Improvements in the repair of pipelines

Abstract

A flexible tubular apparatus (10) is described. The apparatus (10) is for supplying heat to a liner (105) in a pipeline (101). The apparatus (10) comprises one or more resistive heating elements (18) and has opposing open ends (14, 16). The apparatus (10) is configured to be removed from the pipeline (101) after being 5 brought into contact with the liner (105) in the pipeline (101) and supplying heat to the liner (105) in the pipeline (101). A method and system incorporating the apparatus are also described.

Description

[0001] IMPROVEMENTS IN THE REPAIR OF PIPELINES

[0002] Cross Reference to Related Applications

[0003] This application claims the benefit of and priority to U.K. Patent Application No. 2406616.9, entitled “Improvements in the Repair of Pipelines” and filed May 10, 2024, the entire disclosure of which is hereby incorporated by reference in its entirety.

[0004] Technical Field of the Invention

[0005] The present invention relates to a flexible tubular apparatus for supplying heat to a liner in a pipeline and a method of lining a pipeline which utilises the flexible tubular apparatus.

[0006] Background to the Invention

[0007] In the field of pipeline repair, it is known to repair a pipeline using a liner which is run along the pipeline to cover over any cracks or unwanted holes formed in the pipeline. The so called “inversion technique” may be used to do this. The “inversion technique” involves everting (or inverting) the liner within the pipeline and securing the everted (inverted) liner to the inner surface of the pipeline. Alternatively, the liner may simply be dragged through the pipeline by a rope or cable and then inflated against the inner surface of the pipeline. The liner may be secured to the inner surface of the pipeline using a heat-curable resin with which the liner is impregnated. The liner may be provided with elongate conductors which extend longitudinally along the length of the liner. When a current is passed along those conductors, the conductors generate heat, which cures the heat-curable resin, thereby securing the liner to the inner surface of the pipeline. These conductors add complexity and expense to the manufacture of the liner, as specific processes are required to attach the conductors to the liner.

[0008] It is an object of the present invention to mitigate or obviate at least one problem with prior arrangements / methods for lining a pipeline.

[0009] Summary of the Invention

[0010] According to a broad aspect of the present invention, there is provided a tubular apparatus. The apparatus may be flexible. The apparatus may be for supplying heat to a liner in a pipeline. The apparatus may comprise resistive heating elements. The apparatus may comprise opposing open ends. The apparatus may be configured to be removed from the pipeline after being brought into contact with the liner in the pipeline and supplying heat to the liner in the pipeline.

[0011] According to a first aspect of the present invention, there is provided a flexible tubular apparatus for supplying heat to a liner in a pipeline, comprising one or more resistive heating elements and having opposing open ends, wherein the apparatus is configured to be removed from the pipeline after being brought into contact with the liner in the pipeline and supplying heat to the liner in the pipeline.

[0012] The flexible tubular apparatus carries resistive heating elements that supply heat to the heat-curable resin of the liner in the pipeline. This means that the liner itself does not require resistive heating elements, meaning the liner can be less complex and manufactured more easily, saving on cost. The construction of the flexible tubular apparatus with opposing open ends is particularly advantageous because it provides more flexibility in the insertion / installation methods it may be used with. For example, the flexible tubular apparatus may be inverted (or everted) into the lined pipeline. Alternatively, the opposing ends may be tied up and the flexible tubular apparatus inflated once is has been pulled into the pipeline. The construction of the flexible tubular apparatus with opposing open ends also provides more flexibility in terms of repair length in that it can be cut to the required size at site. The flexible tubular apparatus also has environmental benefits in that less energy is required to make liners as they do not require resistive heating elements.

[0013] The flexible tubular apparatus may be reusable. The flexible tubular apparatus may remain flexible after supplying heat to the liner in the pipeline. The flexible tubular apparatus may remain flexible after use. The flexible tubular apparatus may lack heat curable resin (i.e. resin capable of being heat cured). The flexible tubular apparatus may lack heat curable resin suitable to bond the flexible tubular apparatus to the liner in the pipeline.

[0014] The flexible tubular apparatus may be closable at a first position along its length. The flexible tubular apparatus may be closable at a first position along its length so that fluid cannot exit the interior of the flexible tubular apparatus via one of the opposing ends. The flexible tubular apparatus may be closable at the first position and at a second position along its length. The flexible tubular apparatus may be closable at the first position and at the second position along its length so as to define an inflation chamber between the first and second positions. The flexible tubular apparatus may be tieable and / or clampable at the first and / or second positions.

[0015] In practice, the flexible tubular apparatus may be closed along its length by using a clip or forming knots in the flexible tubular apparatus.

[0016] When the flexible tubular apparatus is positioned in the pipeline by pulling the flexible tubular apparatus into the pipeline, the flexible tubular apparatus may be initially closed at the first position. Then the interior of the flexible tubular apparatus may be inflated, using an inflation fluid such as air or water. The inflation fluid may then be retained in the flexible tubular apparatus by closing the flexible tubular apparatus at the second position. Alternatively, after the flexible tubular apparatus is closed at the first position the flexible tubular apparatus may be closed around an injector which supplies inflation fluid to the inflation chamber at the second position.

[0017] When the flexible tubular apparatus is inverted (or everted) into a pipeline one opposing end of the flexible tubular apparatus may be secured to an outlet of an inversion drum. The flexible tubular apparatus may then be closed at the first position adjacent the other opposing end and may then be inverted through the opposing end of the liner secured to the inversion drum and into the pipeline. By closing the flexible tubular apparatus at the first position, the flexible tubular apparatus holds its inflated shape after inversion and makes good contact against the liner in the pipeline.

[0018] The cross-section of the flexible tubular apparatus may be circular, ovoid, non- spherical, eccentric or irregular.

[0019] The flexible tubular apparatus may have a width. The width may be at least 0.05m. The width may be at least 0.1m. The width may be at least 0.15m. The width may be in the range of 0.05m to 5m. The width may be 0.1m, 0.15m or 0.225m. The width may be a greatest lateral width dimension of the flexible tubular apparatus. The width may be an outer diameter of the flexible tubular apparatus.

[0020] The width of the flexible tubular apparatus between the first and second ends may be constant or may be 80% to 160% of the width of the flexible tubular apparatus at the opposing end with the smallest width. In other words, the width of the opposing ends may be similar to the width of the rest of the flexible tubular apparatus.

[0021] The opposing open ends may be centred on a centre axis of the flexible tubular apparatus. The centre axis may extend between the opposing open ends.

[0022] The width of the flexible tubular apparatus may vary along its length. Such a construction with a varying width is advantageous because it is particularly useful when used in operations related to pipelines with varying diameters.

[0023] The flexible tubular apparatus may have first and second sections. The flexible tubular apparatus may include a tapering section (or in other words a narrowing section) that connects the first and second sections. The tapering section may narrow from the first section to the second section. The tapering section may be stretchable.

[0024] The flexible tubular apparatus may have a wall thickness. The wall thickness may be at least 1mm. The wall thickness may be at least 2mm. The wall thickness may be at least 3mm. The wall thickness may be at least 4 mm. The wall thickness may be at least 5 mm. The wall thickness may be in the range of 1mm to 15cm. The flexible tubular apparatus may have an inner circumference. The flexible tubular apparatus may have an outer circumference. The wall thickness may be a shortest distance between the inner and outer circumferences.

[0025] The flexible tubular apparatus may have a length. The length may be greater than 0. Im. The length may be greater than 0.2m. The length may be greater than 0.3m. The length may be greater than 0.4m. The length may be greater than 0.5m. The length may be at least 5m. The length may be at least 10m. The length may be at least 15m, 25m or 50m. The length may be 15m to 50m. The length may be up to 15m or up to 50m. The width may be measured in a direction perpendicular to the length.

[0026] The one or more resistive heating elements may comprise one or more elongate conductors. The one or more elongate conductors may extend longitudinally along the flexible tubular apparatus. The one or more elongate conductors may comprise a plurality of elongate conductors. The plurality of elongate conductors may be circumferentially spaced apart. The flexible tubular apparatus may comprise one or more circumferentially extending conductors that extend around a circumference of the flexible tubular apparatus. When the flexible tubular apparatus comprises the plurality of elongate conductors that are circumferentially spaced apart, the one or more circumferentially extending conductors may electrically connect the plurality of elongate conductors.

[0027] The one or more resistive heating elements may extend from a first of the opposing ends to a second of the opposing ends.

[0028] The one or more resistive heating elements may comprise one or more resistive heating lattices. The or each resistive heating lattice may be formed from interconnected elongate elements. The or each resistive heating lattice may be a regular resistive heating lattice.

[0029] The one or more heat resistive elements may be waterproofed. The one or more heat resistive elements may be located in the flexible tubular apparatus. The one or more heat resistive elements may be embedded in the flexible tubular apparatus. The one or more heat resistive elements may be provided with a liquid impermeable coating.

[0030] The one or more resistive heating elements may comprise carbon. Alternatively or additionally, the one or more resistive heating elements may comprise metal. The metal may be copper, steel or nickel. The metal may be an alloy. The alloy may comprise the copper, steel or nickel.

[0031] The flexible tubular apparatus may be gas and liquid impermeable. The flexible tubular apparatus may be inflatable. The flexible tubular apparatus may be invertable (i.e. evertable). In other words, capable of being turned inside out. The flexible tubular apparatus may be configured to be wound around a spool. In practice, the spool may be the spool of an inversion drum.

[0032] The flexible tubular apparatus may be non-adherable. The flexible tubular apparatus may be non-liquid absorbent.

[0033] The flexible tubular apparatus may comprise a heat resistant material. The heat resistant material may be heat resistant to temperatures of 60 to 90°C. The heat resistant material may comprise silicone, Fluorosilicone, or Fluorocarbon. The one or more resistive heating elements may be embedded in the heat resistant material. The flexible tubular apparatus may have at least one elongate conducting element extending along the length of the liner. The at least one elongate conducting element may be in electrical contact with the one or more heat resistive elements. The at least one elongate conducting element may be in direct physical contact with the one or more heat resistive elements. The at least one elongate conductive element may be electrically conductive. The at least one elongate conductive element may be an electrically conductive ribbon or wire. Preferably, the at least one elongate conductive element comprises first and second elongate conductive elements. The first and second elongate conductive elements may be first and second electrically conductive ribbons (or first and second electrically conductive wires).

[0034] The flexible tubular apparatus may have a longitudinal axis. The at least one elongate conductive element may extend between the opposing ends of the flexible tubular apparatus in a direction that is parallel to the longitudinal axis of the flexible tubular apparatus.

[0035] The flexible tubular apparatus may be formed from a rolled sheet. The rolled sheet may have opposing edges which are connected to each other. Preferably, the opposing edges may be connected by at least one thread. Alternatively, staples, adhesive or tape may be used to connect the opposing edges. The first and second elongate conductive elements may be provided adjacent the connected opposing edges. Here “provided adjacent the connected opposing edges” means the first and second elongate conductive elements run alongside the connected opposing edges.

[0036] The flexible tubular apparatus may further comprise at least one temperature sensor. The at least one temperature sensor may have a temperature communication unit and a temperature data store. The temperature communication unit may be operable to communicate with an external device via any suitable communication protocol, including but not limited to FTP (File Transfer Protocol), SMTP (Simple Mail Transfer Protocol), and finger protocol. The at least one temperature sensor may be embedded in the flexible tubular apparatus.

[0037] According to a second aspect of the present invention, there is provided a method involving a pipeline, comprising the steps of: providing a flexible tubular apparatus comprising one or more resistive heating elements and opposing open ends; lining the pipeline with a liner comprising heat-curable resin; positioning the flexible tubular apparatus within the lined pipeline; supplying heat to the liner using the one or more resistive heating elements of the flexible tubular apparatus to cure the heat-curable resin of the liner; and withdrawing the tubular apparatus from the pipeline.

[0038] In the method of the present invention, the liner itself does not require resistive heating elements, meaning the liner can be less complex and manufactured more easily, saving on cost. The construction of the flexible tubular apparatus with opposing open ends is particularly advantageous because it provides more flexibility in the insertion / installation methods it may be used with. For example, the flexible tubular apparatus may be inverted (or everted) into the lined pipeline or the opposing ends tied up and pulled through the lined pipeline. The construction of the flexible tubular apparatus with opposing open ends also provides more flexibility in terms of repair length in that it can be cut to the required size at site. The method also has environmental benefits in that less energy is required to make liners as they do not require resistive heating elements.

[0039] Positioning the flexible tubular apparatus within the lined pipeline may involve inverting (or everting) the flexible tubular apparatus into the lined pipeline. Inverting (or everting) the flexible tubular apparatus into the pipeline may involve using a gas or liquid (such as water) to invert (or evert) the flexible tubular apparatus into the pipeline. Gas is preferred as it is lighter and easier to transport to site. The gas may, for example, be air or helium. Inverting (or everting) the flexible tubular apparatus into the pipeline may involve securing one of the opposing ends of the flexible tubular apparatus to an outlet of an inversion apparatus, and inverting (or everting) the other opposing end through the outlet of the inversion apparatus. The flexible tubular apparatus may be closed along its length at a position distal the opposing end secured to the inversion apparatus. This allows the flexible tubular apparatus to hold its expanded state and to make good contact with the liner in the pipeline when supplying heat to the liner after the flexible tubular apparatus has been inverted (or everted) into the pipeline.

[0040] The inversion apparatus may be an inversion drum.

[0041] Positioning the flexible tubular apparatus within the lined pipeline may involve pulling the flexible tubular apparatus into the pipeline. The method may involve at least partially filling the flexible tubular apparatus with an inflation fluid once the flexible tubular apparatus is located within the pipeline. At least partially filling the flexible tubular apparatus with an inflation fluid may involve: closing the flexible tubular apparatus at a first position along its length; then injecting the inflation fluid into the flexible tubular apparatus, and then closing the flexible tubular apparatus at a second position along its length to trap the inflation fluid within the flexible tubular apparatus. Alternatively, before the flexible tubular apparatus is pulled into the pipeline, the flexible tubular apparatus may be closed at first and second positions along its length so as to define an inflation chamber between the first and second positions, wherein at the first position the flexible tubular apparatus is closed around a fluid injector, and the inflation fluid may be introduced into the inflation chamber using the fluid inj ector once the flexible tubular apparatus is in the pipeline so as to at least partially fill the flexible tubular apparatus with the inflation fluid.

[0042] The inflation fluid may be liquid or gas or a mixture of liquid and gas.

[0043] Lining the pipeline may involve inverting (or everting) the liner into the pipeline. Alternatively, lining the pipeline may involve pulling the liner into the pipeline.

[0044] The method may further comprise cutting the flexible tubular apparatus. The method may further comprise cutting the flexible tubular apparatus to a certain size (i.e. a certain length). The certain size / length may be related to the length of the pipeline.

[0045] The flexible tubular apparatus may be withdrawn from the pipeline after a heating period during which heat is supplied to the liner. The heating period may be greater than Is, or greater than 5s, or greater than 10s, or greater than 15s, or greater than 30s, or greater than 45s, or greater than 60s. The heating period may be 30 to 120 minutes. The heating period may be 30 to 60 minutes. In some embodiments, the flexible tubular apparatus is withdrawn from the pipeline directly after the completion of the heating period. In this context, directly may be within 5 minutes of the end of the heating period. In other embodiments, the flexible tubular apparatus is withdrawn from the pipeline an extended period after the completion of the heating period. In some embodiments, the extended period may be up to say 48 hours.

[0046] The flexible tubular apparatus may be in contact with the liner when it supplies heat to the liner using the one or more resistive heating elements of the flexible tubular apparatus.

[0047] The pipeline may be a first pipeline. The method may involve a second pipeline. The liner may be a first liner. The method may further comprise (optionally after withdrawing the tubular apparatus from the first pipeline) lining the second pipeline with a second liner comprising heat-curable resin. The method may further comprise positioning the flexible tubular apparatus within the lined second pipeline. The method may further comprise supplying heat to the second liner using the one or more resistive heating elements of the flexible tubular apparatus to cure the heat-curable resin of the second liner. The method may further comprise withdrawing the tubular apparatus from the second pipeline.

[0048] The flexible tubular apparatus may be the flexible tubular apparatus of the first aspect.

[0049] The method of the second aspect of the present invention may incorporate any or all features of the flexible tubular apparatus of the first aspect of the present invention as desired or as appropriate.

[0050] According to a third aspect of the present invention, there is provided a system for use in lining a pipeline, comprising: a flexible tubular apparatus in accordance with the first aspect; and a controller operable to control a supply of current to the one or more resistive heating elements of the flexible tubular apparatus.

[0051] In the system of the present invention, the liner itself does not require resistive heating elements, meaning the liner can be less complex and manufactured more easily, saving on cost. The construction of the flexible tubular apparatus with opposing open ends is particularly advantageous because it provides more flexibility in the insertion / installation methods it may be used with. For example, the flexible tubular apparatus may be inverted (or everted) into the lined pipeline or the opposing ends tied up and pulled through the lined pipeline. The construction of the flexible tubular apparatus with opposing open ends also provides more flexibility in terms of repair length in that it can be cut to the required size at site. The system also has environmental benefits in that less energy is required to make liners as they do not require resistive heating elements.

[0052] The flexible tubular apparatus may further comprise at least one temperature sensor. The controller may be in communication with the at least one temperature sensor. The controller may be arranged to adjust the supply of current to the one or more resistive heating elements in response to a signal from the at least one temperature sensor.

[0053] This results in even heating of the liner / heat-curable resin.

[0054] The system may further comprise an alarm in communication with the controller.

[0055] The controller may be arranged to activate the alarm if the controller receives a second signal from the at least one temperature sensor that a sensed temperature has exceeded a pre-determined threshold.

[0056] This ensures that the liner / heat-curable resin is not overheated.

[0057] The system may further comprise a liner for the pipeline. The liner may be invertable (or evertable).

[0058] The system may further comprise an inversion apparatus (such as an inversion drum). The inversion apparatus may be for inverting (or everting) the liner into the pipeline.

[0059] The system of the third aspect of the present invention may incorporate any or all features of the flexible tubular apparatus of the first aspect of the present invention or the method of the second aspect of the present invention as desired or as appropriate. Detailed Description of the Invention

[0060] In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0061] Figure 1 shows a perspective view of a flexible tubular apparatus according to a first embodiment of the present invention;

[0062] Figure 2 shows a perspective view of a flexible tubular apparatus according to a second embodiment of the present invention; and

[0063] Figure 3 is a schematic diagram of a system incorporating the flexible tubular apparatus of Figure 1.

[0064] With reference to Figure 1, there is shown a flexible tubular apparatus 10 in accordance with a first embodiment of the present invention. The flexible tubular apparatus 10 is formed to supply heat to a liner in a pipeline as will be described in detail below and is formed to be used on more than one occasion. In other words, the flexible tubular apparatus 10 is formed to be reusable.

[0065] The flexible tubular apparatus 10 is typically formed from a rolled sheet 12 of heat resistant material (such as silicone, Fluorosilicone, or Fluorocarbon). The sheet 12 is connected along opposing edges 14, 16 thereof to form the flexible tubular apparatus 10. The opposing edges 14, 16 are typically connected using stitches or staples. The sheet has one or more resistive heating elements 18 applied to an external surface of the sheet or embedded within the sheet 12. In the depicted example, the one or more resistive heating elements 18 are applied to an exterior of the sheet 12. The heat resistive material of the sheet is formed to be heat resistant to temperatures of 60 to 90°C and is formed to be liquid and gas impermeable so that fluid within the flexible tubular apparatus 10 cannot escape in a radial direction from the flexible tubular apparatus 10.

[0066] The flexible tubular apparatus 10 has opposing open ends 20, 22, which are centred on a central axis of the flexible tubular apparatus 10. The opposing open ends 20, 22 have the same width in the depicted example. Indeed, the width of the flexible tubular apparatus 10 remains constant along the length of the flexible tubular apparatus 10 in this embodiment. The width of this embodiment is typically 0.05m to 0.5m. The flexible tubular apparatus 10 also has a wall thickness that is measured along the shortest distance between the inner and outer circumferences 24, 26 of the flexible tubular apparatus 10. Typically, the wall thickness of this embodiment is 1mm to 5cm. The flexible tubular apparatus 10 also has a length measured between the opposing ends 20, 22. The length of the flexible tubular apparatus is typically 15 to 50m, but may be adapted like any of the dimensions of the flexible tubular apparatus 10 to suit a particular pipelining operation.

[0067] The one or more resistive heating elements 18 are adapted to provide heat when supplied with a current. They are formed from an electrically conductive material comprising carbon and / or metal. In this embodiment, the one or more resistive heating elements 18 is a regular resistive heating lattice formed from interconnected elongate elements. The regular resistive heating lattice extends between the opposing open ends 20, 22 of the tubular apparatus 10. The flexible tubular apparatus 10 is provided with a temperature sensor 28 that has a temperature communication unit (not shown) and a temperature data store (not shown). The temperature sensor 28 is adapted to monitor the temperature of the flexible tubular apparatus 10 to prevent overheating of the flexible tubular apparatus. If the temperature of the flexible tubular apparatus 10 exceeds a predetermined threshold the temperature sensor 28 is adapted to communicate this to a controller via the temperature communication unit.

[0068] The flexible tubular apparatus 10 also includes first and second electrically conductive ribbons (or wires) 30, 32 provided adjacent the connected opposing edges of the sheet 12 used to form the flexible tubular apparatus 10. These electrically conductive ribbons (or wires) 30, 32 are in electrical contact with the resistive heating lattice along the length of the flexible tubular apparatus 10. In practice, the first electrically conductive ribbon (or wire) 30 has a negative polarity and the second electrically conductive ribbon (or wire) 32 has a positive polarity. This ensures that current flows longitudinally along the first and second electrically conductive ribbons (or wires) 30, 32 but also circumferentially via the resistive heating lattice 18 from the first electrically conductive ribbon (or wire) 30 to the second electrically conductive ribbon (or wire) 32. The flexible tubular apparatus 10 is configured to be positioned within a pipeline lined with a liner comprising heat curable resin and to supply heat to the liner so as to cure the heat-curable resin. The flexible tubular apparatus 10 is formed to be removed from the pipeline after supplying this heat, and therefore is formed to be reusable. In particular, the flexible tubular apparatus 10 has a non-adherable outer circumference 26, and the flexibility of the flexible tubular apparatus 10 remains the same after supplying heat to the liner. Notably, the flexible tubular apparatus 10 lacks heat curable resin suitable to bond the flexible tubular apparatus 10 to the liner in the pipeline.

[0069] The flexible tubular apparatus 10 is formed to be invertable (or evertable). In other words, capable of being turned inside out. This means that the flexible tubular apparatus 10 may be positioned inside the lined pipeline using an inversion (or eversion) method. The flexible tubular apparatus is also closable at first and second positions along its length, meaning an inflation chamber that may be filled with an inflation fluid can be formed between the first and second positions. This means that the flexible tubular apparatus 10 may also supply heat to the liner in the pipeline by being pulled into the pipeline and then inflated. The flexible tubular apparatus 10 is therefore advantageous in that it may be used with a variety of insertion methods.

[0070] With reference to Figure 2, there is shown a flexible tubular apparatus 10’ according to a second embodiment of the present invention. This second embodiment is similar to the first embodiment. However, it differs in a number of aspects as will be described below.

[0071] The flexible tubular apparatus 10’ is formed to have a varying width, which is advantageous because it finds particular utility when used in operations related to pipelines with varying diameters. In particular, the flexible tubular apparatus 10’ has first and second sections 50’, 52’. The first section 50’ has a greater width than the second section 52’. The first and second sections 50’, 52’ are connected by a tapering section 54’, which tapers (or narrows) from the first section 50’ to the second section 52’. The tapering section is formed to be stretchable. The widths of the opposing ends 20’, 22’ are different, but it should be noted that the width of the flexible tubular apparatus 10’ between the opposing ends is in the range of 80% to 160% of the width of the flexible tubular apparatus 10 at the opposing end 20’ with the smallest width.

[0072] The flexible tubular apparatus 10’ also differs from the flexible tubular apparatus 10 in that the one or more resistive heating elements 18’ comprise a plurality of circumferentially spaced apart elongate conductors 18’ (please note that not every elongate conductor 18’ has been allocated a reference numeral due to the large number of elongate conductors). These elongate conductors 18’ are preferably electrically connected by one or more circumferentially extending conductors (not shown). This particular construction of resistive heating elements 18’ is particularly advantageous in the context of the second embodiment as the resistive heating elements 18’ are less susceptible to break when subjected to longitudinal stress when the flexible tubular apparatus 10’ is stretched. However, it should be understood that one or more resistive heating lattices may be employed instead of the elongate conductors 18’.

[0073] Figure 3 shows a system 100 for lining a pipeline 101. As shown the system comprises a flexible tubular apparatus 10 as described above as well as a liner 105 (comprising heat-curable resin) and a controller 102. The controller 102 is in communication with a power supply 103 which supplies current to the resistive heating lattice of the flexible tubular apparatus 10. The system further comprises a display 104 arranged to display data. The display 104 is operable to receive a user input and communicate the user input to the controller 102.

[0074] The controller 102 is in communication with the temperature sensor 28 of the flexible tubular apparatus 10 and is arranged to control the supply of current to the resistive heating lattice of the flexible tubular apparatus 10 in response to a signal from the temperature sensor 28. In this way, the temperature of the resistive heating lattice can be controlled and overheating of the flexible tubular apparatus 10 and / or liner can be prevented.

[0075] With reference to Figure 3, in use, the flexible tubular apparatus 10 and liner 105 with heat-curable resin are transported to site. At this stage, the flexible tubular apparatus 10 may be cut to a required length. The pipeline 101 is then lined with the liner 105. The flexible tubular apparatus 10 is then positioned within the lined pipeline so that it is preferably in contact with the liner 105 in the pipeline 101. This can be done either by (like the liner 105) inverting (or everting) the flexible tubular apparatus 10 into the pipeline 101 using a gas or liquid or by pulling the flexible tubular apparatus 10 into the pipeline 101.

[0076] When the flexible tubular apparatus 10 is inverted (or everted) into a pipeline one opposing end 20 of the flexible tubular apparatus 10 is secured to an outlet of an inversion apparatus (such as an inversion drum). The flexible tubular apparatus 10 is then closed at a first position adjacent the other opposing end 22 and is then inverted (or everted) through the opposing end of the liner secured to the inversion drum and into the pipeline. By closing the flexible tubular apparatus 10 at the first position, the flexible tubular apparatus holds its inflated shape after inversion and makes good contact against the liner 105 in the pipeline 101. Preferably, gas is used to invert (or evert) the flexible tubular apparatus 10 into the pipeline 101 as it is easier to transport to site.

[0077] When the flexible tubular apparatus 10 is positioned in the pipeline 101 by pulling the flexible tubular apparatus 10 into the pipeline 101, the flexible tubular apparatus 10 may be initially closed at a first position along its length. Then once the flexible tubular apparatus has been pulled into the pipeline, the interior of the flexible tubular apparatus 10 is inflated, using an inflation fluid such as air or water. The inflation fluid is then retained in the flexible tubular apparatus 10 by closing the flexible tubular apparatus 10 at a second position along its length. Alternatively, after the flexible tubular apparatus 10 is closed at the first position the flexible tubular apparatus 10 may be closed around an injector (which supplies inflation fluid to an inflation chamber between the first and second positions) at the second position and then inflated once it has been pulled into the pipeline.

[0078] As Figure 3 is a schematic diagram, the flexible tubular apparatus 10 is not shown closed at the first and second positions along its length.

[0079] Once the flexible tubular apparatus 10 is positioned in the pipeline 105, the controller 102 (preferably upon receiving a user input from the display 104) allows the power supply 103 to supply current to the one or more resistive heating elements of the flexible tubular apparatus. This causes the one or more resistive heating elements to heat up and supply their heat to the liner 105, thereby curing the heat-curable resin of the liner and fixing the liner in place within the pipeline 101. Heat is supplied to the liner 105 by the flexible tubular apparatus 10 during a heating period. The heating period is preferably at least 5s to give common heat-curable resins sufficient time to cure. In some embodiments, this may be 30 to 60 minutes.

[0080] Once the heating period is complete, the controller 102 ceases to allow current to be supplied to the one or more resistive heating elements of the flexible tubular apparatus 10 and the flexible tubular apparatus 10 is withdrawn from the pipeline 105 for optional further use in another operation to line another pipeline (not shown). After or as the flexible tubular apparatus 10 is withdrawn from the pipeline, optionally the flexible tubular apparatus 10 may be coiled around the spool of an inversion drum (not shown).

[0081] In the present invention, the flexible tubular apparatus carries resistive heating elements that supply heat to the heat-curable resin of the liner in the pipeline. This means that the liner itself does not require resistive heating elements, meaning the liner can be less complex and manufactured more easily, saving on cost. The construction of the flexible tubular apparatus with opposing open ends is particularly advantageous because it provides more flexibility in the insertion / installation methods it may be used with. For example, the flexible tubular apparatus may be inverted (or everted) into the lined pipeline. Alternatively, the opposing ends may be tied up and the flexible tubular apparatus inflated once it has been pulled into the pipeline. The construction of the flexible tubular apparatus with opposing open ends also provides more flexibility in terms of repair length in that it can be cut to the required size at site. The flexible tubular apparatus also has environmental benefits in that less energy is required to make liners as they do not require resistive heating elements.

[0082] The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

CLAIMS1. A flexible tubular apparatus for supplying heat to a liner in a pipeline, comprising one or more resistive heating elements and having opposing open ends, wherein the apparatus is configured to be removed from the pipeline after being brought into contact with the liner in the pipeline and supplying heat to the liner in the pipeline2. The flexible tubular apparatus of claim 1 , wherein the flexible tubular apparatus is reusable.

3. The flexible tubular apparatus of claim 1 or 2, wherein the flexible tubular apparatus remains flexible after supplying heat to the liner in the pipeline.

4. The flexible tubular apparatus of any preceding claim, wherein the flexible tubular apparatus lacks heat curable resin suitable to bond the flexible tubular apparatus to the liner in the pipeline.

5. The flexible tubular apparatus of any preceding claim, wherein the flexible tubular apparatus is closable at a first position along its length.

6. The flexible tubular apparatus of claim 5, wherein the flexible tubular apparatus is closable at the first position and at a second position along its length.

7. The flexible tubular apparatus of claim 6, wherein the flexible tubular apparatus is closable at the first position and at the second position along its length so as to define an inflation chamber between the first and second positions.

8. The flexible tubular apparatus of any preceding claim, wherein the width of the flexible tubular apparatus between the first and second ends is constant or 80% to 160% of the width of the flexible tubular apparatus at the opposing end with the smallest width.

9. The flexible tubular apparatus of any preceding claim, wherein the opposing open ends are centred on a centre axis of the flexible tubular apparatus.

10. The flexible tubular apparatus of any preceding claim, wherein the width of the flexible tubular apparatus varies along its length.

11. The flexible tubular apparatus of claim 10, wherein the flexible tubular apparatus has first and second sections, wherein the flexible tubular apparatus includes a tapering section that connects the first and second sections.

12. The flexible tubular apparatus of any preceding claim, wherein the one or more resistive heating elements comprise one or more resistive heating lattices.

13. The flexible tubular apparatus of any preceding claim, wherein the flexible tubular apparatus is formed from a rolled sheet, wherein the rolled sheet has opposing edges which are connected to each other.

14. The flexible tubular apparatus of any preceding claim, wherein the flexible tubular apparatus has at least one elongate conducting element extending along the length of the liner, wherein the at least one elongate conducting element is in electrical contact with the one or more heat resistive elements.

15. The flexible tubular apparatus of claim 14 when claim 14 is dependent on claim 13 only, wherein the first and second elongate conductive elements are provided adjacent the connected opposing edges.

16. The flexible tubular apparatus of any preceding claim, wherein the flexible tubular apparatus is invertable.

17. A method involving a pipeline, comprising the steps of: providing a flexible tubular apparatus comprising one or more resistive heating elements and opposing open ends; lining the pipeline with a liner comprising heat-curable resin; positioning the flexible tubular apparatus within the lined pipeline; supplying heat to the liner using the one or more resistive heating elements of the flexible tubular apparatus to cure the heat-curable resin of the liner; and withdrawing the tubular apparatus from the pipeline.

18. The method of claim 17, wherein positioning the flexible tubular apparatus within the lined pipeline involves inverting the flexible tubular apparatus into the lined pipeline.

19. The method of claim 18, wherein inverting the flexible tubular apparatus into the pipeline involves securing one of the opposing ends of the flexible tubular apparatus to an outlet of an inversion apparatus, and inverting the other opposing end through the outlet of the inversion apparatus, wherein the flexible tubular apparatus is closed along its length at a position distal the opposing end secured to the inversion apparatus.

20. The method of claim 17, wherein positioning the flexible tubular apparatus within the lined pipeline involves pulling the flexible tubular apparatus into the pipeline.

21. The method of claim 20, wherein the method involves at least partially filling the flexible tubular apparatus with an inflation fluid once the flexible tubular apparatus is located within the pipeline.

22. The method of claim 21, wherein at least partially filling the flexible tubular apparatus with an inflation fluid involves: closing the flexible tubular apparatus at a first position along its length; then injecting the inflation fluid into the flexible tubular apparatus, and then closing the flexible tubular apparatus at a second position along its length to trap the inflation fluid within the flexible tubular apparatus.

23. The method of claim 21, wherein before the flexible tubular apparatus is pulled into the pipeline, the flexible tubular apparatus is closed at first and second positions along its length so as to define an inflation chamber between the first and second positions, wherein at the first position the flexible tubular apparatus is closed around a fluid injector, and the inflation fluid is introduced into the inflation chamber using the fluid injector once the flexible tubular apparatus is in the pipeline so as to at least partially fill the flexible tubular apparatus with the inflation fluid.

24. The method of any of claims 17 to 23, further comprising cutting the flexible tubular apparatus to a certain size.

25. A system for use in lining a pipeline, comprising: the flexible tubular apparatus of any of claims 1 to 16; and a controller operable to control a supply of current to the one or more resistive heating elements of the flexible tubular apparatus.

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