WO2011027158A2

WO2011027158A2 - Isolation tool and method

Info

Publication number: WO2011027158A2
Application number: PCT/GB2010/051448
Authority: WO
Inventors: Iain Chirnside
Original assignee: Brinker Technology Limited
Priority date: 2009-09-02
Filing date: 2010-09-02
Publication date: 2011-03-10
Also published as: GB2473337A; WO2011027158A3; GB201014567D0; GB0915253D0

Abstract

A tool (1) for isolating a hydrant (3) of a water mains comprises an inflatable bladder (11) adapted for insertion into the riser pipe (2) or in a tee below the hydrant and the bladder comprises means for engagement with a profile on the riser pipe or tee to secure the bladder in position and resist slippage within the riser pipe and means (17; 18) for spacing the bladder above the lower surface of the mains or tee below the hydrant such that the bladder can be secured within the riser pipe without shutting off fluid flow in the water mains.

Description

ISOLATION TOOL AND METHOD

This invention relates to an isolation tool and method and more particularly to a tool for isolating a section of a tubular member from the flow of fluids therein and a method of isolating such a section of tubular member. More specifically, the invention relates to an isolation tool for isolating a hydrant or section of mains water pipe from pressurised water present within the pipe and to a method of isolating a hydrant or section of mains water pipe. The mains water supply carries fresh water to and from central processing plants to domestic or industrial outlets. Access to the mains water supply may be required from time to time for example to allow for inspection, maintenance or repair work to be carried out. Access to the mains supply is provided through a water hydrant which is located at selected points along the mains supply. The hydrant comprises a riser pipe which is in fluid communication with the water mains through a suitable flanged connection. The riser pipe has a cap which has an outlet for providing access to the riser pipe. A valve is located in the cap which can be opened to an intervention tool to be inserted through the outlet of the cap into the riser pipe.

GB 2 443 012A describes a method of isolating a hydrant and accessing the water main and a tool for carrying out such an operation. The tool comprises a bladder which is inserted into the riser pipe through the outlet of the riser and which is then inflated to block the riser pipe against the pressure of water flowing in the mains pipe.

WO 01/16518 describes an inflatable stopper for arresting the flow of a liquid such as water in a pipeline which comprises an inflatable outer bag with an inner flexible bladder. A spine assembly passes through the centre of the inner bladder and facilitates inflation of the bladder and also structurally supports the bladder during insertion into the pipeline. The inflatable bladder is held in position and maintains a seal in the pipe due to the inflation pressure inside the bladder and the resulting frictional contact with the internal surface of the pipe which is dependent on said pressure. The bladder is formed of a plurality of sections of material which are stitched together and the stitching method used enables the use of a finer thread to increase the integrity of the joints between sections of material.

Whilst such methods and tools are useful in isolating a hydrant or pipeline, the pressure of water present in the mains can be considerable or subject to sudden spikes caused by changes in flow and this can lead to slippage of the bladder when inflated which can prevent the bladder from providing an effective blockage within the riser.

It is therefore an object of the present invention to address this problem and to seek to provide an improved tool for isolating a hydrant from the water mains.

Furthermore, it is an object of the present invention to provide an improved method of isolating a hydrant from the water mains.

According to one aspect of the present invention there is provided a tool for isolating a hydrant of a water mains, said tool comprising an inflatable bladder adapted for insertion into the riser pipe or in a tee below a hydrant, the bladder comprising means for engagement with a profile on the riser pipe or tee to secure the bladder in position and resist slippage within the riser pipe and means for spacing the bladder above the lower surface of the mains or tee below the hydrant such that the bladder can be secured within the riser pipe without shutting off fluid flow in the water mains.

In one embodiment the means to resist slippage comprises a region or area of increased width of the bladder. Conveniently the region or area of increased width is provided at one end of the bladder. Most preferably the bladder is elongate in form and the width of the bladder tapers from one end of the bladder to the other. The increasing width of the bladder along its length prevents the bladder from slipping within the riser pipe and ensures that there is a greater surface area of the bladder in contact with the inner surface of the riser pipe. Any increase in pressure acting on the bladder will tend to force the increased width portion of the bladder against the inner surface of the riser pipe and therefore wedge the bladder tighter into the riser pipe thereby preventing slippage of the bladder under pressure.

Additionally the change in diameter along the length of the bag prevents the passage of fluid from one side of the bag to the other through wrinkles caused by an excess of material in an overlarge bag. This shape ensures that full contact is made without folds at one point along the length of the bag.

Alternatively, in a further embodiment of the present invention the bladder comprises a locking means for retaining the bladder in position within the riser pipe against the pressure of water flowing in the mains pipe.

Conveniently the locking means comprises a mechanical lock. Additionally the shape of the bag can be designed such that it creates a lock in the tee.

Preferably the mechanical lock comprises one or more elongate members such as straps or rods stitched onto the bladder.

Advantageously the or each elongate member comprises metal. Most preferably each elongate member is flexible in the same manner as a spring and is flexible enough to adapt to different tee shapes but stiff enough to provide resistance to hold the bag in place.

Preferably the or each elongate member comprises sprung tempered stainless steel. Conveniently, the elongate member(s) is/are adapted to flex when the bladder is inflated thereby holding the bladder in an extended condition. The elongate member(s) is/are adapted to hold a portion of the bladder in an extended position. Preferably the elongate member (s) provide a stop means which has a greater width than the width of the riser or tee at the base of the riser and therefore prevents the bladder from slipping within the riser.

According to a further aspect of the present invention there is provided a tool for isolating a hydrant of a water mains, said tool comprising an inflatable bladder adapted for insertion into the riser pipe or in a tee below the hydrant, the bladder having a length which is at least twice the diameter when inflated.

Advantageously the bladder of either the first of second aspect of the invention comprises an inner spine. Conveniently the spine extends from one end of the bladder to the other. Advantageously the spine is tubular in form and comprises nylon. Preferably the spine is hollow.

Preferably the bladder is provided with a valve. Advantageously the valve is provided at one end of the feed tube to the bladder. Most preferably the valve is in fluid communication with the hollow spine which provides a passage for fluid from the valve into the bladder and then the valve can be closed to lock the fluid within the bladder. Advantageously the bladder comprises nylon and most preferably PU coated nylon. The material from which the bladder is formed is a heavy duty nylon which can be inflated and deflated repeatedly such that the bladder can be reused over a number of operations. The bladder is constructed from a nylon outer layer and an inflatable elastomeric inner layer. Preferably the inflatable inner is the same shape as the outer. The outer gives the strength to the bag, whilst the inner facilitates the sealing and flexibility of the tool. The bag may also be constructed from a nylon outer layer and a plurality of inflatable

elastomeric inner layers.

Advantageously the outer surface of the bladder is provided with ribs and more preferably said ribs form a grid on the outer surface of the bladder. The ribs act to increase the frictional forces acting between the outer surface of the inflated bladder and the inner wall of a riser pipe and also provide structural support to the bladder as it inflates, thereby ensuring correct inflation.

Preferably the means for spacing the lower end of the bladder from the bottom surface of the mains pipe further comprises a sensor which may be a proximity sensor, ultrasonic or light source/photoresistor or photodiode or a camera of any combination of the above. Advantageously the spacing means allows fluid to continue flowing in the mains pipe past the lower end of the bladder.

The spacing means provides a stop to ensure that the lower end of the bladder is not pushed so far into the riser pipe that when it inflates, the portion within the main pipe blocks fluid flow within the mains pipe.

Therefore the apparatus can be used without interrupting flow in the mains pipe which realises a significant time, manpower and cost saving over prior art devices which block flow completely in the pipe.

According to a further aspect of the present invention there is provided a method of isolating a hydrant of a water main comprising the steps of inserting a tool according to either the first or second aspect of the present invention into the riser of the hydrant and inflating the bladder.

Advantageously the method further comprises the step of lowering the bladder within the riser until the bottom of the bladder extends beyond the bottom of the riser and into the mains pipe before inflating the bladder.

Conveniently the method comprises the step of inflating the bladder until the width of at least a portion of the bladder exceeds the width of the riser pipe.

Advantageously the method may comprise inserting two bladders into the riser pipe in series.

Embodiments of the present invention will now be described with reference to and as shown in the accompanying drawings in which:- Figure 1 is a schematic front view of an isolation tool according to one aspect of the present invention during use in the riser of a hydrant;

Figure 2 is a schematic view of an inflatable bladder of the isolation tool of Figure 1 ;

Figure 3 is a part cross-section view of the bladder of Figure 2;

Figure 4 is a schematic front view of an isolation tool according to a further embodiment of the present invention during use in the riser of a hydrant;

Figure 5 is a schematic front view of an isolation tool according to a further embodiment of the present invention during use in the riser of a hydrant;

Figure 6 is a schematic front view of an isolation tool according to a further embodiment of the present invention during use in the riser of a hydrant;

Figure 7 is a schematic front view of a locking mechanism suited to all of the isolation tools of Figure 1 ;

Figure 8 is a schematic side view of the locking mechanism of Figure 7;

Figure 9 is a schematic view of a possible material of the inflatable bladder of the above embodiments; Figure 10 is a schematic view of a still further embodiment of the present invention during use in the riser of a hydrant and Figure 1 1 is a schematic view of a still further embodiment of the present invention during use in the riser of a hydrant.

Turning now to the figures, there is shown in figure 1 an isolation tool 1 according to one aspect of the present invention for use in isolating the riser 2 of a hydrant 3 from fluid flowing in a mains water pipe 4. The riser is in fluid communication with the main pipe through a flanged branch fitting or tee section 5 on the side of the mains pipe. The lower end of the riser has a cooperating flange 6 which allows the lower end of the riser to be mounted to the mains pipe. A head or jumper 7 is mounted on the upper end of the riser pipe. The head may be of a known design with a valve 8 for sealing off the head from the riser and an outlet pipe 9 for allowing access to the riser for inspection, maintenance or repair.

The tool 1 comprises an insertion tube 10 which is adapted to be fed through the outlet pipe 9 of the riser pipe. An inflatable bladder 1 1 is carried within or fed through the insertion tube for deployment within the riser pipe. The upper end of the bladder 12 is provided with a fitting 13 for connection of a hose 14 which extends through the insertion tube and the riser pipe and through which an incompressible fluid such as water can be pumped to inflate the bladder 1 1 .

The bladder is shown in more detail in figures 2 and 3 and comprises a chamfered outer body of heavy duty nylon or PU coated nylon which can withstand a pressure up to between 5 and 9 bar. The outer surface of the body may be provided with ribs 15 such as shown in Figure 9 to provide additional stiffening to the bladder when inflated and also to prevent bursting of the bladder under pressure. In the embodiment shown the ribs are formed as a grid 16 across the outer surface of the bladder. A spine 17 is provided within the bladder which assists in insertion of the bladder through the insertion tube and prevents the bladder from

becoming fouled within the tube. The spine comprises a nylon tube which extends from one end of the bladder to the other. The spine is hollow and may be connected to the fitting 13 in the upper end of the bladder through which fluid is pumped into and out of the bladder. Apertures (not shown) are provided in the spine to allow fluids pumped through the spine to pass into and out of the bladder.

The bladder has an elongate form and the width of the bladder increases from the upper end adjacent to the fitting 13 towards the lower end of the bladder. In the embodiment shown, the bladder is approximately 240 mm in length and the width at the upper end of the bladder is approximately 80 mm whilst the width at the lower end of the bladder is approximately 100 mm. Such a bladder is adapted for use in isolating a 76.2mm riser pipe (3 inch) from a 100 mm (4 inch) mains pipe.

The lower end of the bladder is provided with a location sensor 18 which is preferably spaced from the lower end of the bladder and may be in the form of a proximity sensor, ultrasonic, sonic or light source/photoresistor or photodiode combination or camera. The sensor may be adapted to clip onto the lower end of the bladder and the cable from the sensor may pass through the lower end of the bladder and extend through the spine internally of the bladder to prevent the cable from fouling on the inner surface of the pipe. The spine 17 may be extended through the lower end of the bladder and the sensor 18 may be mounted on the lower end of the spine. Alternatively, the lower end of the spine itself may act as a sensor when it comes into contact with the lower surface of the mains pipe as the operator will feel the resistance to further movement and be alerted that the tool cannot be inserted further into the riser pipe. Alternatively, a short spigot may be provided on the lower end of the bladder and the sensor may be mounted in or to the spigot.

The fitting 13 may be provided with a dedicated gland to receive the cable of the sensor so as not to interfere with the inflation or deflation of the bladder.

Control means (not shown) are provided which enable an operator to control insertion of the bladder into the riser pipe and to inflate the bladder to the required pressure.

In use of the tool, the jumper 7 of the hydrant is sealed off and the insertion tube 10 of the isolation tool 1 is mounted within the outlet pipe 9 of the riser pipe. The deflated bladder 1 1 is pushed from the insertion tube down into the riser pipe of the hydrant, through the flanged branch fitting or tee 5 joining the riser to the mains pipe until the sensor 18 on the lower end of the bladder 1 1 touches the bottom of the main pipe. The spine 17 of the bladder functions to keep the bladder moving through the insertion tube and through the riser pipe without becoming snagged or tangled, it also allows the fluid to pass in and out of the bag to inflate and deflate the bag.

The sensor 18 acts both as an indicator that the bladder has reached the appropriate depth within the riser but also as a safeguard against the lower end of the bladder becoming snagged on the surface of the mains pipe which could cause damage to the bladder and as a safeguard to prevent the whole bladder passing through the tee and into mains pipe.

A signal is sent from the sensor 18 to the operator to stop pushing the bladder through the riser pipe and the operator sends an instruction to the control means to inflate the bladder 1 1 . As fluid passes through the fitting at the upper end of the bladder, the bladder is inflated against the inner walls of the riser pipe. As the width of the bladder increases from the upper end to the lower end, the lower end of the bladder is pushed with a greater force against the inner wall of the riser pipe or the tee section which acts to lock the inflated bladder within the riser pipe and to resist pressure from the fluid flowing in the mains pipe.

The bladder effectively becomes wedged within the riser pipe and any pressure either from above or below the bladder acting on the bladder tends to force the bladder outwards and into increase the force acting to push the bladder against the inner wall of the riser pipe.

The ribs 15 on the outer surface of the bladder act to prevent the bladder from inverting as it is inflated as this can cause wrinkles to form in the surface of the bladder and provide flow paths along which fluid flowing in the mains pipe can bypass the bladder out of the hydrant. The ribs also provide a means for increasing the frictional force between the outer surface of the bladder and the inner wall of the riser pipe thereby assisting to keep the bladder in position within the riser pipe. The outer surface of the bladder may be provided with a roughened texture to further assist in holding the inflated bladder in position. For example the hooks of a hooks and eyes releasable fastening system may be applied to the outer surface of the bladder or the ribs.

The bladder is inflated to a pressure above that of the mains pressure and in the preferred embodiment this is at least 0.5 bar above mains pressure. This ensures that the bladder is not deflated by the pressure of water present in the mains pipe acting against it.

By sensing the bottom of the mains pipe and generating a signal to the operator to stop pushing the bladder through the riser pipe, the lower end of the bladder is held above the bottom of the mains pipe such that when the bladder is inflated within the riser pipe flow in the main pipe is uninterrupted as the fluid can flow around the location sensor. This provides a significant advantage in that intervention work can be carried out without closing off flow in the mains pipe thereby isolating the hydrant from the mains flow.

The bladder can be pulled up by an MDPE pipe or nylon pipe in order to check that the mechanical lock is holding the bladder in position. This may be done when the bladder is only partially inflated to ensure that this resistance of movement is due to mechanical lock in the tee at the base of the riser pipe and not due to friction in the riser pipe. In the embodiment shown in Figure 1 , the bladder is inserted into the riser pipe and through the flange branch fitting or tee such that the lower end of the bladder is within the mains pipe. During inflation as the lower end of the bladder is unrestrained by the inner diameter of the riser pipe, the lower end can be inflated beyond the diameter of the upper end of the bladder. This provides a mechanical lock between the lower end of the bladder and the underside of the opening in the mains pipe which further acts to anchor the bladder in position against slippage.

An annular impact area, as best shown in Figure 1 1 , is defined between the outer surface of the lower end of the bladder as it extends in diameter beyond the diameter of the riser pipe, and the underside of the opening in the mains pipe.

The riser pipe above the inflated bladder is now isolated from the pressure of water flowing in the water main below and inspection, maintenance or repair work that is required such as removing or replacing the jumper of the hydrant can be carried out without risk of leakage of water from the water mains. Once the intervention operation is completed and the jumper 7 of the hydrant is secure, the bladder 1 1 can be deflated by pumping fluid out of the bladder through the valve on the top of the feeder tube. As the bladder deflates, the bladder reduces in width and the pressure wedging the bladder against the inner surface of the riser pipe or tee section reduces and the bladder can be pulled back up through the flange branch fitting or tee 5 of the riser pipe, through the riser pipe and out of the outlet of the riser through the insertion tube.

The insertion tool can then be taken to another hydrant and reused for another isolation operation.

A further embodiment of the present invention is shown in Figure 4. Like reference numerals have been used to identify like elements from the first embodiment. In this embodiment the inflatable bladder 1 1 ' has an elongate form similar to the bladder described above however the outer diameter of the bladder is substantially uniform, the bladder having a length which is at least twice the diameter of the inflated bladder and/or at least twice the diameter of the pipe to be isolated. The elongate bladder is intended for use in longer risers or where there is a requirement for the bladder to be securely located by virtue of the friction between the outer surface of the bladder and the inner surface of the riser alone. By elongating the bladder such that the length of the bladder is at least twice the diameter, this increases the surface area of the bladder which is in contact with the riser wall and therefore provides an increased frictional resistance force. A high friction coating may also be provided on the surface of the bladder to further increase the frictional resistance to movement of the bladder at a given pressure. EPDM or other rubber materials such as silicone which are approved for use in potable water may be used.

A further embodiment of the present invention is shown in Figure 5. Like reference numerals have been used to identify like elements from the earlier embodiments. In this embodiment the lower end of the bladder 1 1 " is modified and has an increased diameter with respect to the rest of the bladder. The area of increased diameter is connected to the main body of the bladder by a substantially horizontal shoulder portion 19.

In use, when the bladder is lowered through the riser pipe 2 and into the mains pipe, the shoulder portion 19 acts as a mechanical lock against the under side of the opening in the mains pipe.

A further embodiment of the invention is shown in Figure 6 and like reference numerals have been used to identify like elements from the earlier embodiments. In this embodiment the lower end of the bladder is provided with one or more projections 20 which extend from the bladder giving the lower end of the bladder a larger diameter than the upper end of the bladder. In the illustrated embodiment the projections comprise a plurality of studs provided in a ring 21 around the lower end of the bladder. The studs may be stitched onto or through the bladder and may be made of rubber, plastic or metal or part of the bag themselves. As with the embodiment of Figure 5, the studs provide a mechanical lock against the under side of the opening in the main pipe and prevent the bladder from slipping back into the riser pipe under pressure from water present in the mains pipe below. Once the bladder is deflated, the diameter of the bladder including the lower end with the projections reduces until the bladder can be pulled from the riser tube.

In a further non illustrated embodiment of the invention one or more metal rods, strips or spokes are attached to the lower end of the spine around the sensor. The rods may comprise Kevlar and may be attached to the lower end of the bladder along part of their length only leaving the outer ends of the rods unattached to the bladder. In this embodiment when the bladder is in an un-inflated condition the rods can extend axially from the lower end of the bladder. However as the bladder is inflated, the diameter of the bladder will increase and the points at which the rods are attached to the bladder will move apart. This has the effect of pushing the free ends of the metal rods apart. The length of the rods is selected such that when the bladder is inflated, the rods extend beyond the outer diameter of the bladder and catch upon the inner surface of the mains pipe surrounding the opening into the riser thereby locking the bladder against movement back into the riser. Once the intervention operation is completed the bladder is deflated. As the bladder deflates, the diameter of the bladder reduces and the distance between the points on the rods which are connected to the bladder also decreases thereby closing the rods together such that the free ends of the rods no longer extend beyond the diameter of the riser and the bladder can be recovered form the riser as before.

The above described embodiments may be combined such that the inflatable bladder may have an elongate form with a tapered diameter wherein the diameter of the bladder increases from the upper end of the bladder to the lower end. The flexible rods may be provided on the lower, increased diameter end of the bladder.

Furthermore, a secondary locking system as shown in Figs 7 and 8 may be provided on any of the embodiments. The secondary locking system comprises a stop member 22 on the hose 14 of the isolation tool which selectively prevents the hose from being withdrawn into the insertion tube 10. In the embodiment shown, the stop member comprises one or more pins 23 which extend radially from the hose. The pins may be stored in a retracted position in which they lie against the surface of the hose.

Extension and retraction of the pins may be controlled by the control means.

During use, the secondary lock is engaged when the bladder 1 1 is inflated but the sensors detect slippage of the bladder within the riser pipe. In this situation a signal is passed to the control means to extend the pins. Once the bladder is depressurised the pins of the secondary lock can be detracted which allows the deflated bladder to be pulled back out of the insertion tube. In a further embodiment of the present invention shown in Figure 10 two inflatable bladders may be inserted into the riser pipe, in series with each other. This provides a backup in the event that one of the bladders is damaged or does not fully inflate. Should fluid be able to seep around the lower bladder, it is likely that the lower bladder would move slowly under the force of the water below it towards the upper bladder which can be used to arrest the movement of the lower bladder. This is because the upper bladder can be designed to provide a resisting force, rather than a pressure holding force For example the outer surface of the upper bladder may be provided with a suitable roughened profile such as with projections or spikes of a material such as nylon or a plurality of metal projections which will assist in holding the upper bladder against the inner wall of the riser pipe without necessarily providing a tight seal against water ingress past the second bladder. Alternatively the upper bladder may be provided by bypass means such as a tube which may provide a pathway for fluid through the upper bladder to reduce fluid pressure on that bladder should fluid seep past the lower bladder. In the event that movement of the lower bladder is not arrested, the operator who will have already removed the top of the hydrant for work to begin, will have a warning that the bladder is not holding which will allow additional time to move to a safer location before the water emerges at high pressure out of the top of the hydrant. In this embodiment the two bladders are inflated from a single source, each through its own valve. The bladders can be isolated separately such that the pressure in either bladder can be maintained independently. A sealed passageway is provided through the upper bladder through which the hose of the lower bladder can pass.

Alternatively a fitting may be provided at the lower end of the upper bladder and the hose of the lower bladder may be connected to the lower valve of the upper bladder.

A still further embodiment of the present invention is illustrated in Figure 1 1 and like reference numerals have been used to identify like elements from the earlier embodiments. In this embodiment, the annular impact area A may further comprise an annular member such as a resilient ring 24, for example a ring of rubber which can be compressed between the bladder and the underside of the opening when the bladder is inflated within the lower end of the riser pipe. Alternatively the annular member may be a metal or plastics ring. The annular member may be integrally formed with the bladder or may be mounted on or within the bladder. The annular member may add further structure to the bladder to aid in preventing the inflated bladder from being forced back up into the riser pipe under pressure of water flowing in the mains pipe.

Features of this embodiment may be incorporated with other embodiments in the application, for example, a bladder comprising the impact area with a compression ring as described may also be provided with metal rods, strips or spokes. In this example, the rods, strips or spokes may be mounted upon or within the impact area or the ring of the bladder. In a further modification, the bladder may comprise an inner skin and an outer skin, each may comprise nylon. The bladders may be stitched together with double stitching along the seams to provide increased strength. The double lined bladder will also have an inflatable inner bag.

Modifications or alterations to the above described embodiments of the present invention are envisaged. In particular, in each of the

embodiments the bladder may comprise an outer layer and an inner layer, the outer layer having a high friction coating applied thereto. It is preferable that the outer layer and inner layer of the bladder have the same shape such that a bladder with a shouldered lower region as illustrated in Figure 5 may have an inner layer having the same shape. This will limit the areas of high stress on the bladder and therefore prevent failure of the bladder. Also a higher internal pressure is possible within the bladder thereby enabling the device to remain in position at higher pressures.

The bladders have been described in use through a vertical riser pipe into a mains pipe below the riser. It is envisaged that any of the embodiments described above could similarly be used for isolating the riser pipe of a hydrant which is connected to the end of a mains pipe. The flexible nature of the bladders which deflated ensures that they can be manoeuvred around bends in the pipes. In a further modification the sensor may be adapted to provide a signal to the operator when the bladder passes through the insertion tube and also through different regions of the hydrant, riser or mains pipe. Suitable transmitters may be mounted at any desired location through which the bladder passes and a receiver in the sensor may detect the position of the bladder based upon signals picked up from the transmitters. Furthermore, the spine of the bladder may be adapted or a conduit or channel provided through the bladder to transmit data such as images from a camera or from sensors attached to the bladder to assist the operator in positioning the bladder at the base of the riser. Alternatively a wireless transmission device may be used to transmit such data.

Each of the embodiments of the present invention provide for a secure isolation of the riser pipe of the hydrant to enable intervention through the riser for inspection, maintenance or repair. The bladder is securely locked in position within the riser against the pressure of water present in the water mains pipe below. This provides a significant advantage over known intervention tools and is a cost effective way of providing secure isolation of the hydrant using a reusable tool which can be easily transported from hydrant to hydrant as required.

Claims

A tool for isolating a hydrant of a water mains, said tool comprising an inflatable bladder adapted for insertion into the riser pipe or in a tee below the hydrant, the bladder comprising means for engagement with a profile on the riser pipe or tee to secure the bladder in position and resist slippage within the riser pipe and means for spacing the bladder above the lower surface of the mains or tee below the hydrant such that the bladder can be secured within the riser pipe without shutting off fluid flow in the water mains.

A tool according to claim 1 , wherein the means to resist slippage comprises a region of increased width of the bladder.

A tool according to claim 2, wherein the area of increased width is provided at one end of the bladder.

A tool according to claims 2 or 3, wherein the bladder is elongate in form and the width of the bladder tapers from one end of the bladder to the other.

A tool according to any of the preceding claims wherein the engagement means comprises a mechanical locking means for retaining the bladder in position within the riser pipe against the pressure of water flowing in the mains pipe.

A tool according to claim 5, wherein the mechanical locking means comprises one or more elongate members stitched onto the bladder.

A tool according to claims 6, wherein the or each elongate member comprises metal.

A tool according to claim 6 or 7, wherein the or each elongate member is flexible.

A tool according to claim 7, wherein the or each elongate member comprises Kevlar.

A tool according to claim 8, wherein the elongate member(s) is/are adapted to flex when the bladder is inflated thereby holding the bladder in an extended condition.

A tool according to any of claims 5-10, wherein the elongate member(s) is/are adapted to hold a portion of the bladder in an extended position.

A tool for isolating a hydrant of a water mains, said tool comprising an inflatable bladder adapted for insertion into the riser pipe or in a tee below the hydrant, the bladder having a length which is at least twice the diameter when inflated.

A tool according to any preceding claim wherein the bladder comprises an inner spine.

14. A tool according to claims 13, wherein the spine extends from one end of the bladder to the other.

15. A tool according to claim 13 or 14, wherein the spine is tubular in form.

16. A tool according to any of claims 13-15, wherein the spine

comprises nylon.

17. A tool according to any of claims 13-16, wherein the spine is hollow.

18. A tool according to any of the preceding claims wherein the bladder is provided with a valve.

19. A tool according to claim 18, wherein the valve is provided at one end of the bladder.

20. A tool according to claim 18 when dependent upon claim 16,

wherein the valve is in fluid communication with the hollow spine which provides a passage for fluid from the valve into the bladder.

21 . A tool according to any of the preceding claims, wherein the

bladder comprises nylon.

22. A tool according to any of the preceding claims, wherein the outer surface of the bladder is provided with ribs.

23. A tool according to claim 22, wherein the ribs form a grid on the surface of the bladder.

24. A tool according to any of the preceding claims further comprising an insertion tube through which the bladder is fed into the riser pipe.

A tool according to claim 24 further comprising a secondary locking mechanism for selectively preventing the bladder from being withdrawn into the insertion tube.

A tool according to claim 25 further comprising a hose for inserting the bladder through the insertion tube.

A tool according to claim 26 wherein the secondary locking system comprises a pin extendible from the surface of the hose to selectively prevent the hose from being withdrawn into the insertion tube.

A tool according to any of the preceding claims wherein the means for spacing the lower end of the bladder from the bottom surface of the mains pipe comprises a sensor .

29. A tool according to any preceding claim further comprising control means.

30. An isolation tool substantially as hereinbefore described with

reference to and as shown in the accompanying drawings.

31 . A method of isolating a hydrant of a water main comprising the steps of inserting a tool according to any of claims 1 -30 into the riser of the hydrant and inflating the bladder.

32. A method according to claim 31 , further comprising the step of lowering the bladder within the riser until the bottom of the bladder extends beyond the bottom of the riser and into the mains pipe before inflating the bladder.

33. A method according to claim 30 or 31 , comprising the step of inflating the bladder until the width of at least a portion of the bladder exceeds the width of the riser pipe.

34. A method according to any of claims 30-33, wherein the bladder is locked in position within the riser.

35. A method according to any of claims 30-34, comprising the step of inserting two bladders into the riser pipe in series.

A method of isolating a hydrant of a water main substantially hereinbefore described.