Lined pipelines

Abstract

A barrier liner for a pipe is made by bending an elongate sheet into a tube about a longitudinal axis of the sheet. The sheet comprises a metallic foil laminated with at least one polymer layer on each side of the foil, so that the tube comprises an outer polymer layer on a radially outer side of the foil and an inner polymer layer on a radially inner side of the foil, wherein, before the sheet is bent to form the tube, the outer polymer layer and the inner polymer layer are each narrower than the foil in a direction transverse to the longitudinal axis. This defines exposed peripheral strips of the foil laterally outboard of each of those polymer layers that are brought together and joined by welding along a seam that extends substantially parallel to the longitudinal axis. The seam and the conjoined peripheral strips are then covered with a polymer infill on each of the radially inner side and the radially outer side of the tube that bridges between sides of the respective polymer layers in mutual opposition about the seam.

Description

[0001] Lined pipelines

[0002] This invention relates to lined pipelines such as subsea flowlines and risers. In particular, the invention aims to simplify installation of a barrier liner into a host steel pipe to protect the host pipe from internal corrosion, especially for use in pipelines that will convey corrosive fluids with high gas content. The invention also contemplates the use of a barrier liner to protect a host pipe from embrittlement where a pipeline will be used to transport hydrogen.

[0003] Corrosion protection is a key issue for pipelines used in the oil and gas industry, which are usually made of carbon steel to reduce their cost over often great lengths. Liners of polymers or composites, for example of high density polyethylene (HDPE), are commonly used to mitigate internal corrosion of pipelines as an alternative to more expensive liners of corrosion-resistant alloys. For brevity, polymer and composite liners will be referred to collectively in this specification as polymer liners unless the context requires otherwise.

[0004] In a lining process described in GB 2252808 and known in the art by the registered trade mark ‘Swagelining’, a polymer liner pipe is inserted into a steel host pipe joint with the assistance of die-drawing. Specifically, the liner pipe initially has an outer diameter that is greater than the inner diameter of the host pipe but is then pulled through a distally-tapering annular swage die, exemplified by GB 2221741 , to fit into the host pipe. By effecting radially-inward elastic contraction, the swage die reduces the outer diameter of the liner pipe to less than the inner diameter of the host pipe. In this narrowed state, the liner pipe is pulled telescopically through the host pipe while longitudinal tension is maintained in the liner pipe between the swage die and a draw line.

[0005] When the liner pipe is in an appropriate longitudinal position with respect to the host pipe, tension applied by the draw line is released. This starts a reversion process in which the liner pipe contracts longitudinally and expands radially outwardly to press against the interior of the host pipe. The elastic radial expansion achieves an exceptionally tight fit and a strong mechanical connection between the liner pipe and the host pipe. When reversion is complete, the ends of the liner pipe are machined back into the corresponding ends of the host pipe to create sockets. When fabricating a pipeline by girth-welding the host pipe joint to a similarly lined pipe joint, their mutually-opposed sockets can receive a tubular polymer liner bridge to maintain continuity of the polymer lining across the interface between the pipe joints.

[0006] Whilst they are generally effective to resist aggressively corrosive fluids, polymer liners suffer from problems in practice. One such problem is permeation of fluids through the liner material. During operation, liquids and especially gases or vapours present in the fluid flowing through the pipeline tend to migrate through the liner wall to enter the micro-annulus between the liner and the surrounding host pipe. There can also be leakage of fluid into the micro-annulus along leakage paths extending around the liner, for example through any gaps at joints between lined pipeline sections.

[0007] Over time, fluid accumulating in the micro-annulus may jeopardise bonding or engagement between the liner and the host pipe and promote corrosion of the host pipe. Also, transfer of fluid into the micro-annulus will continue until the pressure of fluid in the micro-annulus matches that of the fluid flowing through the bore of the pipeline. Thereafter, any rapid reduction of pressure in the bore will lead to an overpressure in the micro-annulus that will not equalise as quickly and could therefore cause the liner to collapse inwardly.

[0008] In enhanced hydrocarbon recovery techniques, polymer-lined pipelines can be used to inject fluids such as water or gas into a well producing hydrocarbons. In pipelines used for water injection, the risk of liner collapse due to migration of gaseous species into the micro-annulus between the liner and the host pipe can be managed simply by specifying a wall thickness for the liner that is sufficient to resist collapse in all operating scenarios. In that case, the pressure of dissolved gas in the service fluid is assumed to be no greater than two bar and a further one bar is added to account for atmospheric pressure during installation. The liner wall thickness required to prevent collapse at this critical pressure is calculated using an industry-accepted model known as the Frost equation.

[0009] Substantial quantities of gas can also be conveyed along pipelines in combination with liquids, either dissolved in liquids or separately from liquids, for example for injection into subterranean reservoirs as part of enhanced recovery or carbon capture techniques. In one such example, alternating slugs of gas and water can be injected into a well in a process known as water alternating gas (WAG) injection to recover more hydrocarbons from a reservoir, more efficiently than using gas or water alone. In another such example known as carbon capture utilisation and storage (CCLIS), carbon dioxide can be conveyed along a pipeline in a highly compressed, supercritical state to be injected into a formation deep underground, for example a depleted hydrocarbon reservoir.

[0010] The high gas content of fluid conveyed by WAG and CCLIS pipelines makes the design of liners challenging. For example, the high gas pressure in the micro-annulus resulting from permeation through the liner wall could require an impractically thick liner to resist collapse when the pipeline is depressurised. WAG and CCLIS environments also contain corrosive gases that can cause corrosion of the host steel pipe after permeating through the liner wall.

[0011] Lined pipelines are also used to convey hydrogen gas, which may for example be manufactured offshore using renewable energy and then transported across the seabed for storage or consumption. Transport of hydrogen through lined pipelines under high pressure presents challenges of permeation of hydrogen not only through the liner wall but also into the wall of the steel host pipe. Thus, in the case of hydrogen, the risk of liner collapse is accompanied by a risk of embrittlement of the steel that forms the host pipe.

[0012] WO 02 / 33298 discloses a conventional solution to equalise pressure between the micro-annulus and the bore of a lined pipe to avoid liner collapse, in which vents penetrate the liner wall. The vents may, for example, comprise porous sintered frit elements. Similarly, WO 2004 / 011840 discloses a liner bridge whose tubular sleeve is penetrated by vents for fluid communication between the micro-annulus and the bore of conjoined lined pipe sections. However, the inner surface of the host pipe remains exposed to the potentially damaging effect of any fluid that enters the micro-annulus by permeation through the liner wall, or via the vents or another leakage path.

[0013] Some lined pipelines require a gas-tight barrier layer that will resist permeation of gases such as hydrogen and corrosive fluids through the liner and into contact with the inner surface of the surrounding host pipe. In this respect, pipe liners comprising gastight barrier layers are known but such liners cannot be installed into host pipes by the Swagelining® process that is required to provide a tight-fitting liner. This is because the stresses and extensions imposed on the liner pipe during the deformation of die drawing would result in delamination and failure of the barrier layer.

[0014] WO 2006 / 111738 describes a barrier pipe in which an intermediate barrier layer is sandwiched between two polymer layers. The polymer layers prevent ingress of liquid and contact of liquid with the barrier layer and the barrier layer blocks gas that can permeate through the polymer layers.

[0015] CN 115264189 discloses an example of a barrier pipe in which aluminium foils are wound around a polymer core pipe. A drawback of this type of barrier pipe is the presence of a leak path for gas at the interfaces between successive turns of the foil.

[0016] Other barrier variants are known. For example, CN 111117041 discloses a graphene barrier. In EP 1716202, a food wrap polymer is modified for deposition of an aluminium film. CN 104290365 discloses electroplating metal onto a polymer pipe. US 9234610 describes welding a barrier layer over a polymer, although the heat of welding could risk melting the polymer.

[0017] GB 2588641 discloses a lined pipe comprising a host pipe lined with a barrier pipe. The barrier pipe comprises a metallic barrier layer surrounded by an outer polymer pipe and an inner polymer pipe, the layers of the barrier pipe being bonded together by an adhesive. The barrier pipe is inserted into the host pipe in a single Swagelining® process.

[0018] US 2016 / 362968 discloses a composite material comprising a first, inner polymer layer, a metal layer and a second, outer polymer layer, which can be formed into a liner and expanded into a host pipe while having a larger diameter than the host pipe, thereby exerting elastic reversionary pressure. To install the liner, a tool can be used to create folds in the liner to allow it to fit inside the host pipe.

[0019] JP H0441015 discloses a method of making a metal / resin composite pipe. A metal sheet is drawn out from a spool and passes through a surface treatment tank and a heating device before being pressure bonded to a resin sheet to make a laminated sheet. The shape of the pipe is then formed by bending the sheet about a longitudinal axis, with the resin sheet facing inwards to bring the sides of the sheet together. The resin sheet is not bonded to the metal sheet at its side edges. This enables a welding machine to weld the abutting side edges of the metal sheet together to form the pipe, with a welding machine subsequently applying welding heat to adhere the loose edges of the resin sheet to each other and to the welded metal sheet.

[0020] GB 2553319 discloses a mechanically lined pipe with an inner polymer liner. The lined pipe comprises a host pipe with a mechanically lined corrosion-resistant liner, which may be applied to the host pipe by hydraulic expansion or thermo-hydraulic shrink fit, for example. An inner polymer liner, whose outer diameter exceeds the inner diameter of the lined pipe is then installed within the lined pipe by a Swagelining® process. The inner polymer liner comprises apertures to balance pressure from gases that migrate in between the inner polymer liner and the corrosion-resistant liner.

[0021] WO 2020 / 217164 discloses an example of a tubular laminate in the form of a multilayer pipe, which may be a laminate of a metallic foil and a polymeric layer, sandwiched between a polymeric inner lining layer and a polymeric outer lining layer.

[0022] JP H0441015 discloses a method of making a metal / resin composite pipe. A metal sheet is drawn out from a spool and passes through a surface treatment tank and a heating device before being pressure bonded to a resin sheet to make a laminated sheet. The shape of the pipe is then formed by bending the sheet about a longitudinal axis, with the resin sheet facing inwards to bring the sides of the sheet together. The resin sheet is not bonded to the metal sheet at its side edges. This enables a welding machine to weld the abutting side edges of the metal sheet together to form the pipe, with a welding machine subsequently applying welding heat to adhere the loose edges of the resin sheet to each other and to the welded metal sheet.

[0023] Against this background, the invention resides in a method of manufacturing a barrier liner for a pipe. The method comprises: forming a tube by bending an elongate sheet about a longitudinal axis of the sheet, the sheet comprising a metallic foil laminated with at least one polymer layer on each side of the foil, so that the tube comprises an outer polymer layer on a radially outer side of the foil and an inner polymer layer on a radially inner side of the foil, wherein, before the sheet is bent to form the tube, the outer polymer layer and the inner polymer layer are each narrower than the foil in a direction transverse to the longitudinal axis, hence defining exposed peripheral strips of the foil laterally outboard of each of those polymer layers; bringing the peripheral strips of the foil together and joining the peripheral strips by welding along a seam that extends substantially parallel to the longitudinal axis; and covering the welded seam and the conjoined peripheral strips with a polymer infill on each of the radially inner side and the radially outer side of the foil that bridges between sides of the respective polymer layers in mutual opposition about the seam.

[0024] The outer polymer layer may be thicker than the inner polymer layer. For example, the outer polymer layer may have a thickness of 1mm to 2mm and the inner polymer layer may have a thickness of 100 to 200 microns.

[0025] The polymer infills may comprise at least one infill strip, in which case the method may further comprise attaching the infill strip to the opposed sides of the outer polymer layer or the inner polymer layer. Alternatively, the polymer infills may comprise at least one polymer flap that is integral with or attached to the outer polymer layer and / or the inner polymer layer on one side of the seam. In that case, the method may further comprise attaching a free end of the at least one flap to the respective polymer layer on an opposite side of the seam. Conversely, the at least one flap may be folded away from the seam while welding along the seam. The infill strip or the flap may be attached by fusing or bonding, or by stitching or knitting. The polymer infills may be at least partially created from filaments of polymer that extend between the opposed sides of the outer or the inner polymer layer.

[0026] At least one of the outer polymer layer and the inner polymer layer may comprise a substrate impregnated with a polymer resin, or may comprise a resin-impregnable substrate, in which case the method may further comprise impregnating the substrate with a polymer resin, for example after forming the sheet into the tube. The resin may then be cured after inserting the barrier liner into a host pipe, for example by applying heat to the resin via the barrier liner or the host pipe.

[0027] Preliminarily, the method may involve manufacturing the laminated sheet by assembling the foil and the outer and inner polymer layers, for example by extruding at least one of the outer polymer layer and the inner polymer layer onto the foil. The method may also involve inserting the barrier liner into a host pipe, for example by collapsing the barrier liner in cross-section to narrow the barrier liner for insertion into the host pipe, and subsequently opening out the barrier liner into a circular crosssection within the host pipe. An additional polymer inner liner may be added within the barrier liner after inserting the barrier liner into the host pipe. The inner liner can be expanded within and against the barrier liner, for example by reversion after die-drawing. One or more vents can penetrate a wall of the inner liner.

[0028] The barrier liner can be inserted into the host pipe when the host pipe is already lined internally with a polymer outer liner, for example after radially expanding the outer liner within the host pipe by a process such as reversion after die-drawing.

[0029] The host pipe can be terminated with a compression ring that is disposed radially within and that acts radially outwardly against the foil of the barrier liner.

[0030] In summary, the invention proposes a novel and advantageous barrier solution that involves a multi-layered polymer barrier pipe system. Installation of the system is divided into operations in which layers are fabricated and installed into a host carbon steel pipe separately. The result is to produce a final assembly that results in a tight- fitting barrier liner, substantially impervious to migration of fluids into the outer microannulus between the barrier liner and the host pipe.

[0031] Installation of the barrier system involves two processes that are performed in sequence. Initially, an outer barrier liner is inserted into and expanded against the host pipe. Then, after the barrier liner is inserted, the pipe is lined additionally with a collapse-resistant internal liner. The internal liner may be of high-density polyethylene such as PE100.

[0032] Resistance to collapse of the internal liner may be achieved by including vents at longitudinal intervals to allow gas accumulations in the inner micro-annulus between the internal liner and the barrier layer to be vented back into the bore of the pipeline during cyclic depressurisation events. The size of the vents and the frequency of the vent locations are determined by the anticipated flow rate through the vents.

[0033] The wall thickness of the internal liner is determined by the maximum transient pressure differential that is expected between the bore of the pipe and the inner microannulus in service, having regard to the pressure-equalising effect of any vents provided in the internal liner. The outer diameter of the internal liner is chosen for optimal tightness of fit of the internal liner to the internal diameter of the host pipe, via the barrier liner that is sandwiched between them. Prior to its installation into the host pipe, lengths of the internal liner are butt fusion welded together using an approved liner welding procedure. The resulting fabricated continuous liner pipe may be installed into the host pipe using a reducing die and allowed to revert against the internal surface of the host pipe in accordance with the aforementioned Swagelining® technique. After a suitable reversion period during which a tight fit will be established for all liner layers, the barrier lined pipeline can be terminated using compression rings of a corrosion resistant alloy.

[0034] The barrier liner comprises a corrosion-resistant barrier layer that is substantially impervious or gas-tight. The barrier layer may be exemplified by a metallic foil tube with a wall thickness of preferably no more than 0.1mm. The metallic foil could be of aluminium but in principle any suitable metallic material can be used to manufacture the barrier liner. High-ductility, soft annealed grades are preferred to avoid damage during installation.

[0035] The barrier layer is thick enough to prevent gas permeation through the wall of the tube but thin and flexible enough to allow the tube to be collapsed, contracted or folded, inserted into the host pipe, and then unfolded or expanded out to meet the internal diameter of the host pipe.

[0036] The tube is fabricated from an elongate flat metallic sheet that is bent across its width to bring its opposed parallel side edges together, whereupon the side edges can be joined by a longitudinal seam weld to form the tube. The weld should be substantially impermeable to migration of gas, providing a hermetic seal along the entire length of the tube to complete a gas-tight structure. The side edges of the sheet can be joined either by a butt joint or a simple overlap joint. Welding methods may include resistance seam welding, HF welding or laser welding; of these, laser welding may be preferred with an overlap joint geometry.

[0037] In an embodiment of the invention, the barrier liner has a laminated structure comprising a corrosion-resistant barrier layer and a polymer layer on each side of the foil that protects the barrier layer. When the barrier layer is formed into a tube, one of the polymer layers will be on the outer side of the tube, hence being regarded as an outer layer. The other polymer layer will be on the inner side of the tube, hence being regarded as an inner layer. The outer layer of polymer may be relatively thick, with a thickness of 1mm to 2mm and may be extruded or laminated onto the metallic foil. The inner polymer layer may be relatively thin in comparison to the outer polymer layer, with a thickness of 100 to 200 microns, for example. Like the outer polymer layer, the inner layer of polymer may be extruded or laminated onto the other side of the metallic foil, opposed to the thicker outer polymer layer.

[0038] In service, the barrier layer provides primary corrosion protection for the steel pipeline whereas the outer and optional inner polymer layers protect the barrier layer from damage and erosion.

[0039] As polymer contamination would result in an imperfect weld, the abutting or overlapping side edge regions of the metallic sheet must remain free from polymer. Thus, the outer and inner polymer layers do not extend across the full width of the sheet but are instead inset from the side edges. This leaves elongate tabs or strips extending along the length of the sheet and extending inwardly from the side edges, where the sheet is left exposed or uncoated.

[0040] After the longitudinal seam weld has been completed between the side edges to form the tube, the exposed metallic areas on the outer face of the tube and on the inner face of the tube are covered with polymer. Infilling those gaps with polymer in this way protects the metallic layer from damage and prevents direct contact of the metallic layer with the inner surface of the steel host pipe.

[0041] The resulting tubular barrier liner structure can then be installed into the host pipe before inserting the internal liner concentrically within the barrier liner using the Swagelining® technique. Radial expansion of the internal liner during elastic reversion presses the barrier liner firmly against the inner surface of the host pipe, with the outer polymer layer of the barrier liner being sandwiched between the steel of the host pipe and the metallic barrier layer of the barrier liner.

[0042] Embodiments of the invention disclose a method to manufacture a barrier pipe, the method comprising: providing a flat metallic foil; assembling a sandwich structure by laying one polymer layer on the metallic foil and one polymer layer below the metallic foil, so that the metallic foil is wider than each polymer layer along one axis; rolling or bending the sandwich to create a tubular barrier pipe by overlapping or abutting ends or edges of the metallic foil; welding the metallic foil at the overlap or edge-to-edge abutment; and covering the welded overlap or abutment by polymer. For example, an extra band or strip of polymer or a preliminarily folded overlength of the polymer layer may be fused, bonded, glued or stitched in place over the weld.

[0043] The method may further comprise lining a carrier or host pipe by inserting the barrier pipe, and adding an extra internal layer of polymer inside the barrier pipe after lining the carrier or host pipe.

[0044] The polymer layers may be layers of a resin-impregnated or resin-impregnable substrate, such as a polymer fabric, that is impregnated with a curable resin before or after rolling or bending the sandwich. The resin may be cured after inserting the barrier pipe to line the carrier or host pipe. The substrate and the resin may be of types used in cured-in-place pipe (CIPP) applications, being a rehabilitation method known for repairing existing pipelines.

[0045] Embodiments of the invention therefore also disclose applying at least one resin- impregnated or resin-impregnable substrate, such as a felt or fabric of polyester or fibreglass cloth, onto a continuous impermeable barrier layer that is integrated into a composite layup during manufacture. The resulting assembly is formed into a tube, inserted into a steel host pipe in one operation, after impregnating the substrate with resin if necessary, and then expanded within the host pipe and heated to cure the resin. This can be followed by insertion of a polymer internal liner by a Swagelining® operation. The polymer liner can include perforations or vents to allow gas flow between the barrier layer and the pipeline bore to mitigate liner collapse.

[0046] During manufacture, the substrate and a metallic barrier layer such as aluminium foil are laminated in a flat form leaving exposed tabs or peripheral strips of the barrier layer running along their length. To form a tube, the laminate is folded, rolled or bent and the sides of the barrier layer are seam welded together to form a continuous impermeable barrier. A further piece of the substrate material can then be stitched to the substrate or otherwise applied over the weld to complete the tube. Impregnation of resin into the substrate could be performed before or after this stage. The tube can then be reeled or delivered in flat form to site.

[0047] In addition to mitigating corrosion of the host steel pipeline and the risk of liner collapse due to migration of gas through the liner, the construction methods of the invention benefit from reduced installation cost compared to alternative technologies that are currently available. There is a significant cost reduction in personnel time and material cost, especially when compared to existing solutions involving corrosion-resistant alloys and metallurgically- or mechanically-lined pipes.

[0048] Secondary advantages may include reduced flow friction at the wall of the liner, less need for maintenance and inspection pigging and a reduced requirement for inhibitor injection, hydrate mediation and biocide injection. Other benefits include the ability to handle complex geometries such as lining bends, reducers and tees, hence presenting opportunities in other parts of system infrastructure. Pipeline repurposing and lining of infield lines would also be a possibility using techniques of the invention.

[0049] Thus, a barrier liner for a pipe can be made by bending an elongate sheet into a tube about a longitudinal axis of the sheet. The sheet comprises a metallic foil laminated on each side with at least one polymer layer, where each polymer layer is narrower than the foil in a direction transverse to the longitudinal axis. This defines exposed peripheral strips of the foil laterally outboard of the polymer layer that are brought together and joined by welding along a seam that extends substantially parallel to the longitudinal axis. The seam and the conjoined peripheral strips are then covered with a polymer infill that bridges between sides of the respective polymer layers in mutual opposition about the seam.

[0050] Embodiments of the invention also disclose a method to insert a barrier pipe inside a carrier or host pipe, which may be of steel. The method comprises: inserting a barrier pipe or tube comprising at least a metallic layer; and die-drawing a polymer layer inside the barrier layer, so that the barrier pipe or tube is pushed in contact with the carrier pipe by the reversion step of the die-drawing method.

[0051] Another polymer layer may be installed in the carrier or host pipe by die-drawing or by any other method before insertion of the barrier pipe or tube.

[0052] The barrier liner may form part of a wider liner system comprising the barrier liner and inner and outer polymer layers that sandwich the barrier pipe. The different layers of the liner system may be fabricated and installed separately and the final assembly results in a tight-fitting barrier liner for the host carbon steel pipeline. In service, the barrier layer of the barrier liner provides the primary corrosion protection for the host pipeline. The inner and outer polymer layers protect the barrier layer from damage and erosion.

[0053] Firstly, the host steel pipe is lined with a minimum wall thickness PE outer liner. In view of the barrier layer of the invention, gas is not expected to permeate through the outer liner. Consequently, as the requirement to design for collapse is eliminated, the outer liner need only have a minimum practical wall thickness to allow installation, preferably by the Swagelining® technique. The outside diameter of the outer liner is chosen to provide an optimum tightness of fit to the internal diameter of the host steel pipeline.

[0054] Next, the tubular barrier liner is inserted and expanded against the installed outer liner. The barrier liner comprises a metallic foil tube with a maximum wall thickness of, for example, 0.1mm. The foil must be sufficiently thick to prevent gas permeation through the wall of the barrier liner but sufficiently thin to allow the tube to be folded, inserted into the pre-lined steel pipe, and then expanded out to meet the internal diameter of the installed outer liner. The outer diameter of the barrier liner can be chosen to match the internal diameter of the outer polymer liner substantially exactly.

[0055] The barrier liner may be supplied as a lay-flat roll and pulled into the lined host steel pipe using a guide rope. After installation, the barrier liner can be secured at its ends and inflated to conform to the internal diameter of the lined steel pipe.

[0056] In a third step, the lined pipe can be further lined with a collapse-resistant PE inner liner, again preferably by the Swagelining® technique. Collapse resistance of this inner liner can be assured by the inclusion of vents at intervals to allow gas accumulations between the barrier layer and the inner liner to be vented back into the bore of the pipeline during cyclic depressurisation events. The flow rate through the vents is used to establish the size and frequency of the vent locations. The wall thickness of the inner liner is established based on the maximum pressure difference expected between the bore and the annulus between the inner liner and the barrier liner.

[0057] In summary, a barrier liner for a pipe can be made by inserting an elongate continuous metallic tubular barrier layer into a host pipe, for example after collapsing the barrier layer in cross-section to narrow it for insertion. The barrier layer is part of a tubular laminate that further comprises an outer polymer layer on a radially outer side of the tubular laminate and an inner polymer layer on a radially inner side of the tubular laminate. A polymer inner liner is then placed within the barrier layer and radially expanded within and against the barrier layer, for example by reversion after diedrawing. The barrier layer may be inserted into the host pipe when the host pipe is already lined internally with a polymer outer liner, which may also be installed by reversion after die-drawing.

[0058] In order that the invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings in which:

[0059] Figures 1a to 1d are a sequence of schematic plan views showing the creation of a laminated sheet to be formed into a barrier liner of the invention;

[0060] Figure 2 is a schematic side view showing a process of extruding a polymer layer onto a metallic barrier layer to form the laminated sheet shown in Figure 1b;

[0061] Figures 3a to 3d are a sequence of schematic end views showing the laminated sheet of Figure 1d being formed into a tubular barrier liner of the invention;

[0062] Figures 4a to 4d are a sequence of schematic end views showing a variant of the laminated sheet being formed into a tubular barrier liner of the invention;

[0063] Figures 5a and 5b are a sequence of schematic perspective views showing a tubular barrier liner of the invention being inserted into a steel host pipe;

[0064] Figures 6a and 6b are a sequence of schematic end views showing a further variant of the laminated sheet being formed into a tubular barrier liner of the invention;

[0065] Figure 7 is a schematic sectional side view showing the barrier liner of Figure 6b inserted into a steel host pipe and resin impregnated into the barrier liner being cured by internal heating;

[0066] Figure 8 is a schematic sectional side view showing a tubular internal liner being inserted into the host pipe within a barrier liner with the assistance of die drawing; Figure 9 is a schematic sectional side view showing reversion of the internal liner within the host pipe and the barrier liner;

[0067] Figure 10 is a schematic sectional side view showing a tubular outer liner being inserted into a steel host pipe with the assistance of die drawing;

[0068] Figure 11 is a schematic sectional side view showing reversion of the outer liner within the host pipe;

[0069] Figures 12a and 12b are a sequence of schematic perspective views showing a tubular barrier liner being inserted into the outer liner within the host pipe;

[0070] Figure 13 is a schematic sectional side view showing a tubular inner liner being inserted into the host pipe within the barrier liner with the assistance of die drawing;

[0071] Figure 14 is a schematic sectional side view showing reversion of the inner liner within the lined host pipe; and

[0072] Figure 15 is a schematic sectional detail side view of a termination arrangement of a pipeline constructed in accordance with the invention.

[0073] Referring firstly to Figures 1a to 1d and Figure 2, these drawings show the creation of a flexible laminated sheet 10 that can be formed into a barrier liner 12 of the invention as shown in Figures 3a to 3d. As best appreciated in Figure 1a, the sheet 10 comprises a barrier layer 14 defined by an elongate, preferably rectangular metallic foil that is of indeterminate length and has mutually parallel side edges 16. The foil of the barrier layer 14 may, for example, be of annealed aluminium with a thickness of 0.1mm.

[0074] Figure 1 b shows a first polymer layer 18 applied to a first major face of the foil barrier layer 14 to form, initially, a two-layer laminated sheet 10. The first polymer layer 18 extends across most but not all of the width of the barrier layer 14 between the side edges 16 and is disposed centrally between the side edges 16, hence being inset slightly from the side edges 16. This leaves elongate rectangular strips 20 outboard of the first polymer layer 18 where the foil of the barrier layer 14 is left exposed or uncoated. Those peripheral strips 20 extend along the length of the barrier layer 14 and inwardly from the respective side edges 16.

[0075] Figure 1c shows the laminated sheet 10 of Figure 1b from the second, as yet uncoated major face on the other side of the barrier layer 14. The outline of the first polymer layer 18 applied to the other major face of the barrier layer 14 is shown here in dashed lines.

[0076] Next, Figure 1d shows a second polymer layer 22 applied to the second major face of the barrier layer 14 to complete a three-layer laminated sheet 10 in which the barrier layer 14 is sandwiched between the first and second polymer layers 18, 22. Again, the second polymer layer 22 does not extend across the full width of the barrier layer 14, being disposed centrally between and inset from the side edges 16 to leave elongate rectangular strips 20 outboard of the second polymer layer 22 where the foil of the barrier layer 14 is left exposed or uncoated. Those exposed or uncoated peripheral strips 20 correspond to and overlie the similarly exposed or uncoated peripheral strips 20 on the first major face of the barrier layer 14.

[0077] Figure 2 shows that the foil of the barrier layer 14 is apt to be unspooled from a reel 24 and passed through an extruder 26 that extrudes the first polymer layer 18 onto the foil to form the two-layer laminated sheet 10 shown in Figure 1b. The second polymer layer 22 can similarly be extruded simultaneously or subsequently onto the other side of the foil to complete the three-layer laminated sheet 10 shown in Figure 1d.

[0078] Figures 3a to 3d show the three-layer laminated sheet 10 of Figure 1d being formed into a barrier liner 12 of the invention. For this purpose, the sheet 10 is bent across its width between the side edges 16 of the barrier layer 14, for example about a cylindrical mandrel 28 as shown in Figures 3a and 3b. The sheet 10 thereby adopts a generally circular cross-section that is curved about a central longitudinal axis 30 of the mandrel 28 extending parallel to the side edges 16.

[0079] When the sheet 10 has been bent through at least 360° of arc as shown in Figures 3a to 3d, the side edges 16 of the barrier layer 14 are brought together in mutual opposition to form a tube. In this example, the exposed or uncoated peripheral strips 20 inboard of the side edges 16 overlap to some extent as best appreciated in Figures 3a and 3b. In other examples, the side edges 16 may simply abut edge-to-edge. After the side edges 16 of the barrier layer 14 are brought together, they are joined together along their mutual interface as shown in Figure 3b, for example by laser welding, to form a circumferentially continuous, gas-impermeable tubular wall. Here, a welding head 32 is shown forming a longitudinal seam weld along the overlap, parallel to the central longitudinal axis 30 of the mandrel 28 and hence of the tube.

[0080] It will be apparent that after welding, gaps remain between the opposed side edges 16 of the polymer layers 18, 22, those gaps corresponding to the exposed or uncoated peripheral strips 20 where the opposed sides of the barrier layer 14 are welded together. Figure 3c shows polymer infill strips 34 being aligned with those gaps on the outside and the inside of the tube and Figure 3d shows one or more joining devices such as welding heads or heat guns 36 being used to weld, bond or otherwise join the infill strips 34 to the adjoining polymer layers 18, 22 along their mutual interfaces. The infill strips 34 bridge between the opposed side edges of the respective polymer layers 18, 22 and cover the gaps. As a result, there is a continuous circumferential coverage of polymer on the outer and inner sides of the barrier layer 14, which is thereby protected against damage and isolated from the inner surface of a host pipe when the barrier liner 12 is installed in the host pipe.

[0081] The polymer layers 18, 22 could differ substantially in thickness. For example, one of the polymer layers could have a thickness of 1mm to 2mm whereas the other of the polymer layers could have a thickness of 100 to 200 microns. In this example, the first polymer layer 18 is outermost in the barrier liner 12 and is thicker than the second polymer layer 22 that is innermost in the barrier liner 12. However, the first polymer layer 18 could be innermost and the second polymer layer 22 could be outermost instead. It is also possible for the second polymer layer 22 to be thicker than the first polymer layer 18.

[0082] In the examples shown, the infill strips 34 are slightly wider than the gaps between the opposed side edges of the polymer layers 18, 22 so that they overlap those side edges. In another example, the infill strips 34 could fit within the gaps in edge-to-edge abutment with the side edges of the polymer layers 18, 22.

[0083] Figures 4a to 4d show a variant of the laminated sheet 10 being formed into a tubular barrier liner 12 in a process akin to that shown in Figures 5a to 5d. Again, like numerals are used for like features. In this variant, infill strips are integral with the polymer layers 18, 22 as side flaps 38 of polymer that overlie, but are not initially bonded to, the exposed peripheral strips 20 of the barrier layer 14. The flaps 38 can therefore be folded back, away from the peripheral strips 20 of the barrier layer 14 as shown in Figure 6a, to provide clearance for welding together the opposed sides of the barrier layer 14 as shown in Figure 6b. The flaps 38 can then be folded back over the peripheral strips 20 of the barrier layer 14 as shown in Figure 6c and bonded or welded together as shown in Figure 6d to cover the gaps around the weld between the sides of the barrier layer 14.

[0084] Figures 5a and 5b show the tubular barrier liner 12 being inserted telescopically into a host pipe 40 of carbon steel. When with a circular cross-section, the external diameter of the barrier liner 12 corresponds closely to the internal diameter of the host pipe 40 as shown in Figure 7b. Thus, to ease insertion into the host pipe 40, the cross-section of the barrier liner 12 is initially collapsed by inward deflection of at least one portion of its tubular wall as shown in Figure 5a. This reduces the external diameter of the barrier liner 12 to achieve an easy sliding fit within the host pipe 40.

[0085] Once the barrier liner 12 reaches the appropriate longitudinal position within and with respect to the host pipe 40, the barrier liner 12 is expanded back out to adopt a circular cross-section as shown in Figure 5b, thus being in intimate contact with the interior of the host pipe 40 continuously around its full circumference. Also, the barrier liner 12 is of substantially the same length as the host pipe 40, thus lining the host pipe 40 continuously along substantially its full length.

[0086] Figures 6a and 6b show a further variant of the laminated sheet 10 being formed into a tubular barrier liner 12 of the invention. Again, like numerals are used for like parts. In this example, the polymer layers 18, 22 each comprise a resin-impregnated or resin- impregnable substrate such as a polyester fabric. As before, the barrier layer 14 is wider than the polymer layers 18, 22 to leave uncoated peripheral strips 20 at which the side edges of the barrier layer 14 are welded together.

[0087] Figure 6a shows the resulting gap between the opposed edges of the polymer layers 18, 22 being filled by knitting or sewing filaments 42 of a corresponding polymer using a knitting or sewing head 44. In an alternative solution, the gap in either or both of the polymer layers 18, 22 of the laminated sheet 10 could instead be filled with an infill strip 34 or flaps 38 like those described previously, made of the same resin-impregnated or resin-impregnable substrate material.

[0088] Figure 6b shows a spraying head 46 applying an impregnating resin to the substrate of the polymer layers 18, 22 of the barrier liner 12, in an optional step where the substrate material of the polymer layers 18, 22 are resin-impregnable rather than preimpregnated. The resin impregnating the substrate is usually a thermoset but could instead be a thermoplastic, especially in a pre-impregnated variant.

[0089] Figure 7 shows the barrier liner 12 of Figure 6b inserted into a steel host pipe 40 and expanded radially, bringing the resin-impregnated polymer layer 18 into close contact with the internal surface of the host pipe 40. A heating apparatus 48 is inserted into the host pipe 40 along its central longitudinal axis 50, in this example applying radiant heat against the inner surface of the barrier liner 12 defined by the barrier layer 14. The heating apparatus 48 could instead apply heat to the barrier liner 12 by other media such as hot water or steam. The metal of the barrier layer 14 conducts that heat efficiently into the surrounding resin-impregnated substrate of the polymer layer 18 to promote curing of the resin and hence adhesion of the barrier liner 12 to the host pipe 40.

[0090] Moving on now to Figure 8, this shows a tubular internal liner 52 being installed into the host pipe 40, within the barrier liner 12, using the Swagelining® technique. The internal liner 52, the barrier liner 12 and the host pipe 40 are in substantially concentric relation about a common central longitudinal axis 50. The internal liner 52 is pulled, from left to right as illustrated, by a draw line 54 that is attached to a tapered distal end of the internal liner 52. The draw line 54 is tensioned by a conventional jack system, which is not shown.

[0091] As shown to the left side of Figure 8, the internal liner 52 initially has an outer diameter that is greater than the inner diameter of the host pipe 40. Then, the internal liner 52 is pulled through an annular swage die 56 that is spaced longitudinally or upstream from a proximal end of the host pipe 40 and that tapers in the downstream or pulling direction. By causing radially-inward elastic deformation or contraction of the internal liner 52, the swage die 56 reduces the outer diameter of the internal liner 52 to less than the inner diameter of the host pipe 40. The internal liner 52 lengthens as its outer diameter reduces. Longitudinally-spaced perforations or vents 58 penetrate the tubular wall of the internal liner 52 to relieve overpressure in the micro-annulus between the internal liner 52 and the barrier liner 12 in operation. The vents 58 may, for example, be as described in WO 2023 / 041917, enabling the vents 58 to be installed into the internal liner 52 upstream of the swage die 56 and so to pass through the swage die 56 together with the internal liner 52 as shown. In principle, however, the vents 58 could instead be installed into the internal liner 52 downstream of the swage die 56.

[0092] In this narrowed and elongated swaged condition, the internal liner 52 is pulled telescopically through the host pipe 40 while longitudinal tension is maintained in the internal liner 52 between the draw line 54 and the swage die 56. Pulling continues until a distal end portion of the internal liner 52 protrudes from a distal end of the host pipe 40 as shown in Figure 8. A proximal end portion of the internal liner 52 is similarly left protruding between the proximal end of the host pipe 40 and the swage die 56 as also shown in Figure 8. The internal liner 52 is eventually severed in planes orthogonal to the central longitudinal axis 50, as shown by the dashed lines 60 in Figure 8.

[0093] When the internal liner 52 is in the correct longitudinal position with respect to the host pipe 40, tension in the draw line 54 is released. This initiates a reversion process that is shown in progress in Figure 9. During reversion, the elasticity of the polymer material of the internal liner 52 draws most of the protruding end portions of the internal liner 52 into the host pipe 40 as the internal liner 52 expands radially outwardly to press against the interior of the host pipe 40 via the barrier liner 12 that is sandwiched between them.

[0094] The radial expansion of the internal liner 52 may help to complete expansion of the barrier liner 12 from its initially collapsed state. The barrier liner 12 may thereby be unfolded to adopt a circular cross-section and / or may undergo elastic or plastic circumferential expansion on being pressed radially into intimate contact with the internal surface of the host pipe 40.

[0095] The vents 58 in the internal liner 52 effect fluid communication between the bore of the internal liner 52 and the inner micro-annulus 62 defined at the interface between the barrier liner 12 and the internal liner 52. An outer micro-annulus 64 is also present at the interface between the barrier liner 12 and the host pipe 40. However, no venting of the outer micro-annulus 64 is required because the barrier layer 14 substantially prevents migration of gas through the barrier liner 12 into the outer micro-annulus 64.

[0096] Figures 10 to 14 show a further variant of the invention in which die-drawing is used to install outer and inner polymer liners 66, 68 with an impermeable barrier liner 12 sandwiched between them in concentric relation. The outer polymer liner 66 is installed first into a host pipe 40 of carbon steel, the barrier liner 12 is installed next within the outer polymer liner 66, and then the inner polymer liner 68 is installed within the barrier liner 12.

[0097] The barrier liner 12 is of the same configuration as those described above, hence comprising inner and outer polymer layers 18, 22 in addition to a metallic barrier layer 14. The metallic barrier layer 14 is apt to be seam-welded from a thin flexible sheet of metal such as aluminium as before, allowing the barrier liner 12 to be collapsed for insertion into the outer polymer liner 66.

[0098] Figure 10 shows the tubular outer liner 66 being installed into the host pipe 40 using the Swagelining® technique. The outer liner 66 and the host pipe 40 are in substantially concentric relation about the common central longitudinal axis 50. A draw line 54 pulls the outer liner 66 through an annular swage die 56 that reduces the outer diameter of the outer liner 66 to less than the inner diameter of the host pipe 40. The outer liner 66 lengthens as its outer diameter reduces.

[0099] In this narrowed and elongated condition, the outer liner 66 is pulled telescopically through the host pipe 40 while longitudinal tension is maintained in the outer liner 66 between the draw line 54 and the swage die 56. Pulling continues until a distal end portion of the outer liner 66 protrudes from a distal end of the host pipe 40 as shown in Figure 10. A proximal end portion of the outer liner 66 is similarly left protruding between the proximal end of the host pipe 40 and the swage die 56 as also shown in Figure 10. The outer liner 66 is eventually severed in planes orthogonal to the central longitudinal axis 50, as shown by the dashed lines 60 in Figure 10.

[0100] When tension in the draw line 54 is released, this initiates a reversion process that is shown completed in Figure 11 . During reversion, the elasticity of the polymer material of the outer liner 66 draws most of the protruding end portions of the outer liner 66 into the host pipe 40 as the outer liner 66 expands radially outwardly to press against the interior of the host pipe 40.

[0101] Figures 12a and 12b show the tubular barrier liner 12 being inserted telescopically into the outer liner 66 installed within the host pipe 40. When with a circular cross-section, the external diameter of the barrier liner 12 corresponds closely to the internal diameter of the outer liner 66 as shown in Figure 12b. Thus, to ease insertion into the outer liner 66, the cross-section of the barrier liner 12 is initially collapsed by inward deflection of at least one portion of its tubular wall as shown in Figure 12a. This reduces the external diameter of the barrier liner 12 to allow an easy sliding fit within the outer liner 66.

[0102] Once the barrier liner 12 reaches the appropriate longitudinal position within and with respect to the outer liner 66, the barrier liner 12 is expanded back out to adopt a circular cross-section as shown in Figure 12b, thus being in intimate contact with the interior of the outer liner 66 continuously around its full circumference. Also, the barrier liner 12 is of substantially the same length as the inner liner 66, thus lining the inner liner 66 continuously along substantially its full length. Conversely, the outer liner 66 serves as a continuous spacer between the barrier layer 14 and the host pipe 40.

[0103] Figure 13 shows the tubular inner liner 68 being installed into the host pipe 40 using the Swagelining® technique. The inner liner 68, the outer liner 66, the barrier liner 12 and the host pipe 40 are in substantially concentric relation about the common central longitudinal axis 50. A draw line 54 pulls the inner liner 68 through an annular swage die 56 that reduces the outer diameter of the inner liner 68 to less than the inner diameter of the barrier liner 12. The inner liner 68 lengthens as its outer diameter reduces.

[0104] In this narrowed and elongated condition, the inner liner 68 is pulled telescopically through the host pipe 40 lined with the outer liner 66 and the barrier liner 12 while longitudinal tension is maintained in the inner liner 68 between the draw line 54 and the swage die 56. Pulling continues until a distal end portion of the inner liner 68 protrudes from a distal end of the barrier liner 12 as shown in Figure 13. A proximal end portion of the inner liner 68 is similarly left protruding between the proximal end of the barrier liner 12 and the swage die 56 as also shown in Figure 13. The inner liner 68 is eventually severed in planes orthogonal to the central longitudinal axis 50, as shown by the dashed lines 60 in Figure 13. When tension in the draw line 54 is released, this initiates a reversion process that is shown in progress in Figure 14. During reversion, the elasticity of the polymer material of the inner liner 68 draws most of the protruding end portions of the inner liner 68 into the barrier liner 12 as the inner liner 68 expands radially outwardly to press against the interior of the outer liner 66 via the barrier liner 12.

[0105] The radial expansion of the inner liner 68 may help to complete expansion of the barrier liner 12 from its initially collapsed state. The barrier liner 12 may thereby be unfolded to adopt a circular cross-section and / or may undergo elastic or plastic circumferential expansion on being pressed radially into intimate contact with the internal surface of the outer liner 66.

[0106] Longitudinally-spaced perforations or vents 58 penetrate the tubular wall of the inner liner 68 to relieve overpressure in the micro-annulus between the inner liner 68 and the barrier liner 12 in operation. Again, the vents 58 may be installed into the inner liner 68 upstream or downstream of the swage die 56.

[0107] The host pipe 40 lined by the barrier liner 12 in conjunction with the internal liner 52 or the outer and inner liners 66, 68 serves as a pipe joint that can be welded end-to-end with the host pipes of similar pipe joints to fabricate a lined pipeline or pipe stalk of any desired length. Thus, when reversion is complete, the ends of the barrier liner 12 and the internal liner 52 or the outer and inner liners 66, 68 are machined back to, or into, the corresponding ends of the host pipe 40. For example, the ends of the various liners 12, 52, 66, 68 may be machined to create sockets to receive polymer liner bridges whose outer shape complements the sockets.

[0108] Finally, after a suitable reversion period, a termination arrangement like that shown in Figure 15 is apt to be provided at an end of a pipeline lined in accordance with the invention. In the example shown in Figure 15, the barrier liner 12 is defined by a three- layer laminated sheet that comprises polymer layers 18, 22 on both sides of a metallic barrier layer 14, made for example by the steps shown in Figures 1a to 3d. Also, in the description of Figure 17 that follows, the outer liner 66 of Figures 12 to 16 could be substituted for the outer polymer layer 18 and the inner liner 68 of Figures 15 to 16 could be substituted for the internal liner 52, or the inner polymer layer 22. Similarly, the barrier liner 12 could be a plain metallic tube defining an uncoated barrier layer 14. Before installing the barrier liner 12 and the internal liner 52, an end portion of the host pipe 40 is mechanically or metallurgically lined with a short tubular inlay 70 of a corrosion-resistant alloy (CRA). An inboard ridged portion 72 of the CRA inlay 70 has a series of internal circumferential ridges that defines a castellated longitudinal section as shown.

[0109] When installed into the host pipe 40, the barrier liner 12 and the internal liner 52 extend together into the inlay 70. After installation, the barrier liner 12 and the internal liner 52 are cut back into the host pipe 40 for part of the length of the inlay 70, leaving a chamfered end that lies outboard of the ridged portion 72.

[0110] The internal liner 52 and the barrier liner 12 are pressed into engagement with the ridged portion 68 of the inlay 70 by radially outward force applied by a CRA compression ring 74 that is received in a circumferential recess 76 on the inner face of the internal liner 52. The recess 76 extends partially through the thickness of the internal liner 52. Engagement with the ridged portion 72 of the inlay 70 locks the internal liner 52 and the barrier liner 12 against longitudinal movement relative to the host pipe 40.

[0111] The barrier layer 14 of the barrier liner 12 is sandwiched between the host pipe 40 and the compression ring 74 via the outer polymer layer 18 on the radially outer side of the barrier layer 14 and the internal liner 52 and the inner polymer layer 22 on the radially inner side of the barrier layer 14.

[0112] Many other variations are possible within the inventive concept. For example, it is not essential that the polymer layers 18, 22 are extruded onto the barrier layer 14. Instead, at least one of the polymer layers 18, 22 could be defined by a flexible web that converges with and is applied to the barrier layer 14, for example after being unspooled from a reel. It would also be possible for at least one of the polymer layers 18, 22, or the infill strip 34, to be sprayed or sputtered onto or otherwise deposited onto the barrier layer 14, or for the barrier layer 14 to be sprayed or sputtered onto or otherwise deposited onto at least one of the polymer layers 18, 22.

[0113] The polymer of the polymer layers 18, 22 is apt to be exemplified by a thermoplastic such as polyethylene, but a thermoset polymer is also possible in principle. At least one polymer layer 18, 22 could comprise a polymer matrix with embedded reinforcing elements to define a composite structure. Die-drawn tubular liners 52, 66, 68 could also be reinforced. In principle, the side edges 16 of the barrier layer 14 could be joined by means other than a weld, such as an adhesive bond, provided that the resulting joint remains substantially impermeable to migration of gas.

Claims

Claims1. A method of manufacturing a barrier liner for a pipe, the method comprising: forming a tube by bending an elongate sheet about a longitudinal axis of the sheet, the sheet comprising a metallic foil laminated with at least one polymer layer on each side of the foil, so that the tube comprises an outer polymer layer on a radially outer side of the foil and an inner polymer layer on a radially inner side of the foil; wherein, before the sheet is bent to form the tube, the outer polymer layer and the inner polymer layer are each narrower than the foil in a direction transverse to the longitudinal axis, hence defining exposed peripheral strips of the foil laterally outboard of each of those polymer layers; bringing the peripheral strips of the foil together and joining the peripheral strips by welding along a seam that extends substantially parallel to the longitudinal axis; and covering the welded seam and the conjoined peripheral strips with a polymer infill on each of the radially inner side and the radially outer side of the foil that bridges between sides of the respective polymer layers in mutual opposition about the seam.

2. The method of Claim 1 , wherein the outer polymer layer is thicker than the inner polymer layer.

3. The method of Claim 2, wherein the outer polymer layer has a thickness of 1 mm to 2mm.

4. The method of Claim 2 or Claim 3, wherein the inner polymer layer has a thickness of 100 to 200 microns.

5. The method of any preceding claim, wherein the polymer infills comprise at least one infill strip and the method further comprises attaching the infill strip to the opposed sides of the outer polymer layer or the inner polymer layer.

6. The method of any of Claims 1 to 4, wherein the polymer infills comprise at least one polymer flap that is integral with or attached to the outer polymer layer and / or the inner polymer layer on one side of the seam and the method further comprises attaching a free end of the at least one flap to the respective polymer layer on an opposite side of the seam.

7. The method of Claim 6, preceded by folding the at least one flap away from the seam while welding along the seam.

8. The method of any of Claims 5 to 7, comprising attaching the infill strip or the flap by fusing or bonding.

9. The method of any of Claims 5 to 7, comprising attaching the infill strip or the flap by stitching or knitting.

10. The method of any preceding claim, comprising at least partially creating the polymer infills from filaments of polymer extending between the opposed sides of the outer polymer layer and / or the inner polymer layer.

11. The method of any preceding claim, wherein at least one of the outer polymer layer and the inner polymer layer comprises a substrate impregnated with a polymer resin.

12. The method of any of Claims 1 to 10, wherein at least one of the outer polymer layer and the inner polymer layer comprises a resin-impregnable substrate and the method further comprises impregnating the substrate with a polymer resin.

13. The method of Claim 12, comprising applying the resin to the substrate after forming the sheet into the tube.

14. The method of any of Claims 11 to 13, further comprising curing the resin after inserting the barrier liner into a host pipe.

15. The method of Claim 14, comprising curing the resin by applying heat to the resin via the barrier liner or the host pipe.

116. The method of any preceding claim, comprising preliminarily manufacturing the laminated sheet by assembling the foil and the outer and inner polymer layers.

17. The method of Claim 16, comprising extruding at least one of the outer polymer layer and the inner polymer layer onto the foil.

18. The method of any preceding claim, further comprising inserting the barrier liner into a host pipe.

19. The method of Claim 18, comprising collapsing the barrier liner in cross-section to narrow the barrier liner for insertion into the host pipe, and subsequently opening out the barrier liner into a circular cross-section within the host pipe.

20. The method of Claim 18 or Claim 19, comprising adding an additional polymer inner liner within the barrier liner after inserting the barrier liner into the host pipe.

21. The method of Claim 20, comprising radially expanding the inner liner within and against the barrier liner.

22. The method of Claim 21, comprising radially expanding the inner liner by reversion after die-drawing.

23. The method of any of Claims 20 to 22, comprising providing one or more vents that penetrate a wall of the inner liner.

24. The method of any of Claims 18 to 23, comprising inserting the barrier liner into the host pipe when the host pipe is already lined internally with a polymer outer liner.

25. The method of Claim 24, comprising inserting the barrier liner after radially expanding the outer liner within the host pipe.

26. The method of Claim 25, comprising radially expanding the outer liner by reversion after die-drawing.

27. The method of any of Claims 18 to 26, comprising terminating the host pipe with a compression ring disposed radially within and acting radially outwardly against the foil of the barrier liner.

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