GB2419392A

GB2419392A - Control valve

Info

Publication number: GB2419392A
Application number: GB0517480A
Authority: GB
Inventors: Mark Ezekiel
Original assignee: Score Group Ltd
Current assignee: Score Group Ltd
Priority date: 2004-09-01
Filing date: 2005-08-26
Publication date: 2006-04-26
Also published as: GB0517480D0; GB0419322D0

Abstract

A fluid control valve comprises a valve body 10 a valve actuator 24 and a valve cover 11 which supports the actuator. The valve body 10 and cover 11 are welded together to form a welded sealing joint between them. Additional connecting means 32 may be used to further strengthen the join between the body 10 and cover 11.

Description

24 1 9392 Fluid Control Valve 1 The present invention relates to valves

used in the 2 handling and transportation of pressurized fluids.

4 Valves that are used in the transportation of pressurised fluids conventionally comprise a valve 6 body either fixed to, or integral with, a pipeline.

7 To this valve body is normally fixed, via bolts, a 8 valve bonnet that carries the valve mechanism for 9 opening and shutting the valve. The valve body and valve bonnet are usually cast as separate components 11 so that access can be made to the internal workings 12 of the valve for maintenance. There is therefore a 13 joint between the body and bonnet that must be 14 sealed before the valve can operate. This seal is made by locating a seal and/or gasket atop the valve 16 body and then bolting the valve bonnet to the body, 17 sandwiching the seal and/or gasket between the two 18 components. The valve is therefore sealed and ready 19 for operation.

1 In applications involving high-pressure fluids, the 2 seal and/or gasket is a potential leak path for the 3 fluid being handled. Although the risk of leakage is 4 acceptable in certain applications, in certain other applications it is critical that leakage is 6 prevented. In these critical applications, for 7 example where hazardous materials are being handled, 8 it is imperative that the joint between the valve 9 body and bonnet is not susceptible to leaks.

11 Is an aim of the present invention to obviate or 12 mitigate the aforementioned disadvantage.

14 According to a first aspect of the present invention, there is provided a fluid control valve 16 comprising a valve body, a valve actuator and a 17 valve cover adapted to support the valve actuator, 18 wherein the valve body and valve cover are welded 19 together so as to form a welded joint therebetween.

21 Preferably, the valve body and valve cover have 22 first and second formations, respectively, adapted 23 to facilitate connection of the body and cover.

24 Preferably, the first formation comprises one or more first flange members projecting radially from 26 the valve body. Preferably, the second formation 27 comprises one or more second flange members 28 projecting radially from the valve cover.

Preferably, the valve further comprises first and 31 second sealing members attached to the valve body 32 and valve cover, respectively. Most preferably, the 1 sealing members are attached to the respective 2 flange members.

4 Preferably, the sealing members are formed from a metal or metal alloy. In one embodiment, the 6 respective sealing members are integrally formed 7 with the valve body and valve cover. In an 8 alternative embodiment, the respective sealing 9 members are welded to the valve body and valve cover.

12 Preferably, the sealing members are adapted so as to 13 be welded together to form the welded joint.

Preferably, the valve further comprises connecting 16 means, the valve body and valve cover fixedly 17 connected to one another by the connecting means.

18 In one embodiment, the connecting means are 19 mechanical connecting means, most preferably comprising at least two bolts.

22 According to a second aspect of the present 23 invention, there is provided a method of producing a 24 fluid control valve comprising a valve body, a valve actuator and a valve cover adapted to support the 26 valve actuator, the method comprising: 27 bringing the valve body and valve cover into 28 contact with one another such that they form a 29 joint; and welding the valve body and valve cover to one 31 another to form a welded joint.

1 Preferably, the method further comprises an initial 2 step of forming first and second sealing members on 3 the valve body and valve cover, respectively, 4 wherein the step of welding the body and cover to one another comprises welding the first and second 6 sealing members to one another.

8 Preferably, the method further comprises the step of 9 forming first and second formations on the valve body and valve cover, respectively, the formations 11 adapted to facilitate connection of the body and 12 cover. Preferably, the first and second sealing 13 members are formed on the first and second 14 formations, respectively.

16 Preferably, the method further comprises the step of 17 fixedly connecting the valve body and valve cover 18 together with a connecting means.

Preferably, the method further comprises a testing 21 step, prior to the step of bringing the valve body 22 and valve cover into contact with one another, the 23 testing step comprising: 24 locating a temporary gasket on either the valve body or valve cover; 26 fixedly connecting the valve body and valve 27 cover together such that the gasket is sandwiched 28 between them to form a seals 29 performing a pressure test on the valve; disconnecting the valve body and valve cover; 31 and 32 removing the gasket.

2 Preferably, the method further comprises the step of 3 machining the first and second formations in order 4 to facilitate access to the joint.

6 A preferred embodiment of the present invention will 7 now be described, by way of example only, with 8 reference to the accompanying drawings, in which: 9 Figure 1 is a vertical section through a prior art pipeline valve; 11 Figure 2 is a detail view of a conventional 12 gasket-sealed valve joint; 13 Figures 3(a)-(f) are detail views showing the 14 steps taken to form a welded valve joint.

16 A prior art gasket-sealed valve is illustrated in 17 Figure 1. The valve comprises a valve body 10 which 18 includes a bore 14. The valve body 10 is either 19 fixed to, or integral with, a pipeline (not shown) so that fluid in the pipeline flows through the bore 21 14. Within the bore 14 is a valve seat 16 in which 22 sits a valve member 18. The valve seat 16 includes 23 a pair of seals 20 which ensure that no fluid may 24 pass the valve member 18 when in the closed position shown in Figure 1. The valve further comprises a 26 valve cover, or bonnet, 11 that supports a valve 27 actuator 24 and a threaded rod 22 that is located in 28 the neck 26 of the valve bonnet 11. The valve 29 member 18 is connected by way of the threaded rod 22 to the actuator 24. Rotating the actuator 24 will 31 either raise or lower the valve member 18, thereby 32 either opening or closing the valve.

2 Both the body 10 and bonnet 11 have respective 3 annular flanges 28,30 which both include a number of 4 apertures for receiving fixing bolts 32. Prior to fitting the body 10 and bonnet 11 together, a gasket 6 34 is located on the upper surface of the annular 7 flange 28 of the body. Once the gasket 34 is in 8 place, the bonnet 11 is placed on the body 10 so 9 that the apertures in the annular flanges 28,30 align with one another. Once the apertures are 11 aligned, the fixing bolts 32 are threaded through 12 the apertures and tightened in place. There is then 13 a sealing fit between the body 10 and bonnet 11.

14 Figure 2 shows a detail view of the joint formed by the body 10 and bonnet 11.

17 Figures 3(a)-(f) show detail views of an alternative 18 sealing joint formed between the body and bonnet of 19 a fluid control valve in accordance with the present invention. Reference to elements of the body and 21 bonnet that are shared with the conventional 22 arrangement illustrated in Figures 1 and 2 will use 23 the same reference numbers, but with a ' suffix 24 (e.g. valve body 10').

26 As a first step, a first sealing member, in the form 27 of a first metal ring 40, is formed on the upper 28 surface of the annular flange 28' of the valve body 29 10', as shown in Figure 3(a). At the same time, a second sealing member, in the form of a second metal 31 ring 42, is formed on the lower surface of the 32 annular flange 30' of the valve bonnet 11', as shown 1 in Figure 3(b). In this particular embodiment, the 2 sealing members are formed by welding the metal 3 rings 40,42 into place on the respective surfaces of 4 the flanges 28',30'. However, it is also possible to produce the valve body 10' and valve bonnet 11' 6 with the sealing members integrally formed on the 7 flanges 28',30'.

9 Once the rings 40,42 have been welded in place, testing of the valve may be carried out, if desired, 11 prior to the final assembly of the valve. In order 12 to test the valve, a temporary gasket 44 is located 13 on the upper surface of the annular flange 28'. As 14 seen in Figure 3(c), the body 10' and bonnet 11' are then brought together and fixed by bolts 32' as 16 described in respect of the conventional valve. The 17 temporary installation of a gasket 44 allows quality 18 testing to be carried out on the components of the 19 valve, prior to the join between the body and bonnet being permanently sealed. If any of the components 21 are found to be defective at this stage, they can be 22 replaced straightforwardly. However, it should be 23 noted that this testing step is not essential in the 24 assembly of the valve.

26 Once the tests, if desired, have been successfully 27 completed, the bonnet 11' is taken off the body 10' 28 and the temporary gasket 44 is removed, so that 29 final assembly of the valve can take place. With the bonnet ll' replaced on the body 10', the annular 31 rings 40,42 are aligned with one another. A weld 46 32 is then made between the two rings 40,42, thereby 1 forming a welded joint between the body 10' and 2 bonnet 11', as can be seen in Figure 3(d).

4 As seen in Figure 3(e), outer portions of the respective upper and lower surfaces of the body 6 flange 28' and bonnet flange 30' can be machined 7 away to allow better access to the joint, if 8 necessary. Finally, in order to complete the join, 9 the bolts 32' are again located in their apertures and tightened such that the body 10' and bonnet 11' 11 are sealing fitted together, as shown in Figure 12 3(f).

14 If the valve should need repaired during service, the bolts are first removed. Then, the weld between 16 the metal rings is ground out, thereby allowing 17 separation of the valve body and valve bonnet from 18 one another. The valve can then be re-assembled 19 after service in the manner described above.

21 As highlighted above, introducing a welded joint 22 into a valve is desirable, as this means that 23 conventional seals and gaskets need not be used. As 24 a result, potential leakage via the seal or gasket is avoided. With the welded joint of the present 26 invention, the valve can be temporarily sealed for 27 testing without welding the joint. Furthermore, 28 with the welded joint of the present invention, the 29 weld metal can be straightforwardly removed when the valve requires a service or overhaul.

1 It will be appreciated that the method described 2 above to produce the fluid control valve of the 3 present invention may also be used to convert 4 conventional gasket-sealed valves into valves according to the present invention. In such 6 instances, the valve body and valve cover of the 7 conventional valve are disconnected, and the gasket 8 seal removed. The valve body and cover can then be 9 refitted in accordance with the method described above to produce the fluid control valve of the 11 present invention.

13 It should be noted that although it is preferable 14 with the present invention to connect the valve body and valve cover together by way of formations, such 16 as flanges, which are formed on the valve body and 17 valve cover, this is not essential. Any suitable 18 method of connection can be used to supplement the 19 welded joint. Furthermore, the invention is not limited to the use of conventional bolts as the 21 supplementary mechanical connecting means for the 22 joint. Other suitable mechanical connecting means 23 can be utilised.

Although the sealing members used in the preferred 26 embodiment are metal rings, alternative sealing 27 members may be used in their place. In addition, 28 whilst it is desirable that the sealing members are 29 made from steel, this is not essential. Other suitable metals or metal alloys may be used in place 31 of steel if requirements dictate.

1 These and other modifications and improvements can 2 be incorporated without departing from the scope of 3 the present invention.

Claims

CLAIMS: 1 1. A fluid control valve comprising a valve body, 2 a valve

actuator and a valve cover adapted to 3 support the valve actuator, wherein the valve body 4 and valve cover are welded together so as to form a welded joint therebetween.

7 2. The valve of Claim 1, wherein the valve further 8 comprises first and second sealing members attached 9 to the valve body and valve cover, respectively.

11 3. The valve of Claim 2, wherein the first and 12 second sealing members are formed from a metal or 13 metal alloy.

4. The valve of Claim 3, wherein the first and 16 second sealing members are integrally formed with 17 the valve body and valve cover, respectively.

19 5. The valve of Claim 3, wherein the first and second sealing members are welded to the valve body 21 and valve cover, respectively.

23 6. The valve of either Claim 4 or Claim 5, wherein 24 the first and second sealing members are adapted so as to be welded together Lo form the welded joint.

27 7. The valve of any preceding claim, wherein the 28 valve further comprises connecting means, the valve 29 body and valve cover fixedly connected to one another by the connecting means.

2 8. The valve of Claim 7, wherein the connecting 3 means comprises mechanical connecting means.

9. The valve of either Claim 7 or Claim 8, wherein 6 the mechanical connecting means comprises at least 7 two bolts.

9 10. A method of producing a fluid control valve comprising a valve body, a valve actuator and a 11 valve cover adapted to support the valve actuator, 12 the method comprising: 13 bringing the valve body and valve cover into 14 contact with one another such that they form a joint) and 16 welding the valve body and valve cover to one 17 another to form a welded joint.

19 11. The method of Claim 10 and further comprising an initial step of forming first and second sealing 21 members on the valve body and valve cover, 22 respectively, wherein the step of welding the body 23 and cover to one another comprises welding the first 24 and second sealing members to one another.

26 12. The method of Claim 11 and further comprising 27 the step of forming first and second formations on 28 the valve body and valve cover, respectively, the 29 formations adapted to facilitate connection of the body and cover, wherein the first and second sealing 31 members are formed on the first and second 32 formations, respectively.

2 13. The method of Claim 12 and further comprising 3 the step of machining the first and second 4 formations in order to facilitate access to the joint.

7 14. The method of any of Claims 10 to 13 and 8 further comprising the step of fixedly connecting 9 the valve body and valve cover together with a connecting means.

12 15. The method of any of Claims 10 to 14 and 13 further comprising a testing step, prior to the step 14 of bringing the valve body and valve cover into contact with one another, the testing step 16 comprising: 17 locating a temporary gasket on either the valve 18 body or valve cover; 19 fixedly connecting the valve body and valve cover together such that the gasket is sandwiched 21 between them to form a seal; 22 performing a pressure test on the valve; 23 disconnecting the valve body and valve cover; 24 and removing the gasket.

27 16. A fluid control valve substantially as 28 hereinbefore described with reference to the 29 accompanying drawings.

1 17. A method of producing a fluid control valve 2 substantially as hereinbefore described with 3 reference to the accompanying drawings.