Permeation barrier and method of manufacture

Abstract

A flexible pipe body for delivering production fluid, a flexible riser, and a method of manufacturing a flexible pipe body are disclosed. The flexible pipe body includes: an internal pressure sheath; a permeation barrier for reducing fluid permeation of the production fluid towards a pipe annulus; a metal armor layer positioned radially outward of the permeation barrier; and a composite tape layer comprising a plurality of fibers, where the composite tape layer is positioned radially between the permeation barrier and the metal armor layer.

Description

Technical Field

[0001] The present invention relates to a flexible pipe body comprising a permeability barrier and a method of manufacturing the same. In particular, but not exclusively, the present invention relates to a permeability barrier for reducing the penetration of fluids into a pipe annulus. Background Art

[0002] Flexible pipes can be used in particular to connect a seafloor location (which may be deep sea) to a sea level location. The pipe may have an inner diameter typically up to about 0.6 meters (e.g., the diameter may be in the range of 0.05 m to up to 0.6 m). Flexible pipes are typically formed as an assembly of a flexible pipe body and one or more end fittings. The flexible pipe body is typically formed as a combination of layered materials that form a pressure-bearing conduit. The pipe structure allows large flexures without causing bending stresses that would impair the function of the pipe during its life. The flexible pipe body is typically constructed as a combined structure comprising polymer layers and / or metal layers and / or composite material layers. For example, the flexible pipe body may include a polymer layer and a metal layer, or a polymer layer and a composite material layer, or a polymer layer, a metal layer and a composite material layer.

[0003] API Recommended Practice 17B provides guidance for the design, analysis, manufacture, testing, installation, and operation of flexible pipes and flexible pipe systems for onshore, subsea, and offshore applications. API Specification 17J, titled "Specification for Unbonded Flexible Pipe," defines the technical requirements for safe, dimensionally and functionally interchangeable flexible pipes that are designed and manufactured to uniform standards and criteria.

[0004] The flexible pipe body generally includes a fluid retaining layer (called a barrier layer or liner), which is generally formed as a polymer jacket or a pressure jacket. Such a layer operates as a main fluid retaining layer. In order to prevent the rupture of such a layer caused by the pressure of the conveying fluid, an interlocking wire layer (called a pressure armor layer) is generally located radially outside the fluid retaining layer. A typical flexible pipe body includes one or more armor layers, optionally including a pressure armor layer. The main load on such a layer is formed by radial forces. The pressure armor layer generally has a specific cross-sectional profile to interlock so that it can maintain and absorb the radial forces generated by the external or internal pressure on the pipe. Therefore, the cross-sectional profile of the winding wire that prevents the pipe from collapsing or rupturing due to pressure is sometimes called a pressure-resistant profile. When the armor layer is formed by a spirally wound wire forming a hoop component, the radial force from the internal or external pressure on the pipe causes the hoop component to expand or contract, thereby applying a tensile or compressive load to the wire, respectively.

[0005] Some known examples of pressure armour layers may be provided in the form of a tape or composite tape that is wrapped or wound around a radially inward layer. The tape has a thickness so as to provide sufficient hoop strength for the flexible pipe body. In addition, the tape is oriented to ensure that its longitudinal strength is arranged circumferentially or substantially circumferentially around the axis of the flexible pipe body. Thus, the tape is wrapped or wound at a lay angle of 80° to 90° relative to the axis to provide a pressure armour layer formed by the tape. In these ways, the tape or composite tape forms a pressure armour layer that is capable of retaining and absorbing radial forces generated by the pressure in the pipe.

[0006] One or more tensile armour layers may be positioned radially outwardly of the pressure armour layers. The tensile armour is used to withstand tensile loads and internal pressure. The tensile armour layers are typically formed from a plurality of wires (to give the layer strength) which are positioned above the inner layer and wound helically along the length of the tube. The tensile armour layers are typically metal layers, such as formed from carbon steel. The tensile armour layers may alternatively be composite tendons of a matrix material reinforced with suitable fibres, such as glass, carbon, aramid, basalt or metal.

[0007] Flexible pipes are used to transport produced fluids such as oil and / or gas and / or water from one location to another. As used herein, "fluid" includes both liquid and gaseous substances. When produced fluids are transported through flexible pipes, fluids such as carbon dioxide and hydrogen sulfide gas, for example, can penetrate the innermost layer (e.g., internal pressure sheath) of the flexible pipe body.

[0008] As used herein, permeation, particularly permeation of a fluid through a layer of a flexible pipe, may include both fluid transmission through the bulk of the layer and fluid leakage through discontinuities or gaps in the layer, as will be readily apparent from the context of the accompanying description.

[0009] These fluids then accumulate in the pipe annulus. This can result in a corrosive environment, particularly when associated with the presence of water in the annulus, such as during an annulus flooding event. Corrosive environments are known to cause pipe failures due to stress corrosion cracking of metal pipe layers, particularly those used within the armor layer. Additionally, the accumulation of annular fluids can result in over-pressurization and mechanical failure of the flexible pipe.

[0010] Some known examples of flexible pipe bodies provide a permeability barrier (also known as a packing layer) radially outside the internal pressure jacket. The permeability barrier is typically configured as a barrier to fluids (ie production fluids) that permeate through the internal pressure jacket due to the internal pressure therein.

[0011] A problem with some flexible pipe bodies is that the permeability barrier does not have sufficient mechanical strength. Specifically, the permeability barrier cannot withstand the uneven and localized layer strains caused by the internal pressure driving the pipe layer material into the interstices of the overlying pipe layer, resulting in localized mechanical damage to the permeability barrier during operation. Mechanical damage to the permeability barrier increases the risk of the permeability barrier being breached by fluids during use, or at least increases the penetration through the permeability barrier layer.

[0012] Another problem is that the permeability barrier may be damaged by contact with an armor layer positioned radially outside the permeability barrier or by the geometry of the armor layer. Such contact or geometry may cause damage to the permeability barrier during manufacturing and / or by interface pressures forcing the permeability barrier against the armor layer. In particular, the permeability barrier may thereby be damaged by interface pressures against an uneven opposing inner surface of an overlying armor layer.

[0013] Metal permeation barriers are well known (e.g. those described in ASTM B479) and for pipes British Standard BS 8588 describes polyethylene pipe incorporating an aluminium barrier layer, however for the reasons discussed above such permeation barriers may not be suitable for use in the case of high pressure flexible pipe where a spiral metal armour layer would be applied to withstand the internal fluid pressure in the flexible pipe.

[0014] Certain examples of the present invention are intended to at least partially solve, mitigate or eliminate at least one of the problems and / or disadvantages associated with the prior art. Certain embodiments are intended to provide at least one of the advantages described below. Summary of the invention

[0015] The invention is set out in the appended claims.

[0016] According to a first aspect, there is provided a flexible pipe body for conveying a production fluid, the flexible pipe body comprising:

[0017] Internal pressure sheath;

[0018] a permeability barrier for reducing fluid penetration of the produced fluid into the pipe annulus; a metal armor layer positioned radially outward of the permeability barrier; and

[0019] A composite tape layer, the composite tape layer comprising a plurality of fibers,

[0020] Wherein the composite tape layer is positioned radially between the permeation barrier and the metal armor layer.

[0021] Undesirable fluid penetration from the produced fluid into the (usually via the transmission) pipe annulus is further reduced or even prevented by providing a metal armor layer and additional composite tape layers to support the permeability barrier. Infiltration is prevented while ensuring the reliability and integrity of the permeability barrier.

[0022] It is known that permeation barriers may include metal tapes or foils, and that permeation through the metal is extremely low, so that permeation that does occur is essentially fluid leakage between and around the turns of such permeation barrier tape. Similarly, polymer tapes or films comprising materials with very low permeation properties (such as PEEK, PEKK or ethylene-vinyl alcohol copolymer (EVOH) or the like) are known and may be used in permeation barriers. The performance of permeation barriers comprising barrier tapes, films or foils may be optimized by reducing the thickness of the tapes and increasing the number of layers of tapes, ensuring overlap of the turns of the tapes to increase the tortuosity of the path that the fluid must take to pass through the permeation barrier. By providing additional layers of composite tape to support the permeation barrier, the permeation barrier is protected from strain damage, and in addition, permeation of undesirable fluids that do migrate through the permeation barrier must also successfully pass through the tortuous permeation path to pass through the composite tape layers, thereby further limiting the exposure of the metal armor layer in the pipe body to undesirable fluids.

[0023] Suitably, the thickness of the permeation barrier tape, film or foil may be between 0.00001 mm and 1.0 mm. Suitably, the thickness of the permeation barrier tape, film or foil may be between 0.005 mm and 0.5 mm. Suitably, the thickness of the permeation barrier tape, film or foil may be between 0.01 mm and 0.5 mm. The composite tape layer is thereby configured to provide optimum support and wear resistance in a convenient and adaptable manner without providing the primary hoop strength of the flexible pipe body. The composite tape layer thereby further provides additional resistance to permeation of acid gas species.

[0024] Suitably, the composite tape layer is positioned radially inwardly of and directly adjacent to the helically wound metal armour layer.

[0025] Suitably, the permeation barrier comprises a spirally wound tape or membrane.

[0026] Suitably, the helically wound band of the permeability barrier comprises a lay angle in the range greater than 20° to less than 80° relative to the axis of the flexible pipe body.

[0027] Suitably, the spirally wound tape or the membrane of the permeation barrier comprises a metal.

[0028] Suitably, the metal armour layer comprises at least one helically wound metal tape having a first longitudinal edge and a second longitudinal edge, and wherein the metal armour layer comprises an overlap region coextensive with the first longitudinal edge of a first tape wrap turn and the second longitudinal edge of a second tape wrap turn of the helically wound metal tape. In this way, the overlap region is a helical overlap region.

[0029] Suitably, the composite tape layer is configured to cover the overlap region between laterally adjacent tape wrap turns of radially adjacent metal armour layers. Typically, laterally adjacent tape wrap turns of the composite tape are provided with the same lay angle. Thus, the overlap may reduce fluid penetration through the composite tape layer by reducing or removing gaps between adjacent tape wrap turns. In particular, fluid leakage through discontinuities between laterally adjacent tape wrap turns or between radially adjacent tape wrap turn sub-layers is thereby reduced.

[0030] Suitably, the helically wound metal armour layer is a pressure armour layer or a tensile armour layer.

[0031] Suitably, the metal armour layer is a pressure armour layer having a lay angle of at least 80° relative to the axis of the flexible pipe body.

[0032] Suitably, the layer of composite tape comprises a helically wound composite tape having a lay angle in the range greater than 20° to less than 80° relative to the flexible pipe axis.

[0033] Suitably, the composite tape layer and the permeation barrier are at least partially bonded to each other. In this way, a composite tape layer is provided which is located on the back side of the permeation barrier.

[0034] Suitably, the composite tape layer and the permeation barrier are at least partially bonded to one another using an adhesive.

[0035] Suitably, the composite tape layer and the permeation barrier are at least partially bonded to one another using melt consolidation or melt bonding, without the need for an adhesive.

[0036] Suitably, the permeation barrier and the internal pressure sheath are at least partially bonded to one another.

[0037] Suitably, the permeability barrier comprises a fluid-impermeable material. That is, the spirally wound band or the membrane of the permeability barrier comprises a fluid-impermeable material. The permeability barrier thereby reduces fluid penetration into the pipe annulus. Specifically, fluid transmission through the permeability barrier is thereby reduced.

[0038] Suitably, the permeation barrier comprises a metal, and preferably wherein the metal comprises stainless steel or an alloy comprising at least one of nickel, titanium, aluminium, zinc, copper, tin or silver.

[0039] Suitably, the permeation barrier comprises a low permeability polymer, and preferably, wherein the low permeability polymer comprises at least one of PFA, PEEK, PEKK, PTFE, polyketone, ethylene vinyl alcohol copolymer, polyethylene, polypropylene, PVDF or PPS.

[0040] Suitably, the permeation barrier comprises ethylene vinyl alcohol copolymer provided as a coextruded tape.More suitably, the coextruded tape comprises at least three layers comprising the ethylene vinyl alcohol copolymer sandwiched between sub-layers of at least one thermoplastic polymer.

[0041] Suitably, the low permeability polymer comprises a filler material.

[0042] Suitably, the filler material comprises particles or fibres. More suitably, the filler material comprises at least one of an oxide, a silicate, a carbonate, carbon, a glass or a basalt.

[0043] Suitably, the plurality of fibres of the composite tape layer are continuous fibres. More suitably, the continuous fibres are arranged along the longitudinal direction of the composite tape.

[0044] Fibers can be long or short to optimize or exploit their strength in one or more directions in the composite. Long, continuous fibers are generally considered to be oriented primarily in one particular direction to provide strength to the composite in that orientation.

[0045] Suitably, the plurality of fibres in the composite tape layer comprises one or more of carbon fibres, glass fibres, basalt fibres, aramid fibres, drawn polymer fibres or metal wires.

[0046] Suitably, the composite tape layer comprises a plurality of sub-layers.

[0047] Suitably, the composite tape layer comprises at least one composite tape, wherein the composite tape has a thickness of less than 1 mm, suitably less than 0.5 mm, and more suitably less than 0.25 mm. In this way, the composite tape provides an effective permeation barrier while being thin, i.e. not thick enough to contribute substantially to the hoop strength of the flexible pipe body. The flexibility of the pipe is maintained.

[0048] Suitably, the composite tape layer has a thickness of less than 5mm, and suitably has a thickness of less than 2mm.

[0049] Suitably, the composite tape layer is less than 50% relative to the thickness of the metal armour layer, suitably less than 30% and more suitably less than 15%.

[0050] According to another aspect, there is provided a flexible riser comprising a flexible pipe body as disclosed herein.

[0051] According to yet another aspect, there is provided a method of manufacturing a flexible pipe body, the method comprising:

[0052] Provides internal pressure sheath,

[0053] providing a permeation barrier layer for reducing fluid penetration;

[0054] providing a composite tape layer, the composite tape layer comprising a plurality of fibers; and

[0055] A metal armor layer is provided radially outwardly of the permeation barrier layer and the composite tape layer such that the composite tape layer is between the permeation barrier layer and the metal armor layer.

[0056] Suitably, the step of providing the permeation barrier comprises winding a helically wound tape onto the flexible pipe body at a lay angle of between greater than 20° and less than 80° relative to the axis of the flexible pipe body. In this way, the method ensures that the resulting flexible pipe body is able to flex without risk of damaging the permeation barrier.

[0057] Suitably, the step of providing the composite tape layer comprises winding the composite tape onto the flexible pipe body at a lay angle of greater than 20° and less than 80° relative to the axis of the flexible pipe body. In this way, the method ensures that the resulting flexible pipe body is able to flex without the risk of damaging the composite tape layer and thereby the permeation barrier layer.

[0058] Suitably, the lay angle of the helically wound tape of the permeation barrier layer is different to the lay angle of the composite tape of the composite tape layer.

[0059] Unless explicitly stated otherwise, all features of the invention are considered to be combinable with each other.

[0060] Certain examples provide the following advantages: A flexible pipe body can be provided with reduced undesirable fluid penetration into the pipe annulus. In particular, penetration through the transmission is reduced. As a result, the resulting annulus environment can be milder than conventional flexible pipe, which can achieve increased pipe life.

[0061] Certain examples provide support for the permeable barrier, thereby reducing or even preventing undesired fluid penetration (particularly via transport) from the produced fluid into the pipe annulus, while ensuring the reliability and integrity of the permeable barrier, preventing penetration.

[0062] Certain examples provide the best support and wear resistance.

[0063] Certain examples provide a more adaptable layer arrangement in a flexible pipe body. Specifically, the permeation barrier and accompanying composite tape layers may be more specifically tailored to the intended use of the flexible pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Embodiments of the present invention are further described below with reference to the accompanying drawings, in which:

[0065] Figure 1 A flexible pipe body is illustrated;

[0066] Figure 2 illustrates a riser system;

[0067] Figure 3 (a) cross-sectional view and (b) enlarged cross-sectional view illustrating an example layer arrangement of a flexible pipe body;

[0068] Figure 4 illustrates (a) a known example of a composite tape layer wrapped around an internal pressure sheath at a lay angle α and (b) an example lay angle β of a layer according to the invention;

[0069] Figure 5 illustrating a cross-sectional view of layers and corresponding sub-layers of an example arrangement of a flexible pipe body;

[0070] Figure 6 Illustrated Figure 5 A top view of an example winding arrangement of sub-layers;

[0071] Figure 7 illustrates a cross-sectional view of another example layer arrangement of a flexible pipe body;

[0072] Figure 8 a flow chart illustrating a method of manufacturing a flexible pipe body; and

[0073] Fig. 9 A flow chart illustrating another method of manufacturing a flexible pipe body.

[0074] In the drawings, like reference numerals refer to like parts. DETAILED DESCRIPTION

[0075] Certain terms used in the following description are for convenience only and are not limiting. The words "inward", "inwardly" and "outwardly", "outwardly" refer to directions toward and away from a designated centerline or geometric center (e.g., central axis) of the described element, respectively, and the specific meaning is readily apparent from the context of the description.

[0076] Furthermore, unless otherwise stated, the use of ordinal adjectives such as "first," "second," and the like merely indicates different instances of similar objects being referred to and is not intended to imply that the objects so described must be in a given order temporally, spatially, in sequence, or in any other manner.

[0077] Throughout the specification reference will be made to flexible pipe.It will be understood that a flexible pipe is an assembly of a portion of a flexible pipe body and one or more end fittings in each of which a respective end of the flexible pipe body terminates. Figure 1 1 illustrates how a flexible pipe body 100 may be formed from a combination of layered materials that form a pressure containing conduit according to one example. Figure 1 Although a number of specific layers are illustrated in the drawings, it should be understood that the flexible pipe body is broadly applicable to coaxial structures including two or more layers made of a variety of possible materials. For example, the flexible pipe body can be formed of polymer layers, metal layers, composite layers, or a combination of different materials. It should also be noted that the layer thicknesses are shown only for illustrative purposes.

[0078] Although some layers of the flexible pipe body may be described as bonded or consolidated, the flexible pipe may generally be considered to be an unbonded flexible pipe. That is, unless otherwise stated, the layers of the flexible pipe body are unbonded and are thus able to move longitudinally relative to adjacent layers during bending or flexing of the flexible pipe body.

[0079] As used herein, a layer may optionally include sublayers. Multiple sublayers are combined to form a layer with a specific purpose. For example, a pressure armor layer may be formed from one or more pressure armor sublayers.

[0080] As used herein, a composite material refers to a material formed from two or more different materials, such as a material formed from a matrix material and reinforcing fibers. In some examples, the composite material may be a composite tape layer. In other examples, the composite material may include an extruded layer. The fibers within the composite material may include any of carbon fibers, glass fibers, aramid fibers, basalt fibers, stretched polymer fibers, metal wires, or any combination thereof.

[0081] As used herein, tape is to be interpreted broadly to encompass any elongated structure of preformed cross-section that is capable of being wound in a spiral manner around an underlying structure. Thus, tape refers to an elongated material provided in a wrappable or windable form so as to form a layer by wrapping or winding around a radially inward layer of a flexible pipe body. For example, a composite tape is a wrappable or windable elongated composite material used to form a composite tape layer.

[0082] As used herein, the term "lay angle" refers to the angle at which a tape or layer is applied to (i.e., wrapped around) the underlying structure of a flexible pipe body. Thus, the lay angle is an angle relative to the longitudinal axis of the flexible pipe body. A tape with a lay angle of 90° would be a tape that wraps around a radius of the cross-section of the flexible pipe body.

[0083] It will be appreciated that the term "radially" is used to refer to a position relative to a radius of the flexible pipe body. For example, the term "radially inward" means a position relatively closer to the center or central longitudinal axis of the flexible pipe body, and "radially outward" means a position relatively further away from the center or central longitudinal axis of the flexible pipe body.

[0084] Reference now Figure 1 , illustrates a conventional layer arrangement of a flexible pipe body 100. In this example, the flexible pipe body 100 includes an optional innermost carcass layer 101. The carcass layer 101 provides an interlocking structure that can be used as an innermost layer to completely or partially prevent the internal pressure sheath 102 from collapsing due to pipe decompression, external pressure, and tensile armor pressure and mechanical breaking loads. The carcass layer 101 is typically a metal layer formed, for example, of stainless steel. The carcass layer 101 can also be formed of a composite material, a polymer, or other material, or a combination of materials. It should be understood that certain embodiments are suitable for "smooth hole" operations (i.e., without a carcass layer) as well as such "rough hole" applications (with a carcass layer).

[0085] The internal pressure sheath 102 acts as a fluid retaining layer and comprises a polymer layer that ensures the integrity of the internal fluid. It should be understood that this layer itself may comprise multiple sub-layers. It should be understood that when the optional carcass layer 101 is used, the internal pressure sheath 102 is generally referred to as a barrier layer by those skilled in the art. In operations without such a carcass layer 101 (so-called smooth hole operations), the internal pressure sheath 102 may be referred to as a liner.

[0086] An optional sacrificial layer or wear layer (not shown) may also be added as an extruded layer or a spirally wound tape layer on either or both of the radially inner or radially outer sides of the internal pressure sheath; these layers respectively provide a relatively smooth (compared to the outer surface of the carcass layer) surface over which the internal pressure sheath is extruded, or provide a sacrificial material layer that can creep under pressure into the gaps between the wrapped turns of the overlying metal armor layer (particularly the pressure armor layer).

[0087] The optional pressure armour layer 103 is disposed radially outside the internal pressure sheath 102. The pressure armour layer 103 is a structural layer that increases the resistance of the flexible pipe to internal and external pressures and mechanical breaking loads. That is, the pressure armour layer 103 bears radial loads. The pressure armour layer 103 specifically provides hoop strength to the flexible pipe body 100.

[0088] The pressure armor layer 103 also structurally supports the inner pressure sheath 102. Figure 4 (a), the pressure armour layer 103 is formed by an interlocking construction of wires wound at a lay angle α relative to the flexible pipe body axis AA. The lay angle α is typically close to 90°. In this way, the laterally adjacent interlocking wires provide a rigid pressure armour layer 103 that provides maximum hoop strength for the entire flexible pipe body 100.

[0089] As shown, the flexible pipe body 100 includes sub-layers including a first tensile armor layer 105 and a second tensile armor layer 106. Each tensile armor layer is used to withstand tensile loads and internal pressures and is wound around the pipe body at angles that are optimized to achieve the desired tensile and pressure load-bearing balance. For example, when pressure armor wires are not used in the design (and the tensile armor must withstand both compression and tension), the lay angle of the tensile armor wires can be about + / -55°, however when pressure armor is incorporated and the tensile armor is primarily intended to withstand tensile loads, their lay angles can be much lower, such as as low as 27° to 30°. Each tensile armor layer is formed of a plurality of wires (to give the layer strength) that are located above the inner layer and are spirally wound along the length of the pipe. The tensile armor layers are typically wound in pairs in opposite directions. The tensile armor layers are typically metal layers, such as formed of carbon steel.

[0090] The flexible pipe body 100 shown also includes optional tape layers 104 provided radially outwardly of the tensile armour layers 105, 106 which help to contain underlying layers and to provide a degree of protection against abrasion between adjacent layers.

[0091] The flexible pipe body 100 also typically includes an optional insulating layer 107 and an outer jacket 108, which includes a polymer layer for protecting the pipe from penetration, corrosion, abrasion and mechanical damage by seawater and other external environments. Additional layers (not shown) may also be added radially outside the outer jacket 108 to provide additional wear / abrasion protection for the pipe and prevent damage to the outer jacket 108.

[0092] Each flexible pipe 100 includes at least one portion (sometimes referred to as a section or segment of the flexible pipe body 100) and an end fitting located at at least one end of the flexible pipe. The end fitting provides a mechanical device that forms a transition between the flexible pipe body and the connector. For example, Figure 1 The different pipe layers shown terminate in end fittings so that loads are transferred between the flexible pipe body and the connector.

[0093] Reference now Figure 2 , shows a known riser assembly 200 suitable for transporting produced fluids such as oil and / or gas and / or water from a seafloor location 201 to a floating facility. Figure 2 In the embodiment, the seafloor location 201 includes a seafloor flow line. The flexible flow line 205 includes a flexible pipe 203 that is fully or partially resting on or buried below the seafloor 204 and is used for static applications. The floating facility can be composed of a platform and / or a buoy or a floating structure such as a mobile station. Figure 2 The vessel 200 shown provides a riser assembly 200 in the form of a flexible riser, ie a flexible pipe 203 connecting the vessel to a seabed facility. The flexible pipe 203 may be located in a section of a flexible pipe body having connecting end fittings.

[0094] It should be understood that there are different types of risers, as is well known to those skilled in the art. Embodiments may be used with any type of riser, such as a freely suspended riser (free catenary riser), a riser constrained to some extent (buoy, chain), a fully constrained riser or enclosed in a tube (I-tube or J-tube). Figure 2 It is also illustrated how portions of the flexible pipe body may be used as flow lines 205 or jumpers.

[0095] Reference now Figure 3 (a) and Figure 3 (b) shows an example layer arrangement of a flexible pipe body 300 in cross section. In this example, the flexible pipe body 300 includes an internal pressure sheath 302. The internal pressure sheath 302 defines a flexible pipe bore. In some examples, a carcass layer (not shown) may be provided radially inwardly of the internal pressure sheath 302 to define the pipe bore.

[0096] The tape layers (not shown), the tensile armour layers 305, 306 and the outer jacket 308 are provided in a radially outer portion of the flexible pipe body 300. Figure 1 These layers are described and therefore will not be described again for the sake of brevity.Although not illustrated, one or more insulating layers and / or abrasion layers may also be included in the flexible pipe body 300 as is known in the art.

[0097] In the example shown, the flexible pipe body 300 in this example includes a metallic pressure armour layer 303. The pressure armour layer 303 is a helically wound pressure layer, typically formed of carbon steel. The metallic pressure armour layer 303 is positioned radially outwardly of the permeation barrier 310.

[0098] The metal armor layer 303 includes one or more metal armor tapes. The metal armor tapes are helically wrapped or wound radially outside of the permeation barrier 310. In the example shown, successive wrapping turns of the metal pressure armor tape are wrapped directly around the composite tape layer 320 to provide an overlap area between laterally adjacent wrapping turns of the tape. It should be understood that a sacrificial layer or wear layer may be introduced between the composite material layer and the metal armor layer. Such sacrificial layers or wear layers may include tape or extruded polymers, as known in the art.

[0099] The metal armor layer 303 has an interlocking structure (Z-shaped profile). Each metal armor wire includes opposing longitudinal edges 303a, 303b that include interengaging features as known in the art. In this manner, transversely adjacent tape wrap turns of the metal armor layer 303 interlock in the overlapping areas between the transverse longitudinal edges. In this manner, the metal armor layer 303 primarily provides hoop strength to the flexible pipe body 300. The metal armor layer 303 bears radial loads on the flexible pipe body 300.

[0100] The metal armor layer 303 is arranged radially outside the internal pressure sheath 302 .

[0101] It will be appreciated that for tubes of a design where interlocking metal pressure armor is not required and the metal tensile armor provides both pressure reinforcement and tensile reinforcement to the tube, Figure 3 The pressure armor layer 303 shown in FIG. 3 can be omitted. In such a design, the tensile armor is a metal armor layer.

[0102] The flexible pipe body 300 comprises a permeation barrier 310 positioned radially inwardly of the metal armour 303. In the example shown, the permeation barrier 310 is disposed between the internal pressure sheath 302 and the metal armour 303. The internal pressure sheath 302 is positioned radially inwardly of the permeation barrier 310.

[0103] The permeability barrier layer 310 reduces fluid penetration through the flexible pipe body 300 by virtue of the features described herein. Undesirable fluid penetration from the production fluid into the pipe annulus is thereby prevented or reduced.

[0104] In the example shown, the permeability barrier 310 is a tape, film or foil. Advantageously, the film or foil ensures that the permeability barrier layer 310 is a continuous permeability barrier layer (all edges of the permeability barrier tape are covered by further permeability barrier tape segments or wrap turns, optionally bonded to each other), thereby providing a continuous permeability barrier along the flexible pipe body 300. In particular, the permeability barrier is a metal tape, film or foil providing a fluid impermeable layer along the flexible pipe body 300. Undesirable fluid penetration (particularly via transport) from the produced fluid into the pipe annulus, in particular into the metal armor layer, is thereby further reduced or even prevented.

[0105] By providing a flexible pipe body having a permeation barrier of continuous construction, the internal pressure sheath is thereby surrounded by the sleeve without gaps or discontinuities, even when the flexible pipe body is bent. Undesirable penetration of fluids into the pipe annulus through leaks is reduced or even prevented. Furthermore, the internal pressure sheath is thereby surrounded by a sleeve of substantially fluid-impermeable material, so that the transmission of fluids is greatly reduced. As a result, the resulting annulus environment can be milder, e.g., less corrosive, than conventional flexible pipes, thereby increasing pipe life.

[0106] Application of the permeation barrier layer may be accomplished by spirally winding a tape, film, or foil wherein adjacent spirally wound turns or overlying wound turns at least partially overlap, or by applying a film or foil oriented longitudinally relative to the tube axis wherein the width of the film or foil wraps circumferentially around the tube, or by other suitable means, such as spray application or vapor deposition.

[0107] The flexible pipe body 300 also includes composite tape layers 320. The composite tape layers 320 are configured to support the permeation barrier 310, thereby improving the reliability and integrity of the permeation barrier 310. The composite tape layers 320 are thin composite tape layers 320 as described herein to provide support and wear resistance in a convenient and adaptable manner.

[0108] The composite tape layer 320 includes a helically wound composite tape. The helically wound composite tape is wrapped or wound around the permeation barrier 310 to form the composite tape layer 320. Successive tape wrap turns of the helically wound composite tape are wrapped around the permeation barrier to provide a series of laterally adjacent tape wrap turns. Thus, the overlap can reduce fluid permeation through the composite tape layer 320 by reducing or eliminating gaps between adjacent tape wrap turns that might otherwise provide leakage paths.

[0109] The helically wound composite tape includes two surfaces and a first longitudinal edge and a second longitudinal edge. The first longitudinal edge and the second longitudinal edge are mutually opposite edges extending in the longitudinal direction of the helically wound composite tape. Thus, when the helically wound composite tape is wrapped around the permeability barrier 310, a first longitudinal edge of a first tape wrap turn abuts or overlaps a second longitudinal edge of a laterally adjacent second tape wrap turn.

[0110] The composite tapes of the composite tape layer 320 are helically wound at a lay angle relative to the axis of the flexible pipe body 300. Figure 4 (b), in the example shown, the composite tape layer 320 is helically wound at a lay angle β relative to the axis BB of the flexible pipe body 300. In the example shown, the lay angle β is 40°. Therefore, this lay angle provides a reduced minimum bending radius of the composite tape layer 320. Therefore, the lower minimum bending radius can make the flexible pipe body 300 have greater flexibility.

[0111] The composite tape layer 320 includes a plurality of fibers. The plurality of fibers in the composite tape of the composite tape layer 310 are primarily or exclusively continuous fibers. The continuous fibers are arranged along the length direction of the composite tape. That is, the continuous fibers are arranged longitudinally within the composite tape. The composite tape is helically wound around the underlying layer, which in this example is the internal pressure jacket 302. Where the composite tape is wound around the internal pressure jacket 302, the continuous fibers of the composite material have a lay angle that is substantially the same as the lay angle β of the composite tape layer 310.

[0112] The composite tape layer 320 is configured to cover the overlap region between laterally adjacent tape wrap turns of the metal armor layer 303. The composite tape of the composite tape layer 320 thus extends between a first longitudinal edge of a first tape wrap turn and a second longitudinal edge of a laterally adjacent second tape wrap turn. In this manner, the composite tape layer 320 covers uneven portions or gaps extending between laterally adjacent tape wrap turns of the metal armor layer 303.

[0113] Advantageously, the composite tape layers 320 can deform toward uneven portions of the metallic armor layer 303. Specifically, the composite tape layers 320 can deform toward the void spaces between laterally adjacent tape wrap turns of the metallic armor layer 303. Thus, interfacial pressures during use of the flexible pipe body cause the composite tape layers 320 to conform to any uneven portions in the metallic armor layer, thereby protecting the integrity of the permeation barrier 310.

[0114] In the example shown, the composite tape layer 320 and the permeation barrier 310 are bonded to each other. Basically, the permeation barrier 310 and the composite tape layer 320 are provided in the form of a metal film with a composite tape layer backing. Therefore, the mutually adjacent surfaces of the composite tape layer 320 and the permeation barrier 310 are bonded to limit the relative longitudinal movement between the composite tape layer and the permeation barrier.

[0115] In use, the flexible pipe body 300 including the above-described example composite tape layer 320 and permeability barrier 310 may be provided with suitable connectors to enable the flexible pipe body 300 to form a flexible pipe for conveying produced fluids, such as reference Figure 2 By providing as reference Figure 3 The described layer arrangement may provide a flexible pipe body having reduced undesired fluid penetration into the pipe annulus.A flexible pipe body may be provided having a more resilient permeation barrier.

[0116] Additional references Figure 5 and Figure 6 , shows a close-up view of the composite tape layer 320. The composite tape layer 320 includes a first sub-layer 320a of composite tape and a second sub-layer 320b of composite tape. The first sub-layer 320a is disposed radially inward of the second sub-layer 320b.

[0117] In the example shown, the first sub-layer 320a is consolidated with the second sub-layer 320b. In this manner, the sub-layers are substantially bonded together to form a single composite tape layer 320. Thus, the sub-layers collectively function as a composite tape layer 320 to support and protect the integrity of the permeability barrier 310, as described herein.

[0118] The composite tape of each of the first sublayer 320a and the second sublayer 320b has the properties of the composite tape as described herein. One or more properties of the composite tape of the first sublayer 320a may be different from one or more corresponding properties of the second sublayer 320b.

[0119] The first sublayer 320a is wound at a first lay angle β1 relative to the axis of the flexible pipe body 300. The second sublayer 320b is counter-wound at a second lay angle β2 relative to the axis of the flexible pipe body 300. In this manner, fluid permeation through the composite tape layers 320 is reduced by removing gaps or discontinuities between consecutive wrap turns of the composite tape sublayers 320a, 320b that might otherwise provide leak paths.

[0120] Advantageously, by forming the composite tape 320 from two sub-layers 320a, 320b, more options are provided for the design and manufacture of the flexible pipe body 300. The consolidation of the sub-layers provides the ability to adapt the composite tape 320 according to the specific support or deformability requirements of the permeability barrier layer. For example, the first sub-layer may preferentially prevent the penetration, i.e., transmission, of a first production fluid, and the second sub-layer may preferentially prevent the penetration, i.e., transmission, of a second production fluid. Thus, the composite tape can be adapted according to the production fluid contained within the flexible pipe body 300.

[0121] Reference now Figure 7 , shows a schematic example of a composite tape layer 420, such as provided in reference Figure 3 A composite tape layer in a flexible pipe body is depicted. The composite tape layer 420 includes a plurality of fibers 422 within a matrix 424. Each fiber 422 is embedded in the matrix 424.

[0122] The plurality of fibers 422 are arranged in the longitudinal direction of the composite tape. Therefore, when the composite tape is spirally wound around the underlying layer, the fibers 422 extend spirally.

[0123] In the example shown, the composite tape has a thickness of 0.22 mm. In some examples, a series of such spirally wound composite tapes are provided in the flexible pipe body. Each composite tape provides a sub-layer of the composite tape layer 420, such that the thickness of the composite tape layer is greater than the thickness of the composite tape. For example, the composite tape layer may have a thickness of 3 mm or more.

[0124] Advantageously, the composite tape layers 420 can be sufficiently deformed in response to pressure within the flexible pipe body. Specifically, the composite tape layers 420 can deform relative to the unevenness of the metallic armor layer radially outward. For example, the composite tape layers 420 can deform toward the void spaces between laterally adjacent tape wrap turns of the metallic armor layer. Thus, interface pressures during use of the flexible pipe body cause the composite tape layers 420 to conform to the unevenness in the metallic armor layer, thereby protecting the integrity of the radially adjacent permeation barrier.

[0125] Advantageously, the matrix 424 of the composite tape layer 420 also contains nanoparticles to further increase the tortuosity of the permeation path that the undesired fluid must traverse to pass through the composite tape layer and thus further reduce the permeability of the layer.

[0126] Reference now Figure 8 , shows a flow chart illustrating a method 500 of manufacturing a flexible pipe body, such as those described herein. The method may be performed using any suitable operating options, such as mechanically or manually winding the layers.

[0127] The first step 510 comprises providing an internal pressure sheath for the flexible pipe body, optionally over a carcass layer (not shown). Suitably, the internal pressure sheath is formed by an extrusion process known in the art.

[0128] The second step 520 includes providing a permeation barrier layer. The permeation barrier layer is suitable for reducing fluid permeation through the flexible pipe body. Optionally, the method provides a permeation barrier layer formed of a spirally wound tape, film or foil or at least one axially oriented film or foil, the permeation barrier layer being located radially outward of the internal pressure jacket. Successive tape wrap turns of the spirally wound tape can be wound around the internal pressure jacket to provide a series of laterally adjacent tape wrap turns.

[0129] Optionally, laterally adjacent tape wrap turns of the spirally wound tape are coupled via a connecting portion. The laterally adjacent tape wrap turns are coupled using a bonding process such that the connecting portion forms a portion of a continuous metal permeation barrier layer. The connecting portion forms a bond between the laterally adjacent tape wrap turns. In an example method, the connecting portion is a weld bond.

[0130] Advantageously, the bonding process ensures that the permeability barrier layer is a continuous permeability barrier layer, thereby providing a continuous permeability barrier along the flexible pipe body. In particular, the barrier is a continuous barrier of metal. Undesirable fluid penetration (particularly via transmission) from produced fluids into the pipe annulus is thereby prevented or at least reduced.

[0131] In an example, the method uses a bonding process to connect a first longitudinal edge of a first spiral tape wrap turn with a second longitudinal edge of a second tape wrap turn. The bonding process thereby provides a connection portion that extends around the circumference of the flexible pipe body. The bonding process thereby provides a connection portion that extends together between the opposite first and second longitudinal edges of adjacent tape wrap turns of the spirally wound tape on the flexible pipe body. In this way, the bonding process (e.g., a welding process) follows the pitch of the spirally wound tape. Similarly, the bonding process can be applied to the longitudinal edges of the axially applied film or foil to ensure the continuity of the permeation barrier layer around the circumference of the pipe. Bonding can also be achieved by applying heat and / or pressure to the overlapping portions of the tape, film or foil.

[0132] The third step 530 includes providing a composite tape layer. The composite tape layer is wound on the flexible pipe body. Optionally, the composite tape layer can be arranged on the flexible pipe body as multiple sub-layers overlapping each other. In this way, the first sub-layer and the second sub-layer are wound on the flexible pipe body in sequence.

[0133] The fourth step 540 includes providing a metal armor layer radially outside the composite tape layer. Typically, the metal armor layer is provided by spirally winding a suitable tape onto the underlying layer. In this manner, the method provides a metal armor layer to primarily provide hoop strength to the flexible pipe body.

[0134] Reference now Fig. 9 , shows a flow chart illustrating another method 600 of manufacturing a flexible pipe body, such as those described herein. The method may be performed using any suitable operating options, such as mechanically or manually winding the layers.

[0135] The method 600 is similar to the method of reference 1 except that the permeation barrier layer and the composite tape layer each have a lay angle less than 80° relative to the axis of the flexible pipe body. Figure 8 The methods described are essentially the same.

[0136] Thus, a first step 610 comprises providing an internal pressure sheath for the flexible pipe body. Suitably, the internal pressure sheath is formed by an extrusion process known in the art.

[0137] The second step 620 includes providing a permeation barrier layer. The permeation barrier layer is suitable for reducing fluid penetration through the flexible pipe body. The method provides a permeation barrier layer formed by a spirally wound tape, film or foil or a longitudinally oriented film or foil, which is located radially outside the internal pressure sheath. The tape, film or foil of the permeation barrier can be provided by winding the spirally wound tape onto the lower layer of the flexible pipe body at a lay angle less than 80° relative to the axis of the flexible pipe body. Typically, the lay angle is in the range of greater than 20° to less than 80°. One or more longitudinally oriented films or foils can be wrapped around the lower pipe layer, ensuring overlap of the longitudinal edges of the films or foils to ensure continuity of the permeation barrier layer around the circumference of the pipe.

[0138] The third step 630 includes providing a composite tape layer. The composite tape layer is wound onto the flexible pipe body at a lay angle of less than 80° relative to the axis of the flexible pipe body. In this way, the structure of the composite tape layer will be flexible. Typically, the lay angle is in the range of greater than 20° to less than 80°.

[0139] A fourth step 640 includes providing a metallic armor layer radially outwardly of the composite tape layer. Suitably, the metallic armor layer is provided and arranged in accordance with any of the example metallic armor layers described herein. For example, the metallic armor layer may be provided by helically winding a metallic pressure armor wire onto an underlying layer. In this manner, the method provides a metallic armor layer to primarily provide hoop strength to the flexible pipe body.

[0140] It will be appreciated that the addition of other layers to the tube structure is permissible. For example, a sacrificial or wear layer may be introduced between the composite tape layer and the overlying metal armor layer.

[0141] It will also be appreciated that the permeation barrier layer may be applied over a sacrificial layer or wear layer covering the inner carcass. In this case, the provided structure may be characterized as the permeation barrier layer and the composite tape layer being located radially inwardly of the internal pressure sheath. Alternatively, the provided structure may be characterized as the permeation barrier layer and the composite tape layer being separated by the internal pressure sheath and being radially inwardly of the overlying metallic armor layer.

[0142] Various modifications to the detailed arrangements described above are possible.

[0143] In some examples, the permeation barrier layer of the flexible pipe body may include a helically wound tape. The tape is a barrier tape. The helically wound tape may be a helically wound metal tape. The helically wound tape is wrapped or wound around the internal pressure jacket to form the permeation barrier layer. Successive tape wrap turns of the helically wound tape are wrapped around the internal pressure jacket to provide a series of laterally adjacent tape wrap turns.

[0144] The spirally wound tape of the permeability barrier layer may include a first longitudinal edge and a second longitudinal edge. The first longitudinal edge and the second longitudinal edge are mutually opposite edges extending in the elongation direction of the spirally wound tape. Thus, when the spirally wound tape is wound around the internal pressure sheath, the first longitudinal edge of a first tape wrap turn abuts or overlaps the second longitudinal edge of a second laterally adjacent tape wrap turn.

[0145] The permeability barrier layer may include a connecting portion configured to connect laterally adjacent tape wrap turns of the spirally wound tape. The connecting portion forms a bond between laterally adjacent tape wrap turns. Typically, the connecting portion is a welded bond. Advantageously, the bond ensures that the permeability barrier layer is a continuous permeability barrier layer, thereby providing a continuous permeability barrier along the flexible pipe body. Undesirable fluid penetration from the produced fluid into the pipe annulus is thereby further reduced or even prevented.

[0146] The connecting portion forms a weld bond between an adjacent first longitudinal edge of the first tape wrapped turn and a second longitudinal edge of the second tape wrapped turn.

[0147] Alternatively, the helically wound tape of the permeability barrier may be wrapped so as to provide an overlap region between laterally adjacent tape wrap turns. In this manner, the connecting portion may form a welded bond between a first longitudinal edge of a first tape wrap turn and a surface portion of a second tape wrap turn. The surface portion of the second tape wrap turn may be an inner surface portion or an outer surface portion of the second tape wrap turn.

[0148] Regardless of whether the connecting portion connects adjacent tape wrap turns or overlapping tape wrap turns, the connecting portion may extend around the circumference of the flexible pipe body. The connecting portion may coexist between adjacent first and second longitudinal edges of adjacent tape wrap turns of the helically wound tape on the flexible pipe body. Alternatively, the connecting portion coexists with overlapping first longitudinal edges of tape wrap turns of the helically wound tape. In these ways, the connecting portion follows the pitch of the helically wound tape to form a bond.

[0149] The permeation barrier may thereby comprise a lay angle relative to the axis of the flexible pipe body.

[0150] In some examples, the composite tape layer and the permeation barrier can be at least partially bonded to each other using an adhesive. Alternatively, the composite tape layer and the permeation barrier can be at least partially bonded to each other using a fusion consolidation portion or a fusion bonding portion without an adhesive.

[0151] In some examples, the permeability barrier and the internal pressure sheath may be at least partially bonded to one another.

[0152] It will be apparent to those skilled in the art that the features described with respect to any of the above embodiments may be applied interchangeably between the different embodiments.The above embodiments are examples for illustrating the various features of the present invention.

[0153] Throughout the detailed description and claims of this specification, the words "comprise" and "contain" and their variations mean "including but not limited to", and they are not intended to (and do not) exclude other parts, additives, components, wholes or steps. Throughout the detailed description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. Specifically, where the indefinite article is used, the specification should be understood to contemplate both the plural and the singular unless the context otherwise requires. It should also be understood that throughout this specification, language expressed in the general form of "X for Y" (where Y is some action, activity or step, and X is some means for performing the action, activity or step) covers means X that are specifically (but not exclusively) adjusted or arranged to perform Y.

[0154] Unless otherwise expressly stated, each feature disclosed in this specification may be replaced by an alternative feature used for the same, equivalent or similar purpose. Therefore, unless otherwise expressly stated, each feature disclosed is only an example of a general series of equivalent or similar features.

[0155] The features, structures, entities, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention should be understood to be applicable to any other aspect, embodiment or example described herein, unless incompatible therewith. All features disclosed in this specification (including any attached claims, abstract and drawings) and / or all steps of any method or process so disclosed may be combined in any combination, except that at least some of such features and / or steps are mutually exclusive combinations. The present invention is not limited to the details of any foregoing embodiments. The present invention extends to any novel feature structure or any novel combination of the features disclosed in this specification (including any attached claims, abstract and drawings), or to any novel step or any novel combination of the steps of any method or process so disclosed.

[0156] The reader's attention is directed to all papers and documents filed in connection with this patent application concurrently with or before this specification and which disclose public inspection of the present specification, and the contents of all these papers and documents are incorporated herein by reference.

Claims

1. A flexible pipe body for conveying produced fluid, the flexible pipe body comprising: Internal pressure sheath; a permeability barrier, the permeability barrier being used to reduce fluid penetration of the produced fluid toward the pipe annulus; a metal armor layer positioned radially outward from the permeability barrier; and A composite material tape layer, the composite material tape layer comprising a plurality of fibers, Wherein the composite tape layer is positioned radially between the permeation barrier and the metal armor layer.

2. A flexible pipe body as claimed in claim 1, wherein the permeation barrier comprises a spirally wound tape or film or foil.

3. A flexible pipe body as claimed in claim 2, wherein the helically wound tape comprises a lay angle in the range of greater than 20° to less than 80° relative to the axis of the flexible pipe body.

4. Flexible pipe body according to any one of claims 2 or 3, wherein the helically wound tape or the film comprises a metal.

5. The flexible pipe body of claim 1, wherein the permeation barrier comprises at least one tape, film or foil oriented longitudinally along the axis of the flexible pipe body and wrapped around underlying layers.

6. A flexible pipe body according to any preceding claim, wherein the metallic armour layer comprises at least one helically wound metal tape having a first longitudinal edge and a second longitudinal edge, and wherein the metallic armour layer comprises an overlap region which is coextensive with the first longitudinal edge of a first tape wrapped turn and the second longitudinal edge of a second tape wrapped turn of the helically wound metal tape.

7. The flexible pipe body of claim 6, wherein the composite tape layer is configured to cover the overlap region between the first tape wrapped turns and the second tape wrapped turns of a radially overlying metallic armour layer.

8. A flexible pipe body as claimed in any preceding claim wherein the metal armour layer comprises a helically wound metal tape having a lay angle of at least 80° relative to the axis of the flexible pipe body.

9. A flexible pipe body as claimed in any preceding claim, wherein the composite tape layer comprises a helically wound composite tape having a lay angle in the range greater than 20° to less than 80° relative to the flexible pipe axis.

10. A flexible pipe body as claimed in any preceding claim wherein the composite tape layer and the permeation barrier are at least partially bonded to one another.

11. The flexible pipe body of claim 10, wherein the composite tape layer and the permeation barrier are at least partially bonded to one another using an adhesive.

12. The flexible pipe body of claim 10, wherein the composite tape layers and the permeation barrier are at least partially bonded to one another using melt consolidation or melt bonding without the need for an adhesive.

13. Flexible pipe body according to any preceding claim, wherein the permeation barrier and the internal pressure sheath are at least partially bonded to one another.

14. A flexible body according to any preceding claim, wherein the permeability barrier comprises a fluid impermeable material.

15. The flexible body of claim 14, wherein the permeation barrier comprises a metal, and preferably wherein the metal comprises stainless steel or an alloy comprising at least one of nickel, titanium, aluminum, zinc, copper, tin or silver.

16. The flexible body of claim 14, wherein the permeation barrier comprises a low permeability polymer, and preferably, wherein the low permeability polymer comprises at least one of PFA, PEEK, PEKK, PTFE, polyketone, ethylene vinyl alcohol copolymer, polyethylene, polypropylene, PVDF or PPS.

17. A flexible body according to claim 16, wherein the permeation barrier comprises ethylene vinyl alcohol copolymer provided as a coextruded tape, and preferably, wherein the coextruded tape comprises at least three layers, the at least three layers comprising the ethylene vinyl alcohol copolymer sandwiched between sublayers of at least one thermoplastic polymer.

18. A flexible pipe as claimed in claim 16 or 17, wherein the low permeability polymer comprises a filler material, and preferably wherein the filler material comprises particles or fibres.

19. The flexible pipe body of claim 18, wherein the filler material comprises at least one of an oxide, a silicate, a carbonate, carbon, a glass or a basalt.

20. A flexible pipe body as claimed in any preceding claim, wherein the plurality of fibres of the composite tape layer are continuous fibres.

21. The flexible pipe body of claim 20, wherein the continuous fibres are aligned in a longitudinal direction of the composite tape.

22. A flexible pipe body as claimed in any preceding claim, wherein the plurality of fibres in the composite tape layers comprise one or more of carbon fibres, glass fibres, basalt fibres, aramid fibres, drawn polymer fibres or metal wires.

23. The flexible pipe body according to any preceding claim, wherein the composite tape layer comprises a plurality of sub-layers.

24. A flexible pipe body according to any preceding claim, wherein the composite tape layer comprises at least one composite tape, wherein the composite tape has a thickness of less than 1 mm, suitably less than 0.5 mm and more suitably less than 0.25 mm.

25. A flexible pipe body as claimed in any preceding claim in which the composite tape layers have a thickness of less than 5 mm, and suitably less than 2 mm.

26. A flexible pipe according to any preceding claim, wherein the composite tape layers are less than 50%, suitably less than 30% and even more suitably less than 15% thick relative to the thickness of the metal armour layers.

27. A flexible riser comprising a flexible pipe body according to any preceding claim.

28. A method of manufacturing a flexible pipe body, the method comprising: Provides internal pressure sheath, providing a permeation barrier layer, the permeation barrier layer being used to reduce fluid penetration; providing a composite tape layer, the composite tape layer comprising a plurality of fibers; as well as A metallic armor layer is provided radially outwardly of the permeation barrier layer and the composite tape layer such that the composite tape layer is between the permeation barrier layer and the metallic armor layer.

29. A method according to claim 28, wherein the step of providing the permeation barrier comprises winding a spirally wound tape onto the flexible pipe body at a lay angle of between greater than 20° and less than 80° relative to the axis of the flexible pipe body.

30. A method according to any one of claims 28 or 29, wherein the step of providing the composite tape layer comprises winding the composite tape onto the flexible pipe body at a lay angle greater than 20° and less than 80° relative to the axis of the flexible pipe body.

31. The method of claim 29 or 30, wherein the lay angle of the spirally wound tape of the permeability barrier layer is different from the lay angle of the composite tape of the composite tape layer.

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