GB2450686A

GB2450686A - An electrical continuity device

Info

Publication number: GB2450686A
Application number: GB0712752A
Authority: GB
Inventors: Ian Smith
Original assignee: Saint Gobain Pipelines PLC
Current assignee: Saint Gobain PAM UK Ltd
Priority date: 2007-07-02
Filing date: 2007-07-02
Publication date: 2009-01-07
Anticipated expiration: 2027-07-02
Also published as: GB2450686B; IE20070912A1; GB0712752D0

Abstract

An electrical continuity device for electrically connecting two pipes comprises a reaction member (11) having protruding therefrom each on the same side of the reaction member at mutually spaced locations a pair of reaction limbs (12, 13) and a continuity member 14. The limbs, which may be a tongue (12) and a hook 13, are engageable with opposite sides of a lip 18 of one pipe, and are held in place by the gasket 21 of the pipe. The continuity member protrudes from a joint with the reaction member, the continuity device in the vicinity of the joint and/or in the continuity member being deformable so that the continuity member may be forced into engagement with a further component, such as a second pipe 19, after engagement of the reaction limbs with a lip.

Description

AN ELECTRICAL CONTINUITY DEVICE AND RELATED

ASSEMBLIES

This invention concerns an electrical continuity device and related assemblies.

In the field of pipe installations, electrical continuity is an important subject.

Taking the example of metal (typically, cast iron) drainage pipes that are installed in commercial and public buildings and spaces, these are manufactured in lengths of a few metres (eg. 3 metres) so they can readily be transported eg. on flatbed trucks. When it is necessary to install such drainage pipes they are secured seriatim extending vertically or horizontally and are joined together by way of pipe couplings.

When so installed the pipes are used typically for the drainage of rain water that falls onto the roof of a building (or other structure such as a shopping centre); or they are connected to sanitary fittings (such as lavatories) so as to permit the discharge of flowable waste.

Manufacturers of pipes for use in such instances as described typically provide different versions of the pipes intended respectively for use below ground and above ground. The "below ground" and "above ground" versions of the pipes differ among other aspects in that the protective coatings on the outsides of the pipes are not the same. Instead they are chosen to suit the environments in which the pipes are used.

Typically the "above ground" pipes are coated externally with eg. a rust-resisting primer that is suitable for painting following installation of the pipes. It is also commonplace in the art additionally or alternatively to coat the pipes with an epoxy or acrylic coating. These various types of coating are efficient in preventing corrosion and damage to the metal of the pipes, but they also interrupt the conduction of electrical current from one pipe in a series to the next.

This is an important problem in above-ground metal waste pipes since they may be accessible to people in their vicinity. It is essential from the viewpoint of electrical safety for the whole length of a series of such pipes to be earthed in an effective manner so as to minimize the risks of dangerous electric shocks. The risk of electric shocks arises eg. in the event of an electrical fault in the vicinity of the pipes.

Earthing of the pipes may be effected by securing an earthing strap or collar to the lowermost pipe in the series and connecting the strap / collar to ground for example by connecting it conductively to one of the below-ground pipes or to a ground spike.

Clearly this maimer of earthing the pipes is only effective if all the pipes in the series are conductingly connected one to another and hence are equipotentiate, but the external coatings of the above ground pipes prevent this unless particular measures are adopted.

In this regard it is known in the prior art to apply devices to the series of pipes in the regions of the pipe connections, the devices serving electrically to connect the pipes one to another. The nature of the devices in such as to bypass the insulative effect of any coating so that the electrical conduction "bridges" each joint thereby rendering the pipes in a series equipotentiate.

The joints between connected pipes in a series typically each include an annular, elastomeric sealing member that is clamped to the pipes by an annular, tightenable clamping collar.

Each sealing member is non-conducting but can be modified by the addition of an electrically conducting metal clip. Once fitted this clip defines an electrical conduction path extending from one end of the sealing member to the other. Since in use the sealing member interconnects the joined pipes an electrical conduction path from pipe to pipe may be established. This in turn results from the action of the collar, on tightening, in pressing the clip so that parts of it penetrate the coatings on the pipes to engage the metal beneath.

The known electrical continuity clips of this kind are effective in use, but nonetheless suffer from numerous practical disadvantages.

One is that once the joints are formed the collars obscure the clips. As a result it is difficult, without dismantling the coupling between each pair of joined pipes, to check whether the clips are present or in what condition they are. Clearly checking a large number of the joints in this way is time-consuming and risks compromising the leak-proofing of the joints.

Furthermore the clips can only be added during assembly (or re-assembly) of the joints. This makes installing the clips either in newly formed joints or as "retro-JItted" components, again a time-consuming exercise.

IS

An aim of the invention is to overcome or ameliorate at least some of the defects of known pipe continuity arrangements.

To this end in a first aspect according to the invention there is provided an electrical continuity device comprising a reaction member having protruding therefrom each on the same side of the reaction member at mutually spaced locations a pair of reaction limbs that are engageable with opposite sides of a lip; and a continuity member that protrudes from a joint with the reaction member, the continuity member and/or the joint being deformable so that the continuity member may be forced into engagement with a further component after engagement of the reaction limbs with a lip.

Such a device may be manufactured in the manner of a simple, one-piece spring clip the installation of which is a straightforward process. In essence in order to install the continuity device of the invention it is necessary only to attach the reaction limbs so as to engage about the sides of a lip of a pipe socket; and then to bend the continuity member into contact with the surface of a pipe that is received in the pipe socket in order to provide an electrical connection between the adjacent a pipes. The step of bending the continuity member may be achieved through use of eg. a hammer or another tool.

A very important advantage of the clip of the invention is that, unlike the prior art clip described above, it is fitted to the exterior of a "spigot and socket" pipe joint in which an annular elastomeric gasket lies interposed between the spigot and the socket.

In a manner described below the clip of the invention takes advantage of the resilient deformability of the gasket material since one of the reaction limbs of the clip is inserted between the gasket and the socket. The resilient deformability of the gasket holds this reaction limb, and hence the whole clip in place. The other reaction limb, and the continuity member, may as a result be forced into electrically conducting contact respectively with the metal of the socket and the spigot.

Since the clip is fitted from outside a pipe joint it may be retro-fitted to existing joints with the same ease as to newly formed joints. Furthermore its presence on the exterior of a joint means that its condition is easily visually checked; and it is immediately apparent to an observer whether the clip is present.

Preferably a first said reaction limb protrudes from a first location on the reaction member at approximately 90 thereto. It is also preferable that a second said reaction limb protrudes from a second location, on the reaction member, that is spaced from the first said location, the second reaction limb extending at approximately 90 degrees to the reaction member.

Thus in a preferred embodiment of the invention the reaction members extend generally parallel to one another on the same side of the reaction member. This arrangement renders the continuity device of the invention particularly suited for attachment about a lip defined on the periphery of a push fit metallic pipe joint of the aforesaid socket and spigot type.

In a preferred embodiment of the invention the first reaction limb extends from a location part-way along the length of the reaction member and the second reaction limb protrudes from a location at one end of the reaction member.

Such an arrangement permits space, on the reaction member, for the attachment of the continuity member that may extend from the free end of the reaction member at the opposite end thereof to that having one of the reaction limbs secured thereto.

One of the reaction limbs preferably includes a cranked portion that in use underlies a part of a said lip. This feature of the device of the invention advantageously permits secure attachment of the continuity device to the lip of a pipe socket that is of aper se known profile.

In one arrangement according to the invention the continuity member extends at an angle of less than ninety degrees to the reaction member.

This important feature of the invention permits the continuity member to be located initially in a position that is not engaged with the further component. This facilitates installation of the continuity device. Thereafter the continuity member may be bent into engagement with the further component so as to complete the electrical continuity connection that is the aim of installing the device.

As noted herein, preferably the continuity member may protrude from an end of the reaction member. This feature further facilitates an arrangement in which the continuity member is initially clear of the further component and may be bent or otherwise forced into contact therewith following fitting of the continuity device about the lip.

According to one preferred aspect of the invention the continuity member optionally includes an edge portion that is profiled to conform to the shape of a said further component.

This feature is of particular benefit when the further component has a convex outer surface as is the case in a metal pipe. As a consequence the continuity a member, when forced into contact with the further component, may assure electrical connection over a significant length of the surface of the further component. This in turn improves the reliability of the continuity device.

To this end, therefore, the profiling of the edge portion includes a concave recess in a preferred embodiment of the invention.

The profiling of the edge portion may, further, optionally include one or more points for penetrating material of a said further component.

The use of a pointed profile to the continuity member means that it includes a portion that is capable of penetrating an insulative coating on the exterior of the further component. In the case of a metal pipe such an insulative coating may be a layer of paint that typically is supplied to the pipe exterior. In some cases other compounds may be applied to the exteriors of the pipes; and it is also known to coat the inside of pipes with protective compounds. Such compounds include but are not limited to epoxy or acrylic coatings and other anti-corrosion measures. It is further possible that the exterior of a pipe includes regions covered in non conducting oxides. The provision of at least one pointed part of the continuity member assists in assuring electrical conduction between the adjacent pipes, notwithstanding the presence of all the aforesaid types of coating.

Preferably the first said reaction limb includes an edge portion that is profiled to conform to the shape of part of a said lip. It is also preferable that the first reaction limb includes one or more formations that are capable of penetrating a coating on a said lip In a similar maimer to the continuity member and the first reaction limb preferably the second reaction limb includes an edge portion that is profiled to conform to the shape of a said further component. It is also preferable that the profiling of the edge portion of the second said reaction limb includes a concave recess.

In a practical embodiment of the invention at least the continuity member and/or the joint of the continuity device is manufactured from any of a range of metals, including but not limited to stainless steel.

In practice it is most economical if the entire continuity device is made from such a material.

In a second aspect the invention relates to a pipe connection comprising a pipe socket defining a lip including two opposed sides, the socket having received therein a pipe spigot; and a gasket that is interposed between the pipe socket and the pipe spigot so as to define an annular junction between the gasket and the pipe socket adjacent a first side of the lip, the pipe connecting including at least one continuity device, in accordance with the invention, having a first said reaction limb engaged with a first said side of the lip; a second said reaction limb engaged with a second said side of the lip, the engagement of the reaction limbs being such as to retain the continuity device relative to the pipe connection; and the continuity member engaged with the pipe spigot.

Thus the invention relates in addition to a pipe connection the electrical continuity of which is promoted through the inclusion of at least one continuity device as defined herein.

In practice probably a pair of the continuity devices would represent the best compromise between electric potential equalisation on the one hand and economy on the other. It would be expedient in the case of a connection for circular pipes (which constitute the overwhelming majority of metal pipes of the kind in question in service) for the pair of continuity devices to be installed respectively on opposite sides of the pipes.

Preferably the first said reaction limb of the continuity device incorporated into such a pipe connection generally lies between the gasket and the said first side of the lip.

It is further preferably that the first said reaction limb includes a cranked portion that underlies a part of the lip.

In yet a further, preferable aspect of the invention at least one of the said reaction limbs penetrates the surface of the pipe socket.

Finally, in a practical embodiment of the invention the continuity member penetrates the surface of the pipe spigot whereby the continuity device (which of course is electrically conducting) promotes equalisation of electrical potential between the thus-connected pipes.

There now follows a description of preferred embodiments of the invention, by way of non-limiting example, with reference being made to the accompanying drawing in which: Figure 1 is a perspective view of a continuity device in accordance with the invention; Figure 2 is a partly sectioned view of a pipe connection, according to the invention, incorporating the pipe connection device of Figure 1 before bending of its continuity member into contact with a pipe forming part of the connection; and Figure 3 is a perspective view showing the Figure 2 components after such bending of the continuity member.

Referring to the drawings, a continuity device 10 according to the invention is formed eg. by stamping from a suitable, conducting metal such as but not limited to stainless steel. Any of a wide range of alternative electrically conducting materials is also possible within the scope of the invention.

As best shown in Figure 1, the device 10 according to the invention has a clip-like construction including a rectangular, essentially planar reaction member 11.

The reaction member 11 includes a first reaction limb 12 that protrudes from reaction member 11 at a point approximately mid-way along the length of the reaction member 11.

As shown in Figure 1, in the preferred embodiment of the invention the reaction limb 12 is formed by pressing a tongue of the material of the continuity device 10 outwardly from a central region of the reaction member 11 such that the first reaction limb 12 has a width that is less than the entire width of the reaction member 11. In the embodiment shown the first reaction limb 12 extends approximately at 900 to the major surface of reaction member 11.

A second reaction limb 13 extends approximately at 90 to the major surface of reaction member 11 also at 9Q0 thereto, and on the same side of reaction member as first reaction limb 12. Second reaction limb 13 is joined to reaction member 11 as shown at one free end I Ia thereof. Reaction limb 13 may be formed by a simple folding operation of a kind that will be known to those skilled in the art of metalworking.

At its end 1 lb opposite 1 Ia reaction member 11 has protruding therefrom a continuity member 14 that may in the embodiment shown be regarded as an extension of the material of reaction member 11 that protrudes from a joint 1 lb therewith.

Continuity member 14 therefore is a flat, plate-like device that extends from reaction member 11 at an angle that is greater than 90 thereto. Indeed in the preferred embodiment of the invention shown the angle at which continuity member extends is approximately 130 to the side of reaction member 11 from which first and second reaction limbs 12, 13 extend.

For reasons explained in more detail below, the first and second reaction limbs 12, 13 are capable of engagement with opposite sides of a lip forming part of eg. a pipe coupling.

The continuity member 14 itself andlor the joint with the reaction member 11 labelled at numeral lib is deforrnable so as to be selectively engageable with a further component in conjunction with which the continuity device 10 is useable.

The choice of angle at which continuity member 14 protrudes therefore is chosen (again as described below) such that the continuity member 14 on initial installation of the continuity device 10 is out of engagement with such a further component, and may be moved (eg. by forcing, pressing or hammering) into engagement therewith in completion of the installation of the continuity device 10.

Engagement of the first and second reaction limbs 12, 13 about the lip is facilitated by virtue of the first reaction limb 12 including at its free end, spaced from reaction member 11, a cranked portion that in the preferred embodiment is shown as a round-ended tongue 16. Such a tongue may readily be formed by a simple fabrication operation following punching or pressing of first reaction limb 12 from the material of reaction member 11.

As best shown in Figure 2, a typical pipe coupling comprises a generally cylindrical pipe socket 17 having formed at its open end a flange 18 that defines a lip.

In a pipe coupling as shown in Figure 2 a pipe spigot 19 forming one end of a metal pipe or a fitting is received within the open end of socket 17 in a per se known manner.

An annular (typically rubber) gasket 21 is on assembly of the pipe coupling received in the open end of socket 17 so as to space the outer surface of spigot 19 from the inner surface of socket 17 in a per se known, liquid-proof manner.

As a result of this construction a portion 21 a of the gasket 21 protrudes on the exterior of pipe spigot 19 so as to lie generally flush with the flange 18 defining a lip as aforesaid. The result of this is the creation of an annular junction 21b between the gasket 21 and a first side 18a of the lip defined by flange 18.

As best shown in Figure 2, it is possible as a consequence to insert the first reaction limb 12 of the continuity device 10 into the annular junction 21b such that the major part of first reaction limb 12 lies adjacent first side l8a of flange 18.

This may be achieved by pushing the first reaction limb 12 into the annular junction 21b, whereupon the tongue 16 may be caused to engage about a bead 22 formed on the interior surface of socket 17 adjacent its open end.

This action of inserting the first reaction limb into the annular junction 21b at the same time causes second reaction limb 13 to move into engagement with the socket 17 on the opposite side 18b of flange to that of side 18a.

The results of such an assembly of a pipe connection is as shown in Figure 2, ie.

the continuity member 14 protrudes from the vicinity of the flange 18 of socket 17 at an angle towards the outer surface of pipe spigot 19. In the initially configured arrangement shown in Figure 2, however, the continuity member 14 is clear of the outer periphery of pipe spigot 19 by a short distance.

A further step in the assembly of the pipe connection shown in Figure 2 therefore involves forcing the continuity member 14 into engagement with the outer surface of pipe spigot 19. This may be achieved typically by tapping the continuity member 14 with a hammer, or through use of another tool such as a pair of pliers, to bend the continuity member 14 about the joint 11 b visible in Figure 1.

It is preferable that the continuity member 14 bends about the joint 11 b since the joint llb may be designed for this purpose. It is however within the scope of the invention of course to provide an alternative arrangement in which the continuity member 14 bends at another point (or at multiple points) as desired.

In order to promote electrical continuity between the socket 17 and the spigot 19 it is necessary for the second reaction limb 13 and the continuity member 14 to be capable of penetrating any coatings on the surfaces respectively of the socket 1 7 and the pipe spigot 19.

To this end each of the aforesaid parts of the continuity device is profiled to confirm to the exterior of the respective component with which it is engageable.

I

Thus, as best shown in Figure 1 at numeral I 3b, second reaction limb 1 3 is formed with a concave recess therein that is of the same radius of curvature as the exterior of the socket 17. In consequence on insertion of first reaction limb 12 into annular junction 2 lb the second reaction limb 13 is formed into conducting engagement with the exterior of socket 17.

In like manner the free end I 4b of continuity member 14 is formed with an arcuate, concave recess as shown that is of the same radius of curvature as the exterior of pipe spigot 19.

As is best seen in Figure 1, the radius of curvature of the recess I 4b of continuity member 14 is less than that of the recess 13b of second reaction limb 13. As a result at its ends the recess 14b is formed as a pair of points 14c, 14d. These assist in causing penetration of the continuity member 14 into any external coating on pipe spigot 19 so as to effect electrical conduction between the socket 17 and the pipe spigot 19.

It will thus be apparent that following installation of the continuity device 10 of the invention a reliable means of equalizing electrical potentials between adjacent parts in a pipe network may be achieved.

In an optional refinement of the clip 10 of the invention the free end of the first reaction limb 12 may be arranged to penetrate any insulative coating on the interior surface of the spigot 19. The tongue 16 may on its own achieve this effect, or in some embodiments of the invention it may be augmented or even replaced by sharp projections such as teeth or spikes.

Figure 3 shows in perspective view the continuity device 10 in its fully installed condition. In other words, in Figure 3 the continuity member 14 is shown after it has been bent into engagement with the exterior of pipe spigot 19.

The continuity device of the invention is, as indicated, useable both in the case of a connection between a socket arid a pipe; and, for example, a socket and a fitting (ie. a non-pipe component that is of circular cross-section). The pipe spigot 19 shown in Figures 2 and 3 is intended to be representative of all types of spigot that may be inserted into a socket that incorporates a gasket 21 of the kind mentioned.

Also as described hereinabove, it is desirable that the pipe connection includes a pair of the continuity devices 10 preferably disposed on opposite sides of the socket 17. Such an arrangement has been found to represent an economical Compromise between potential equalisation performance on the one hand and cost saving on the other.

Claims

1. An electrical continuity device comprising a reaction member having protruding therefrom each on the same side of the reaction member at mutually spaced locations a pair of reaction limbs that are engageable with opposite sides of a lip; and a continuity member that protrudes from a joint with the reaction member, the continuity member and/or the joint deformable so that the continuity member may be forced into engagement with a further component afier engagement of the reaction limbs with a lip.

2. A continuity device according to Claim I wherein a first said reaction limb protrudes from a first location on the reaction member at approximately 90 degrees thereto.

3. A continuity device according to Claim 2 wherein a second said reaction limb protrudes from a second location, on the reaction member, that is spaced from the first said location, the second reaction limb extending at approximately degrees to the reaction member.

4. A continuity device according to Claim 3 wherein the first reaction limb extends from a location part-way along the length of the reaction member and the second reaction limb protrudes from a location at one end of the reaction member.

5. A continuity device accordmg to any preceding claim wherein one of the reaction limbs includes a cranked portion that in use underlies a part of a said lip.

6. A continuity device according to any preceding claim wherein the continuity member extends at an angle of greater than ninety degrees to the reaction member.

7. A continuity device according to any preceding claim wherein the continuity member protrudes from and end of the reaction member.

8. A continuity device according to any preceding claim wherein the continuity member includes an edge portion that is profiled to conform to the shape of a said further component.

9. A continuity device according to Claim 8 wherein the profiling of the edge portion includes a concave recess.

10. A continuity device according to Claim 8 or Claim 9 wherein the profiling of the edge portion includes one or more points for penetrating material of a said further component.

11. A continuity device according to Claim 2 or any preceding claim depending therefrom wherein the first said reaction limb includes an edge portion that is profiled to conform to the shape of part of a said lip. Is

12. A continuity device according to Claim 2 or any preceding claim depending therefrom, wherein the first said reaction limb includes one or more formations that are capable of penetrating a coating on a said lip

13. A continuity device according to Claim 3 or any preceding claim depending therefrom wherein the second said reaction limb includes an edge portion that is profiled to conform to the shape of a said further component.

14. A continuity device according to Claim 13 wherein the profiling of the edge portion of the second said reaction limb includes a concave recess.

15. A continuity device according to any preceding claim at least the continuity member and/or the joint of which is manufactured from stainless steel.

16. A pipe connection comprising a pipe socket defining a lip including two opposed sides, the socket having received therein a pipe spigot; and a gasket that is interposed between the pipe socket and the pipe spigot so as to define an annular junction between the gasket and the pipe socket adjacent a first said side of the lip, the pipe connection including at least one continuity device, according to any preceding claim, having a first said reaction limb engaged with a first said side of the lip; a second said reaction limb engaged with a second said side of the lip, the engagement of the reaction limbs being such as to retain the continuity device relative to the pipe connection; and the continuity member engaged with the pipe spigot.

17. A pipe connection according to Claim 16 wherein the first said reaction limb generally lies between the gasket and the said first side of the lip.

18. A pipe connection according to Claim 16 or Claim 17 wherein the first said reaction limb includes a cranked portion that underlies a part of the lip.

19. A pipe connection according to any of Claims 16 to 18 wherein at least one of the said reaction limbs penetrates the surface of the pipe socket.

20. A pipe connection according to any of Claims 16 to 19 wherein the continuity member penetrates the surface of the pipe spigot.

21. A continuity device generally as herein described, with reference to and/or as illustrated in the accompanying drawings.

22. A pipe connection generally as herein described, with reference to and/or as illustrated in the accompanying drawings.