Inflatable sleeve and method of manufacturing same

An inflatable sleeve including one or more tubular portions including zones having different dimensions (e.g. thickness and/or diameter) and/or physical properties (e.g. elastic modulus) to enable control over the inflation characteristics of each zone, and a method of manufacturing same. The present invention further relates to a pipe junction sealing packer incorporating such an inflatable sleeve.

FIELD OF THE INVENTION

The present invention relates to an inflatable sleeve including one or more tubular portions including zones having different dimensions (e.g. different thickness and/or diameter) and/or physical properties (e.g. different elastic modulus) to enable control over the inflation characteristics of each zone, and a method of manufacturing same. The present invention further relates to a pipe junction sealing packer incorporating such an inflatable sleeve.

BACKGROUND OF THE INVENTION

In domestic sewage collection systems, there is regularly a need to repair the lateral connection between house service pipes and the sewer main. In order to avoid digging into soil or breaking up concrete or the like, an installation apparatus (also referred to herein as a “sealing packer” or “packer” or “packer assembly”) is typically pushed (or pulled) through a sewer main extending between human access chambers, and the lateral connection is sealed using an inflatable sleeve that positions a resin-impregnated liner material into the junction. The junction shapes are typically 90 degree tees or 45 degree wyes.

FIGS.1-3show an example of a prior art packer assembly10used to apply a textile liner60impregnated with resin to an internal connecting region11between a sewer main12and a house service line13.

The assembly10includes a main body14and a lateral arm15which extends outwardly from the main body portion14intermediate its ends. The main body14has end ring flanges16located at both ends. The lateral arm15has at its distal end a guide means, typically in the form of a launcher17, which acts as a guide for positioning of the lateral arm15. The launcher17is pivotally attached to the lateral arm15through use of a flexible rod (not shown) which extends inside the main body14from one of the end ring flanges16to which it is fixed, through the lateral arm15to the launcher17, which itself is pivotally connected to the free end of the flexible rod.

A lateral arm restrainer cable (not shown) is also connected between the launcher17and end ring flange16to prevent the launcher from becoming detached. Further, the launcher17has a pair of rollers26to assist in its movement. The free end26of the launcher17is resiliently moveable with respect to the main body14such that, in use within the main pipe12, the wheels26press against the inside wall12′ of the main pipe12to provide a lead-in into the target branch pipe13. The resilient movement of the wheels26with respect to the inside wall12′ is achieved through use of a spring (not shown) associated with steel plate25which is pivotally mounted to a ring flange16′, the steel plate25supporting the rollers26. In other words, the spring (not shown) is arranged to pivotally pull the free end of the launcher17into contact with the inside wall of the main pipe12.

A stiffening rod30is also shown inFIG.1and is adapted to be secured to the inside of the hose19to assist in rigidity. Also shown is a rod connector adaptor31secured to the end ring flanges16and used to connect push rods (not shown) to the packer assembly10to allow it to be manoeuvred into position and subsequently removed. Closed-Circuit TeleVision (CCTV) cameras (not shown) are used to assist in the movement of the assembly and an electric power lead32is used to power the cameras and light source required.

The packer10is pushed (or pulled) along the main pipe12until it reaches the target junction. As described above, the provision of a spring-biased launcher17at the distal end of lateral arm15provides an automatic lead-in into the target branch pipe13and thereby enables the operator to insert the liner60into position by pushing (or pulling) the packer assembly10through the main pipe12using the push rods (not shown). In particular, when at the junction, the packer10is positioned such that the distal end of the lateral arm15is located centrally in the junction opening. The packer10is then pushed (or pulled) a known distance and the lateral arm15moves up the junction to its “home position” (i.e. the position shown inFIG.1).

An inflatable sleeve18forms the outer surface of the main body14and lateral arm15, and is secured at its ends by bands28. Air hose connectors29are located at both the ends of the end ring flanges16and are adapted to be used to input air from an air hose (not illustrated) into a cavity inside the sleeve18in the main body14and within the lateral arm15. Once the packer assembly10has been moved into the correct position, the air supply can be input from either end as required. The packer assembly10is inflated and the resin-impregnated liner60is pressed against the interior12′ of the main12, the interior13′ of the house service line13, at the connecting region11.

FIG.2shows the packer assembly10and liner60, with the sleeve18associated with each of the main body14and lateral arm15inflated. While the inflatable sleeve18is expanded to the size of the main12and the house service line13, the resin is allowed to cure. The sleeve18remains inflated until the resin is cured and then the packer10is deflated and dislodged from the liner60, and removed from the main12as is shown inFIG.3. Remaining in place is the cured (hardened) liner60, hence the connecting region11between the main12and house service line13is repaired.

Traditionally, inflatable lateral packer sleeves are made from extruded tubes62of rubber that are vulcanised64together to form a Tee or Wye shape, as shown in the illustration right of the main perspective view ofFIG.1. In this way, the rubber sleeves have a constant diameter and thickness along their straight lengths, and each sleeve component is made of the same rubber compound.

When designing a lateral packer, such as packer10shown inFIGS.1to3, there are several size trade-offs that need to be made.

On one hand, one might want the packer (and rubber sleeve) to be as large in diameter as possible. In this way, the rubber sleeve would not have to stretch very far to press the liner60against the walls of the pipes12and13. In other words, it could operate at low pressures. It would also mean that the degree of stretch of the material, i.e. % elongation of the rubber, would be low. Accordingly, making the packer (and rubber sleeve) larger in diameter can simplify the rubber sleeve design, make the sleeves last longer and inevitably lower the cost. However, this also results in a packer having a large footprint and hence is likely to be more difficult to transport into and out of pipes12and13.

There may be a preference for the packer to have as small a footprint as possible since this makes it easier to move the packer into and out of the pipe12and lateral13. Since the packer10is typically equipped with other devices such as a CCTV camera for allowing the user to remotely view inside of the pipe during insertion and removal, the smaller the apparatus the better the vision. However, the smaller the packer, the smaller the rubber sleeves and hence the more that the rubber needs to stretch.

The Applicant has recognised a need for improving inflatable sleeves and the method by which packers and in particular the inflatable sleeves are manufactured to achieve an optimum or near optimum balance between the size of the packer (and sleeve) and the % elongation required to cause the sleeve to press the resin-impregnated liner material against the inside surface of the pipe(s) during inflation.

Another problem can arise during positioning of the packer and subsequent inflation of the sleeves. In this regard, it is very important for the packer assembly10to be lined up accurately prior to inflation such that the circumference of the lateral portion of the liner60is substantially concentric with the circumference of the lateral pipe13. If the assembly is pushed (or pulled) too far, for example, even by ±1 centimetre (cm), there can be adverse consequences including wrinkling in the liner60through contact with the internal wall13′ of the branch pipe13. As mentioned above, a CCTV camera is positioned such that it views the assembly from one or both ends thereof, and enables an operator to view the packer being positioned and subsequently inflated. The camera will generally be located at one end of the main section of the packer and provides the operator with a view of the packer and the liner material. The better the view the CCTV camera has, the better the view the operator has, hence positioning and inflating of the assembly can be improved by improving the view of the CCTV camera. The use of traditional inflatable sleeves and traditional methods of inflating the sleeves do not lend themselves to providing optimum camera views.

Inflating the sleeve18and hence the liner60is typically achieved in two steps, i.e. by first applying a gas pressure sufficient to inflate the central and branch portions of the liner60just to press against the internal wall of the main and branch pipes respectively, and then increasing the pressure to cause a final press against the wall to promote adhesion of the resin-impregnated liner. Ensuring this sequence of steps is currently difficult due to the main inflatable sleeve largely obstructing the view of the CCTV camera as a result of the initial inflation. The Applicant has recognised a need for an operator to retain vision of the liner material for as long as possible during inflation to enable the operator to see the liner material being pressed against the host pipe.

In addition to the abovementioned problems, when the sleeve18expands and then remains in a fully expanded state, there is an excessive amount of pressure placed on the clamping members (i.e. bands28) holding the sleeve in place at each of its ends. Excessive inflation at these points can result in rubber failure and bursting.

It is an object of the present invention to overcome at least some of the aforementioned problems or to provide the public with a useful alternative.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides an inflatable sleeve for inflation inside a constrained vessel, the inflatable sleeve including a first zone that when inflated forms a first substantially tubular portion of the sleeve, and at least one further zone that when inflated forms at least one further substantially tubular portion of the sleeve, wherein the first and at least one further zone define an internal cavity of the sleeve into which gas pressure is introduced to inflate the sleeve, wherein the first and at least one further zone are made from the same blank of material, or from individual blanks of material, and each zone is shaped and then joined along or adjacent at least two edges thereof into a substantially tubular form, and wherein the first and at least one further zone are configured such that the first zone has a different dimension and/or physical property as compared with the at least one further zone, thereby causing the zones to inflate in a predetermined sequence and/or require a different gas pressure to reach an inner wall of the constrained vessel.

In an embodiment, said different dimension is achieved by causing the different zones to have a different thickness and/or diameter, and said different physical property is achieved by causing the different zones to be made of a different rubber compound, each rubber compound having a different elastic modulus (also known as modulus of elasticity).

In an embodiment, each blank of material is shaped into a substantially tubular form by being folded about a line of symmetry.

In an embodiment, the blank material is a rubber compound, or fibre reinforced rubber compound, capable of elongation in a radial direction relative to a longitudinal axis associated with each substantially tubular zone.

In an embodiment, when the first and at least one further zone are dimensioned such that the first zone has a greater thickness than the at least one further zone, and the first and at least one further zones are of substantially equal diameter, the at least one further zone will inflate first followed by the first zone when gas pressure is introduced inside said cavity.

In an embodiment, when the first and at least one further zone are dimensioned such that the first zone has a greater diameter than the at least one further zone, and the first and at least one further zones are of substantially equal thickness, the first zone will inflate first followed by the at least one further zone when gas pressure is introduced inside the cavity.

In an embodiment, when the first and at least one further zone have different physical properties in that each zone is made of a different rubber compound and hence has a different elastic modulus, wherein the greater the elastic modulus, the lesser the elongation at any given supply pressure.

In an embodiment, the sleeve includes at least one zone dimensioned such that when shaped and joined into a substantially tubular form, the resulting tubular portion is tapered and includes an increasing or decreasing lengthwise diameter.

In an embodiment, the vessel is a straight length of pipe, and joining two zones together includes joining an axial end of a first zone with an axial end of a second zone such that the two joined zones extend along a common axis.

In an embodiment, the vessel includes a main pipe and a lateral pipe, and joining two zones includes joining an end of the first tubular portion to an intermediate location along the second tubular portion such that the first tubular portion extends along a first axis inside the main pipe and the second tubular portion extends along a second axis inside the lateral pipe.

In an embodiment, the inflatable sleeve includes five zones that in use form a tubular sleeve having a main and a lateral tubular portion associated with each of the main pipe and lateral pipe respective.

In an embodiment, a first zone of the five zones forms a central part of the main tubular portion, a second zone forms a central part of the lateral tubular portion, a third and fourth zone are located at distal free ends of the main tubular portion, and a fifth zone is located at a distal free end of the lateral tubular portion.

In an embodiment, a thickness of the second zone is greater than a thickness of the first zone, and a thickness of the third, fourth and fifth zones is greater than the thickness of the first and second zones, and a diameter of the tubular portions formed by the first and second zones is substantially equal, said diameter being greater than a diameter of the tubular portions formed by each of the third, fourth and fifth zones, the sleeve thereby operable to cause the first zone to inflate prior to the second zone which will inflate prior to inflation of the third, fourth and fifth zones when gas is introduced inside the cavity.

In an embodiment, each of the third and fourth zones are dimensioned such that the resulting tubular portions are tapered and decrease in diameter as they extend away from the tubular portion formed by the first zone, and the fifth zone is dimensioned such that the resulting tubular portion is tapered and decreases in diameter as it extends away from the tubular portion formed by the second zone, the free ends of tubular portions formed by the third, fourth and fifth zones thereby dimensioned to facilitate clamping of the free ends.

In an embodiment the zones are joined using a vulcanisation process.

In a second aspect, the present invention provides one or more blanks of material for forming an inflatable sleeve configured in accordance with any one of the preceding statements.

In a third aspect, the present invention provides a method of manufacturing an inflatable sleeve configured in accordance with any one of the preceding statements, the method including shaping one or more blanks of material corresponding with each zone into substantially tubular form by folding each blank of material thereby causing at least two edges thereof to be drawn together, and joining the at least two edges to maintain the zone in said substantially tubular form.

In a fourth aspect, the present invention provides a method of manufacturing an inflatable sleeve configured in accordance with any one of the preceding statements, the method including shaping at least one blank of material to form the first zone, shaping at least one further blank of material to form the at least one further zone, joining at least two edges of the first zone to form a first tubular portion, joining at least two edges of the at least one further zone to form at least one further tubular portion, and joining the first and at least one further tubular portions to form said inflatable sleeve.

In a fifth aspect, the present invention provides a pipe liner installation apparatus for installing a flexible liner into an internal connecting region between a main pipe and a target branch pipe, the apparatus deployable from within the main pipe and including an elongate body, a lateral arm including a proximal end connected to the body and a distal end, an inflatable sleeve extending at least partially over the body and the lateral arm, the inflatable sleeve including a first zone that in use forms a first tubular portion of the sleeve extending at least partially over the body, and a second zone that in use forms a second tubular portion of the sleeve extending at least partially over the lateral arm, the first and second tubular portions defining a cavity into which gas pressure is introduced to inflate the sleeve, each zone made from the same blank of material, or from individual blanks of material, and each zone shaped and then joined along or adjacent at least two edges thereof into a substantially tubular form, and the first and second zones configured such that the first tubular portion has a different dimension and/or physical property as compared with the second tubular portion, thereby causing the zones to inflate in a predetermined sequence and/or require a different gas pressure to reach an inner wall of the constrained vessel.

In an embodiment, inflation of the sleeve causes the sleeve to press the flexible liner against inner walls of both the main pipe and the branch pipe until the liner is fixed in place.

In a sixth aspect, the present invention provides a method of installing a flexible liner into a junction between a main pipe and a branch pipe, the method including the steps of fitting the flexible liner over an installation apparatus, the apparatus including an elongate body, a lateral arm including a proximal end connected to the body, and a distal end, and an inflatable sleeve extending at least partially over the body and the lateral arm, the inflatable sleeve configured in accordance with one or more of the preceding statements, inserting the installation apparatus and fitted liner into the main pipe via an access opening, pushing or pulling the installation apparatus and fitted liner along the main pipe towards an entrance to the branch pipe, further pushing or pulling the installation apparatus and fitted liner along the main pipe so that the lateral arm is driven through the entrance of the branch pipe into the branch pipe, inflating the sleeve one or more times so as to press the fitted liner against the inner walls of both the main pipe and the branch pipe until the liner is fixed in place, deflating the sleeve, and withdrawing the installation apparatus from within the liner fixed within the branch and main pipes.

DETAILED DESCRIPTION OF EMBODIMENT(S) OF THE INVENTION

The present invention relates to improvements in inflatable sleeves for use in a pipe liner installation apparatus such as the sleeves used in the prior art packer assembly10shown inFIGS.1-3. However, it is to be understood that the principle of the present invention could be applied to other applications in which a sleeve is required to be inflated in a controlled manner inside a constrained vessel.

In the pipe liner installation example, the inflatable sleeve sits over a skeleton (not shown) of the apparatus10shown inFIG.1and defines a cavity into which gas, e.g. air, is supplied for the purpose of inflating the sleeve and causing the flexible, resin-impregnated liner60to be installed into the internal connecting region11between the main pipe12and the lateral branch pipe13, as previously described.

The inflatable sleeve (e.g.100a,100b,100c,100d) embodying the present invention may have a different dimension (e.g. thickness t and/or a different diameter D) and/or a different physical property (e.g. different elastic modulus associated with different rubber compounds) in specific locations to achieve one or more advantages, including but not limited to providing improved control over the inflation of the sleeve inside a constrained vessel102, minimising overall pressures required for the inflation of the sleeve100whilst not significantly increasing its overall footprint, and minimising damage to the sleeve100and potentially other components by allowing certain parts of the sleeve100adjacent clamps and the like to only minimally inflate or not inflate at all.

An inflatable tubular sleeve100inside a constrained vessel102is shown inFIG.4. It can be appreciated that the tubular sleeve100started as a flat sheet100′ (also referred to herein as a blank, or a blank of material) including at least two opposed edges106, before being shaped (in this example folded along a line of symmetry104) and joined along or adjacent the at least two edges106, to form a tubular shape. Any suitable means of shaping and joining the blank of material may be utilised, for example, the blank may be shaped into a tube by wrapping same around a cylindrical structure such as a mandrel (not shown), and joined using a rubber vulcanisation process. The resulting join line108along the length of the sleeve100is also shown inFIG.4.

The sleeve100inFIG.4is made entirely from of the same rubber compound and has a uniform thickness t and diameter D along its length, hence when gas110is introduced into a cavity112defined by the sleeve100, the sleeve100inflates (or elongates) in a radial direction114(i.e. in an outward direction relative to the generally longitudinal axis of the sleeve100) substantially uniformly along its length, and when sufficiently inflated will press against the internal wall116of the constrained vessel102.

FIGS.5-9illustrate embodiments of the present invention in which a sleeve (100a,100b,100c,100d) includes two or more zones (118,120) of a different dimension (e.g. thickness and/or diameter) and/or physical property (e.g. elastic modulus), to afford control over the inflation of the sleeve. For example, a sleeve100may include a first zone118and a second zone120, wherein the first and second zones are of a different thickness and/or diameter and/or rubber compound, which may affect the extent and/or sequence of inflation of the different zones.

In other words, the present invention provides an inflatable sleeve (100a,100b,100c,100d) including at least a first zone (118a′,118b′,118c′,118d′) that in use forms a first tubular portion (118a,118b,118c,118d) of the sleeve, and at least one further zone (120a′,120b′,120c′,120d′) that in use forms a further tubular zone (120a,120b,120c,120d), wherein the first and second zones are configured such that the resulting first tubular portion (118a,118b,118c,118d) has a different dimension (e.g. diameter D and/or different thickness t) and/or different physical property (e.g. elastic modulus based upon the rubber compound used) as compared with the second tubular portion (120a,120b,120c,120d). This enables the first and second tubular portions to inflate in a controlled manner (e.g. predetermined sequence) inside a constrained vessel102when gas110is introduced inside the sleeve cavity112.

In one example (not shown), the two zones could have the same thickness t and the same diameter D, but be made of different rubber compounds and hence have a different elastic modulus. For example, one zone may be made of rubber compound having an elastic modulus which causes it to elongate to a lesser extent at any given supply pressure as compared with the rubber compound used in the other zone, hence the sequence of inflation can also be controlled by altering the material (e.g. rubber compound) used in each zone.

There are benefits that arise from different zones having different physical properties (e.g. the use of hard rubber in one zone compared with soft rubber in another, or where one zone includes fibre-reinforced rubber and the other zone is not fibre-reinforced). In an example, a packer that is configured for use in a 300 mm main and 100 mm lateral pipe includes a sleeve having a main and a lateral zone made of the same rubber compound. By using 12 mm thick rubber in the 300 mm zone, and 6 mm rubber in the 100 mm lateral zone, each zone will reach the internal wall of the respective host pipe at the same time (based upon introduction of gas pressure of approximately 80 kPa). However, 12 mm thick rubber in the 300 mm zone is substantial and heavy, and by adjusting the physical properties of that zone, it is possible for rubber of a reduced thickness to be used. For example, if that zone is changed to a harder rubber compound, the thickness can be reduced to 6 mm whilst the softer rubber in the lateral is maintained at 6 mm thickness (such that there is now consistent thickness across both zones), and both will still reach the internal wall at the same time. Using different physical properties across different zones is particularly useful when dealing with pipes of larger diameter that would otherwise require proportionately larger zone thicknesses to ensure that the zones reach the internal wall of the host pipe at the same time.

Fibre-reinforced rubbers are rubber compounds which incorporate fibres that enable control over directional behaviour of a particular zone. As compared with a rubber compound that does not include fibre reinforcement that stretches (elongates) in three dimensions, a fibre-reinforced rubber compound may elongate in one or more directions to the exclusion of one or more other directions. For example, if the fibre is disposed lengthways in a particular zone, then the zone will not extend lengthways. Similarly, if the fibre is disposed circumferentially, then the zone will not elongate circumferentially during inflation. One skilled in the art will appreciate that by controlling the disposition of the fibre, one may control the extent to which a particular zone elongates in one or more directions. In one example, where a 9 mm thick zone is to include a fibre reinforcement, the zone may be built up using three overlapping 3 mm layers of rubber compound, wherein the fibre layer is sandwiched between two of the layers.

There are also benefits associated with different zones having different dimensions. In the example122shown inFIG.5, the first118a′ and second120a′ zones of blank100a′ are dimensioned such that the resulting second tubular portion120ahas a greater diameter D2than diameter D1associated with the resulting first tubular portion118a. In this embodiment, the first118a′ and second120a′ zones are made of the same or similar rubber compound and are of substantially equal thickness t. As shown inFIG.6(a), as a result of varying the diameter of the two zones, the second tubular portion120awill inflate first until it presses against the internal wall116of the vessel102, followed by the first tubular portion118aas shown inFIG.6(b).

There may be applications that require a sleeve zone to have a tapered body such that the sleeve includes an increasing or decreasing lengthwise diameter.FIG.7shows an example124of a sleeve100bconfigured in this way, wherein a first118b′ and second120b′ zone of blank100b′ are dimensioned such that the resulting second tubular portion120bhas a greater diameter D3than diameter D2associated with the first tubular portion118b. The diameter D2of the resulting first tubular portion118bdecreases in a lengthwise direction when moving away from the resulting second tubular portion120bsuch that the distal free end of first tubular portion118bhas the smallest diameter D1. It can be appreciated that this configuration is a result of the edges106associated with the first zone118b′ being tapered, whilst the thickness t and the rubber compound used in the respective zones remain constant.

FIG.8shows a further example126, namely, sleeve100cin which the second zone120c′ of the sleeve blank100c′ has a greater thickness t2than the thickness t1associated with the first zone118c′. These zones are dimensioned such that each of the resulting first118cand second120ctubular portions are of substantially equal diameter D and each zone is also made of the same or a similar rubber compound. As shown inFIG.8(a), the first tubular portion118cwill inflate first until it presses against the internal wall116of the vessel102, followed by the second tubular portion120cwhich also then presses against the internal wall116of the vessel102as shown inFIG.8(b).

It will be appreciated that by manufacturing an inflatable sleeve100in the manner described above, one may vary the diameter and/or thickness and/or rubber compound used in the sleeve's manufacture at any part of the product.

Different sleeve zones can be formed using a single blank of material, as described above. Alternatively, two or more different zones can be formed separately in two or more blanks and subsequently joined to form a single blank (e.g. by a vulcanisation process).

Achieving different thicknesses can also be achieved using one of several methods. For example, two different zones of a single sleeve could achieve a different thickness t by overlapping two separate blanks of material in the zone that is to be of greater thickness. For example, if a first zone is to be 6 mm thick, and a second zone is to be 9 mm thick, a single blank of 6 mm thickness could be used for both zones, with an appropriately dimensioned 3 mm thick blank used to overlap over the second zone only. When joined to the second zone, creating a total thickness of 9 mm is created in the second zone as compared with a 6 mm thickness in the first zone.

The sleeves100need not be limited to tubular portions which extend along a single axis. In this regard, multiple sleeves may be constructed and then joined to form, for example, 45 degree wyes or 90 degree tees. For a 90 degree tee, for example, two sleeve blanks may be constructed to form two tubular portions, and then the two tubular portions may be joined at 90 degrees. One method of achieving this is by first forming an appropriately sized aperture intermediate the ends of one tubular portion (e.g. formed in a blank prior to folding and joining the blank to form the tubular portion), and then joining an end of the second tubular portion to the first tubular portion along the circumference of the aperture in the first tubular portion. If the material used is a rubber compound, then a vulcanisation process could be used to join the two tubular portions in order to form the tee, although other materials and other joining processes could equally be used.

The inflatable sleeves described herein may be used in any application in which it may be useful to manage the inflation of a sleeve inside a constrained vessel. One such application is the repair of sewer pipe junctions in which an inflatable sleeve is required to be inflated by an apparatus for installing a resin-impregnated liner in the junction for repairing the junction.FIG.10illustrates an example130of an inflatable sleeve100dthat may be associated with such an apparatus (the apparatus itself not shown), the sleeve100dconfigured to sit inside the junction of a 90 degree tee. In the embodiment shown, the 90 degree tee is a 90 degree tee junction132between a main pipe134and a lateral pipe136. In this embodiment, the sleeve100dis made up of five zones including a main tubular zone A located centrally in main pipe134, a lateral tubular zone B that is joined to the main tubular zone A at a 90 degree angle and extends into the lateral pipe136, two end zones C associated with the main tubular zone A, and an end zone D associated with the lateral tubular zone B. Each of the end zones C and D are tapered, similar to the tapered first tubular zone118bof sleeve100bshown in example124ofFIG.7.

FIGS.11-12then show the sequential inflation of the sleeve100dof example130according to a particular embodiment. In this embodiment, the diameter D of tubular zones A and B is greater than the diameter of the end zones C and D, the thickness t of tubular zone B is greater than the thickness of the tubular zone A, and the thickness of the end zones C and D is greater than the thickness of zones A and B. Further, the material used to manufacture each zone is the same or a similar rubber compound.

It can be appreciated that in this scenario, when gas110is introduced into the sleeve cavity112, the central tubular zone A inflates in a radial direction138first until it presses against the internal wall of the main pipe134of the junction132, followed by inflation of the lateral tubular zone B in a radial direction140which causes the tubular zone B to press against the internal wall of the lateral pipe136. At this point, zones C and D are yet to inflate.

The tapered configuration of the end zones C and the fact that they are yet to inflate means that any camera located at an end of the packer assembly and configured to provide the operator with a view of the inflation sequence will not be obstructed and will allow the operator to view the main zone of liner being pressed against the wall of the main pipe. It is at this point, once the operator is satisfied that the liner is locked in place in the correct position, that the air pressure may be increased to provide an additional force and promote adhesion of the liner to the wall. When further air is supplied, the end zones C and D may then inflate, although this is not shown inFIG.11or12. For reasons described above, it may be beneficial for the end zones C and D to remain uninflated or only minimally inflate.

Accordingly, the central part A of the main packer will inflate first and lock the packer in place. Next, the lateral part B would inflate and finally, although not necessarily required for reasons described above, the rubber at the end elements C and D may remain uninflated or only minimally inflate. In a further embodiment (not shown), the sleeve may include additional end zones, i.e. one end zone at each of the distal free ends of zones C and D, to provide additional surface area for clamping of the sleeve ends to the packer assembly.

It should now be appreciated that the inflation attributes (including pressures and sequence of inflation) are a function of dimension (e.g. rubber thickness t and diameter D), and/or physical properties (e.g. selection of rubber compound material), associated with each respective zone. One may characterise this relationship as pressure being proportional to elastic modulus*thickness/diameter, such that as the diameter of one zone increases, the thickness of the zone needs to increase proportionally to ensure that the pressure required to inflate the zone remains the same. Similarly, if the thickness and diameter remain constant but the modulus of elasticity of the zone doubles, for example, the pressure required to inflate the zone will need to be doubled.

The skilled addressee would realise the benefits of the embodiments of the present invention. When using the inflatable sleeve100din a pipe liner installation application, for example, sealing sleeves may be constructed from flat blanks of rubber compound and joined in such a way to achieve desired size, shape, inflation and pressure outcomes. Furthermore, during inflation, the sleeve may be made to inflate such that only the zone(s) of the packer with the liner attached increases in diameter in the first instance, and the zone(s) of the packer between the liner and the end element remains largely uninflated. In this way, the operator retains vision of the liner material and is able to see it being pressed against the host pipe. Once the liner is in place, the zone(s) of the packer sleeve between the liner and the end elements can be made to inflate or can remain uninflated depending on the operator's preference.

The following paragraphs describe a practical implementation of the present invention according to an embodiment in which there is a 90 degree tee junction132similar to that shown inFIGS.11-12but having a main pipe diameter of 150 mm and a reduced lateral pipe diameter of 100 mm. In this example, to achieve a desired inflation sequence such as that described above with reference toFIGS.11-12, a rubber thickness of 6 mm could be used in the central tubular zone A, 6 mm in lateral tubular zone B, and 9 mm in the end tubular zones C and D. It will be appreciated that the thickness of zone B is no longer greater than the thickness of zone A (as in the example ofFIGS.11-12). If additional end clamping portions (not shown) are utilised, then these too could have a 6 mm thickness, for example.

In this example, the diameter of zone A is also no longer equal to the diameter of zone B. In particular, the diameter in the central tubular zone A is 80 mm (outer diameter), and the diameter in the lateral tubular zone B is 65 mm (outer diameter). In each tubular zone C, the diameter may reduce lengthwise from 80 mm down to 60 mm (outer diameter) at the free end of each of the end tubular zones C.

The reason for the size of zone D being small is quite different to the reason for zone C being small. Since the objective of zone D is to be as small as possible so that the distal end of the lateral arm can enter into the lateral pipe, zone D will generally have the smaller diameter section. For example, zone D may reduce lengthwise down to an internal diameter of 40 mm whilst maintaining a 9 mm thickness along its length so that the end cap at the end of the lateral arm can be small (the metal end cap being the first part that enters into the lateral pipe).

The pressure required to reach full inflation of portions A and B, in this example, would be approximately 80 kPa (the approximate gas pressure required to make the sleeve in the region of the liner reach the wall), which means that the rubber has only stretched by 50% and the rest of the rubber sleeve, including zones C and D, has hardly inflated at all. The gas pressure may then be increased by an additional 50 kPa, for example, to ensure that the liner material and resin is pressed hard against the host pipe. This force maximises the ability of the liner to adhere strongly to the host pipe. For example, if 80 kPA was needed for a particular region where the liner sits to reach the wall, this process now being viewable using the CCTV camera, then the total pressure applied to the packer would be 130 kPa.

It is to be understood that the pressure required to reach the pipe walls will vary from size to size but one of the objectives might be to design the sleeves using the method described above to ensure that all packers of various sizes and shapes always reach the wall at 80 kPa pressure.

Accordingly, it should now be appreciated that an optimum size, pressure and inflation scenario may be achieved. In the above example, the central zone A of the main inflates first and touches the host pipe wall when a pressure of less than 100 kPa is applied (e.g. 80 kPa according to the above example, where 60 kPa may be supplied to inflate zone A, and lateral zone B made to subsequently inflate when a second pressure approximately 20 kPa higher than the central part of the main is supplied). By making the diameter of zone A approximately 50% of the host pipe diameter (e.g. 80 mm in a pipe of diameter 150 mm), the % elongation is maintained at approximately two which is well beneath the yield point of the rubber. The zones C and D near the end caps inflate last or remain largely uninflated.

The packer has already been positioned very accurately lengthwise using the camera and some other geometric means. The objective is for the main region of the liner associated with zone A to reach the wall first in order to “lock” the packer in place lengthwise. The packer should remain in place lengthwise and not shift by the lateral arm inflating, and this result is achieved by first inflating zone A. Then (shortly afterwards), i.e. by increasing the pressure by approximately 20 Kpa, the lateral arm inflates in zone B in the region of the liner. At this point, the liner is pressed against the wall and is still in the correct position. The camera looking at the packer (e.g. over the main end) can see the liner is pressed against the wall and hasn't moved. The additional 50 kPa may then be added to cause the liner to press against the wall and promote adhesion of the resin. During this final pressing, zone A of the sleeve will obstruct the view of the camera but at this point vision is no longer required. Accordingly, a packer for installing a liner at a pipe junction may now be designed to inflate in exactly the correct sequence, at low pressures and with less than 200% elongation, for example.

If it was not desirable for the zones C and D to inflate at all, then this could be achieved by making the rubber very thick and/or the diameter very small in those zones. Alternatively, the rubber in these zones could be fibre reinforced in order to control the extent to which the zones elongate in any one direction as described earlier. Additionally, if it was desirable to only half inflate the end zones C and D, a suitable rubber thickness and/or diameter and/or rubber compound could be selected to achieve that result.

The configurations of the end zones C and D may also be adjusted to address what is known as the “end effect”. The “end effect” occurs in view of the sleeve having a finite length and hence, in practice, in the regions near the ends of the sleeve, the rubber inflates quite differently to the middle. In say a 1 metre length of sleeve having a diameter 60 mm, the 180 mm length adjacent to each end will inflate slower than the bulk. This effect is also relevant and may be used to guide the user when selecting a length, rubber compound, diameter and/or thickness at the end zones in order to control the inflation of the ends C and D. As mentioned above, additional end clamping zones could also be used, which may also serve to prevent or minimise the “end effect”.

Throughout this specification and claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to mean the inclusion of a stated feature or step, or group of features or steps, but not the exclusion of any other feature or step, or group of features or steps.

The reference to any prior art in this specification is not, and should not be taken as an acknowledgement, or any suggestion that, the prior art forms part of the common general knowledge.