WO2011098774A1

WO2011098774A1 - Pipe seal

Info

Publication number: WO2011098774A1
Application number: PCT/GB2011/000190
Authority: WO
Inventors: William G. Menzies; Peter Hall; John Menzies
Original assignee: Air Bag Stopper Holdings Limited
Priority date: 2010-02-11
Filing date: 2011-02-11
Publication date: 2011-08-18
Also published as: GB2491075A; GB201216091D0

Abstract

An apparatus for sealing a pipe near a junction includes: at least one inflatable bag (20) attached to deployment means such as an elongate member (22). The deployment means (22) is formed and arranged to deploy the inflatable bag (20) along a pipe. The apparatus includes means for inflating the inflatable bag when deployed in a pipe; and a pipe engaging anchor (28), operable to engage with pipe work, typically a junction in pipe work, forward of the inflatable bag (20). The pipe engaging anchor (28) may include one or more limbs (30) for engaging a pipe. The limbs may be deployed with the assistance of control members pivotally connected to the limbs (30). Pipe engaging anchors and methods for sealing a pipe are also described.

Description

Pipe Seal

The present invention relates to an apparatus and method for sealing a pipe near a pipe work junction or locations in a pipe system where the cross sectional area of the pipe system changes.

Pipe work carrying a fluid, for example a liquid such as water or a gas such as natural gas, requires maintenance and repair from time to time. Other work that may be carried out includes extending the pipe system, for example to deliver the fluid to new locations. Working on a pipe system can be inconvenient and expensive as the section of pipe to be worked on may have to be isolated - sealed from the rest of the pipe system - and the fluid may have to be removed or drained from the isolated section of pipe to allow work to commence. If isolating valves are not provided at convenient locations on the pipe work, or if they are faulty, then isolating and draining of an extensive section of a pipe system may be required.

To reduce this inconvenience apparatus that seals a pipe even where a suitable valve is not provided is known. For example the inflatable devices provided by Sarco Stopper Ltd of Broxburn West Lothian UK. Typically a 'saddle' arrangement is clamped in sealing engagement to a section of pipe near where maintenance, repair or the creation of new connections is required. A small hole is then drilled in the pipe wall, through the saddle, whilst maintaining the seal, and a probe or 'nose' is inserted through the hole. The nose carries an inflatable bag (or bags) which is/are inflated to extend across the interior of the pipe to seal it. Where the pipe contains a fluid at significant pressure flowing through it (e.g. water at mains pressure) the inflated bag may not grip the interior wall of the pipe sufficiently to prevent the bag being moved from its location by the pressure differential when the fluid is removed from the downstream side of the inflated bag. This effect can be countered to some extent by inflating the bag to higher pressures to increase its grip on the pipe wall but such an approach is limited in efficacy and requires stronger bag materials and a higher pressure inflation system. The bag will still tend to slide along the pipe. Therefore the bag and nose assembly is arranged so that the nose is downstream (on the lower pressure side) of the bag. A bag deployment assembly is attached to the saddle and the nose and bag are extended through the hole made in the pipe and across the interior diameter of the pipe, thus acting as a fixed support preventing the inflated bag moving downstream.

Once sealed, the pipe can then be drained, downstream of the inflatable bag, to allow maintenance, repair or replacement of defective components. After operations are complete the bag can be deflated and removed together with the nose through the small hole which is then closed with a threaded completion plug to prevent leakage of fluid. Such prior art arrangements are discussed further hereafter and with reference to figure 1.

Whilst this approach is used successfully in a wide variety of circumstances, it does require access to a section of pipe wall that is not covered. For example a buried section of pipe needs to be excavated to expose its surface for fitting the saddle. Furthermore a hole has been made in the side of the pipe which can leak if the sealing plug is not fitted correctly. A common requirement in pipe maintenance is to isolate a branch pipe from a main pipe system in order to repair or replace a valve or other fitting (or to make new connections) at some point on the branch. For example fire hydrants are branches from a main water pipe which have a fitting for connecting to a fire fighting hose and a valve to turn on and off the water supply from the main pipe. Repair or replacement of the valve and/or the connection for a hose pipe can be carried out by sealing off the branch pipe using an inflatable arrangement such as discussed above. Once the branch pipe (for example a riser pipe extending vertically from a main water pipe) is sealed the maintenance work can be carried out without needing to interfere with the flow in the main pipe. However, excavation around the hydrant is often required to find a suitable portion of the branch pipe for clamping the saddle to. More generally when pipe systems are being worked on it is often convenient to isolate a portion of the system from the rest, at or near a junction, so that flow of fluid may be allowed to continue in the pipe system, except for the branch that has been sealed off.

It is an object of the present invention to provide apparatus and methods for sealing a pipe near a junction, reducing or preventing fluid flow past the seal.

Thus according to a first aspect the present invention provides an apparatus for sealing a pipe near a junction, the apparatus comprising:

at least one inflatable bag attached to deployment means, said deployment means being formed and arranged to deploy the inflatable bag along a pipe;

means for inflating the inflatable bag when deployed in a pipe; and

a pipe engaging anchor, operable to engage with pipe work, forward of the inflatable bag. Whilst a single inflatable bag may be employed in many applications, two (or more) bags may also be used. Two inflatable bags may be used to provide safety in the event of a failure of one of the bags. The use of two bags, spaced apart, also allows the possibility of pressurising the pipe system in the space between the inflated bags. In the following description, where a single inflatable bag is referred to, it will be understood that two or more inflatable bags may be provided if desired. The pipe engaging anchor is formed to engage the pipe forward of the inflatable bag. Where the seal is to be made at or near a junction the pipe engaging anchor will generally engage the pipe work junction, acting as a pipe junction engaging anchor to anchor the apparatus near the junction. Inflating the bag will then seal the pipe at or near the junction. However, it should be appreciated that the pipe engaging anchor may also be operable to engage with a pipe in other locations, in particular where a pipe narrows or otherwise changes in cross sectional area thus allowing sealing at a location away from a pipe junction in some circumstances as described hereafter with reference to particular examples. By providing an apparatus that can be deployed along a pipe the requirement for drilling through a side wall to insert the inflatable bag is removed. The deployment means may comprise an elongate member such as a rod, tube or wire which has the inflatable bag attached towards or at one end. Where the pipe to be sealed is not filled with fluid before the apparatus is deployed then deployment can be by inserting the end of the elongate member with the inflatable bag attached into an open end of the pipe and pushing the inflatable bag towards the junction using the elongate member. Conveniently, to allow for bends or constrictions (such as a valve assembly in the pipe), the elongate member is chosen to be resilient (flexible yet sufficiently stiff) to allow the bag to be pushed into place, even round a bend or through an (opened) valve. More usually the pipe system will contain fluid, often under significant pressure, and the bag is deployed into the fluid filled pipe. This can be done by providing a launch housing for the inflatable bag (a "bag tube") that can be attached to an end of the pipe system, for example the hose connection on a fire hydrant. The launch housing is fluid tight or substantially fluid tight when attached to a pipe. If the deployment means comprises an elongate member it passes out of the housing via an orifice with a seal (e.g. of the stuffing box type) that allows the elongate member to be pushed in or out as required to deploy the inflatable bag to the desired location. After opening the valve to allow communication between the inside of the housing and the fluid (water in the case of a fire hydrant) the bag is deployed down the pipe via the open valve.

When deployed in a suitable location the bag may be inflated by any suitable means.

A convenient method is to pump a fluid that may be a liquid, typically water, or a gas, typically air or an inert gas (if flammable or explosive conditions are to be avoided), into the bag from a supply. The supply may be a source of pressurised fluid such as a water pipe, or a pump or a cylinder that is connected to the bag via a suitable hose.

Conveniently the hose is concentric with an elongate member used to deploy the bag.

This arrangement has the advantage that only a single outlet from the casing of a launch housing, for the passage of both the elongate member and the inflation tubing, is required. Alternative inflation could be, for example, by activating a chemical reaction to produce a gas or a foam from a substance or mixture of substances placed within the bag. A fluid such as a resin that sets after inflation of the bag may also be used. The apparatus of the invention is provided with a pipe engaging anchor that engages a junction of pipe work (or other location in the pipe), forward of the inflatable bag. Conveniently the anchor is attached towards the end of an elongate member used to deploy the inflatable bag. Alternatively the anchor may be attached directly to the inflatable bag.

Conveniently for some applications, for example where the anchor and inflatable bag are deployed through a valve in a pipe system the anchor and inflatable bag are spaced apart by a flexible or a hinged connector piece. The flexible connector piece allows bending of the bag and anchor assembly, which is generally rectilinear on the elongate member used to deploy the bag. This allows easier passage through constrictions or bends and in some cases may be necessary in order to allow deployment of suitably sized anchors and bags, which can provide the appropriate security of sealing and avoidance of dangerous failure under pressure. A hinged connector piece can provide the same advantages. In addition as a hinged connector may pivot about only one axis, more control may be exercised in the direction taken by the anchor in e.g. passing round a bend may be obtained. Furthermore a compact hinged connector piece can readily be constructed.

For example in a typical hydrant arrangement (illustrated by an example hereafter) a valve operates on top of a straight pipe section vertically connected to a horizontal mains water pipe. A "J" shaped branch from the vertical pipe is used to provide water supply to a hose when required by opening the valve. In such an arrangement the anchor and the inflatable bag are launched from a launch housing, as described above, that is fitted to the "J" branch. The bag and anchor must then be deployed round the bend of the J and through the valve to the correct location for anchoring to the pipe, at the mains pipe and vertical pipe junction, and for inflating the bag to seat the vertical pipe from the mains. The deployment of a suitably sized anchor and bag into this arrangement is facilitated by having a bag and anchor that are connected by a flexible or by a hinged connector piece. The flexible connector piece may be of any suitably flexible material that can sustain the tension forces between the bag and the anchor on deployment. Conveniently a section of flexible hosing, typically reinforced flexible hosing is employed. For example a flexible plastics or rubber hose with metal or other braiding reinforcement within or external to the hose walls. Use of flexible hosing allows the elongate member used to deploy the bag to pass through to the anchor, for example carrying means to activate the anchor. Where a hinged connector piece is employed it may be provided with a suitable through bore for the passage of the elongate member. The anchor may comprise one or more limbs, for example metal bars or rods that are attached to the elongate member. Two limbs can be particularly effective and three or even more may be used. Conveniently the limbs are each connected at one end by a pivot or hinge to the elongate member. The limb or limbs may lie close alongside the elongate member or project forwards of the end of the elongate member before being activated to engage with a pipe junction or another location on the pipe where the apparatus is to be deployed. This allows easy passage of the anchor and inflatable bag assembly down the pipe.

When positioning the apparatus in a pipe to engage at a pipe junction, the limb or limbs of the anchor are first pushed past the end of the pipe down which the inflatable bag is delivered and into the pipe junction. The limbs are then activated to pivot outwards, projecting out beyond the circumference of the pipe. The apparatus is then withdrawn slightly to engage the radially outwards projecting limbs with the end of the pipe. Resistance to further withdrawal of the apparatus from the pipe indicates that the anchor and hence the inflatable bag is correctly located at/near the pipe junction. Where the apparatus is used in another location the limb or limbs are activated outwards in the same way to engage with the wall of the pipe, at least following slight withdrawal of the apparatus as described hereafter with reference to specific examples. The inflatable bag is subsequently inflated in the pipe it has been passed down, close to the junction or other selected location. The pipe junction engaging anchor provides the benefit of securely holding the apparatus, especially the inflatable bag, in the correct location for sealing the pipe, close to the junction or other suitable location. Even when the fluid is removed from the pipe downstream of the bag (or when the pressure downstream of the bag is reduced) the bag is prevented from being pushed along the pipe, by difference in fluid pressure, as it is connected to the anchor.

However the secure location of the inflated bag and its good sealing engagement with the sides of the pipe can be further enhanced by the provision of a support means, downstream of the inflatable bag (i.e. on the lower pressure side of the sealing point), against which the bag rests when inflated. For example the support means may take the form of a plate or plates, or other rigid member(s) (e.g. rods) attached to an elongate member used to deploy the inflatable bag. For ease of deployment the plates or other rigid members are pivotally attached to the elongate member so that they can lie close alongside it when the apparatus is deployed down the pipe. The plate(s) or other rigid member(s) may also be attached to the surface of the inflatable bag so that when it is inflated they are automatically pivoted outwards, across the diameter of the pipe, to provide support for the inflated bag. Alternatively the plates or rigid members may be separately activated into position, before the inflation of the bag.

The pipe engaging anchor can be operated in a number of ways. For example where the anchor comprises one or more limbs, each connected at one end by a pivot or hinge to an elongate member, the limb or limbs may be held in a stowed position (close alongside the elongate member or projecting forwards of the end of the elongate member) by means of a latch. The limbs may be spring loaded so as to be biased towards a radially outwards operating position when the latch is released. Release of the latch can be achieved in a number of ways, for example by an operating button on the front end of the elongate member, close to the anchor and inflatable bag, that connects to the latch and releases it when the button is depressed by contact with the wall of a pipe. This arrangement can be used when the apparatus is inserted into a typical (T shaped) pipe junction as described hereafter with reference to an example.

Alternatively the latch may be released from the distal end of the elongate member by an operator using a control cable that may for example pass through a bore down the centre of the elongate member to the latch. A further advantageous alternative is to provide an elongate member for deploying the apparatus that has an externally threaded portion, near the end to which the anchor is attached. The threaded portion of the elongate member passes through a corresponding threaded nut of the anchor assembly which is formed and arranged so that when the elongate member is rotated by an operator the nut moves along the elongate member causing the limbs of the anchor to move to their operating position as described hereafter with reference to an example.

Conveniently and as further described hereafter with reference to a specific embodiment a "scissor" type mechanism is employed to deploy limbs of an anchor, making use of a control arm (control member) that pivotally connects at one (proximal) end to the nut and at the distal end to an anchor limb. Typically two control arms are used each connected to a corresponding limb disposed diametrically opposite to each other on the threaded portion. Turning the threaded portion of the elongate member moves the nut along the threaded portion towards the pivot connection of the limbs to the elongate member. This has the effect of pushing the control arms and their corresponding connected anchor limbs outwards as the nut approaches the pivot connection point between the anchor limbs and the elongate member.

More conveniently two (first and second) nuts are employed, each being located on an oppositely threaded part of the threaded portion of the elongate member (one part "left hand thread", the other "right hand thread"). The first nut carries the control arms (members) each pivotally connected at one end to it. The second nut carries the anchor limbs each pivotally connected at one end to it. The distal end of each control member is pivotally connected to its corresponding anchor limb as in the above described arrangement. Where two nuts are employed in this fashion rotation of the threaded portion of the elongate member, in the appropriate direction, causes both nuts to advance towards each other simultaneously, resulting in a more rapid outwards deployment of the control arms and corresponding connected anchor limbs. Turning the threaded potion the opposite way will cause the two nuts to move apart causing the anchor limbs to move inwards towards their stowed position, close to the elongate member for deployment.

A further advantage of this arrangement is that (because of the use of the opposite threading and the connection between the nuts provided via the control members and the anchor limbs), the anchor limbs are firmly locked in a given position if the elongate member is prevented from rotating.

A yet more convenient arrangement, where two nuts are employed as discussed above is to provide oppositely threaded parts of the threaded portion of the elongate member that are different in diameter. The end part of the threaded portion (distal to the inflatable bag) has a smaller diameter than the oppositely threaded part that is closer to the inflatable bag. The difference in diameter is sufficient to allow the nut on the larger diameter part to pass freely over the smaller diameter part. This arrangement allows the anchor assembly to be easily unscrewed from the end of the elongate member as described hereafter. This is advantageous in many applications where the inflatable bag is replaceable. For example for safety (avoiding use of a damaged bag) and/or hygiene reasons the inflatable bag may be replaced on each occasion the apparatus is used to seal off a potable water supply.

The inflatable bag may be manufactured of any suitable material of sufficient strength and durability for the application contemplated. Typical bags may be of polyurethane coated nylon that may be reinforced with aramid stitching. Rubber (synthetic or natural) based materials may also be used, alone or in combination with reinforcing material.

Conveniently the inflatable bag is a replaceable item that can be removed from the rest of the apparatus and replaced, for example if the bag is damaged or worn. In some applications a replaceable bag is particularly useful. For example when used in pipes carrying potable water, the regulations in some countries will only permit contact of bag materials such as a rubber with the potable water for a limited period e.g. eight hours. The regulation is directed to avoiding contamination of the water caused by deterioration of, or leaching from, the bag material. In such circumstances the bag becomes a disposable item that is used once and replaced before the apparatus is used again. Various other modifications may be made to an apparatus of the invention. For example in some situations the apparatus may include a so called "sniffer tube" that passes through the bag or through the bag and the anchor assembly. The sniffer tube, which may be concentric with (normally inside) an elongate member used to deploy the inflatable bag can carry a camera to view upstream of the inflated bag. The sniffer tube may also be employed to deploy sensors, such as temperature sensors or microphones. The sniffer tube may be used to permit purging of the pipe work by passing through inert gas flow. A yet further use of the sniffer tube is to supply grout or other material into the pipe, for sealing or other construction purposes.

In some applications, for example where the pipe carries a water supply, the sniffer tube may be used to pass pressurised fluid (for example water at mains pressure) through the inflatable bag and out of the pipe system to a hydraulic device. The pressurised fluid is used to drive a hydraulic ram that pumps inflating fluid (e.g. water) into the inflatable bag. This approach avoids the need for a separately driven pump or other source of pressurised fluid to inflate the bag.

According to a second aspect the present invention provides a method for sealing a pipe comprising: providing an apparatus according to the first aspect of the invention; deploying the inflatable bag or bags and pipe engaging anchor along a pipe;

engaging the pipe with the pipe engaging anchor; and

inflating the bag or bags to seal the pipe.

The pipe engaging anchor may engage the pipe at a junction or at a location where the cross sectional area or shape of the pipe changes. The method may further comprise deployment of a support means. According to a third aspect the present invention provides pipe engaging anchors suitable for use with an apparatus for sealing a pipe near a junction as described herein. Further preferred features and advantages of the present invention will appear from the following detailed description given by way of example of some preferred embodiments illustrated with reference to the accompanying drawings in which:

Fig.1 shows a prior art apparatus in use for sealing a pipe;

Figs. 2a to 2i illustrate schematically the deployment and use of apparatus of the invention;

Figs. 3a to 3d illustrate the use of a pipe engaging anchor according to the invention; Figs. 4a to 4 c illustrate the use of a support means of the invention;

Figure 5 illustrate the use of another pipe engaging anchor of the invention;

Figures 6a to 6d illustrates fitting of the anchor of figure 5 to an apparatus of the invention;

Figures 7a to 7c illustrate another apparatus of the invention and its use; and

Figures 8a and 8b illustrate a further example of an apparatus of the invention.

In figure 1 a prior art apparatus is shown in use. A pipe 1 has had a probe 2 (a "nose") inserted transversely though a hole 4 that has been drilled though its wall. Leakage of fluid from the pipe via the orifice 4 is prevented by clamping a sealing system (not shown in detail but indicated by the dashed line box 6 to the wall of the pipe 1 prior to drilling the hole 4 and insertion of the probe 2. An inflatable bag 8, attached to the probe 2 has been inflated from a supply of fluid 10 (such as air or water) passed though the probe 2. The bag 8 seals the pipe 1 allowing maintenance or repair to be carried out on the downstream side 12 of the pipe 1. Whilst this maintenance or repair is being carried out and pressure on the downstream side 12 of the bag 8 is reduced or even removed (if the fluid is drained) the pressure on the upstream side 14, indicated by the arrow P is maintained. The pressure P will tend to displace the inflated bag 8 downstream, even if the bag is inflated to a high pressure to grip the wall of the pipe 1 more tightly. This tendency is countered by the probe 2 which is downstream of the bag 8 and held in place by the sealing system 6 clamped to the pipe 1. The probe 2 acts as a support for the bag 8.

Figure 2a shows schematically an apparatus of the invention 16 that includes a launch housing 18 in the form of an open ended tube (a "bag tube") with an external screw thread 19 at one end for screwing onto a pipe work connection. The launch housing contains an inflatable bag 20 in an uninflated state that is attached to a deployment means that takes the form of a flexible elongate member 22 - a flexible rod - that is contained within a tube 24 that can be used to inflate the bag 20 as described hereafter. The deployment means 22 and tube 24 pass out through a seal 26 (of the stuffing box type).

Pushing or pulling on the deployment means as indicated by the double headed arrow allows the bag 20 to be deployed to a selected location down a pipe that the launch housing 18 is screwed onto. The connection of the launch housing 18 to a pipe can be made by alternative means to the screw thread 19 by providing a suitable end to the housing appropriate for the pipe work connection being used.

In general deployment of the bag 20 is carried out by first attaching the launch housing 18 to a pipe work connection. A valve on the pipe system is opened to provide fluid communication between the interior of the launch housing 16 and the fluid in the pipe system. The bag is then deployed into the pipe system via the valve by pushing on the elongate member 22. The apparatus 16 also includes a pipe engaging anchor 28 that includes two limbs or arms 30 pivotally connected to the deployment means 22 and lying close along side it. A support means 32 attached to the tube 24, above the inflatable bag 20, includes two plates 34 pivotally connected to a collar 36. The structure and operation of a pipe junction engaging anchor 28 and support means 32 is described more fully hereafter with reference to the specific example of figures 3 and 4.

Figures 2b to 2e illustrate schematically various aspects of the deployment and use of apparatus 16 of figure 2a and of some possible variants. In these figures the tube 24 and deployment member 22 are shown as a single line passing through the bag 20 for clarity. In figure 2b the apparatus 16 of figure 2a is shown after deployment of the bag 20 and associated anchor assembly 28 and support means 32 down a pipe branch 38, which in this case makes a junction 40 with a main pipe 42 - a T junction.

When the anchor assembly 28 is in the junction 40 it is activated to allow the limbs 30 to move outwards in the direction shown by the curved arrows to project radially outwards from the elongate member 22. Activation of the limbs 30 can be achieved in a number of ways. For example the limbs 30 may be spring loaded but held in their launch position by a latch mechanism (not shown) that is released when a button on the end 44 of the elongate member 22 strikes the wall 46 of the main pipe 42. Alternative activation is described with reference to figures 3.

Figure 2c shows the arrangement of figure 2b after activation of the limbs 30 of the anchor 28 and withdrawal of the deployment member 22 and tube 24 until the limbs 30 engage with the walls of the pipes at the junction 40. As shown in figure 2d the bag 20 is then inflated to seal the branch pipe 38. The inflation also causes deployment, radially outwards, of the plates 34 of the support means 32 resulting in the arrangement shown in figure 2d. The inflated bag 20 seals the branch pipe 38 but allows flow to continue in the main pipe 42 if desired. Meanwhile the branch pipe 38 may be drained for maintenance or repair. The inflated bag 20 is held in place even against significant pressure in the main pipe 42 at it is attached to the anchor 28 via the elongate member 22 and, in this example; the support means 32 provides additional support downstream of the bag 20, reducing the strength requirements for the bag whilst still providing a reliable seal. Figure 2e shows an arrangement similar to that of figure 2d except that the bag 20 is smaller and displaced a short distance up the branch pipe from the junction 40 rather than right at the junction 40.

Figure 2f shows an alternative anchor 28 where before deployment the limbs 30 project forward of the elongate member 22 of the deployment means before activation and then move outwards as indicated by the curved arrows.

Figure 2g shows a similar apparatus to that of figures 2a to 2f but in use in a Ύ' shaped junction. The limbs 30 of the anchor 28 have been activated to project outwards. Withdrawal of the elongate member 22 in the direction of the arrow A will engage the limbs 30 with the edges 48 of the Y junction 40, bending the flexible elongate member 22 as required. Thus an apparatus of the invention can be used in pipe junctions that are not T junctions. Figure 2h shows a similar apparatus to that of figures 2a to 2f but not in use at a pipe junction. The pipe 1 has a taper so that withdrawal of the apparatus in the direction of the arrow A engages the limbs 30 with the pipe wall. Similarly figure 2i shows an apparatus in use where the pipe diameter changes in a stepwise fashion, from wide to narrow. In general the pipe engaging anchor may be used wherever the cross sectional area of the pipe changes as well as at a pipe junction. Figures 3 show in more detail an example of a pipe engaging anchor 28 in use. Before use the anchor 28 is in a stowed position as shown in figure 3a. The anchor 28 is attached by a collar 50 to tube 24 about an elongate member 22 (flexible rod) that has a screw threaded end portion 52. Before the collar 50 the tube 24, includes an orifice 54 to allow an inflation fluid into a bag (not shown). The elongate member 22 is free to rotate inside the tube 24 and the collar 50 and passes through a threaded nut 56 at the end of the anchor that has a rounded shape for easy passage down a pipe and through obstacles such as bends or valves. Two pipe engaging limbs 30 are connected by pivots 58 to the collar 50. More limbs for example three may employed. In the stowed position shown the limbs 30 lie close alongside the elongate member 22 and inside slots (see figure 3d) of control members 60. The control members 60 are connected by pivots 62, 64 to the limbs 30 and to the nut 56.

After launch to the desired position in a pipe junction the limbs 30 of the anchor 28 are activated by turning the elongate member 22 as indicated by the arrow in figure 3a. The screw threaded end portion 52 of the elongate member 22 screws through the nut 56 causing it to move upwards along the screw thread. This results in the outwards motion of the limbs 30 caused by the outwards motion of the control members 60 as indicated by the curved arrows in figure 3b where the limbs 30 are part way towards their fully activated (fully deployed) position.

The fully activated position is shown in figure 3c where the limbs, in this example, are at right angles to the elongate member 22. However it can be advantageous to provide an apparatus where the fully activated position of the limbs 30 is as shown in figure 3d (discussed below).

After activation of the limbs 30 the apparatus is then withdrawn by pulling on the other end of the elongate member 22 until the extended limbs 30 engage with the walls of pipes at the junction such as is shown in figure 2d. Inflation means such as a supply of pressurised water or an air cylinder or a pump is then connected to the pipe 24 to inflate the bag 20 via the orifice 54. The arrangement shown in figures 3 has the advantage of being fully controlled by an operator who turns the elongate member to activate the limbs 30. This arrangement also has good strength in the activated position provided by the triangulation between the limbs 30 and control members 60. Figure 3d shows in perspective view an apparatus similar to that of figures 3a to 3c but wherein the limbs 30, when fully activated project forwards, at an angle of less than right angles to the elongate member 22. The position of the limbs 30, can provide a degree of self centring to the apparatus when it is withdrawn slightly to engage the ends of the limbs with a pipe junction or narrowing pipe wall. Even more self centring action may be provided by providing three limbs 30, disposed around the elongate member 22, desirably at a 120 degree spacing from each other (not shown).

The slots 65 in the control members 60 that accept the limbs 30, when stowed, can be seen in this view. In this example the slots 65 have a back 66 that connects the front and rear plates of the control members 60 together.

Figure 4a shows in schematic elevation a support means 67. The support means 67 includes a collar 68 that is fixed to a tube 24 of the same type shown in figures 3. The support means also includes two rectangular plates 70 (see plan view figure 4c) that move about pivots 72 in the direction shown by the curved arrows when the bag 20 is inflated. Figure 4b shows the plates 70 fully deployed by the inflated bag 20 with the angled surfaces 72 of the collar 68 acting as stops to prevent further pivoting of the plates. In this position the plates support the bag 20, holding it in the desired position and resisting pressure from the fluid downstream of the seal formed. In alternative support means the support plates may be attached to the bag as well as to the pipe 24 to ensure deployment as the bag inflates. Alternative support means may also include more plates that may fan out to form a larger plate formed of overlapping smaller plates or a disc, centred on the elongate member.

Other arrangements to those described in the examples above or following may be used in an apparatus of the invention. For example the elongate member 22 having the form of a rod described above may instead take the form of a tube, through which a fibre optic viewing system may be passed to allow remote inspection of the pipe system upstream of the bag; either before during or after inflation. It will also be understood that it may be convenient to construct the elongate member or any other part of apparatus described out of more than one part. For example the elongate member 22 may be largely of a flexible coil structure, akin to a tightly wound spring, for most of its length but having a screw threaded portion attached at the end for use as described above in respect of Figures 3. Where necessary, for example to form a seal as it passes through an inflatable bag the flexible coil structure may be interrupted and replaced by solid rod or tube sections. Figure 5 shows an alternative form of anchor assembly 28, similar to that shown in figure 3d, in partial cross section. In this example only one control member 60 and one limb 30 is shown in the drawing for clarity but it will be understood that a similar arrangement is fitted at the pivot points 58 and 64 at the other side of the elongate member 22. The threaded portion 52 of the elongate member 22 has two parts in this example. The end part 74 is of a smaller diameter and oppositely threaded to the part 76 distal from the extreme end 78 of the elongate member 22. The nut 56 carrying the control members 60 is screwed onto the end part 74 of the threaded portion 52. In contrast to the arrangement of figure 3d the limb(s) 30 of the anchor are not on a fixed collar but are carried by a second nut 80 that is screwed onto the larger diameter threaded part 76. In this example the second nut 80 is elongate for strength and secure fixing. The second nut 80 includes a collar 81 that can be threaded for connection to a tubing or flexible connector as described below with respect to figures 7.

As a consequence of the oppositely threaded nuts 56, 80 and corresponding threaded parts 74,76, together with the connection provided by the control members 60 and limbs 30, the two nuts simultaneously move in opposite directions; either towards each other or away from each other when the elongate member 22 is rotated. In figure 5 the nuts 56, 80 are at the end of their respective threads and locked in contact with the limbs 30 fully deployed outwards. Rotating the elongate member 22 the opposite way leads to a stowed position, similar to that shown for the alternative example illustrated in figure 3a. The arrangement shown makes use of threaded part 74, 76 diameters that are sized so that the second nut 80 can pass over it for assembly and dismantling. For example the threaded parts and corresponding nuts may have M6 and 8 diameters (6mm and 8mm).

A detachable anchor assembly 28 is advantageous where the inflatable bag is to be replaced (see figure 7 and the discussion thereon below). The fitting of the detachable anchor is shown schematically in figures 6a to 6d. In these schematic elevation drawings the anchor limbs 30, and control members 60 are shown simply as connected straight lines, the threaded parts 74, 76 are to be understood to have opposite threads indicated by the opposed diagonal hatchings 82, 84.

Figure 6a shows the nuts 56, 80 spaced far apart and the larger diameter nut 80, having been passed over the smaller diameter threaded part 74 being screwed onto the larger diameter threaded part 76, with the curved arrow indicating rotation and the straight arrow direction of motion of the nut 80 along the thread 76.

In Figure 6b the larger diameter nut 80 is well advanced along its thread 76 so that the smaller diameter nut 56 is at the extreme end 78 of the elongate member 22. The direction of rotation of the anchor assembly is now reversed as indicated in figure 6c to screw the smaller diameter nut 56 along the thread 74. At the same time and as indicated by the straight arrows the two nuts 56, 80 are advancing towards each other, moving the control members 60 and anchor limbs outwards.

In figure 6d the two nuts are in contact ("locked") and the limbs 30 deployed to their maximum extent as when the apparatus is anchored in a pipe. The anchor 28 can be readily removed by reversal of the above procedure. Figure 7a shows schematically an apparatus of the invention 16 in perspective cross section that includes a flexible connector 86 between the inflatable bag 8 and the anchor assembly 28 (a similar assembly to that of figures 5 and 6). The inflatable bag is detachable and has a tube 24 passing through it (to lower end collar 88) that can carry an elongate member 22 as discussed above with respect to figures 3. Passages 54 in the wall of the tube 24 may be used for the liquid or gas that inflates the bag in use. The bag 8 is fitted (swaged) to collars 87, 88. The collar 88 at the lower end of the bag has a spigot 90 to which a flexible connector or link 86 (of a steel braided reinforced flexible (rubber) tubing) is swaged. The other end of the flexible connector 86 is swaged to a spigot 94 screwed into the collar 81 of the nut 80. As discussed above the elongate member 22 may be of a coiled steel wire structure except for the threaded portion 52 and, in this example, where it passes through the lower end collar 88 of the inflatable bag where a gas tight seal is required. There, the elongate member 22 may be of a solid rod 93 or rigid tubing with sliding and fluid tight sealing connection (for example assisted by "o" rings 97) to the interior surface of the collars. This arrangement allows rotating and linear motion (relative to the collar 88) of the elongate member 22 to occur when operating the anchor assembly, without losing inflation pressure in the bag 8. Figure 7b shows in cut away perspective view the apparatus 16 of figure 7a being deployed in a typical hydrant with a "J" branch outlet 95, and a straight tube 98 that forms a a T connection to a water main 100. A valve (96 in schematic elevation view Figure 7c, not shown in 7b) operates up and down in the straight tube to seal the J branch from the main 100 as required. The apparatus has been deployed from a launch housing 18, fitted to the J branch 95 (Figure 7c). The launch housing 18 includes a guidance tube 102 in this example a curved tube that guides the apparatus 16 into the straight tube 98. Conveniently the launch housing has a detachable guidance tube 102 so that different guidance tubes of different sizes and shapes may be attached depending on the work being undertaken (geometry of the pipe assembly.). The flexible connector 86 allows the anchor 28 and the inflatable bag 8 sufficient freedom to bend round into the straight tube 98 in a manner that would not be possible with similar sized components that were attached close together on the elongate deployment member 22.

Figure 8a shows in perspective a similar anchor arrangement to that of figure 7a except that the connection between the collar 88 for the inflatable bag (bag not shown in this drawing) and the anchor assembly 28 is in the form of a hinged connector 104. The elongate member 22 (having a coiled steel wire structure) passes through the hinged connector 104 to a threaded portion 52. A spring clip 106 is employed in this example to lock the anchor assembly 28 to the connector 104. The hinge or pivot 108 of the hinged connector 104 allows pivoting about the axis X. Passage of the apparatus round a bend can therefore occur in a similar fashion to that shown in Figure 7b for example. Figure 8b shows the arrangement of figure 8a but with the control members 60 and the corresponding limbs 30 of the anchor assembly 28 shown in their deployed positions.

Claims

1. An apparatus for sealing a pipe near a junction, the apparatus comprising:

at least one inflatable bag attached to deployment means, said deployment means being formed and arranged to deploy the inflatable bag along a pipe; means for inflating the inflatable bag when deployed in a pipe; and

a pipe engaging anchor, operable to engage with pipe work, forward of the inflatable bag.

2. An apparatus according to claim 1 wherein the deployment means comprises an elongate member which has the inflatable bag or bags attached towards or at one end.

3. An apparatus according to claim 1 or claim 2 wherein the pipe engaging anchor comprises one or more limbs for engaging a pipe in use of the apparatus.

4. An apparatus according to claim 3 wherein the deployment means comprises an elongate member which has the inflatable bag or bags attached towards or at one end and the limb or limbs of the pipe engaging anchor lie close alongside the elongate member or project forwards of the end of the elongate member before being activated to engage with a pipe.

5. An apparatus according to claim 3 or claim 4 wherein the deployment means comprises an elongate member and the limb or limbs of the pipe engaging anchor are each connected by a pivot or hinge to said elongate member.

6. An apparatus according to claim 5 wherein the elongate member has an externally threaded portion, near the end to which the pipe engaging anchor is attached and passing through a corresponding threaded nut of the pipe engaging anchor; the pipe engaging anchor being formed and arranged so that when the elongate member is rotated by an operator the nut moves along the elongate member causing the limb or limbs of the pipe engaging anchor to move to their operating position.

7. An apparatus according to claim 6 wherein the pipe engaging anchor comprises at least one control member pivotally connected at a proximal end to the nut and at a distal end to a corresponding limb of the pipe engaging anchor.

8. An apparatus according to claim 7 wherein the pipe engaging anchor comprises two control members each connected to a corresponding limb, the limbs being disposed diametrically opposite each other on the threaded portion of the elongate member.

9. An apparatus according to any one of claims 6 to 8 wherein;

the pipe engaging anchor comprises oppositely threaded first and second nuts, each nut disposed on correspondingly threaded first and second parts of the externally threaded portion of the elongate member; and

wherein the or each control member is pivotally connected at a proximal end to the first nut and at a distal end to a corresponding anchor limb, with the or each anchor limb being pivotally connected at one end to the second nut.

10. An apparatus according to claim 9 wherein the oppositely threaded first and second parts of the externally threaded portion of the elongate member are sufficiently different in diameter to allow the nut on the larger diameter part to pass freely over the smaller diameter part.

11. An apparatus according to any one of claims 3 to 5 wherein the limb or limbs are held in a stowed position by means of a latch.

12. An apparatus according to claim 11 wherein the limb or limbs are spring loaded so as to be biased towards a radially outwards operating position when the latch is released.

13. An apparatus according to claim 12 wherein the latch is releasable by an operating button on the front end of the elongate member.

14. An apparatus according to claim 12 wherein the latch is releasable from the distal end of the elongate member by means of a control cable.

15. An apparatus according to any preceding claim wherein the pipe engaging anchor and inflatable bag are directly connected.

16. An apparatus according to any one of claims 1 to 14 wherein the pipe engaging anchor and inflatable bag are spaced apart by a flexible or a hinged connector piece.

17. An apparatus according to any preceding claim further comprising a launch housing for the inflatable bag or bags that can be attached to an end of a pipe.

18. An apparatus according to claim 17 when dependent from claim 2; wherein the elongate member passes out of the launch housing via a seal.

19. An apparatus according to claim 2 or any one of claims 3 to 18, when dependent from claim 2, wherein a hose concentric with the elongate member is used to supply fluid for inflating the bag or bags.

20. An apparatus according to any one of claims 1 to 18 wherein inflation of a bag is by activating a chemical reaction to produce a gas or a foam from a substance or mixture of substances placed within the bag; or wherein inflation of a bag is by filling the bag with a fluid such as a resin that sets after inflation of the bag.

21. An apparatus according to any preceding claim further comprising a support means, downstream of an inflatable bag, against which the inflatable bag rests when inflated.

22. An apparatus according to claim 21 wherein the support means comprises a rigid member or members attached to an elongate member used to deploy the inflatable bag.

23. An apparatus according to claim 22 wherein the support member or members are plates, discs or rods.

24. An apparatus according to any claim 22 or claim 23 wherein the support member or members are pivotally attached to an elongate member which has the inflatable bag or bags attached towards or at one end.

25. An apparatus according to any preceding claim further comprising a sniffer tube that passes through a bag or through a bag and the anchor assembly.

26. An apparatus according to claim 25 further comprising a hydraulic device that includes a hydraulic ram for pumping inflating fluid into the inflatable bag; and wherein the sniffer tube is formed for passing pressurised fluid from a pipe being sealed through the inflatable bag to drive the hydraulic ram.

27. A method for sealing a pipe comprising:

providing an apparatus according to any one of claims 1 to 26;

deploying the inflatable bag or bags and pipe engaging anchor along a pipe; engaging the pipe with the pipe engaging anchor; and

inflating the bag or bags to seal the pipe.

28. A pipe engaging anchor for an apparatus for sealing a pipe near a junction, the anchor comprising:

oppositely threaded first and second nuts, each nut being disposable in use on correspondingly threaded first and second parts of an externally threaded portion of an elongate member of a deployment means of a said apparatus; and

at least one control member pivotally connected at a proximal end to the first nut and at a distal end to a corresponding anchor limb, with the or each anchor limb being pivotally connected at one end to the second nut.