GB2432642A

GB2432642A - Closing off a conduit with an expandable foam sealant

Info

Publication number: GB2432642A
Application number: GB0623779A
Authority: GB
Inventors: Andrew Harrison; Richard Ditte
Original assignee: STEVE VICK INTERNAT Ltd
Current assignee: STEVE VICK INTERNAT Ltd
Priority date: 2005-11-28
Filing date: 2006-11-28
Publication date: 2007-05-30
Anticipated expiration: 2026-11-28
Also published as: GB0524212D0; GB0623779D0; GB2432642B

Abstract

An elongate bag 10, dimensioned to fit fairly snugly into a conduit to be sealed off, receives a sachet (50,52; figure 4) of expandable, settable, foam composition, preferably in an openable 23 compartment 12. Expansion of the foam urges the sachet against a cutter 26 that is present within the bag, rupturing it. The expanding foam may pass through a partition 16 into a further compartment 14 which becomes filled. A minor proportion of the foam escapes through the porous or semi-porous cylindrical wall 46, sealing to a wall (60; figure 5) of the conduit. The risk of the operator coming into contact with the foam composition is minimised. In an alternative embodiment the sachet and cutter (128; figure 9) are placed in a porous second bag (180; figures 7 and 8) which is then placed in an outer bag (110; figure 6) having a porous or semi-porous cylindrical wall (114; figure 6) and non-porous end walls (148; figure 6).

Description

Closing Of f Conduits The present invention relates to a method and

apparatus for closing off conduits, or providing seals or plugs in conduits or other cavities.

Our earlier patent, GB 2 157 390 entitled "Stopping A Flow passage" describes a technique in which a flow passage, particularly in a gas main, is sealed off by inserting a porous bag into the passage and then passing a settable foam composition into the bag to expand it.

Some foam seeps through the wall of the bag and seals the wall of the passage as the foam cures. For passing the composition into the bag, an injection gun assembly is required. This has to be coupled to the bag. A sealant composition is mixed and passed into a cartridge in the gun, and injected into the bag. Subsequently, the gun assembly is removed. In GB 2 226 855 we provided an improved injection gun assembly, in which the expandable foam sealant composition is initially prepared in a sealed socket, which is placed in a special gun cartridge having a cutter adjacent its cutlet. As the foam begins to expand, the sachet is forced against the cutter which ruptures it, allowing the foam to be dispensed.

At least for some purposes, it would be desirable to avoid the need for the special injection gun assembly. Even with the improvements offered by GB 2 226 855, there is still some risk of the operator coming in contact with the foam compositions.

We have now devised a system that can be employed with little or no additional equipment. Furthermore, the risk of the foam composition coming in contact with the operator, or otherwise getting where it should not, is further reduced. Sealing can be carried out quickly, with low equipment costs.

In one aspect the invention provides an apparatus for use in closing off a conduit comprising an elongate bag defining an interior compartment, and a cutter disposed in said compartment so that an expanding sachet of expandable foam sealant composition in said compartment will tend to abut the cutter and be ruptured thereby; said bag having a porous or semi-porous external wall portion.

Preferably there are two compartments: a first compartment for holding the sachet and being provided with the cutter, and a second compartment which, in use, is in flow communication with the first compartment so that, after the sachet has ruptured, the still-expanding foam can pass into the second compartment, which has a porous or semi-porous external wall portion which is intended to contact the wall of the conduit and through which foam can pass.

The first compartment controls the amount by which the foam expands before the sachet is ruptured. This is selected so as to allow sufficient time for the elongate bag to be positioned where it is required, typically in a conduit at a site up to 20 meters from where the bag was introduced into the conduit.

In one type of embodiment, the two compartments are provided by a single elongate bag. This may be generally cylindrical. It has two compartments separated by a partition. The first compartment is openable to receive a sachet of expandable foam sealant composition, and closable to trap the sachet. The partition is porous and/or has a through passage.

Mounted on or adjacent the partition there is a cutter.

Thus the sachet can be activated to cause its contents to begin expanding, and then placed in the first compartment. Continued expansion causes the socket to press against the cutter and be ruptured thereby.

Continued expansion then causes the composition to pass into the second compartment. The second compartment is at least partly defined by external walls which are porous. Thus continued expansion can cause the second compartment to fill, and composition to pass through porous wall portions. Preferably the second compartment has an end wall remote from the first compartment which is non-porous. Preferably the external walls of the first compartment (or at least the end wall remote from the second compartment) are non-porous.

In a second aspect the invention provides a kit comprising the above apparatus and a suitable sachet.

In a second type of embodiment, the first compartment is provided by a second bag that can be placed within the elongate bag, whose interior is the second compartment. In such an embodiment, the elongate bag is openable and closable. The cutter is provided within the second bag which is porous and which, in use, also contains the sachet. The second bag is highly porous, so that the foam composition, once liberated from the sachet, can easily pass out of the second bag.

It is still within the first, elongate bag. That preferably has an external wall portion that, though porous, offers more resistance to the passage of foam.

It may be termed "semi-porous". Thus the expanding foam composition should fill the elongate bag completely, causing it to adopt its "full" shape and abut the wall of the conduit, before a significant amount of foam escapes. (This also applies to the first type of embodiment.) In another aspect the invention provides a method of closing off a conduit or providing a seal or plug in a conduit or cavity by means of apparatus according to the first aspect, comprising inserting into said conduit or cavity a said elongate bag containing said sachet, causing the expandable foam sealant composition to expand, and allowing the sachet to be ruptured by the cutter and the expanding composition to fill the bag and partially escape through the porous or semi-porous external wall portion. Preferably the method involves activatIng a sachet of expandable foam sealant composition, placing it in the appropriate compartment, closing that compartment, and inserting the bag into the conduit or cavity. Desirably the bag dimensions are selected so that the bag, when full, is a fairly snug fit in the conduit or cavity. Desirably the total internal volume of the bag is slightly less than the volume of the fully expanded foam, e.g. 70-95% thereof. Thus the expanded foam fills the bag fully, the bag becomes quite taut, and a minor proportion of the foam escapes and contacts the inner wall of the conduit or cavity.

Desirably the first compartment, or second bag, has an internal volume somewhat greater than the volume of the unexpanded composition, e.g. 150-300%, of that volume. Thus the user can get the sachet into it even after expansion has begun, but the expansion will soon fill it and cause rupture of the sachet while the composition is still freely flowable.

Inserting the bag into the conduit may involve moving it along the conduit to a desired location, e.g. by means of a pushing rod, preferably pushing on a non-porous end wall of the bag (e.g. of the second compartment).

The conduit or cavity is typically up to 300 mm in diameter.

It may contain components such as cables and pipes that require to be sealed around. It may be, for example, a drain, sewer or cable conduit. It may be a pipeline contaminated with nuclear waste. A length of pipeline containing contamination can be plugged at each end by means of the invention, and then safely sawn out for disposal.

The foamable composition may be as disclosed in our earlier applications referred to above. GB 2 226 855 discloses a two-part polyurethane composition. Mixing the parts initiates a curing reaction and the generation of gas. A suitable composition is fully expanded and at least partly cured in 5-30 minutes at normal temperatures. ft may undergo a 10-fold expansion.

The cutter may be an annular cutter with multiple points, which may be disposed so as to surround the through-passage in the partition. Such a cutter is disclosed in GB 2 226 855.

Some embodiments of the invention will now be described with reference to the accompanying drawings to which: Fig 1 is a side elevation of a bag which is an embodiment of the invention; Fig 2 is an end elevation in the direction of the arrow A in Fig 1, showing the first compartment open; Fig 3 is a side view of a larger scale, showing the cutter assembly; Fig 4 is a schematic view of a sealant sachet; Fig 5 is a small scale view showing a conduit sealed by means of an embodiment of the invention; Fig 6 is a perspective view of an elongate bag used in a second embodiment; Fig 7 is a plan view of a second bag also used in the second embodiment, in its closed state; Fig 8 is a perspective view of the second bag open; and Fig 9 is a perspective view of a cutter used in the second embodiment.

Fig 1 shows a bag 10 which is generally cylindrical. It has a smaller first compartment 12 separated from a larger second compartment 14 by a partition wall 16. The outer end region 18 of the first compartment is connected to the rest of the bag by a hinge portion 20 and a zip-type fastener 22. Thus, as shown in Fig 2, the end portion 18 can be opened and pulled back to reveal the interior of the first compartment. The exterior walls of the first compartment, particularly including the end portion 18, are made of a substantially non-porous fabric.

The partition wall 16 has a central opening 24. A short externally threaded tube 26 extends through this.

An annular cutter assembly 28 (see Figs 2 and 3) is engaged over this. A pair of nuts 30,32 are threadedly engaged over the tube 26, one on each side, so that the cutter assembly 28 is held in place, engaging the fabric of the partition 16.

As seen in Fig 2, the cutter assembly is cruciform.

Each arm 34 terminates in a point 36 which curves forwardly. The sides 38 of each arm carry forwardly pointing blades 40(see Fig 3) The second compartment 14 has a main cylindrical body 46 formed of porous fabric, and an end portion 48 formed of substantially non-porous fabric.

Fig 4 shows a sachet containing a two-part foamable, curable polyurethane composition. A polyethylene bag is divided into two compartments 50, 52 by being passed round a central rod 54 and clamped by a spring clip 56. For use, the spring clip 56 and rod 54 are removed. The compartments 50, 52 thus communicate freely. The operator rapidly squeezes the contents to and fro a few times to mix them. The composition then begins to expand. A relatively slowly expanding and curing composition is used, typically taking around 15 minutes for complete expansion, and rather longer for cure. Thus, the operator can spend a reasonable amount of time mixing the components. The sachet is then pushed into the first compartment into which it should be a reasonably tight fit. The compartment is then closed via means of the zip fastener 22 (using a tab 23). The container is then pushed into a conduit 60 (Fig 5). If the seal is to be produced a fairly short distance from the open end of the conduit, then the operator may push it in by hand, second compartment first. If, however, it is to be dispatched to a more remote location, it may be preferred for it to be pushed, first compartment first, by means of a pusher rod engaging the end wall of the second compartment.

Once the bag is in place, the expansion of the composition continues, so that part of the bag is pressed against the cutter. It ruptures, and the contents are urged through the passageway 24 into the second compartment (the composition may also pass through the partition wall, since this will generally be porous). The composition fills the second compartment, and continues to expand. Thus, the second compartment becomes fully inflated. Desirably, it is shaped and dimensioned so that it then substantially fills the conduit, so there is little or no gap between its external wall 46 and the conduit. Continued expansion of the foam will cause some of the composition to escape out through the porous wall 46, and engage the wall of the conduit. Since the end wall 48 of the second compartment is not porous, not much of the composition will escape beyond the bag in that direction. Likewise, since the first compartment is substantially non-porous, little or none of the composition will extend beyond the first compartment.

In the second embodiment, shown in Figs 6-9, the elongate bag 110 is a simple cylindrical bag, with a single internal compartment. It is openable by means of a zip-type fastener 122 extending circumferentially in an intermediate region (e.g. about 1/3 of the way along). The end walls 148 are of non-porous material.

The cylindrical wall 114 has some porosity, such that pressurised foam can exude through it.

The sachet bag 180 is approximately rectangular, and can lie flat, as shown in Fig 7. A zip-type fastener 182 extends centrally of both major faces, over most of their length. Thus the bag 180 can be opened wide so that an expanding foam sachet can be easily and rapidly inserted. A cutter 128 is also inserted (or could be provided within the bag, secured or loose) The sachet bag is zipped up again and inserted into the elongate bag 110. The sachet bag is formed of fully porous material. It constrains the expanding sachet until that is ruptured by the cutter. The foam then passes easily through the wall of the sachet bag.

Continued expansion enables some foam to escape through the cylindrical wall 114 of the elongate bag 110, to seal to the interior of the conduit or other cavity into which it has been inserted.

A suitable cutter 128 is shown in Fig 9. It is formed from a plate of mild cold rolled steel with bent-up tangs 140.

The sachet may be as in the first embodiment. It may be made from clear polythene. The resin and hardener are kept separate by a dividing clip that runs the width of the sachet.

The central dividing clip is removed and the two parts are mixed by massaging the sachet until the foam appears to be a consistent colour. This should take 35-seconds. The mixed foam is then squeezed to one end of the sachet and the empty polythene is folded over and rolled down to reduce its size and keep all the foam in one "chamber. The sachet can then be inserted into the sachet bag along with the piercing knife or cutter. The bag is zipped shut, and can then be inserted into the elongate bag which is then zipped up ready for insertion into the conduit to be blocked.

Claims

Claims: 1. Apparatus for use in closing off a conduit comprising an

elongate bag defining an interior compartment, and a cutter disposed in said compartment so that an expanding sachet of expandable foam sealant composition in said compartment will tend to abut the cutter and be ruptured thereby; said bag having a porous or semi-porous external wall portion.

2. Apparatus according to claim 1 wherein said bag has two compartments separated by a partition, wherein: the first compartment is openable to receive a sachet of expar3dable foam sealant composition, and closable to trap the sachet; the partition is porous and/or has a through passage; and said cutter is mounted on or adjacent the partition; and wherein the second compartment is at least partly defined by external walls which are porous.

3. Apparatus according to claim 2 wherein the second compartment has an end wall remote from the first compartment which is non-porous.

4. Apparatus according to claim 2 or claim 3 wherein the external end wall of the first compartment, which is remote from the second compartment is non-porous.

5. Apparatus according to claim 4 wherein all the external walls of the first compartment are non-porous.

6. Apparatus according to claim 1 wherein said elongate bag is openable and closable, and wherein said cutter is provided within a porous second bag which, in use, also contains said sachet and is located within said compartment of the first, elongate bag.

7. Apparatus according to claim 6 wherein said first, elongate bag has non-porous end walls and a cylindrical wall which is, at least in part, porous or semi-porous.

8. Apparatus according to claim 6 or claim 7 wherein said second bag is openable and closable.

9. Apparatus for use in closing off a conduit comprising an elongate bag containing a cutter, substantially as herein described, with reference to and as illustrated in the accompanying drawings.

10. A kit of parts comprising apparatus according to any preceding claim and a sachet of expandable foam sealant composition dimensioned so as to be locatable in said elongate bag and adapted to generate a volume of expanded foam sealant composition which exceeds the internal volume of the bag.

11. A kit of parts for producing apparatus according to claim 6, 7 or 8 comprising said first elongate bag, said porous second bag, and said cutter.

12. A kit according to claim 11 also including a sachet of expandable foam sealant composition which, prior to expansion, is dimensioned to be locatable in the second bag which is then locatable in the first bag; said sachet being adapted to generate a volume of expanded foam sealant composition which exceeds the internal volume of the first bag.

13. A method of closing off a conduit or providing a seal or plug in a conduit or cavity by means of apparatus according to any of claims 1-9, comprising inserting into said conduit or cavity a said elongate bag containing said sachet, causing the expandable foam sealant composition to expand, and allowing the sachet to be ruptured by the cutter and the expanding composition to fill the bag and partially escape through the porous or semi-porous external wall portion.

14. A method according to claim 13 wherein the apparatus is according to any of claims 2-5, the method including preliminary steps of activating the sachet, placing it in said first compartment, and closing said first compartment.

15. A method according to claim 13 wherein the apparatus is according to claim 6, 7 and 8, including a step of placing said second bag containing the sachet and cutter into the elongate bag.

16. A method according to claim 15 wherein the apparatus is according to claim 8, the method including preliminary steps of activating the sachet, placing it in said second bag, and closing said second bag.

17. A kit according to claim 10, 11 or 12 or a method according to any of claims 13-16 wherein the total internal volume of the elongate bag is 70-95% of the volume of the freely expanded foam.

18. A kit according to claim 10, 11, 12 or claim 17, or a method according to any of claims 13-17, wherein said compartment of the first bag for receiving S the sachet or said second bag has a volume which is 150- 300% of the volume of the unexpanded composition.

19. A method of closing off a conduit or providing a seal or plug in a conduit or cavity substantially as herein described with reference to and as illustrated in the accompanying drawings.