GB2473182A

GB2473182A - Apparatus and method for sealing a gap in a pipe

Info

Publication number: GB2473182A
Application number: GB0913010A
Authority: GB
Inventors: Paul Hope-Darby
Original assignee: WATER SERVICES GROUP Ltd
Current assignee: WATER SERVICES GROUP Ltd
Priority date: 2009-07-27
Filing date: 2009-07-27
Publication date: 2011-03-09
Also published as: GB0913010D0

Abstract

An apparatus and method for sealing a gap in a hollow pipe structure 1a, 1b, the apparatus comprising: a rigid, hollow, tubular, open ended liner 5; a flexible, substantially enclosed bag 7 having an inner surface and an outer surface and being suitably dimensioned so that the bag may be placed around the liner, with the inner surface of the bag lying against an outer surface of the liner, to form an inflatable layer around the liner 5 whilst leaving the hollow interior of the liner 5 substantially unobstructed, the outer surface of the bag having an outwardly expandable section 11 formed thereon, the bag having at least one inlet 13 to allow a settable substance such as micro-concrete to be delivered into the interior of the bag. Preferably, the liner 5 is formed from a plurality of sections that are joined together. Possibly more than one outwardly expandable section 11 is provided.

Description

Title: "An Apparatus and Method for Sealing a Gap"

Description of Invention

THIS INVENTION relates to a apparatus and method for sealing a gap, and in particular concerns an apparatus and method for sealing a gap in an elongate pipe structure.

The formation of pipe structures from multiple interconnecting sections is well-known, for instance in the transportation of liquids such as oil and water.

To ease in the manufacturing of such pipes, the sections from which the pipes are formed are typically formed to be identical to one another. One method of forming a composite pipe is shown in figure 1, which shows a cutaway view of a pipe structure. Each pipe section 1 is generally hollow and tubular, having a circular cross-section and having a wall 2 of a substantially constant thickness. At a first end of each pipe section 1, the wall 2 has an interior groove 3, which runs around the entire interior circumference of the wall 2. The result is that the thickness of the wall 2 is reduced in the region of the interior groove 3.

At the second end of each pipe section 1, opposite to the first end, an exterior groove 4 is formed, running round the entire exterior circumference of the pipe section 1. The effect of this is again to reduce the width of the wall 2.

It will be understood that the pipe sections 1 may then be fitted together, end-to-end, so that the narrowed portion of the wall 2 formed by the interior groove 3 at the first end of each pipe interlocks with the narrowed portion of the wall 2 formed by the exterior groove 4 at the second end of an adjoining pipe section 1.

Alternatively, each pipe section may be of substantially constant diameter apart from a widened portion at a first end. This widened portion is suitably dimensioned to fit over the end of an adjacent pipe section that does not include the widened portion.

With either of the two designs discussed above, an "o ring" or similar seal may be incorporated into a space in the interior wall between two pipe sections.

When a composite pipe of this nature is formed, the gaps between the pipe sections 1 are typically made to be as small as possible, so that the pipe is effectively liquid-tight. However, through use and wear of the pipe, the sections may become separated and/or axially misaligned with one another, causing the gaps between the pipe sections to widen, often leading to leakages of liquid into and/or out of the pipe.

Furthermore, once pipe sections have begun to become axially misaligned, the deterioration of the pipe structure as a whole tends to accelerate rapidly.

It is therefore important to repair misalignment of the pipe sections. One known way of doing so is to insert a liner, formed for instance from thin sheet metal, into a pipe structure so that the liner covers the gap between two adjacent pipe sections 1. The liner includes an expanding bolt including left and right-hand screw threads (as is well known in the art). Once the liner is in place, the liner is expanded to fit snugly against the interior of the pipe, thus blocking the gap between the pipe sections 1, and preventing ingress or egress of fluid through the gap.

Such a measure does very little to increase the structural stability of the pipe, however, and deterioration of the alignment of the pipe sections is likely to continue.

It is an object of the present invention to seek to provide a method and apparatus which addresses some or all of the above difficulties.

Accordingly, one aspect of the present invention provides an apparatus for sealing a gap in a hollow pipe structure, the apparatus comprising: a rigid, hollow, tubular, open ended liner; a flexible, substantially enclosed bag having an inner surface and an outer surface and being suitably dimensioned so that the bag may be placed around the liner, with the inner surface of the bag lying against an outer surface of the liner, to form an inflatable layer around the liner whilst leaving the hollow interior of the liner substantially unobstructed, the outer surface of the bag having an outwardly expandable section formed thereon, the bag having at least one inlet to allow a settable substance to be delivered into the interior of the bag.

Advantageously, the outwardly expandable section comprises a gap in the outer surface of the bag, with a length of material being provided between the edges of the gap which is substantially longer than the distance between the edges.

Preferably, the bag has one or more outlet ports or valves.

Conveniently, the liner is formed from a plurality of sections that are joined together.

Advantageously, the outwardly expandable section is provided substantially midway along the length of the bag.

Preferably, the length of the bag is approximately the same as that of the liner.

Conveniently, the outwardly expandable section extends over only a part of the periphery of the bag.

Advantageously, the cross-sectional area of the outwardly expandable section varies around the periphery of the bag.

Preferably, the bag has a plurality of outwardly expandable sections.

Conveniently, the plurality of outwardly expandable sections are generally aligned with one another.

Advantageously, the plurality of outwardly expandable sections are provided at spaced apart locations along the length of the bag.

Another aspect of the present invention provides a method of sealing a gap in a hollow pipe structure, comprising the steps of: placing a rigid, hollow, tubular, open ended liner within the pipe; providing a flexible, substantially enclosed bag having an inner surface and an outer surface, the outer surface of the bag having an outwardly expandable section formed thereon, and the bag having at least one inlet to allow a settable substance to be delivered into the interior of the bag; placing the bag around the liner so that the inner surface of the bag lies against an outer surface of the liner, forming an inflatable layer around the liner whilst leaving the hollow interior of the liner substantially unobstructed; and introducing a settable substance into the interior of the bag so that the bag at least partially fills with the settable substance and the outwardly expandable section at least partially fills with the settable substance and protrudes outwardly from the remainder of the bag.

Preferably, the settable substance is a concrete.

Conveniently, the settable substance is a micro-concrete.

Advantageously, the liner and bag are positioned within the pipe structure so that the outwardly expandable section is aligned with the gap.

In order that the present invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying figure, in which: figure 1 shows a known composite pipe structure; figure 2 shows a liner suitable for use with the present invention; figures 3 and 4 show a bag suitable for use with the present invention; and figures 5 and 6 show stages in the use of the liner and bag of figures 2 to 4.

Turning to figure 2, a liner 5 suitable for use with the present invention is shown. The liner 5 takes the form of a hollow cylindrical member formed from a rigid material such as a plastic or composite material, or steel or another metal. In the embodiment shown in figure 2 the liner 5 has a circular or substantially circular cross-section.

The liner 5 may be formed from a plurality of sections 6 which are joined together, for instance by welding, to form the finished liner 5. The liner 5 may be formed from sections 6 because, for example, access to the interior of a pipe is limited, and an entire, finished liner may be too large to be transported to the required location. However, if access is not limited, the liner 5 may be formed as a single, unitary element.

Turning to figures 3 and 4, a flexible bag 7 is shown. The bag 7 takes the form of an inflatable tube having a hollow interior, and has an inner surface 8 and an outer surface 9, a substantially enclosed interior 10 being defined between the inner and outer surfaces 8,9. The bag may be formed from any suitably robust flexible material, for instance a fabric or plastic material.

Formed on the outer surface 9 is an outwardly-expandable section 11, which takes the form of a gap 12 in the outer surface 9, with an excess length of the material from which the bag 7 is formed being provided between (and sealed against) the edges of the gap 12. Preferably, the outwardly-expandable section 11 is formed all or substantially all of the way around the circumference of the bag 7. When the bag 7 is in an uninflated state, the outwardly expandable section 11 may lie substantially flat against the outer surface 9 of the bag 7, and for instance may be concertina-folded.

The bag 7 is dimensioned so that the bag 7 may, in its uninflated state, be placed around the linerS, so that the interior surface 8 of the bag 7 lies against the outside of the liner 5. Preferably, the length of the bag 7 is equal or similar to the length of the liner 5.

The bag 7 includes one or more inlet ports 13, to allow fluid to be delivered into the interior 10 of the bag 7. The bag 7 may also be provided with one or more outlet valves or ports (not shown) to allow fluid to escape from the interior 10 of the bag 7 if the fluid pressure within the interior 10 becomes too great.

Use of the liner 5 and bag 7 to seal a gap in pipe structure will now be described.

Turning to figure 5, a join is shown between two adjacent pipe sections 1 a,1 b, of the type described above in relation to figure 1. The pipe sections la,lb will typically be formed from a robust, durable material such as a concrete material. The pipe sections 1 a,1 b have become separated from one another, while remaining generally axially aligned, so that a relatively wide gap 14 exists between the interior surfaces of the pipe sections 1 a,1 b.

The liners is positioned within the pipe formed by the pipe sections la,lb, so as to be substantially axially aligned with the pipe. The diameter of the liner 5 is smaller than the interior diameter of the pipe, so that a clearance exists between the liner 5 and the interior walls of the pipe.

As discussed above, the liner 5 may need to be introduced into the pipe in sections 6, which are then assembled to form the finished liner 5.

The bag 7 is placed around the exterior of the liner 5, in its uninflated state (this may be done before or after the linerS is introduced into the pipe). The outwardly expandable portion 11 of the bag 7 is arranged to be roughly midway along the length of the liner 5.

The liner 5 and bag 7 are positioned within the pipe so that the mid-point of the length of the liner 5 is approximately aligned with the gap 14 (it will be understood that the outwardly expandable portion 11 of the bag 7 is also, therefore, substantially aligned with the gap 14).

A delivery tube 15 is attached to the inlet port 13 of the bag 7. The delivery tube 15 is connected to a source of a settable substance, such as concrete (preferably micro-concrete), or a suitable foam or epoxy resin. The source of the settable substance is likely to be outside the pipe, and if this is the case then the delivery tube 15 will extend outside the pipe.

A settable substance is then introduced under pressure into the interior 10 of the bag 7 through the delivery tube 15. The settable substance inflates the bag 7, so that the bag 7 expands and at least substantially fills the gap between the liner 5 and the interior surfaces of the pipe sections 1 a, lb. The bag 7 preferably inflates so as to press against the exterior of the liner 5 and the interior of the pipe, and this may occur over the whole or substantially the whole length of the bag 7.

As the bag 7 continues to expand, the outwardly expandable portion 11 will fill with the settable substance, and will expand into the gap 14 between the pipe sections 1 a,1 b, substantially filling the gap 14. It will be understood that, when the bag 7 is inflated, the outwardly expandable portion will adopt the form of a protruding ridge running around the periphery of the bag 7, at or around its midpoint.

As discussed above, one or more outlet ports or valves may be formed in the bag 7 to allow some of the settable substance to "bleed" out of the bag 7 in the event that the pressure inside the bag 7 becomes too high.

Whilst the bag 7 is substantially full of the settable substance, the flow of the settable substance into the bag 7 is stopped, and the delivery tube 15 is disconnected from the bag 7. The settable substance is then left to set.

Once the settable substance has set, a rigid composite lining arrangement, including the liner 5 and the bag 7 filled with the settable substance, is formed around the interior of the pipe in the region of the gap 14 between the pipe sections 1 a,1 b. Moreover, the outwardly expandable section 11 is expanded to fill substantially the gap 14, and hence forms a "keystone" within the gap 14 to stabilise the pipe. Not only will this composite lining arrangement be effective in preventing the leakage of fluid out of the pipe to the exterior, or the unwelcome ingress of fluid or other materials from outside the pipe into the interior, but the composite lining element will also provide a significant structural reinforcement to the pipe as a whole, thus helping to prevent further deterioration or misalignment of the pipe structure.

Once the settable substance has set, the bag 7 is largely redundant, and the bag 7 may be eroded or bio-degraded over time without significantly affecting the performance of the composite lining arrangement.

One or more internal shaping elements (not shown) may be provided within the bag 7 to help the bag 7 to maintain the correct shape during inflation thereof. These may include tethers, straps or sewn seams within the bag 7, as is known in the art.

The above has been described with reference to a cylindrical pipe structure, and for this reason the liner S and bag 7 have been described as adopting a generally cylindrical formation. However, the present invention may be used with hollow, tubular pipes of any cross-section, for instance ovoid, hexagonal, octagonal or square. As will be appreciated by a skilled person, the cross-sectional shape of the liner 5 in bag 7 may simply be formed so as to match, at least partially, the interior cross-section of the pipe.

The description above relates to a sealing of gaps in pipe structures, and in the described embodiments the bag includes an outwardly expandable section which is aligned with a particular gap that has already formed in a pipe structure. It is, however, also envisaged that a similar technique may be used in regions of a pipe where a gap may be expected to form, for instance because a small gap has already begun to appear (although the gap is too small to be filled using the above-described technique), or if a section of the pipe is, as a result of its location or other external factors, likely to come under considerable stress during its lifetime. In such circumstances, a similar technique may be used, but with a bag that does not include an outwardly expandable section. A liner and bag could therefore be introduced into a pipe in the region of a join which may be expected to form a sizeable gap, and the bag filled with the settable substance so as to reinforce the pipe in that region. The provision of bags that do not include an outwardly extendible portion is therefore envisaged.

It is also envisaged that a bag may be used that includes an outwardly expandable section that extends only a part of the way around the circumference of the bag. This could be used in situations, for example, where two pipe sections have become axially misaligned, so that a relatively large gap has appeared between the pipe sections at one side of the pipe, but little or no gap is present at the other side of the pipe. In this case, a bag could be provided that has an outwardly expandable section extending halfway around its periphery. The bag is oriented, prior to inflation, so that the outwardly expandable section is aligned with the widest parts of the gap.

When the bag is filled with the settable substance, the outwardly expandable section will inflate to fill the widest parts of the gap. Parts of the bag which do not have an outwardly expandable section will simply inflate to press against the inner surfaces of the pipe in the region where the gap is narrowest.

A further alternative is that the cross-sectional area of the outwardly expandable section may vary around the circumference of the bag, so that the cross-sectional area is at its maximum at one point on the periphery of the bag, at its minimum at the opposite side of the periphery of the bag, and varies, preferably smoothly, in between these points. Such a bag may be useful in situations such as those outlined above, where a gap is much wider on one side of a pipe structure than on the other.

Bags having more than one discrete outwardly expandable section are also envisaged, each section extending around a part of the periphery of the bag, with the sections being generally aligned with one another. Bags may be formed in this manner to seal unusually-shaped gaps, or for simplicity of manufacture.

Bags may also have respective outwardly expandable sections provided at more than one location along the length of the bag. Bags may be formed in this manner to fill a series of gaps, or to plug the ends of one long gap. It is also envisaged that outwardly expandable sections may be provided at spaced apart locations along the length of a bag, with the spacing between the outwardly expandable sections corresponding to the length of pipe sections making up a pipe structure. In this way a single bag, which is longer than the pipe sections making up the pipe structure, may be used to fill more than one gap between the pipe sections.

It will be appreciated that embodiments of the present invention will provide a convenient, cost-effective and robust method of sealing gaps in, and reinforcing, pipe structures.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CL/U MS: 1. An apparatus for sealing a gap in a hollow pipe structure, the apparatus comprising: a rigid, hollow, tubular, open ended liner; a flexible, substantially enclosed bag having an inner surface and an outer surface and being suitably dimensioned so that the bag may be placed around the liner, with the inner surface of the bag lying against an outer surface of the liner, to form an inflatable layer around the liner whilst leaving the hollow interior of the liner substantially unobstructed, the outer surface of the bag having an outwardly expandable section formed thereon, the bag having at least one inlet to allow a settable substance to be delivered into the interior of the bag.
2. An apparatus according to claim 1, wherein the outwardly expandable section comprises a gap in the outer surface of the bag, with a length of material being provided between the edges of the gap which is substantially longer than the distance between the edges.
3. An apparatus according to any preceding claim, wherein the bag has one or more outlet ports or valves.
4. An apparatus according to any preceding claim, wherein the liner is formed from a plurality of sections that are joined together.
5. An apparatus according to any preceding claim vtherein the outwardly expandable section is provided substantially midway along the length of the bag.
6. An apparatus according to any preceding claim, wherein the length of the bag is approximately the same as that of the liner.
7. An apparatus according to any preceding claim, wherein the outwardly expandable section extends over only a part of the periphery of the bag.
8. An apparatus according to any preceding claim, wherein the cross-sectional area of the outwardly expandable section varies around the periphery of the bag.
9. An apparatus according to any preceding claim, wherein the bag has a plurality of outwardly expandable sections.
10. An apparatus according to claim 9, wherein the plurality of outwardly expandable sections are generally aligned with one another.
11. An apparatus according to claim 9 or 10, wherein the plurality of outwardly expandable sections are provided at spaced apart locations along the length of the bag.
12. A method of sealing a gap in a hollow pipe structure, comprising the steps of: placing a rigid, hollow, tubular, open ended liner within the pipe; providing a flexible, substantially enclosed bag having an inner surface and an outer surface, the outer surface of the bag having an outwardly expandable section formed thereon, and the bag having at least one inlet to allow a settable substance to be delivered into the interior of the bag; placing the bag around the liner so that the inner surface of the bag lies against an outer surface of the liner, forming an inflatable layer around the liner whilst leaving the hollow interior of the liner substantially unobstructed; and introducing a settable substance into the interior of the bag so that the bag at least partially fills with the settable substance and the outwardly expandable section at least partially fills with the settable substance and protrudes outwardly from the remainder of the bag.
13. A method according to claim 12, wherein the settable substance is a concrete.
14. A method according to claim 13, wherein the settable substance is a micro-concrete.
15. A method according to any one of claims 12 to 14, wherein the liner and bag are positioned within the pipe structure so that the outwardly expandable section is aligned with the gap.
16. An apparatus substantially as hereinbefore described, with reference to figures 2 to 6 of the accompanying drawings.
17. A method substantially as hereinbefore described, with reference to figures 2 to 6 of the accompanying drawings.
18. Any novel feature or combination of features disclosed herein.