GB2253020A - Toggle lever operated pipe clamps with lugs - Google Patents

Abstract

A releasable clamp which is for use in conjunction with a pressurised pipe or vessel joint comprises a toggle assembly which includes a cam means that enables the assembly to be open by a predetermined amount so as to release any pressure within the pipe or vessel and then further to be opened fully so that the clamp can be removed from the pipe or vessel. Further, a connector for use with a releasable ridge shaped clamp comprises a fastening device and at least one lug, which lug is ridged shaped so as to mate with the outer surface of the clamp. <IMAGE>

Description

Improvements Relating to Clamps This invention relates to clamps and more particularly, though not exclusively, to releasable clamps used in pressurised systems for containing liquids, fluids, and fluidised powders.

The pressurising of any fluid or fluidised powder within a closed vessel, as is well known, can be hazardous if the integrity of the vessel is impaired. Where potentially harmful fluids are contained within a vessel, for example in the instance where corrosive fluids are contained, the escape of large quantities under pressure due to accidental opening of the system can be dangerous. Where a vessel is made of a plurality of parts for example where a vessel comprises a container and a lid the rupture of a seal connecting the two parts can result not only in a leakage of the contents but also in an explosion resulting in the comprisant parts being blown apart. This is particularly dangerous and is a hazard which any industry using a pressurised system safeguards against.

In the instance where a pressurised vessel comprises a container and a lid the two parts are typically provided with peripheral flanges which mate to form a joint. A clamp in the form of a peripheral band is typically adapted to overlie the joint and the clamp is positioned around the joint before being secured in order to seal the pressurised container.

An example of a prior art clamp is shown in Figs. A and B, and the clamp will now be described in greater detail. In Fig. A a container 1 is provided with a flanged upper rim 2 which is of U-section. A lid 3 fits on top of container 1 and it is provided with a flange 4. A bored rubber seal 5 is positioned between the flanges 2 and 4. Seal 5 is bored f and contains a metal ring of similar cross section area as that of the bore this arrangement prevents radial extrusion of the seal. A ridged flange clamp 6 is positioned about the lid and container joint. The ends of clamp 6 are releasably held together by means of a toggle lever 10, as shown in Fig. 2.Toggle levers are well known in the art and will not be described herein in great detail, suffice to say that toggle lever 10 is provided with a handle 11 and when handle 11 is raised upwards and rearwards, with respect to the arrangement of the toggle lever 10, the adjacent ends of the clamp 6 part in order to release the clamp. A disadvantage of this arrangement is that once the toggle lever 10 has been raised beyond the over-centre position the clamp ceases to exert force on the lid and container joint and therefore if there is any pressure within the container fluid will escape via the joint and the pressure may cause the handle 11 to fly backwards. In the instance where a significant pressure is present within the container the pressure may also force the two parts of the container apart.

In order to safeguard against the above, pressurised containers are provided with additional safety features and a typical example of such a feature is shown in Fig. A. The feature comprises an inlet 20 made in the surface of the container which is typically sealed by means of a rubber bung 21. The uppermost face of bung 21 is provided with a steel pin which is in turn connected to a lever 22. The end of lever 22 is further provided with a stop 23 which is made to fit over handle 11 of toggle lever 10. Lever 22 is pivoted about pivot joint 24 in order that stop 23 may be swung into and out of contact with clamp 6. Lever 22 is further provided with a screw fastening 25 which is adjustable by means of a nut 26. The lower end 27 of screw 25 makes contact with lid 3 when screw 25 is fastened securely.In use, when clamp 6 is positioned over the lid and container joint and stop 23 is positioned over lever 11 an operator would unfasten screw 25 by a predetermined amount in order to raise lever 22 slightly above lid 3. This would result in bung 21 being raised out of inlet 20. If there was a pressure within container 1 this would be detected and released by means of fluid seeping from inlet 20. If on the other hand there was no pressure within container 1 the operator would know that it was safe to unscrew nut 25 such that stop 23 could be completely removed from clamp 6 and then toggle lever 11 could be raised in order to release clamp 6 from the lid joint.

Although the above system works to a reasonable extent it has certain disadvantages in that a pressurised container must be provided with an additional security feature as above described. Further, the success of the security feature depends upon the diligence and dexterity of the operator.

Accordingly, there is a need to provide a releasable clamp which has incorporated therein a security feature whereby the pressurised state of a vessel can be determined and if a pressure is present within the vessel it can be controllably released such that in due course the vessel can be safely opened.

According to a first aspect of the invention there is therefore provided a releasable clamp for securing a pressurised pipe or vessel joint comprising at least a toggle lever whose operation is controlled by means, which means enables partial opening of the clamp to relieve any pressure within the pipe or vessel, and which means is also operable to enable further opening of the clamp whereby the clamp is released.

Preferably the said means is a stopping means.

Preferably at least a part of the lever is operationally connected to the stopping means.

Preferably the stopping means is provided by way of a cam surface on a part of the toggle lever, the cam surface having positioned therealong at least one notch; a pin adapted to travel along the cam surface and to be retained within the notch when the clamp is in the partially open position; and a second lever attached to the pin whereby the pin can be released from the said notch in order to enable the clamp to be fully opened.

Thus it will be understood that the lever can be opened from a position where the clamp is partially open to a position where the clamp is fully open by moving the second lever which in turn releases the pin from the notch.

Preferably the pin is attached to a spring which biases the pin towards the surface of the cam.

Preferably the toggle lever is of U-section.

According to a further aspect of the invention there is provided a further means for connecting theretogether two ends of a ridged flange or V-flange clamp.

As is well known in the art ridged flange clamps or V-flange clamps are favoured when connecting two members about their periphery because the shape of the clamp is the best design for withstanding high pressures. Unfortunately, in the instance where releasable clamps are used, in the region where the two ends of the clamp are connected, there is a significant reduction in the pressure resistance of the clamp. Indeed, it is thought that there is a 40% reduction in yield strength at the clamp connection site. In practise this often means that the clamp in this region yields under pressure and distorts. This is an obvious disadvantage as it represents a weakness in the sealing system of a pressurised vessel. In order to overcome this disadvantage there is a need to provide an efficient connecting means for connecting the ends of clamps.

According to the invention there is therefore provided a connector for a ridged or V-shaped or U-shaped split ring clamp comprising a fastening means for connecting the ends of the split ring, the fastening means including at least one lug attached to at least one end of the ring, the lug being adapted to conform to the shape of the ring.

Preferably at least one lug is provided on each end of the split ring, which ends are to be connected, and the lugs are held together at their outermost parts by means of a fastening device.

Preferably the fastening device comprises a pivotable bolt attached to a first lug and a second lug is provided with a recess having an internal lip, the recess is adapted to receive the bolt and further there is provided a nut which is attached to the bolt when the bolt is in the said recess such that as the nut is tightened it is brought into contact with the lip and so secures the bolt within the recess.

An embodiment of the invention will now be described by way of example only with reference to the accompanying figures, wherein Fig. 1 is a diagrammatic section of a releasable clamp when in a closed position; Fig. 2 is a diagrammatic section of a releasable clamp when in an open position; Fig. 3 is a plan view of the clamp shown in Fig. 1; Fig. 4 is a diagrammatic view of a section of a clamp connector in accordance with the invention; Fig. 5 is an end view of a second lug of a clamp connector in accordance with the invention.

Referring to the figures and firstly to Fig. 1, a ridged flange clamp 30 is dimensioned and configured to overlie the edges of a pre-selected joint. The ends A and B of clamp 30 are provided with a toggle lever assembly 100A which is in turn provided with a lever 11A and a handle 17A. The toggle lever assembly 100A is connected to ends A and B by means of specialised lugs 6A and 10A respectively which lugs are of hollow section and so comprise front (as shown in Figures 1 and 2) and rear (not shown) sides. Lug 10A is provided with aligned slots 90A in the front and rear sides of lug l0A.

Lugs 6A and 10A will be described in greater detail hereinafter.

Lever 11A is of hollow section and comprises an upper curved side 99A, a front side 60A which is shown in Fig. 1, and a rear side (as shown).

Toggle lever assembly 100A is provided with a first pivot point 7A and a second pivot point 18A which points 7A and 18A are connected by means of a curved arm 8A. Arm 8A is connected to lever lIA at pivot 18A so that when lever 11A is raised arm 8A pivots about the points 7A and 18A in a conventional fashion.

Lever 11A at first end 20A is shaped in a predetermined manner so that on both its front 60A and rear sides there is provided an upper surface 21A and a lower surface 22A.

Front and rear lower surfaces 22A are provided with a cam face, each cam face having two notches 23A and 24A. Notches 23A and 24A are adapted to accommodate a pin 25A.

Pin 25A extends transversely across the inside of lever 11 and so between the opposing front 60A and rear sides of lug 10A. Further pin 25A is located through aligned slots 90A provided in the front and rear sides of lug 10A. Attached to the mid-point of pin 25A and extending perpendicular therefrom is a spring 15A which biases the pin against the cam faces 22A of lever 11. Spring 15A is further anchored to a pivot 9A located at the lowermost end of lever 11.

Attached to pin 25A between the opposing front and rear sides of lug 10A is a releasing lever 12A. When the lever 11A is in the closed position the second lever 12A is inaccessible as it is positioned below the upper curved side 99A of lever 11A. This represents a preferred arrangement although it will be understood that second lever 12A may be positioned in an accessible position.

In use, lever 11A is raised such that it pivots about and 9A and arm 8A pivots about 7A and 18A, simultaneously pin 25A is caused to move along surfaces 22A within slots aligned 90A until pin 25A occupies notch 23A. At this point lever 11A is substantially perpendicular to ends A and B. This represents the partially open position of the clamp 30 and it can be seen that lever 11A is held in this position by means of pin 25A resting in slot 23A. In this position, ends A and B are moved apart by a pre-selected amount. The amount is determined by the geometry of cams 22A and arm 8A. It will therefore be realised that when ends A and B are moved apart by a pre-determined amount the pressure exerted by the clamp on the container is released by a pre-determined amount.If therefore there is any pressure within the container a small amount of fluid contained therein can leak from the joint underneath the clamp 30. Once the pressure has been released in this fashion, lever 11A can be released from the afore partially open position by way of depressing exposed lever 12A which pulls pin 25A out of notch 23A and because of the nature of the afore described arrangement simultaneously extends spring 15A. Once lever 11A is thus released it can be moved rearwards towards end A, again pivoting about point 9A and causing arm 8A to pivot about 7A and 18A until lever 11A lies substantially parallel with arm 8A and thus against the uppermost surface 26A of lug 6A. When this happens ends A and B will be forced further apart and the clamp is released ready for removal.

It can therefore be seen that the dual action of the lever enables the lever to be moved to and secured in a first position whereby the clamp is partially opened and an amount of pressure can, if necessary, be released and then to a second position whereby the clamp itself can be released and removed.

Turning to a second aspect of the invention which is illustrated in Figs. 4 and 5, there is shown a connector for a ridged flange clamp.

It will be understood that ridged shape clamps are preferably used to seal joints as the design of the clamp is most suitable for withstanding high pressures. However, in the region where a clamp is bisected to enable same to be released there is a considerable reduction in the yield strength of the clamp and in order to fortify the clamp at this region ridged shaped lugs in accordance with the invention are provided. Ridged shaped lugs 50 and 51 reinforce the clamp at the site of the connection in a way which preserve the integrity of the clamp and thus safeguard against yielding and possible fracturing of the clamp.

The connector comprises a first lug 50 and a second lug 51.

Lugs 50 and 51 are welded to the outer surface of flange clamp 30.

With reference to Fig. 5 both lugs 50 and 51 are provided with a U or V sectioned lower edge 53 which is adapted to mate with ridged flange 30. Lugs 50 and 51 are further provided with a U-sectioned recess 60 in their upper part 70.

Within a U-sectioned recess 60 of lug 50 there is provided a transverse pivot pin 56. An end 72 of a bolt 57 is arranged to pivot on pin 56. Within the base of U-sectioned recess 60 of lug 51 there is provided a lip 55 which extends halfway along the length of recess 60 from the mating side of lug 51 to the middle of recess 60.

In use, bolt 57 is pivoted so that it overlies end B of clamp 30 and lugs 51 and 50 are brought theretogether. Bolt 57 is then pivoted through approximately 1800 about pin 56 so that it lies in recess 60 of lug 51. A Nut 58 attached to bolt 57 is then tightened until it abuts lip 55 in recess 60 of lug 51 thus securing bolt 57 in lug 51. At this point ends A,B of clamp 30 have been connected and are retained theretogether.

Claims (12)

1. A releasable clamp for securing a pressurised pipe or vessel joint comprising a toggle lever assembly whose operation is controlled by means, which means enables partial opening of th clamp to releave any pressure within the pipe or vessel, and which means is also operable to enable further opening of the clamp whereby the clamp is released.

2. A releasable clamp according to Claim 1 wherein the means comprises a stop member provided with at least a first and second limit means whereby opening of the clamp can be performed in at least first and second stages of operation.

3. A releasable clamp according to Claim 2 wherein the stop member comprises a part of the lever.

4. A releasable clamp according to Claims 2 or 3 wherein the stop member comprises a cam surface provided on a lower face of the lever.

5. A releasable clamp according to Claim 4 wherein the cam surface is provided with at least a first and second notch defining first and second limit means.

6. A releasable clamp according to Claims 4 or 5 wherein a cam co-operating member is attached to the clamp and arranged to travel along the cam face of the lever and said member is adapted to be retained within a said notch when the lever is raised to a predetermined position.

7. A releasable clamp according to Claim 6 wherein a release means is attached to the cam co-operating member so as to selectively release the cam co-operating member from the said notch to enable further opening of the clamp.

8. A releasable clamp according to Claim 6 or 7 wherein the cam co-operating member is provided with a resilient means to urge the member against the surface of the cam.

9. A releasable clamp according to Claim 8 wherein the means is a spring.

10. A connector for use with a releasable ridge shaped clamp comprising a fastening means for connecting releasable ends of the clamp theretogether, the fastening means including at least one lug attached to at least one end of the clamp wherein the lug is ridged shaped and so adapted to mate with the shape of the clamp.

11. A releasable clamp according to Claim 10 wherein at least one lug is provided on each releasable end of the clamp and the lugs are held together by means of a fastening device.

12. A releasable clamp according to Claim 11 wherein the fastening device comprises a pivotable member attached to a first lug and a recess provided in a second lug wherein the recess is adapted to accommodate the member when the two lugs are brought together, and further there is provided a securing means for securing the member within the recess.