Fluid leak repair

Abstract

A fluid leak repair kit comprises a putty 14, a self-amalgamating tape 18, a flexible bistable band 16 and a flexible sheet or tape. The band is movable between a first, axially straight, state and a

Description

Field of the Invention This invention relates to a kit and method for repairing a fluid (e.g. steam, gas or water) leak in a pipe or conduit. Background of the Invention A “fluid” used herein is intended to be broadly interpreted as referring to any gas or liquid that flows under pressure in a pipe or conduit. An example used herein is a natural gas supply pipe, but it is to be understood that the invention is not necessarily intended to be limited in this regard. Gas supply systems in commercial and domestic settings typically comprise a network of sections of rigid pipework connected together in a required configuration via screw threaded joints or coupling members, wherein a jointing paste is applied to the inner surface of a coupling member and / or the outer distal end of a pipe section and the coupling member id screwed or pushed onto that end of the pipe section. A further pipe section can be similarly joined on the other end of the coupling member so as to create a fluid tight seal between the two pipe sections that permits fluid flow therethrough. Coupling members of various shapes and configurations can be utilised to create straight connections or bends, for example, in the pipework and the ultimate aim is to create a sealed system in the form of a rigid network of permanently connected pipework through which fluid can flow under pressure. Difficulties arise, however, in the event of a leak in one of the pipe sections, which causes fluid to leak from the system. In all cases, this would cause an unacceptable pressure drop in the fluid flow system, but in some cases (e.g. in a gas supply system), the resultant health and safety implications and danger posed by fluid flowing into the surrounding atmosphere creates an emergency situation that requires immediate remedial action. In the case of, for example, a gas supply system, the gas supply must be switched off unless and until the leak has been adequately repaired. Permanently and reliably repairing a leak in a rigid pipe network, using some known methods, is a complex task which must be undertaken by one or more trained operative. In most cases, the first repair is temporary and a permanent repair may require that the affected pipe section be removed and replaced. However, this is not a straightforward task because, not only does the fluid supply have to be switched off for some time, loosening and removing a section of pipe from the rigid network can result in other couplings and pipe sections being undermined. US Patent Application No. US2007 / 0125437 describes a repair kit for a natural gas pipe, comprising a deformable leak sealant, a pressure sealant and a so-called encapsulator. The leak sealant is a curing or hardening putty, such as an epoxy putty, and is applied at the location of the leak. Next a rubber tape (the pressure “sealant”) is wrapped around the leak sealant, forcing it into a pinhole leak or joint leak as the epoxy putty cures. Finally, an “encapsulator” in the form of a cloth-like wrap that hardens after setting, is applied around the repair to maintain the leak sealant and pressure sealant in position so that they maintain a seal when the pressure is increased (i.e. the pipe is brought back on-line). However, the described kit is only suitable for repairing natural gas pipes, and requires a significant pressure reduction whilst the repair is undertaken, to allow time for the putty to harden and also for the encapsulator to harden, because it is these two elements which effect and maintain the seal once higher pressures are applied (whereas the rubber tape used in the described method does not continue to exert a significant force around the pipe after application). Thus, repairing a leak using the described kit and method takes a relatively long time, during which the pipe cannot be used under pressure. European Patent No. EP3273132 describes a kit and method for repairing a fluid leak in a pipe or conduit that ameliorates the problems described above. In this document, there is described a kit comprising a putty, a self-amalgamating tape and a composite material comprising a flexible sheet or tape and a matrix component in the form of a resin or water-activated matrix component which, when cured, forms an outer shell. The associated repair method comprises applying a layer of the putty to the pipe or conduit at the location of the leak to seal it, wrapping, at tension, the self-amalgamating tape around the layer of putty to completely cover it, contacting the flexible sheet or tape with either a resin or water (to activate the water-activated matrix component), and encompassing the self-amalgamating tape with the flexible sheet or tape such that the resin or water-activated matrix component binds with the flexible sheet or tape to form an outer shell to surround the repair. This method has been demonstrated to be a very quick and easy, and highly safe and effective, way of effecting a permanent repair of fluid leaks in pipes or conduits, even under pressure, without requiring the fluid flow network to be taken out of commission during the repair. However, in cases where the damage to a pipe comprises a relatively large hole caused by corrosion or impact for example, the above-described method may not be effective because the putty, when pushed into and moulded to the hole by the high-tension selfamalgamating tape can be cut and broken at the sharp / jagged edges of the hole, and fall through the hole into the pipe. Thus, it is an object of aspects of the invention to provide a pipe / conduit repair kit and method that addresses this issue and provides an equally quick, easy, safe and effective means of repairing a pipe or conduit without having to take the fluid flow network of which it is a part out of commission. Statements of Invention In accordance with an aspect of the invention, there is provided a fluid leak repair kit, comprising: - a putty; - a self-amalgamating tape; - a flexible bistable band, movable, in use, between a first state in which it is axially straight, and a second, ring-like state, and having a yield point, said band being configured such that, in use, generally radial application of pressure at an end of the band causes it to move, under its own tension, from said first state to said second state; and - a flexible sheet or tape and a matrix component for binding said flexible sheet or tape, the matrix component comprising resin or water-activated matrix component which, when cured, forms an outer shell. Beneficially, at least one surface of the flexible bistable band is covered in a layer of resiliently flexible plastic, rubber or silicone. In an embodiment, the flexible bistable band is encapsulated in a layer of resiliently flexible plastic, rubber or silicone. In an embodiment, said flexible sheet or tape may comprise a woven material, fibre glass or carbon fibre material. Beneficially, said flexible sheet or tape may be pre-impregnated with the matrix material or a component for forming the matrix material. In an embodiment, the matrix component may be a polymeric water soluble or water-activated substance, such as polyurethane resin. Alternatively, the matrix component may comprise 1-2-propaniedol, 2-ethyl-2-(hdroxymethyl), or polymer with bis(isocyanatomethyl)benzene. Optionally, the kit may further comprise a stretch wrap material for, in use, placing over said flexible sheet or tape whilst said matrix component cures. The self-amalgamating tape may comprise a silicone self-amalgamating tape. Beneficially, the putty may be a non curing putty, such as a silicone non curing putty. However, in some embodiments, the putty may be a two-part curing putty, such as a two-part curing silicone putty. In accordance with another aspect of the invention, there is provided a method of repairing a fluid leak in a pipe or conduit, the method comprising: - bringing an end of a bistable band into contact with the layer of putty, and applying sufficient radial pressure thereto to cause said band to move, under its own tension, from a first, axially straight configuration to a second, ring-like configuration, such that it encircles the pipe or conduit, covering, said leak; - applying a layer of putty at an edge of said bistable band; - wrapping, at tension, a self-amalgamating tape around said bistable band and layer of putty to cover them; - contacting a flexible sheet or tape with either a resin or water to activate a water-activated matrix component; and encompassing the self-amalgamating tape with the flexible sheet or tape such that the resin or water-activated matrix component bonds with the flexible sheet or tape to form an outer shell with the flexible sheet or tape to substantially surround the pipe or conduit at the location of the leak. Beneficially, a layer of putty is applied at both side edges of the bistable band, optionally such that each layer of putty forms an incline angle of 40-50 degrees incline from the surface of the pipe or conduit to the top of the bistable band. Beneficially, the incline angle is substantially 45 degrees. Beneficially, the self-amalgamating tape may be wrapped at tension, in which its width is 75% or less of its original width. Optionally, the method may further comprises, after wrapping, at tension, the self-amalgamating tape around the layer of putty and the bistable band to create a high tension wrapped region, wrapping, at low tension, a further layer of self-amalgamating tape around the high tension wrapped region to cover it. The putty may, beneficially comprise a non-curing putty such as a silicone non-curing putty. However, in some embodiments, the putty may comprise a two-part curing putty such as two-part curing silicone putty. The flexible sheet or tape may comprise a woven material. Alternatively, the flexible sheet or tape may comprise a fibre glass or carbon fibre material. In some embodiments, the flexible sheet or tape may be pre-impregnated with the matrix material or a component for forming the matrix material, such as a polymeric water-soluble or water-activated substance. Alternatively, the matrix component may be polyurethane resin. In some embodiments, the matrix component may comprise 1, 2 propaniedol, 2-ethyl-2 (hydroxymethyl). Or polymer with bis (isocyanatomethyl) benzene. In some embodiments, the method may further comprise wrapping a stretch wrap material over the flexible sheet or tape while the matrix component cures. Optionally, the self-amalgamating tape may comprise a silicone self-amalgamating tape. In some embodiments, the method may comprise cutting lengths of the selfamalgamating tape prior to wrapping each length of self-amalgamating tape, at tension, around the layer of putty and the bistable band. Optionally, the lengths of selfamalgamating tape may be cut at an angle, for example 45°. These and other aspects of the invention will be apparent from the following detailed description. Brief Description of the Drawings An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which Figures 1A to 1L are schematic diagrams illustrating, respectively, steps of a method according to an exemplary embodiment of the invention for repairing a fluid leak in a pipe or conduit. Detailed Description A kit according to an exemplary embodiment of the invention may be used to create permanent repairs of fluid leaks in pipes or conduits. An example will now be described in which the fluid is natural gas within a domestic or commercial gas supply system. However, it is to be understood that the present invention is in no way intended to be limited in this regard. In general, a gas leak repair kit according to an exemplary embodiment of the invention comprises a non-curing silicone putty, a bistable band, a high grade silicone selfamalgamating tape (SSAT) and a woven glass fibre bandage with a water-activated binder. The bistable band comprises a flexible metal strip that is movable, in use, between a first state, in which it is axially straight, and a second, ring-like state, and has a yield point, the band being configured such that, in use, generally radial application of pressure exceeding the yield point to an end of the metal strip causes it to move, under its own tension, from the first state to the second state. The flexible metal strip is beneficially covered with a layer of silicone, although a resiliently flexible plastic or rubber may alternatively be used. It will be appreciated that, using the kit and method according to this exemplary embodiment of the invention, a permanent gas leak repair can be effected quickly, reliably and efficiently, by a single operative, and without having to decommission the fluid flow network. An exemplary method is set out below: Preparation When a leak is detected in a fluid flow network, its source must first be identified. In view of the types of leak for which this exemplary method is particularly suitable, the source of the leak will likely be eminently visible. Referring to Figure 1A of the drawings, a sizeable hole 10 is located along the length of a pipe 12. The hole 10, which may be caused by corrosion or impact, for example, has jagged, uneven and sharp edges, and the hole 10 is likely to be of non-uniform diameter. The surface of the pipe 12, around the hole 10, can be prepared by first removing rust and debris using a wire brush, and then sanded to achieve a smooth finish. Finally, clean water can be used to wash away any abrasion grit, and the surface of the pipe 12 around the hole 10 can be dried with a clean rag. Bistable band Referring to Figures 1B and 1C of the drawings, the end of the bistable band 16 is placed against the surface of the pipe 12, over the location of the hole 10, and gentle pressure exerted to cause the bistable band to move, under its own tension, to the second, ring-like state such that it wraps itself around the pipe 12, over the hole 10. As shown in Figure 1C of the drawings, a piece of self-amalgamating tape 18 is applied, under tension, around the bistable band 16 to fix and secure the bistable band 16 in place completely. Putty Referring to Figure 1D of the drawings, a layer of putty 14 is pressed into place around the edges of the bistable band 16, such that the putty forms a 45-degree incline from the surface of the pipe 12 to the top of the bistable band 16. Self-amalgamating tape Referring to Figures 1E and 1F of the drawings, next, a self-amalgamating tape 18 is wrapped, under tension, around the pipe 12 to completely cover (and extend beyond the outer edges of) the putty 14. This may be achieved using individual strips of tape, cut at a 45° angle; or it may be achieved by adhering an end of a roll of tape to the bistable band, and wrapping the tape straight from the roll (optionally utilizing a wrapping tool specially designed for the purpose). Either way, the wrapping should be done at full tension, which occurs when the tension is such that the colour lightens and the width is reduced to at least % of its original width. As illustrated in Figure 1F of the drawings, the length of the wrapped area is such that it completely covers the bistable band and putty and also extends beyond the outer edges of the putty. The very high tensile strength of the SSAT causes the tightly wrapped layer to produce a significant ‘squeeze’ around the pipe 12, and pushes the putty into any gaps between the edges of the bistable band 16 and the surface of the pipe 12. The layers of tape bond together through molecular fusion. Once applied, the final wrap retains all of the applied tension. The resultant high tension silicone sleeve can ‘squeeze’ down for 50 years or more (subject to environmental conditions). As there is no adhesive, this SSAT will endure harsh temperature fluctuations, full submersion an UV light. Once the high tension layer is complete, the operative may wrap back over the wrapped region with a low tension layer, which acts as impact protection. Sufficient tension should be applied to prevent air from becoming trapped therein and the operative can push down on the low tension layer to aid fusion. Armour Referring to Figures 1G to 1J of the drawings, the final step in the method involves applying the so-called 'armour'. Thus, the operative removes the glass fibre bandage from its packaging and places it in water to activate the binder this can be done by soaking or using a spray bottle containing water during the wrapping process. The bandage may, for example, comprise a woven fibreglass tape and may be pre-impregnated with 1,2-propaniedol, 2-ethyl-2-(hydroxymethyl), polymer with bis(isocyanatomethyl) benzene. Once moist, the bandage 20 is wrapped around the SSAT wrapped region, starting in the centre and wrapping with a 50% (approximately) overlap. The operative wraps back and forth, covering around 20mm beyond the end of the SSAT wrap and ending with all strands on top of previously wrapped layers. Next, the operative quickly applies a stretch wrap (not shown) tightly over the bandaged area and compresses the region while it cures to ensure a close cell structure is formed, to maximise its strength. Once the armour 20 is hard (around 30 minutes, depending on the surrounding ambient temperature) the stretch wrap can be removed. Thus, in an exemplary embodiment, wherein the bandage is a woven fibre glass material pre-impregnated with 1,2-propaniedol, 2-ethyl-2-(hydroxymethyl), polymer with bis(isocyanatomethyl) benzene, the SSAT wrapped or repair region wrapped therewith may be left for about 30 minutes, until the 1,2-propaniedol, 2-ethy1-2- (hydroxymethyl), polymer with bis(isocyanatomethyl) benzene has formed a hard outer shell substantially encompassing and extending along the length of the repair region. It will, of course, be appreciated that the time required for the joint to set may depend on several factors such as type of composite materials, ambient temperature and other environmental factors. The armour, in this exemplary embodiment, will be fully cured after around 60 minutes and can accept paint, if required, around 24 hours after the stretch wrap has been removed. Once cured, the layer provides a puncture proof barrier, safeguarding the seal against damage. It also adds strength back to the damaged pipeline by building an effective pipe around the damaged pipe, restoring its strength, It will be appreciated by a person skilled in the art, from the foregoing description, that modifications and variations can be made to the described embodiments without departing from the scope of the invention as defined by the appended claims. For example, the armour may be formed using woven carbon fibre bandage, instead of glass fibre. The bandage may, as described above, be impregnated with a matrix material or a component of a matrix material that is water soluble or water activated (for example, the matrix may be polyurethane). However, in alternative embodiments, the matrix component may be epoxy resin (and the kit may include a supply of epoxy resin) which, when applied to the woven bandage, sets and hardens to provide the required armour. Indeed, two part resins (for example, epoxy based resin systems) are available which may be suitable for provision in a kit form and mixed when required.

Claims

1. A fluid leak repair kit, comprising:- a putty;- a self-amalgamating tape;- a flexible bistable band, movable, in use, between a first state in which it is axially straight, and a second, ring-like state, and having a yield point, said band being configured such that, in use, generally radial application of pressure at an end of the band causes it to move, under its own tension, from said first state to said second state; and- a flexible sheet or tape and a matrix component for binding said flexible sheet or tape, the matrix component comprising resin or water-activated matrix component which, when cured, forms an outer shell.

2. A fluid leak repair kit according to claim 1, wherein at least one surface of the flexible bistable band is covered in a layer of resiliently flexible plastic, rubber or silicone.

3. A fluid leak repair kit according to claim 2, wherein the flexible bistable band is encapsulated in a layer of resiliently flexible plastic, rubber or silicone.

4. A fluid leak repair kit according to any of the preceding claims, wherein said flexible sheet or tape comprises a woven material, fibre glass or carbon fibre material.

5. A fluid leak repair kit according to any of the preceding claims, wherein said flexible sheet or tape is pre-impregnated with the matrix material or a component for forming the matrix material.

6. A fluid leak repair kit according to claim 5, wherein the matrix component is a polymeric water soluble or water-activated substance, such as polyurethane resin.

7. A fluid leak repair kit according to claim 5, wherein the matrix component comprises 1-2-propaniedol, 2-ethyl-2-(hdroxymethyl), or polymer with bis(isocyanatomethyl)benzene.

8. A fluid leak repair kit according to any of the preceding claims, further comprising a stretch wrap material for, in use, placing over said flexible sheet or tape whilst said matrix component cures.

9. A fluid leak repair kit according to any of the preceding claims, wherein said selfamalgamating tape comprises a silicone self-amalgamating tape.

10. A fluid leak repair kit according to any of the preceding claims, wherein the putty is a non curing putty, such as a silicone non curing putty.11 .A fluid leak repair kit according to any of claims 1 to 9, wherein the putty is a two-part curing putty, such as a two-part curing silicone putty.

12. A method of repairing a fluid leak in a pipe or conduit, the method comprising:- bringing an end of a bistable band into contact with the surface of the pipe or conduit, adjacent the leak, and applying sufficient radial pressure thereto to cause said band to move, under its own tension, from a first, axially straight configuration to a second, ring-like configuration, such that it encircles the pipe or conduit, covering the leak;- applying a layer of putty at a joint between a side edge of the bistable band and the surface of the pipe or conduit;- wrapping, at tension, a self-amalgamating tape around said bistable band and layer of putty to cover them;- contacting a flexible sheet or tape with either a resin or water to activate a water-activated matrix component; andencompassing the self-amalgamating tape with the flexible sheet or tape such that the resin or water-activated matrix component bonds with the flexible sheet or tape to form an outer shell with the flexible sheet or tape to substantially surround the pipe or conduit at the location of the leak.

13. A method according to claim 12, wherein the self-amalgamating tape is wrapped at tension, in which its width is 75% or less of its original width.

14. A method according to claim 12 or claim 13, further comprising, after wrapping, at tension, the self-amalgamating tape around the layer of putty and the bistable band to create a high tension wrapped region, wrapping, at low tension, a further layer of self-amalgamating tape around the high tension wrapped region to cover it.

15. A method according to any of claims 12 to 14, wherein the putty comprises a non-curing putty such as a silicone non-curing putty.

16. A method according to any of claims 12 to 14, wherein the putty comprises a two-part curing putty such as two-part curing silicone putty.

17. A method according to any of claims 12 to 16, wherein the flexible sheet or tape comprises a woven material.

18. A method according to any of claims 12 to 16, wherein the flexible sheet or tape comprises a fibre glass or carbon fibre material.

19. A method according to any of claims 12 to 18, wherein the flexible sheet or tape is pre-impregnated with the matrix material or a component for forming the matrix material, such as a polymeric water-soluble or water-activated substance.

20. A method according to any of claims 1 to 18, wherein the matrix component is polyurethane resin.21 .A method according to any of claims 12 to 18, wherein the matrix component comprises 1, 2 propaniedol, 2-ethyl-2 (hydroxymethyl). Or polymer with bis (isocyanatomethyl) benzene.

22. A method according to any of claims 12 to 21, further comprising wrapping a stretch wrap material over the flexible sheet or tape while the matrix component cures.

23. A method according to any of claims 12 to 22, wherein the self-amalgamating tape comprises a silicone self-amalgamating tape.

24. A method according to any of claims 12 to 23, comprising applying a layer of putty at the joints between both side edges of the bistable band and the surface of the pipe and conduit.

25. A method according to any of claims 12 to 24, wherein the step of applying a layer of putty comprises applying a layer of putty and shaping said layer of putty such that forms an incline angle of 40-50 degrees from the pipe to the top of the bistable band.

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