry flow has been addressed in several ways. One solution has been to use a flexible sleeve, for example, a silicone rubber sleeve, within a pipeline which can be squeezed by a gate valve closure. A common problem with such valve is that, with time, the valve closure damages the sleeve and renders it ineffective. The use of a valve closure having a spherical abutment surface was accordingly used, thereby preventing the contact of any sharp edges on the sleeve. While more effective, such a valve closure is costly since it must be machined by sophisticated tooling to very fine tolerances.

Other valves have been used which do not include an inner sleeve but which make use of a resilient valve closure instead. Such a closure is sufficiently flexible to conform to the surface of the pipe but is sufficiently rigid to withstand the fluid pressure in the wr pipeline and not buckle. This avoids the problems associated with the inner sleeve.

However, the problem with the use of a resilient valve closure is that it does not effectively prevent the ingress of slurry into the valve shaft, so that, with time, this valve is also rendered ineffective.

OBJECT OF THE INVENTION

The object of this invention is to provide a valve for controlling slurry flow which at least partially alleviates the abovementioned problems.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a valve including a flexible and stretchable sleeve defining a fluid passageway locatable inside a conduit, and a resilient valve closure movable relative to the sleeve between an open position in which it is spaced from the sleeve and a closed position in which it squeezes and stretches the sleeve so as to close the fluid passageway.

In an example embodiment, the sleeve is cylindrical with straight side walls.

In an alternate example embodiment, the sleeve comprises a fluted or bellows-type side wall that can be flattened when it is squeezed into its closed position.

In an example embodiment, the sleeve terminates in flanges that are arranged to secure the sleeve to the conduit.

Further in accordance with the invention, there is provided for the sleeve to be manufactured from polyurethane, sterethane 700 or ultra high molecular weight polyethylene.

Still further in accordance with the invention, there is provided for the valve closure to have a ductile iron core sheathed in a silicone rubber. The closure may have an abutment surface thereon which is complementarily shaped to the inner surface of the conduit.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a cross-sectional side view of a valve according to a first example embodiment of the invention;

Figure 2 shows a cross-sectional side view of a sleeve according to a second example embodiment of the invention; and

Figure 3 shows a cross-sectional side view of a valve fitted with the sleeve shown in Figure 2, in use.

DETAILED DESCRIPTION OF THE INVENTION

Referring first to Figure 1, a valve 1 is shown comprising a cylindrical polyurethane sleeve 3 defining a fluid passageway 5, the sleeve 3 being snugly fitted within a length of pipe 7 Each end 9 and 11 of the sleeve is bent outwardly to form an annular securing flange 13 which seats against complementary flanges 15 extending from each end of the pipe length 7. The flanges 15 on either end of the pipe length 7 are bolted to complementary outer flanges 17 on a pipeline thereby compressing the sleeve flanges 13 and securing the sleeve 3 to the pipe.

A vertical standpipe 19 extends halfway along the pipe length 7 and houses a valve closure 21 therein. The closure 21 is sectionally circular and its diameter conforms to the inner diameter of the pipe 7. The closure 21 has a valve stem 23 extending vertically therefrom which is connected to a shaft 25 carrying a handwheel 27 The closure 21 1s operable by the handwheel 27 to move linearly relative to the pipe 7 into and out of the sleeve 3 between a closed position (as illustrated) in which it is inside the fluid passageway 5 and one wall of the sleeve 3 is squeezed against the opposite side, and an open condition in which the closure 21 is spaced from the valve sleeve 7. The valve closure 21 is manufactured from a ductile iron core sheathed in resilient rubber. !

When the closure 21 is in an open position, the fluid passageway 5 is unobstructed and the outer surface of the sleeve 3 abuts the inner surface of pipe 7. The sleeve 3 also covers the opening to the standpipe 19, thereby preventing any slurry conveyed in the pipeline from entering the valve housing and affecting the operation of the valve 1.

The surface of the closure 21 conforms to the inner diameter of the length of pipe 7, thereby ensuring a sealed closure. Should there by a tear in the sleeve 3 or if the sleeve 3 becomes detached from the pipe 7, the closure 21 itself provides a sealed closure of the pipe 7.

A weep hole 28 may be provided in the pipe 7 so as to allow slurry caught between the pipe 7 and the sleeve to escape, which in turn provides an indication that the valve 1 and sleeve 3 need replacement

Turning now to Figures 2 and 3, a sleeve 29 according to a second embodiment comprises a flexible and stretchable fluted or bellows-type side wall 31 terminating in outwardly bent securing flanges 33. Components that are similar in structure and function as those described and illustrated above with reference to Figure 1 have been numbered similarly, and will accordingly not be elaborated on in any further detail. Thus, for example, the fitment of the sleeve 29 within the pipe length 7 is the same as with the first embodiment shown in Figure 1.

The fluted side wall 31 allows the sleeve 29 to accommodate the extended, protruding valve closure 21 when a valve 35 fitted with the sleeve 29 is in a closed position (as illustrated in Figure 3). In use, in the closed position shown in Figure 3, the side wall 31 of the sleeve 29 flexibly accommodates the extended valve closure 21. Assuming that the slurry is flowing from left to right in Figure 3, the pressure of the slurry will fill the fluid passageway 5 and force the side wall 31 against the inner walls of the pipe length 7 and also against the valve closure 21. This causes the relevant portion of the side wall 31 of the sleeve 29 to stretch, so as to further enhance the sealing ability of the valve 35

Advantageously, the sleeve 29 is sufficiently flexible and stretchable, yet unreinforced, to accommodate the extended valve closure 21. In an example embodiment, the sleeve 29 is made from ultra high molecular weight polyethylene.

A circumferential seat 37 is provided midway along the sleeve 29, the seat 37 including a high density polyethylene insert 39. The insert 39 acts as a spring against which the end of the valve closure 21 abut, thereby improving the sealing and opening arrangement of the valve 35.

The invention is not confined to the specific embodiment described above, and it will be appreciated that many variations exist which fall within its scope. For example, the sleeves 3, 29 may be manufactured from any other material which is sufficiently hard and resilient and which has the same memory as polyurethane. Similarly, the closure may be manufactured from any other suitable materials. It will be readily appreciated that this invention provides a simple and cost effective yet effective means for preventing the ingress of slurry into the valve housing. It further provides an effective slurry valve which does not require constant replacing of the sleeve.

Claims (8)

CL CLAIMS

1. A valve including a flexible and stretchable sleeve defining a fluid passageway locatable inside a conduit, and a resilient valve closure movable relative to the sleeve between an open position in which it is spaced from the sleeve and a closed position in which it squeezes and stretches the sleeve so as to close the fluid passageway.

2. The valve of claim 1, wherein the sleeve is cylindrical with straight side walls.

3 The valve of claim 1, wherein the sleeve comprises a fluted or bellows-type side wall that can be flattened when it is squeezed into its closed position.

4. The valve of any one of the preceding claims, wherein the sleeve terminates in flanges that are arranged to secure the sleeve to the conduit.

5. The valve of any one of the preceding claims, wherein the sleeve is manufactured from polyurethane, sterethane 700 or ultra high molecular weight polyethylene.

6. The valve of any one of the preceding claims, wherein the valve closure comprises a ductile iron core sheathed in a silicone rubber.

7. The valve of any one of the preceding claims, wherein the valve closure comprises an abutment surface thereon which is complementarily shaped to the inner surface of the conduit.

8. A valve substantially as herein described and illustrated. DATED THIS 4™ DAY OF MAY 2009 a BOWMAN GILFILLAN INC. (JOHN & KERNICK) FOR THE APPLICANT