Method of manufacturing a pipe

Abstract

A method of manufacturing a pipe (10) comprises providing a first tubular member (12) comprising a composite with conductive non-metallic elements (14) mixed into a thermoplastic polymer, and the second tubular member (16) comprising a thermoplastic polymer, disposing one of the tubular members around the other, and heating the conductive non-metallic elements (14) to partially melt and thereby bond the two tubular member (12, 16) to one another. Also provided is a pipe (10). The conductive non-metallic elements (14) may comprise carbon fibre, graphite, graphene, carbon nanotubes, black phosphorus, selenium, boron, silicon, germanium, arsenic, antimony, and tellurium. A third tubular member (126) made of thermoplastic may be provided and around which the first tubular member (12) is provided. One tubular member may be extruded or wound helically as a tape to dispose it onto another tubular member.

Description

[0001] Method of manufacturing a pipe

[0002] TECHNICAL FIELD

[0003] The invention relates to a method of manufacturing a pipe or pipe body, and to an associated pipe or pipe body. Particularly, though not exclusively, the invention relates to a method of manufacturing a pipe or pipe body for transport of production fluid, and to a pipe or pipe body for transport of production fluid.

[0004] BACKGROUND

[0005] Pipe is used for transport of production fluid, such as gas (for example, methane, ethane, or CO2), hydrocarbon fluids (for example, oil), water, or other fluids such as hydrogen, and is typically used in onshore or offshore water applications.

[0006] Pipe typically has a multi-layer pipe wall structure, including at least a layer formed of a composite and a layer (for example, an extruded polymer layer) formed of a polymer. The layers of the pipe are often bonded to one another during manufacturing, such that the pipe has, in effect, a single consolidated layer having multiple sub-layers. The composite layer and the polymer layer may be bonded, at least in part, to one another using a number of methods, including infrared radiant heating, hot gas convection heating, and laser heating. Each method heats the composite layer and polymer layer, such that polymer constituents of the composite layer bond to polymer constituents of the polymer layer. However, known methods may expose the pipe to too high temperatures, which may deform other layers of the pipe, fail to achieve a uniform bond between the layers, and / or are expensive and / or complex. Additionally, with known methods, it can be particularly difficult to control the temperature of the outermost layer of composite during the application of an outer polymer cover layer, and therefore to ensure bonding therebetween. It is an object of embodiments of the invention to provide an improved method of manufacturing a pipe or pipe body, and / or at least mitigate one or more problems associated with known arrangements.

[0007] SUMMARY OF THE INVENTION

[0008] According to an aspect of the invention, there is provided a method of manufacturing a pipe or pipe body, the method comprising: providing first and second tubular members, the first tubular member comprising a composite formed of a plurality of conductive elements and a first polymer with which the plurality of conductive elements are mixed, and the second tubular member comprising a second polymer; disposing one of the first and second tubular members about an outer surface of the other of the first and second tubular members to form a pipe assembly; and heating the plurality of conductive elements by induction heating to cause at least one of the first polymer and the second polymer to partially melt and thereby bond the first tubular member and the second tubular member to one another. Heating the plurality of conductive elements by induction heating may allow for more precise control of the heating of the first and / or second tubular members, compared to known methods. Moreover, heating the plurality of conductive elements by induction heating may allow heat to be applied uniformly throughout the first and / or second tubular members, such that a uniform, complete and / or sufficiently strong bond between the first and second tubular members may be achieved. Lower temperatures compared to known methods may be possible, owing to better control.

[0009] According to a further aspect of the invention, there is provided a method of manufacturing a pipe or pipe body, the method comprising: providing first and second tubular members, the first tubular member comprising a composite formed of a plurality of conductive non-metallic elements and a first thermoplastic polymer with which the plurality of conductive non-metallic elements are mixed, and the second tubular member comprising a second thermoplastic polymer; disposing one of the first and second tubular members about an outer surface of the other of the first and second tubular members to form a pipe assembly; and heating the plurality of conductive non-metallic elements by induction heating to cause at least one of the first thermoplastic polymer and the second thermoplastic polymer to partially melt and thereby bond the first tubular member and the second tubular member to one another. In certain embodiments, the plurality of conductive non-metallic elements may comprise at least one of fibres, filaments, particles, and yarns. Additionally, or alternatively, the plurality of conductive non-metallic elements may comprise at least one of carbon fibre, graphite, graphene, carbon nanotubes, black phosphorus, selenium, boron, silicon, germanium, arsenic, antimony, and tellurium.

[0010] In certain embodiments, the first thermoplastic polymer may comprise a polymer matrix and the plurality of conductive non-metallic elements may be disbursed in the polymer matrix. The plurality of conductive non-metallic elements may be disbursed homogeneously or non-homogeneously in the polymer matrix, i.e. the plurality of conductive non-metallic elements may be disbursed uniformly or non-uniformly throughout the polymer matrix.

[0011] In certain embodiments, one or more of the plurality of conductive non-metallic elements may be discontinuous. Additionally, or alternatively, the plurality of conductive non-metallic elements may be substantially aligned with one another. Additionally, or alternatively, one or more of the plurality of conductive non-metallic elements may be interlaced with one another, for example at least one of woven, knitted, braided and twisted.

[0012] In certain embodiments, the plurality of conductive non-metallic elements may comprise at least 30% and / or up to 60% by volume of the composite.

[0013] In certain embodiments, the disposing the one of the first and second tubular members about the outer surface of the other of the first and second tubular members may comprise extruding the one of the first and second tubular members about the outer surface of the other of the first and second tubular members.

[0014] In certain embodiments, the first thermoplastic polymer and the second thermoplastic polymer may be substantially the same as one another. Additionally, or alternatively, at least one of the first thermoplastic polymer and the second thermoplastic polymer may comprise at least one of a fluoropolymer, a polyamide, a polyether ether ketone, a polyetherketoneketone, a thermoplastic elastomer, a polyketone, a polyolefin, for example polyethylene or polypropylene, and high temperature adapted thermoplastic polymer resin materials.

[0015] In certain embodiments, the first tubular member may comprise one or more layers and each layer may comprise the composite. The one or more layers may be formed by helically wrapping a tape formed of the composite.

[0016] In certain embodiments, the heating of the plurality of conductive non-metallic elements may comprise heating only spaced apart regions along a length of the pipe assembly to bond the first tubular member and the second tubular member to one another at predetermined locations along a length thereof.

[0017] In certain embodiments, the heating the plurality of conductive non-metallic elements may comprise introducing the pipe assembly into an induction heating coil; and applying a current to the coil to cause the coil to generate a magnetic field and thereby induce circulating eddy currents in the plurality of conductive non-metallic elements. The coil may be coaxial with a longitudinal axis of the pipe assembly. The current may comprise a frequency of at least 10 kHz and / or up to 100 kHz.

[0018] In certain embodiments, prior to the disposing the one of the first and second tubular members about the outer surface of the other of the first and second tubular members, the method may further comprise: providing a third tubular member comprising a third thermoplastic polymer; and disposing the other of the first and second tubular members about an outer surface of the third tubular member. The heating the plurality of conductive non-metallic elements by induction heating may be a temperature less than the melting point of the third thermoplastic polymer. After the disposing the other of the first and second tubular members about an outer surface of the third tubular member, the method may further comprise bonding the other of the first and second tubular members and the third tubular member to one another.

[0019] According to a further aspect of the invention, there is provided a pipe or pipe body comprising: a first tubular member comprising a composite formed of a plurality of conductive elements and a first polymer with which the plurality of conductive elements are mixed; and a second tubular member comprising a second polymer, wherein one of the first and second tubular members are disposed about an outer surface of the other of the first and second tubular members to form a pipe assembly, and the first tubular member and the second tubular member are bonded to one another.

[0020] According to yet a further aspect of the invention, there is provided a pipe or pipe body comprising: a first tubular member comprising a composite formed of a plurality of conductive non-metallic elements and a first thermoplastic polymer with which the plurality of conductive non-metallic elements are mixed; and a second tubular member comprising a second thermoplastic polymer, wherein one of the first and second tubular members are disposed about an outer surface of the other of the first and second tubular members to form a pipe assembly, and the first tubular member and the second tubular member are bonded to one another.

[0021] In certain embodiments, the first tubular member may comprise one or more layers. The one or more layers may be formed by a helically wrapped tape formed of the composite. In certain embodiments, the pipe or pipe body may be a flexible pipe or pipe body for transport of production fluid. In certain embodiments, the pipe or pipe body may comprise multiple layers including one or more of a structural layer and a permeation barrier layer, the structural layer and / or the permeation barrier layer provided at least in part by the first tubular member.

[0022] The features of all the above-described aspects are intended to be, and should be understood to be, combinable with one another, unless mutually exclusive.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying Figures, in which:

[0025] Figure 1 is a cross-sectional view of a pipe body according to an embodiment of the invention;

[0026] Figure 2 is a cross-sectional view of a further pipe body according to an embodiment of the invention;

[0027] Figure 3 is a cross-sectional view the pipe body of Figure 1 and an induction heating coil in which the pipe body is introduced;

[0028] Figure 4 is a flowchart of a method of manufacturing a pipe body according to an embodiment of the invention;

[0029] Figure 5 is a partial perspective view of a further pipe body according to an embodiment of the invention; and

[0030] Figure 6 is a schematic view of a riser assembly. DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0031] Figure 1 illustrates a pipe body 10 according to an embodiment of the invention. Reference will be made herein to the pipe body 10, and it should be understood that the pipe body 10 may be an assembly of a portion of a pipe body and one or more end fittings, in each of which a respective end of the pipe body is terminated. The pipe body 10 may have particular application for use as, or in, a pipe, including a flexible pipe, for transportation of production fluid in onshore or offshore water applications. More specifically, the pipe body 10 may have application for use as, or in, one of a reinforced thermoplastic pipe (RTP) , such as, for example, described in the standard API 15S, a thermoplastic composite pipe, an offshore pipe, such as, for example described in standard API 17J, and a hybrid pipe, where elements of different types of pipe bodies are combined into one pipe. Production fluid may include at least one of gas (for example, methane, ethane, hydrogen or CO2), hydrocarbon fluids (for example, oil), water, or other fluids such as slurry.

[0032] The pipe body 10 is formed from a combination of layered materials that form a pressure-containing conduit. Although a number of particular layers are illustrated in Figure 1 , it is to be understood that the pipe body 10 is broadly applicable to coaxial structures including two or more layers manufactured from a variety of possible materials. For example, the pipe body 10 may be formed from polymer layers, metallic layers, composite layers, or a combination of different materials. The pipe body 10 may include further layers (not shown), including unbonded metallic or non-metallic helically wrapped armour tendons, an insulation layer and / or an abrasion resistance layer. The pipe body 10 may have an internal diameter of at least 2 inches and / or up to 8 inches. The layer thicknesses are shown for illustrative purposes only. As used herein, the term “composite” is used to broadly refer to a material that is formed from two or more different materials, for example, a material formed from a matrix material and a reinforcement material, such as reinforcement fibres.

[0033] The pipe body 10 includes a first tubular member 12 including a composite formed of a plurality of conductive non-metallic elements 14 and a first thermoplastic polymer with which the plurality of conductive non-metallic elements 14 are mixed. The first tubular member 12 provides a pipe layer of a pipe, or a flexible pipe layer of a flexible pipe. The pipe body 10 further includes a second tubular member 16 including a second thermoplastic polymer. The second tubular member 14 also provides a pipe layer of a pipe, or a flexible pipe layer of a flexible pipe. As shown in Figure 1 , in this embodiment, the second tubular member 16 is disposed about an outer surface 20 of the first tubular member 12 to form a pipe assembly 18. However, in other embodiments, the first tubular member 12 may be disposed about an outer surface 22 of the second tubular member 16 to form the pipe assembly 18. In the illustrated embodiment, the second tubular member 16 is disposed about the outer surface 20 of the first tubular member 12 such that there is substantially no gap therebetween, and the first and second tubular members extend coaxially with one another. The first tubular member 12 and the second tubular member 16 are bonded to one another by a method according the invention as described herein. The plurality of conductive non- metallic elements 14 are heatable by induction heating, such that the first thermoplastic polymer is heatable by conduction of the heat generated in the plurality of conductive non-metallic elements 14.

[0034] The plurality of conductive non-metallic elements 14 may include any suitable elements. Particularly suitable elements may include at least one of fibres, filaments, particles, and yarns. The fibres may be staple fibres or filaments, the filaments being continuous stands of fibre and including monofilament fibres and multifilament fibres. The fibres and / or the filaments maybe by interlaced with one another to form yarns, for example to provide monofilament or multifilament yarns. The yarns may be interlaced with one another. Therefore, it should be understood that one or more of the non-conductive elements 14 may be continuous, elongate members, allowing the first tubular layer 12 to be continuously reinforced. Additionally, or alternatively, one or more of the plurality of conductive non-metallic elements 14 may be discontinuous, allowing the first tubular layer 12 to be discontinuously reinforced, for example by staple fibres or the particles. The particles may be nanoparticles and / or microparticles. The filaments may have a tow size of from 3000 and / or up to 12,000. The term “interlaced” refers to being, for example, woven, knitted, braided or twisted The first thermoplastic polymer may be a polymer matrix, with the plurality of conductive non-metallic elements 14 disbursed in the polymer matrix. The polymer matrix may be a monolithic material. The plurality of conductive non-metallic elements 14 may be disbursed non-homogeneously in the polymer matrix. For example, the plurality of conductive non-metallic elements 14 may be disbursed such that they are distributed in a higher concentration / proportion towards the outer surface 20 or the inner surface 24 of the first tubular member 12 and / or at specific points along a length of the first tubular member 12. Disbursing the plurality of conductive non-metallic elements 14 non-homogenously may allow for improved control over the locations which the first and second tubular members 12, 16 are heated, and subsequently partially melted and bonded to the second tubular member 16. The quantity of the plurality of conductive non-metallic elements 14 may be adjusted, accordingly. Alternatively, the plurality of conductive non-metallic elements may be disbursed homogenously in the polymer matrix. For example, the plurality of conductive non- metallic elements 14 may be disbursed throughout the polymer such they are distributed in a substantially uniform concentration / proportion along a length, depth and / or circumference of the first tubular member 12. Additionally, or alternatively, the plurality of conductive non-metallic elements 14 may be formed as a first laminar layer. In such embodiments, the first polymer may be a second laminar layer, and the first laminar layer may be disposed about an inner and / or outer surface the second laminar layer.

[0035] The plurality of conductive non-metallic elements 14 may be provided by any suitable material. Particularly suitable materials for providing the plurality of conductive non- metallic elements 14 include carbon fibre, graphite, graphene, carbon nanotubes, black phosphorus, selenium, boron, silicon, germanium, arsenic, antimony, and tellurium. In certain embodiments, the plurality of conductive non-metallic elements 14 may comprise carbon fibre filaments. The plurality of conductive non-metallic elements may be substantially aligned with one another. In other words, the plurality of conductive non-metallic elements may be unidirectional. The plurality of conductive non-metallic elements may be aligned parallel with a direction of loading so as to improve the strength of the pipe body 10 in said direction and / or a direction of flux of a magnetic field so as to improve conductivity of the plurality of conductive non-metallic elements in said direction. Alternatively, the plurality of conductive non-metallic elements may be bidirectional, where the plurality of conductive non-metallic elements include at least a first set of conductive non- metallic elements oriented in a first direction and a second set of conductive non- metallic elements oriented in a second direction, different from the first direction. The first set of conductive non-metallic elements may be oriented perpendicular to the second set of conductive non-metallic elements. In certain embodiments, the plurality of conductive non-metallic elements may be substantially randomly oriented in relation to one another. Randomly orientating the plurality of conductive non-metallic elements may improve the resistance of the pipe body 10 to loads acting in multiple directions.

[0036] In certain embodiments, the first thermoplastic polymer may comprise a plurality of polymer elements (not shown). For example, the plurality of polymer elements may include at least one of fibres, filaments, and yarns. The plurality of conductive non- metallic elements 14 may be mixed with the plurality of polymer elements, for example by commingling or interlacing. In this way, the uniformity of the distribution of the plurality of conductive non-metallic elements 14 along a length, depth, and / or circumference of the first tubular member 12 may be improved.

[0037] The plurality of conductive non-metallic elements may be at least 30% and / or up to 60% of a volume of the composite. For example, the plurality of conductive non- metallic elements may be 60% of the volume of the composite. The first thermoplastic polymer may constitute the remaining volume of the composite. Alternatively, where the composite includes further constituents, the remaining volume may include the first thermoplastic polymer and the further constituents of the composite. The first tubular member 12 may include one or more layers and each layer may be formed from the composite. Increasing the number of layers of the first tubular member 12 may increase the strength of the pipe body 10. Each of the layers of the first tubular member 12 may be homogenous. Alternatively, the layers of the first tubular member 12 may be non-homogenous. For example, the layers of the first tubular member 12 disposed towards an inner or outer surface 20, 112 of the first tubular member 12 may have a higher, or lower, concentration of the plurality of conductive non-metallic elements 14. The one or more layers may be layers of a helical wrapped a tape formed of the composite. The one or more layers of the first tubular member 12 may be wrapped having a lay angle of at least 45° and / or up to 90°. For example, the one or more layers may be wrapped having a lay angle of 55°. The one or more layers of the first tubular member 12 may be wrapped having an overlap between adjacent layers of the first tubular member 12 of at least 0% and / or up to 80%.

[0038] Additionally, the first tubular member 12 may comprise a combination of tapes presenting different concentrations of conductive non-metallic elements 14, or tapes comprising areas of different concentrations of conductive non-metallic elements in order to change or promote flexibility of the tubular member 12 and / or the pipe body 10. The areas of lower concentration of conductive non-metallic elements may essentially comprise only polymer, while other areas may comprise up to 60% of a volume of the composite. The concentration of conductive non-metallic elements may vary through the thickness of the first tubular member 12, increasing or decreasing, as desired, to change the physical properties of the first tubular member 12 and / or the pipe body 10.

[0039] Figure 2 illustrates a further pipe body 100 according to another embodiment of the invention. The pipe body 100 has the same features as the pipe body 100 described above with reference to Figure 1 , with like features denoted by reference numerals offset by a factor of 100, and has the same applications. The pipe body 100 additionally includes a third tubular member 126, which includes a third thermoplastic polymer. As shown in Figure 2, in this embodiment, the first tubular member 112 is disposed about an outer surface 128 of the third tubular member 126. In the illustrated embodiment, the first tubular member 112 is disposed about the outer surface 128 of the third tubular member 126 such that there is substantially no gap therebetween, and the first, second and third tubular members 112, 116, 126 extend substantially coaxially with one another. However, in certain embodiments, the second tubular member 116 may be disposed about the outer surface 128 of the third tubular member 126, with the first tubular member 112 disposed about the outer surface 122 of the second tubular member 116. In the illustrated embodiment, the first tubular member 112 is bonded to the outer surface 128 of the third tubular member 126. Of course, in view of the above, in other embodiments, the second tubular member 116 may be bonded to the outer surface 128 of the third tubular member 126.

[0040] Each or any of the first, second and third thermoplastic polymers may be formed of at least one of a fluoropolymer, a polyamide, a polyether ether ketone, a polyetherketoneketone, a thermoplastic elastomer, a polyketone, a polyolefin, for example polyethylene or polypropylene, and high temperature adapted thermoplastic polymer resin materials. The fluoropolymer may be polyvinylidene fluoride (PVDF). The polyamide may be at least one of polyamide / nylon 11 (PA 11 ) and polyamide / nylon 12 (PA 12). Any of the thermoplastic polymers may be compatible with one or more of the others. The third thermoplastic polymer may have a melting point greater than the melting point of the first and / or second thermoplastic polymers, for example a melting point greater than 150 °C.

[0041] The plurality of conductive non-metallic elements 14 are heatable by induction heating. In order to heat the plurality of conductive non-metallic elements 14, the elements 14 may be introduced into an electromagnetic field.

[0042] Figure 3 illustrates the pipe body 10 of Figure 1 and an induction heating coil 30, for generating a magnetic field. Figure 4 illustrates a flowchart of a method 40 of manufacturing a pipe body 10 according to an embodiment of the invention, primarily described with reference to the pipe body 10 illustrated in Figure 1 , in which the conductive non-metallic elements 14 are heated by induction heating.

[0043] The method 40 comprises a first step 42 including providing the first and second tubular members 12, 16. As shown in Figure 4, in this embodiment, the method comprises a second step 44 including disposing the second tubular member 16 about the outer surface 20 of the first tubular member 12 to form the pipe assembly 18. Alternatively, in other embodiments, the method may include disposing the first tubular member 12 about the outer surface 22 of the second tubular member 16 to form the pipe assembly 18. The method 40 comprises a third step 46 including heating the plurality of conductive non-metallic elements 14 by induction heating. The heating of the elements 14, in turn, heats the first thermoplastic polymer, by conduction of the heat generated in the elements 14, thereby causing it to at least partially melt and bond the first tubular member 12 and the second tubular member 16 to one another. The bond may fully form only after cooling of the first thermoplastic polymer, and / or the wider arrangement of the described features. In certain embodiments, disposing the second tubular member 16 about the outer surface 20, of the first tubular member 12 may include extruding the second tubular member about the outer surface of the other of the first tubular member 12, or visa versa. The first or second tubular member 12, 16 may be extruded such that the first or second tubular member 12, 16 corresponds in shape to the outer surface 20, 22 of the other of the first and second tubular member 12, 16. In this way, there may be substantially no gap between the first and second tubular members 12, 16.

[0044] The first and second tubular member 12, 16 may be formed a tape, and the disposing the one of the first and second tubular members 12, 16 about the outer surface 20, 22 of the other of the first and second tubular members 12, 16 may include helically wrapping the tape of one of the first and second tubular members 12, 16 about the outer surface 20, 22 of the other of the first and second tubular members 12, 16. For example, the tape of the second tubular member 16 may be helically wrapped about an outer surface 20 of the first tubular member 12. Following helically wrapping the tape, pressure may be applied to the tape by rollers, such that the tape and the other of the first and second tubular members 12, 16 adhere to one another. The rollers may follow the tape position and lay angle of the tape.

[0045] The heating the plurality of conductive non-metallic elements may include introducing the pipe assembly 18 into the induction heating coil 30. For example, the pipe assembly 18 may be inserted into the induction heating coil 30, or the induction heating coil 30 may be disposed about the pipe assembly 18. An electric current may be applied to the coil 30 to cause the coil 30 to generate a magnetic field and thereby induce eddy currents in the plurality of conductive non-metallic elements.

[0046] The coil 30 may be helical, including a plurality of turns spaced from one another along a length of the coil 30. The coil 30 may include any number of turns. As shown in Figure 3, the coil 30 may be coaxial with the first tubular member 12 and / or the pipe assembly 18. The coil 30 may extend along at least part of the length of the pipe assembly 18. The internal diameter of the coil 30 may substantially correspond to, though be slightly larger than, the outer diameter of the pipe assembly 18. In this way, the coil 30 is spaced from the outer surface 22 of the second tubular members 16 to delimit an annular gap therebetween. The plurality of conductive non-metallic elements may be heated to a temperature from 120°C and / or up 150°C.

[0047] The current may have a frequency from 10 to 100 kHz. For example, the current may have a frequency of 20 kHz. The current applied to the coil 300 may be adjusted so as to control the depth of the pipe assembly 18 (measured inwardly from an outer surface 20, 22 of the pipe assembly 18) which the magnetic field penetrates (i.e., increasing the current applied to the coil 30 reduces the penetration depth of the magnetic field). In certain embodiments, the electric current may be configured such that the magnetic field penetrates only outer layers 20, 22 of the pipe assembly 18 (for example, at least the first tubular member 12), or parts thereof. In this way, the circulating eddy currents may be confined to a subset of elements of the plurality of conductive non-metallic elements 14. This configuration avoids heating conductive elements disposed in layers of the pipe body 10 which are not to be bonded. The current may be an alternating current. The current may be applied to the coil 30 by an electrical source (e.g., mains electricity or a generator).

[0048] Heating of the plurality of conductive non-metallic elements may include heating only spaced apart regions along a length of the pipe assembly 18 to bond the first tubular member 12 and the second tubular member 16 to one another at predetermined locations along a length thereof. End sections of a pipe body 10 may be bonded to facilitate transport, storage, and use of lengths of the pipe body 10. In such an example, the coil 300 may be placed at the predetermined locations along the length of the pipe assembly 18 so as to heat the spaced apart regions.

[0049] The first, second and third steps 42, 44, 46 are chronological, though not necessarily consecutive, so the method 40 may include additional steps intermediate one or more of the first, second and third steps, 42, 44, 46. In certain embodiments, as shown in Figure 4, there may first and second intermediate steps 48, 50, which occur between the first and second steps 42, 44, and which are described below with reference to the pipe body 100 illustrated in Figure 2.

[0050] The first intermediate step 48 includes, prior to disposing second tubular member 116 about the outer surface 120 of the first tubular memberl 12, providing the third tubular member 126. The second intermediate step includes disposing the first tubular member 112 about the outer surface 128 of the third tubular member 126. In certain embodiments, the first tubular member 112 may be a tape, and the tape may be helically wrapped about the outer surface 128 of the third tubular member 126. Pressure may be applied to the tape by rollers, such that the tape and the third tubular member 126 adhere to one another.

[0051] In certain embodiments, there may be further intermediate steps (not shown). For example, after disposing the first tubular member 112, 116 about the outer surface of the third tubular member, the method may further include bonding first tubular member 112 and the third tubular 126 to one another. The bonding of the first tubular member 112 to the outer surface 128 of the third tubular member 126 may include heating the first and / or third thermoplastic polymers to cause the first and / or third thermoplastic polymers to partially melt and thereby bond the other of the first and second tubular member 112, 116 to the third tubular member. Such heating may be by any one of infrared radiant heating, hot gas convection heating, and laser heating. Heating the plurality of conductive non-metallic elements by induction heating may be to a temperature less than the melting point of the third thermoplastic polymer. Consequently, the third tubular member 126 may not be adversely heated during bonding the first and second tubular members 102, 104 to one another, thereby protecting the third tubular member 126 from damage or deformation, including delamination or debonding from adjacent members and / or layers.

[0052] Further steps may be added to the method 40, wherein additional layers are applied around the outer surface of the second tubular member 16, 116, for instance unbonded metallic or non-metallic helically wrapped armour tendons, an insulation layer and / or an abrasion resistance layer. A further extruded polymer outer cover may also be applied as an outer sheath for wear protection and / or to prevent ingress of water (resulting in corrosion) to armour elements.

[0053] Figure 5 illustrates a further pipe body 60 according to an embodiment of the invention. As with the pipe bodies 10, 100 described with reference to Figures 1 and 2, the pipe body 60 may have particular application for use as, or in, a flexible pipe body, including a flexible pipe, for transportation of production fluid in onshore or offshore water applications. More specifically, the pipe body 10 may have application for use as, or in, one of a reinforced thermoplastic pipe (RTP) such as, for example, described in the standard API 15S, a thermoplastic composite pipe, an offshore pipe, such as, for example described in standard API 17J, and a hybrid pipe, where elements of different types of pipe bodies are combined into one pipe.

[0054] As illustrated in Figure 5, the pipe body 60 includes an optional innermost carcass layer 62. The carcass 62 provides an interlocked construction that can be used as the innermost layer to prevent, totally or partially, collapse of an internal pressure sheath 64 due to pipe decompression, external pressure, and tensile armour pressure and mechanical crushing loads. The carcass layer 62 is often a metallic layer, formed from stainless steel, for example. The carcass layer 62 could also be formed from composite, polymer, or other material, or a combination of materials. It will be appreciated that certain embodiments are applicable to ‘smooth bore’ operations (i.e., without a carcass layer 62) as well as such ‘rough bore’ applications (i.e., with a carcass layer 62).

[0055] The internal pressure sheath 64 acts as a fluid retaining layer and includes a polymer layer that ensures internal fluid integrity. It is to be understood that this layer 64 may itself include a number of sub-layers. It will be appreciated that, when the optional carcass layer 62 is utilised, the internal pressure sheath 64 is often referred to by those skilled in the art as a barrier layer. In operation, without such a carcass 62 (so-called smooth bore operation), the internal pressure sheath 64 may be referred to as a liner.

[0056] An optional pressure armour layer 66 is a structural layer that increases the resistance of the flexible pipe to internal and external pressure and mechanical crushing loads. The layer 66 also structurally supports the internal pressure sheath 64, and typically may be formed from an interlocked construction of wires wound with a lay angle close to 90°. The pressure armour layer 66 is often a metallic layer, formed from carbon steel, for example. The pressure armour layer 66 could also be formed from composite, polymer, or other material, or a combination of materials.

[0057] The pipe body 60 also includes an optional first tensile armour layer 70 and optional second tensile armour layer 72. Each tensile armour layer 70, 72 is used to sustain tensile loads and internal pressure. The tensile armour layer 70, 72 is often formed from a plurality metallic of wires (to impart strength to the layer) that are located over an inner layer and are helically wound along the length of the pipe body 60 at a lay angle typically between about 10° to 55°. The tensile armour layers 70, 72 are often counter wound in pairs. The tensile armour layers 70, 72 are often metallic layers, formed from carbon steel, for example. The tensile armour layers 70, 72 could also be formed from composite, polymer, or other material, or a combination of materials.

[0058] The pipe body 60 shown also includes optional layers of tape 68 which help contain underlying layers and to some extent prevent abrasion between adjacent layers. The tape layer 68 may be a polymer, composite, or a combination of materials.

[0059] The pipe body 60 may include optional layers of insulation 74 and an outer sheath 76, which includes a polymer layer, used to protect the pipe body 60 against penetration of seawater and other external environments, corrosion, abrasion, and mechanical damage.

[0060] One or more of the above-described layers 62, 64, 68, 70, 72, 74, 76, may be provided by a first tubular member 12, 112 as described with reference to Figures 1 and 2, with the second tubular member 16, 116 and / or third tubular layer 126 providing adjacent layer or layers. Generally, a pipe or pipe body may include multiple layers including one or more of a structural layer and a permeation barrier layer. The structural layer may be provided at least in part by the first tubular member 12, 112. Additionally, or alternatively, the permeation barrier layer may be provided in part by the first tubular member 12, 112. Figure 6 illustrates a riser assembly 80 suitable for transporting production fluid such as oil and / or gas and / or water from a sub-sea location 82 to a floating facility. In Figure 6, the sub-sea location 82 includes a sub-sea flow line 90. The flexible flow line 90 includes a pipe (or flexible pipe), wholly or in part, resting on the sea floor 88 or buried below the sea floor 88 and used in a static application. The floating facility 84 may be provided by a platform and / or buoy or, as illustrated in Figure 6, a ship. The riser assembly 80 is provided as a flexible riser 86, that is to say a pipe (or a flexible pipe) connecting the ship to the sea floor installation. The pipe of the flow line 90 and / or the flexible riser 86 may be in segments of pipe body with connecting end fittings. The pipe body may be provided as described above. Portions of pipe can be utilised as a flow line 90 or jumper 92

[0061] It will be appreciated that there are different types of riser, as is well-known by those skilled in the art. Embodiments may be used with any type of riser, such as a freely suspended (free, catenary riser), a riser restrained to some extent (buoys, chains), totally restrained riser, or enclosed in a tube (I or J tubes).

[0062] The invention is not restricted to the details of any foregoing embodiments. Throughout the description and claims of this specification, the words “comprise”, “contain”, “having” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers, or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0063] Features, integers, and characteristics, described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. In particular, the phrase “certain embodiments” is to be understood to mean any embodiment described, illustrated, or otherwise disclosed herein. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A method of manufacturing a pipe or pipe body, the method comprising: providing first and second tubular members, the first tubular member comprising a composite formed of a plurality of conductive non-metallic elements and a first thermoplastic polymer with which the plurality of conductive non-metallic elements are mixed, and the second tubular member comprising a second thermoplastic polymer; disposing one of the first and second tubular members about an outer surface of the other of the first and second tubular members to form a pipe assembly; and heating the plurality of conductive non-metallic elements by induction heating to cause at least one of the first thermoplastic polymer and the second thermoplastic polymer to partially melt and thereby bond the first tubular member and the second tubular member to one another.

2. A method according to claim 1 , wherein the plurality of conductive non- metallic elements comprises at least one of fibres, filaments particles, and yarns.

3. A method according to claim 1 or 2, wherein the plurality of conductive non- metallic elements comprises at least one of carbon fibre, graphite, graphene, carbon nanotubes, black phosphorus, selenium, boron, silicon, germanium, arsenic, antimony, and tellurium.

4. A method according to any preceding claim, wherein the first thermoplastic polymer comprises a polymer matrix and the plurality of conductive non-metallic elements are disbursed in the polymer matrix.

5. A method according to claim 4, wherein the plurality of conductive non- metallic elements are disbursed non-homogeneously in the polymer matrix.

6. A method according to any preceding claim, wherein one or more of the plurality of conductive non-metallic elements are discontinuous.

7. A method according to any preceding claim, wherein the plurality of conductive non-metallic elements are substantially aligned with one another.

8. A method according to any preceding claim, wherein one or more of the plurality of conductive non-metallic elements are interlaced with one another.

9. A method according to any preceding claim, wherein the plurality of conductive non-metallic elements comprises at least 30% and / or up to 60% by volume of the composite.

10. A method according to any preceding claim, wherein the disposing the one of the first and second tubular members about the outer surface of the other of the first and second tubular members comprises extruding the one of the first and second tubular members about the outer surface of the other of the first and second tubular members.

11. A method according to any preceding claim, wherein the first thermoplastic polymer and the second thermoplastic polymer are substantially the same as one another.

12. A method according to any preceding claim, wherein at least one of the first thermoplastic polymer and the second thermoplastic polymer comprises at least one of a fluoropolymer, a polyamide, a polyether ether ketone, a polyetherketoneketone, a thermoplastic elastomer, a polyketone, a polyolefin, for example polyethylene or polypropylene, and high temperature adapted thermoplastic polymer resin materials.

13. A method according to any preceding claim, wherein the first tubular member comprises one or more layers and each layer comprises the composite.

14. A method according to claim 13, wherein the one or more layers is formed by helically wrapping a tape formed of the composite.

15. A method according to any preceding claim, wherein the heating of the plurality of conductive non-metallic elements comprises heating only spaced apart regions along a length of the pipe assembly to bond the first tubular member and the second tubular member to one another at predetermined locations along a length thereof.

16. A method according to any preceding claim, wherein the heating the plurality of conductive non-metallic elements comprises: introducing the pipe assembly into an induction heating coil; and applying a current to the coil to cause the coil to generate a magnetic field and thereby induce circulating eddy currents in the plurality of conductive non-metallic elements.

17. A method according to claim 16, wherein the coil is coaxial with a longitudinal axis of the pipe assembly.

18. A method according to any of claims 16 or 17, wherein the current comprises a frequency of at least 10 kHz and / or up to to 100 kHz.

19. A method according to any proceeding claim, wherein prior to the disposing the one of the first and second tubular members about the outer surface of the other of the first and second tubular members, the method further comprises: providing a third tubular member comprising a third thermoplastic polymer; anddisposing the other of the first and second tubular members about an outer surface of the third tubular member.

20. A method according to claim 19, wherein the heating the plurality of conductive non-metallic elements by induction heating is to a temperature less than the melting point of the third thermoplastic polymer.

21. A method according to claim 19 or 20, wherein after the disposing the other of the of the first and second tubular members about an outer surface of the third tubular member, the method further comprises bonding the other of the first and second tubular members and the third tubular member to one another.

22. A pipe or pipe body comprising: a first tubular member comprising a composite formed of a plurality of conductive non-metallic elements and a first thermoplastic polymer with which the plurality of conductive non-metallic elements are mixed; and a second tubular member comprising a second thermoplastic polymer, wherein one of the first and second tubular members are disposed about an outer surface of the other of the first and second tubular members to form a pipe assembly, and the first tubular member and the second tubular member are bonded to one another.

23. A pipe of pipe body according to claim 22, wherein the first tubular member comprises one or more layers and each layer is formed by a helically wrapped tape formed of the composite.

24. A pipe according to claim 22 or 23, wherein the pipe or pipe body is a flexible pipe or pipe body for transport of production fluid.

25. A pipe according to any of claims 22 to 24, wherein the pipe or pipe body comprises multiple layers including one or more of a structural layer and a permeation barrier layer, the structural layer and / or the permeation barrier layer provided at least in part by the first tubular member.

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