Permeation-barrier and method of manufacture

Abstract

A flexible pipe body for transporting production fluids and a method of producing a flexible pipe body are disclosed. The flexible pipe body includes an internal pressure sheath (402); a wear layer (403) positioned radially outward of the internal pressure sheath; and an interlocked armour layer (404) positioned radially outward of the wear layer. A first polymeric permeation-barrier layer (406) is provided between the internal pressure sheath (402) and the wear layer (403) and is at least partially bonded to the internal pressure sheath (402) using a melt consolidation or a melt bond (408). A second polymeric permeation-barrier layer (407) is provided radially inward of the interlocked armour layer (404) and is at least partially bonded to one of the first polymeric permeation-barrier layer (406) and the wear layer (403) using a melt consolidation or a melt bond (409).

Description

[0001] PERMEATION-BARRIER AND METHOD OF MANUFACTURE

[0002] Technical field

[0003] The present invention relates to a flexible pipe body including a permeation-barrier layer, and a method of manufacturing said flexible pipe body. In particular, but not exclusively, the present invention relates to a flexible pipe body including a continuous polymeric permeation-barrier layer that is melt consolidated or melt bonded to the flexible pipe body.

[0004] Background

[0005] Flexible pipe is particularly useful in connecting a sub-sea location (which may be deep underwater) to a sea level location. The pipe may have an internal diameter of typically up to around 0.6 metres (e.g. diameters may range from 0.05 m up to 0.6 m). Flexible pipe is generally 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-containing conduit. The pipe structure allows large deflections without causing bending stresses that impair the pipe’s functionality over its lifetime. The flexible pipe body is generally built up as a combined structure including polymer, and / or metallic, and / or composite layers. For example, a flexible pipe body may include polymer and metal layers, or polymer and composite layers, or polymer, metal and composite layers.

[0006] API Recommended Practice 17B provides guidelines for the design, analysis, manufacture, testing, installation, and operation of flexible pipes and flexible pipe systems for onshore, subsea and marine 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.

[0007] Flexible pipe body typically includes a fluid-retaining layer (known as a barrier layer or liner) formed generally as a polymer sheath or pressure sheath. Such a layer operates as a primary fluid retaining layer. To prevent rupture of such a layer caused by the pressure of the transported fluid, an interlocked wire layer (known as a pressure armour layer) is often located radially outwards of the fluid-retaining layer. A typical flexible pipe body includes one or more armour layers, optionally including a pressure armour layer. The primary load on such layers is formed from radial forces. Pressure armour layers often have a specific cross- sectional profile to interlock so as to be able to maintain and absorb radial forces resulting from outer or inner pressure on the pipe. The cross-sectional profile of the wound wires which thus prevent the pipe from collapsing or bursting as a result of pressure are sometimes called pressure-resistant profiles. When armour layers are formed from helically wound wires forming hoop components, the radial forces from inner or outer pressure on the pipe cause the hoop components to expand or contract, putting respectively tensile or compressive loads on the wires.

[0008] One or more tensile armour layers may be positioned radially outward of a pressure armour layer(s). Tensile armour is used to sustain tensile loads and internal pressure. The tensile armour layer is often formed from a plurality 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. The tensile armour layers are often metallic layers, formed from carbon steel, for example. The tensile armour layers may alternatively be composite tendons, of a matrix material reinforced with suitable fibres, for instance of glass, carbon, aramid, basalt, or metal.

[0009] As used herein, an armour layer refers to a tensile armour layer or a pressure armour layer.

[0010] Flexible pipe is utilised to transport production 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 a production fluid is conveyed through a flexible pipe, fluids such as carbon dioxide and hydrogen sulphide gases, for example, can permeate the inner most layers of the flexible pipe body (for example the internal pressure sheath). As used herein, permeation, particularly permeation of a fluid through a layer of a flexible pipe, may include both transmission of the fluid through a body of the layer as well as leakage of the fluid through discontinuities or gaps in the layer, the particular meaning being readily apparent from the context of the accompanying description.

[0011] These fluids then accumulate in the pipe annulus. This may result in a corrosive environment, in particular when associated with water present in the annulus, for example during an annulus flooding event. The corrosive environment is known to lead to pipe failure due to stress corrosion cracking of the metallic layers used within armour layers. Furthermore, a build-up of annulus fluids can cause over pressurization and mechanical failure of the flexible pipe.

[0012] Certain known examples of a flexible pipe body provide a tape layer radially outward of the internal sheath layer. As used herein, a tape refers to an elongate material provided in a wrapable or windable form, so as to form a layer by winding around a radially inward layer of the flexible pipe body. The tape layer is typical formed by winding a tape around the internal sheath layer so that a longitudinal edge of a first tape wrap overlaps the opposing longitudinal edge of the tape of a laterally adjacent tape wrap.

[0013] A problem of certain flexible pipe bodies is that fluid permeates therethrough to a pipe annulus. Fluid may permeate to the pipe annulus by transmission through a body of a layer. Additionally, or alternatively, fluid may permeate to the pipe annulus by leakage through discontinuities or gaps in a layer. In particular, while winding provides overlapping edges along the longitudinal edge of a tape, the reliability of the seal to prevent leaks depends upon surface to surface engagement. Repetitive flexing causes the overlapping surfaces to disengage from one another. Thus, fluid leaks due to it being forced between adjacent tape wraps by the pressure of the production fluids transported in the fluid pipe.

[0014] A further problem is that certain barrier layers place limits on the bending and loading limits of the flexible pipe body such that the flexible pipe cannot be flexed without damaging the barrier layer. In particular, the flexible pipe has a minimal bending radius limit which restricts the degree of permitted flex of the flexible pipe in use. That is, a flexible pipe has a lower limit for the curvature radius around which it may be bent or flexed. Flexing the flexible pipe more tightly than the minimum bending limit causes the overlapping surfaces to disengage from one another. Again, fluid leaks due to it being forced between adjacent tape wraps by the pressure of the production fluids transported in the fluid pipe.

[0015] It is an aim of certain examples of the present invention to solve, mitigate or obviate, at least partly, at least one of the problems and / or disadvantages associated with the prior art. Certain examples aim to provide at least one of the advantages described below.

[0016] Summary of the Invention

[0017] The invention is set out in the appended claims.

[0018] According to a first aspect of the present invention there is provided a flexible pipe body for transporting production fluids, the flexible pipe body comprising an internal pressure sheath and a wear layer positioned radially outward of the internal pressure sheath. A polymeric permeation-barrier layer is provided between the internal pressure sheath and the wear layer and is at least partially bonded to the internal pressure sheath using a melt consolidation or a melt bond.

[0019] The polymeric permeation-barrier layer may be a first polymeric permeation-barrier layer. An interlocked armour layer may be positioned radially outward of the wear layer. A second polymeric permeation-barrier layer may be provided radially inward of the interlocked armour layer. The second polymeric permeation-barrier layer may be at least partially bonded to the first polymeric permeation-barrier layer using a melt consolidation or a melt bond. Alternatively, the second polymeric permeation-barrier layer may be at least partially bonded to the wear layer using a melt consolidation or a melt bond.

[0020] According to an aspect of the present invention there is provided a flexible pipe body for transporting production fluids, the flexible pipe body comprising an internal pressure sheath; a wear layer positioned radially outward of the internal pressure sheath; and an interlocked armour layer positioned radially outward of the wear layer. A first polymeric permeationbarrier layer is provided between the internal pressure sheath and the wear layer and is at least partially bonded to the internal pressure sheath using a melt consolidation or a melt bond. A second polymeric permeation-barrier layer is provided radially inward of the interlocked armour layer and is at least partially bonded to the one of first polymeric permeation-barrier layer and the wear layer using a melt consolidation or a melt bond.

[0021] The internal pressure sheath may have a thickness. The first polymeric permeation-barrier layer may impregnate less than or equal to 30%, for example less than or equal to 25%, for example less than or equal to 20% of the internal pressure sheath thickness.

[0022] The first polymeric permeation-barrier layer may impregnate at least 10%, for example at least 15% of the internal pressure sheath thickness.

[0023] The first polymeric permeation-barrier layer may impregnate between 10% and 30%, for example between 15% and 30% of the internal pressure sheath thickness.

[0024] The first polymeric permeation-barrier layer may impregnate between 10% and 25%, for example between 15% and 25% of the internal pressure sheath thickness.

[0025] The first polymeric permeation-barrier layer may impregnate between 10% and 20%, for example between 15% and 20% of the internal pressure sheath thickness.

[0026] The wear layer may have a thickness. The second polymeric permeation-barrier layer may impregnate less than or equal to 30%, for example less than or equal to 25%, for example less than or equal to 20% of the wear layer thickness.

[0027] The second polymeric permeation-barrier layer may impregnate at least 10%, for example at least 15% of the wear layer thickness.

[0028] The second polymeric permeation-barrier layer may impregnate between 10% and 30%, for example between 15% and 30% of the wear layer thickness.

[0029] The second polymeric permeation-barrier layer may impregnate between 10% and 25%, for example between 15% and 25% of the wear layer thickness.

[0030] The second polymeric permeation-barrier layer may impregnate between 10% and 20%, for example between 15% and 20% of the wear layer thickness.

[0031] The first polymeric permeation-barrier layer may have a thickness. The second polymeric permeation-barrier layer may impregnate less than or equal to 30%, for example less than or equal to 25%, for example less than or equal to 20% of the first polymeric permeationbarrier layer thickness.

[0032] The second polymeric permeation-barrier layer may impregnate at least 10%, for example at least 15% of the first polymeric permeation-barrier layer thickness.

[0033] The second polymeric permeation-barrier layer may impregnate between 10% and 30%, for example between 15% and 30% of the first polymeric permeation-barrier layer thickness.

[0034] The second polymeric permeation-barrier layer may impregnate between 10% and 25%, for example between 15% and 25% of the first polymeric permeation-barrier layer thickness.

[0035] The second polymeric permeation-barrier layer may impregnate between 10% and 20%, for example between 15% and 20% of the first polymeric permeation-barrier layer thickness.

[0036] The first polymeric permeation-barrier layer may be a tape or a film. The tape or film of the first polymeric permeation-barrier layer may have a thickness of at least 0.3 millimetres, for example at least 0.5 millimetres, for example at least 1 millimetre.

[0037] The thickness of the tape or film of the first polymeric permeation-barrier layer may be less than or equal to 5 millimetres, for example less than or equal to 3 millimetres.

[0038] The thickness of the tape or film of the first polymeric permeation-barrier layer may be between 0.3 millimetres and 5 millimetres, for example between 0.5 millimetres and 5 millimetres, for example between 1 millimetre and 5 millimetres.

[0039] The thickness of the tape or film of the first polymeric permeation-barrier layer may be between 0.3 millimetres and 3 millimetres, for example between 0.5 millimetres and 3 millimetres, for example between 1 millimetre and 3 millimetres.

[0040] The second polymeric permeation-barrier layer may be a tape or a film. The tape or film of the second polymeric permeation-barrier layer may have a thickness of at least 0.3 millimetres, for example at least 0.5 millimetres, for example at least 1 millimetre.

[0041] The thickness of the tape or film of the second polymeric permeation-barrier layer may be less than or equal to 5 millimetres, for example less than or equal to 3 millimetres.

[0042] The thickness of the tape or film of the second polymeric permeation-barrier layer may be between 0.3 millimetres and 5 millimetres, for example between 0.5 millimetres and 5 millimetres, for example between 1 millimetre and 5 millimetres. The thickness of the tape or film of the second polymeric permeation-barrier layer may be between 0.3 millimetres and 3 millimetres, for example between 0.5 millimetres and 3 millimetres, for example between 1 millimetre and 3 millimetres.

[0043] The first polymeric permeation-barrier layer may have a thickness of at least 5 millimetres, for example at least 10 millimetres.

[0044] The thickness of the first polymeric permeation-barrier layer may be less than or equal to 20 millimetres, for example less than or equal to 15 millimetres.

[0045] The thickness of the first polymeric permeation-barrier layer may be between 5 millimetres and 20 millimetres, for example between 5 millimetres and 15 millimetres.

[0046] The thickness of the first polymeric permeation-barrier layer may be between 10 millimetres and 20 millimetres, for example between 10 millimetres and 15 millimetres.

[0047] The second polymeric permeation-barrier layer may have a thickness of at least 5 millimetres, for example at least 10 millimetres.

[0048] The thickness of the second polymeric permeation-barrier layer may be less than or equal to 20 millimetres, for example less than or equal to 15 millimetres.

[0049] The thickness of the second polymeric permeation-barrier layer may be between 5 millimetres and 20 millimetres, for example between 5 millimetres and 15 millimetres.

[0050] The thickness of the second polymeric permeation-barrier layer may be between 10 millimetres and 20 millimetres, for example between 10 millimetres and 15 millimetres.

[0051] The first polymeric permeation-barrier layer and / or the second polymeric permeation-barrier layer may comprise a low permeation polymer.

[0052] The low permeation polymer may comprise at least one of perfluoroalkoxy alkane (PFA), polyether ether ketone (PEEK), polyetherketoneketone (PEKK), polytetrafluoroethylene (PTFE), polyketone, ethylene-vinyl alcohol co-polymer, polyethylene, polypropylene, polyvinylidene fluoride (PVDF), polyphenylene sulphide (PPS), polyimide.

[0053] According to an aspect of the invention there is provided a flexible riser comprising the flexible pipe body of any preceding aspect of the invention.

[0054] According to another aspect of the present invention there is provided a method of manufacturing a flexible pipe body, the method comprising: providing an internal pressure sheath; providing a first polymeric permeation-barrier layer radially outward of the internal pressure sheath; and heating the first polymeric permeation-barrier layer to at least partially bond the first polymeric permeation-barrier layer to the internal pressure sheath using a melt consolidation or a melt bond.

[0055] The method may include providing a wear layer radially outward of the first polymeric permeation-barrier layer; providing a second polymeric permeation-barrier layer; and heating the second polymeric permeation-barrier layer to at least partially bond the second polymeric permeation-barrier layer to one of the first polymeric permeation-barrier layer and the wear layer using a melt consolidation or a melt bond.

[0056] According to an aspect of the present invention there is provided a method of manufacturing a flexible pipe body, the method comprising: providing an internal pressure sheath; providing a first polymeric permeation-barrier layer radially outward of the internal pressure sheath; and heating the first polymeric permeation-barrier layer to at least partially bond the first polymeric permeation-barrier layer to the internal pressure sheath using a melt consolidation or a melt bond; providing a wear layer radially outward of the first polymeric permeationbarrier layer; providing a second polymeric permeation-barrier layer; and heating the second polymeric permeation-barrier layer to at least partially bond the second polymeric permeation-barrier layer to one of the first polymeric permeation-barrier layer and the wear layer using a melt consolidation or a melt bond.

[0057] The step of providing a first polymeric permeation-barrier layer radially outward of the internal pressure sheath may include winding a helically wound tape or film of the first polymeric permeation-barrier layer material onto the internal pressure sheath of the flexible pipe body.

[0058] The step of providing a first polymeric permeation-barrier layer radially outward of the internal pressure sheath may include extruding the first polymeric permeation-barrier layer material onto the internal pressure sheath of the flexible pipe body.

[0059] The step of providing a second polymeric permeation-barrier layer may include winding a helically wound tape or film of the second polymeric permeation-barrier layer material onto the wear layer of the flexible pipe body.

[0060] The step of providing a second polymeric permeation-barrier layer may include extruding the second polymeric permeation-barrier layer material onto the wear layer of the flexible pipe body.

[0061] The step of providing a second polymeric permeation-barrier layer may include winding a helically wound tape or film of the second polymeric permeation-barrier layer material onto the first polymeric permeation-barrier layer of the flexible pipe body. The step of providing a second polymeric permeation-barrier layer may include extruding the second polymeric permeation-barrier layer material onto the first polymeric permeationbarrier layer of the flexible pipe body.

[0062] Certain embodiments of the invention provide the advantage that the thickness of the permeation-barrier layer of a flexible pipe body can be reduced. A further advantage of the present invention is that the amount of material required to form a permeation-barrier layer for a flexible pipe body is reduced, and thus the cost of manufacturing a flexible pipe body is reduced. Further advantageously, smaller drums are required for the manufacture of such flexible pipe bodies, and so more flexible pipe bodies can be produced. Furthermore, the process time for the manufacture of flexible pipe bodies according to the present invention is reduced.

[0063] Brief Description of the Drawings

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

[0065] Fig. 1 illustrates a flexible pipe body;

[0066] Fig. 2 illustrates a riser system;

[0067] Fig. 3 illustrates an example pressure armour layer including wires wound at a certain lay angle;

[0068] Fig. 4 illustrates a cross-sectional view of a layer arrangement of a flexible pipe body including a permeation-barrier; and

[0069] Fig. 5 illustrates a cross-sectional view of a layer arrangement of a flexible pipe body according to an embodiment of the invention.

[0070] In the drawings like reference numerals refer to like parts.

[0071] Detailed Description

[0072] Certain terminology is used in the following description for convenience only and is not limiting. The words ‘lower’ and ‘upper’ designate directions in the drawings to which reference is made and are with respect to the described component when assembled and mounted. The words ‘inner’, ‘inwardly1and ‘outer’, ‘outwardly’ refer to directions toward and away from, respectively, a designated centreline or a geometric centre of an element being described (e.g. central axis), the particular meaning being readily apparent from the context of the description. Further, unless otherwise specified, the use of ordinal adjectives, such as, ‘first’, ‘second’, ‘third’ etc. merely indicate that different instances of like objects are being referred to and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking or in any other manner.

[0073] Throughout this description, reference will be made to a flexible pipe. It will be understood that a flexible pipe is an assembly of a portion of pipe body and one or more end fittings in each of which a respective end of the pipe body is terminated. Fig. 1 illustrates how pipe body 100 is formed in accordance with an embodiment from a combination of layered materials that form a pressure-containing conduit. Although a number of particular layers are illustrated in Fig. 1 , it is to be understood that the pipe body is broadly applicable to coaxial structures including two or more layers manufactured from a variety of possible materials. For example, the pipe body may be formed from polymer layers, metallic layers, composite layers, or a combination of different materials. It is to be further noted that 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 reinforcement fibres.

[0074] While some layers of the flexible pipe body may be described as bonded or consolidated, the flexible pipe may generally be considered an unbonded flexible pipe. That is, unless otherwise specified the various layers of the flexible pipe body are unbonded and thereby have the capacity to move longitudinally in relation to the adjacent layers during the bending or flexion of the flexible pipe body.

[0075] As used herein, layers may optionally include sub-layers. A plurality of sub-layers cooperate to form a layer with a specific purpose. For example, a sacrificial layer may be formed of one or more sub-layers.

[0076] In some examples, a composite may be a composite tape layer. In other examples a composite may include an extruded layer. Fibres within a composite material may include any of carbon fibres, or glass fibres, or basalt fibres, or tensilized polymer fibres, or metal wires, or any combination thereof. It will be understood that throughout this specification, reference is made to a tape and it will be understood that this term is to be broadly construed as encompassing any elongate structure having a preformed cross section that can be wound in a helical manner around an underlying structure.

[0077] A tape refers to an elongate material provided in a wrapable or windable form, so as to form a helically wound tape by winding around a radially inward layer of the flexible pipe body. In an example, a tape is a metallic tape which is a wrapable or windable, such as the metallic material used to form a helically wound metallic tape. A tape typically includes a pair of mutually opposed longitudinal edges with a tape body therebetween. As used herein the term lay angle refers to the angle at which a tape or layer is applied to, that is wound around, the flexible pipe body, relative to the longitudinal axis of the flexible pipe body. A tape with lay angle of 90° would be a tape wound around a radius of a crosssection of the flexible pipe body (i.e. perpendicular to the longitudinal axis of the pipe body).

[0078] It will be understood that the term radially is used to refer to a position in relation to the radius of the flexible pipe body. For example, the term radially inward is intended to refer to a position which is relatively closer to the centre, or central longitudinal axis, of the flexible pipe body and radially outward is intended to refer to a position which is relatively more distant from the centre, or central longitudinal axis, of the flexible pipe body.

[0079] Referring now to Fig. 1 , a traditional layer arrangement of flexible pipe body 100 is illustrated. In this example the flexible pipe body 100 includes an optional innermost carcass layer 101. The carcass layer 101 provides an interlocked construction that can be used as the innermost layer to prevent, totally or partially, collapse of an internal pressure sheath 102 due to pipe decompression, external pressure, and tensile armour pressure and mechanical crushing loads. The carcass layer 101 is often a metallic layer, formed from stainless steel, for example. The carcass layer 101 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) as well as such ‘rough bore’ applications (with a carcass layer).

[0080] The internal pressure sheath 102 acts as a fluid retaining layer and includes a polymer layer that ensures internal fluid integrity. It is to be understood that this layer may itself comprise a number of sub-layers. It will be appreciated that when the optional carcass layer 101 is utilised the internal pressure sheath 102 is often referred to by those skilled in the art as a barrier layer. In operation without such a carcass (so-called smooth bore operation) the internal pressure sheath 102 may be referred to as a liner.

[0081] The flexible pipe body 100 includes armour layers, having a pressure amour layer 103 as well as first and second tensile armour layers 105, 106. As will be appreciated, the pressure armour layer 103 is optional such that, without a pressure armour layer 103, the first and second tensile armour layers 105, 106 may also substantially withstand pressure as well as tension in the flexible pipe body 100.

[0082] The optional pressure armour layer 103 is provided radially outward of 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 pressure and mechanical crushing loads. That is, the pressure armour layer 103 sustains radial loads. The pressure armour layer 103 provides hoop strength to the flexible pipe body 100. The pressure armour layer 103 also structurally supports the internal pressure sheath 102. Referring additionally to Fig. 3, the pressure armour layer is formed from a helically wound arrangement of wires. The wires form an interlocked construction of wires wound with a lay angle a relative to a flexible pipe body axis A-A. The lay angle a is typically close to 90°. In this way laterally adjacent interlocking wires provide a rigid pressure armour layer 103 that provides maximal hoop strength to the entire flexible pipe body 100.

[0083] The flexible pipe body 100 also includes a first tensile armour layer 105 and a second tensile armour layer 106. Each tensile armour layer is used to sustain tensile loads and internal pressure. Further tensile armour layers may also optionally be added. A tensile armour layer is formed from a plurality 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 at a lay angle typically between about 10° to 55°. The tensile armour layers are often wound and counter-wound in pairs to balance torque in the pipe body. The tensile armour layers are often metallic layers, formed from carbon or alloy steel, for example, but may be higher alloy or stainless steel, or may be composite tendons.

[0084] The flexible pipe body 100 shown also includes optional tape layers 104 provided radially outward of the tensile armour layers 105, 106 which help contain underlying layers and to some extent prevent abrasion between adjacent layers.

[0085] The flexible pipe body 100 also typically includes optional layers of insulation 107 and an outer sheath 108, which includes a polymer layer used to protect the pipe against penetration of seawater and other external environments, corrosion, abrasion and mechanical damage.

[0086] Each flexible pipe includes at least one portion, sometimes referred to as a segment or section of flexible pipe body 100 together with an end fitting located at at least one end of the flexible pipe. An end fitting provides a mechanical device which forms the transition between the flexible pipe body and a connector. The different pipe layers as shown, for example, in Fig. 1 are terminated in the end fitting in such a way as to transfer the load between the flexible pipe and the connector.

[0087] Referring now to Fig. 2, there is shown a known riser assembly 200 suitable for transporting production fluid such as oil and / or gas and / or water from a sub-sea location 201 to a floating facility. For example, in Fig. 2 the sub-sea location 201 includes a sub-sea flow line. The flexible flow line 205 includes a flexible pipe 203, wholly or in part, resting on the sea floor 204 or buried below the sea floor and used in a static application. The floating facility may be provided by a platform and / or buoy or, as illustrated in Fig. 2, a ship 200. The riser assembly 200 is provided as a flexible riser, that is to say a flexible pipe 203 connecting the ship to the sea floor installation. The flexible pipe may be in segments of flexible pipe body with connecting end fittings. 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). Fig. 2 also illustrates how portions of flexible pipe can be utilised as a flowline 205 or jumper.

[0088] Referring now to Fig. 4 an example layer arrangement of a flexible pipe body 300 is shown in cross-section. In this example, the flexible pipe body 300 includes an internal pressure sheath 302. The internal pressure sheath 302 defines the flexible pipe bore. In some examples a carcass layer (not shown) may be provided radially inward of the internal pressure sheath 302 to define the pipe bore.

[0089] Tape layers (not numbered), and an outer sheath 308 are provided in the radially outer portion of the flexible pipe body 300. These layers are described above with reference to Fig. 1 and so will not be described again for brevity. Although not illustrated, one or more insulating layers, as is known in the art, may also be included in the flexible pipe body 300.

[0090] The flexible pipe body 300 includes an armour layer 320. In the example shown, the armour layer 320 includes a pressure armour layer formed as helically wound armour layer 323.

[0091] The armour layer 320 also includes tensile armour layers 325, 326. The tensile armour layers 325, 326 are described above with reference to Fig. 1 and so will not be described again for brevity.

[0092] The helically wound armour layer 323 includes pressure armour wires. The pressure armour wires are wrapped or wound around a continuous permeation-barrier layer 310. The pressure armour wires are wound around the continuous permeation-barrier layer 310 at a lay angle relative to the axis of the flexible pipe body of more than 80°.

[0093] The helically wound armour layer 323 is provided radially outward of the internal pressure sheath 302. In this example shown, the helically wound armour layer 323 is provided radially outward of the continuous permeation-barrier layer 310.

[0094] The helically wound armour layer 323 has an interlocked construction. Each pressure armour wire includes opposing longitudinal edges 323a, 323b having mutually engaging features, as is known in the art. With the helically wound armour layer wound onto the flexible pipe body 300 laterally adjacent wire wraps of the helically wound armour layer 323 interlock in the region of overlapping longitudinal edges 323a, 323b. In this way, the helically wound armour layer 323 predominantly provides the hoop strength for the flexible pipe body 300.

[0095] The flexible pipe body 300 includes a continuous permeation-barrier layer 310 positioned radially inward of the helically wound armour layer 323. In the example shown, the continuous permeation-barrier layer 310 is provided between the internal pressure sheath 302 and the pressure armour layer 323. The internal pressure sheath 302 is positioned radially inwards of the continuous permeation-barrier layer 310. In the example shown, the internal pressure sheath 302 is positioned directly radially adjacent to the continuous permeation-barrier layer 310.

[0096] The continuous permeation-barrier layer 310 includes a helically wound tape 312, 313. The helically wound tape 312, 313 is a helically wound polymeric tape. The helically wound tape

[0097] 312, 313 is wrapped or wound around the internal pressure sheath 302 to form the permeation-barrier layer. Successive tape wraps of the helically wound tape 312, 313 are wound around the internal pressure sheath 302 to provide a series of laterally adjacent tape wraps.

[0098] The helically wound tape 312, 313 includes two surfaces and a first longitudinal edge and a second longitudinal edge. The first and second longitudinal edges are mutually opposed edges extending along the helically wound tape 312. Thus, with the helically wound tape 312 wound around the internal pressure sheath 302 a first longitudinal edge 312a of a first tape wrap 312 abuts a second longitudinal edge 313a of laterally adjacent second tape wrap

[0099] 313.

[0100] The continuous permeation-barrier layer 310 includes a connection portion 318 configured to join laterally adjacent tape wraps of the helically wound tape 312. The connection portion 318 forms a bond between laterally adjacent tape wraps. In the example shown, the connection portion 318 is a weld bond. Advantageously, the bond ensures that the permeation-barrier layer is a continuous permeation-barrier layer 310 thereby providing a continuous permeation-barrier along the flexible pipe body 300 (i.e. with no gaps, even when the pipe bends). Permeation of the undesirable fluids from the production fluids to the pipe annulus through leakage is thereby limited. In particular, the barrier is a continuous barrier of a polymer. The adjacent tapes 312, 313 may overlap and be welded or melt bonded together at the point of overlap. The tapes 312, 313 may be heated during application and / or in situ to melt bond them to radially adjacent polymer layers (polymer wear layers or polymer internal pressure sheath for instance). Heat may come from a supply of hot gas, in the form of incident radiant heat, laser, or the like. The application of pressure to the outside of the tapes 312, 313, using rollers, during or after winding onto the pipe body, may be adopted to ensure a high degree of, or complete bonding between the permeation-barrier layer and the radially adjacent pipe body layers. Rollers may traverse around the circumference of the pipe, optionally following a similar helical angle to that of the applied tapes 312, 313, or may move axially along the pipe. The melt bonding of the layers together ensures not only continuity of the continuous permeation-barrier layer but also the ability to minimize or eliminate voids between the permeation-barrier layer and the radially adjacent polymer layers. Multiple layers of polymer wear layer and continuous permeation-barrier layer may be applied to the pipe body in order to further improve permeation resistance. Permeation of the undesirable fluids from the production fluids to the pipe annulus through transmission is thereby minimised.

[0101] In the embodiment shown in Figure 4, the connection portion 318 forms a weld bond between the abutting first longitudinal edge 312a of the first tape wrap 312 and the second longitudinal edge 313a of the second tape wrap 313. The connection portion 318 extends around the circumference of the flexible pipe body. The connection portion 318 coextends between first and second opposing longitudinal edges of adjacent tape wraps of the helically wound tape 312, 313 on the flexible pipe body. In this way, the connection portion 318 forms a bond following the pitch of the helically wound tape 312, 313. Additional layers of permeation-barrier tape may be applied directly over the first layer in a “brick” structure, in which the joins between tapes 312 and 313 are covered by an overlying tape wrap. Multiple layers of permeation-barrier tape may be melt bonded together, using heat and / or pressure just as the first tapes layer was bonded to the underlying pressure sheath 302.

[0102] A flexible pipe body 400 according to an embodiment of the invention will now be described with particular reference to Fig. 5. The flexible pipe body 400 includes an interlocked carcass layer 401 , an internal pressure sheath 402, a wear layer 403, and anti-wear tape 404 and an interlocked armour layer 405. The carcass layer 401 is provided radially inward of the internal pressure sheath 402 and defines the pipe bore.

[0103] Tape layers (not shown), and an outer sheath (not shown) are provided in the radially outer portion of the flexible pipe body 400. These layers are described above with reference to Fig. 1 and so will not be described again for brevity. Although not illustrated, one or more insulating layers, as is known in the art, may also be included in the flexible pipe body 400.

[0104] The flexible pipe body 400 includes a first polymeric permeation-barrier layer 406 and a second polymeric permeation-barrier layer 407.

[0105] The first polymeric permeation-barrier layer 406, which may be in the form of a polyimide tape (e.g. Kapton® tape) is provided intermediate the internal pressure sheath 402 and the wear layer 403. In other words, the first polymeric permeation-barrier layer 406 is radially outward of the internal pressure sheath 402 and radially inward of the wear layer 403.

[0106] The first polymeric permeation-barrier layer 406 is applied to the outer surface of the internal pressure sheath 402 and heated, for example using a laser, infra-red radiation, hot gas, or the like, such that at least a portion of the first polymeric permeation-barrier layer material melts and becomes tacky. That portion of the first polymeric permeation-barrier layer impregnates the internal pressure sheath 402, thereby forming a melt bond 408. The melt bond 408 is an alloy of the material, for example the polymer, of the internal pressure sheath 402 and the first polymeric permeation-barrier layer material.

[0107] The wear layer 403 may then be positioned radially outward of the first polymeric permeation-barrier layer 406.

[0108] The second polymeric permeation-barrier layer 407, which may also be in the form of a polyimide tape (e.g. Kapton® tape) is provided intermediate the wear layer 403 and the interlocked armour layer 405. In other words, the second polymeric permeation-barrier layer 407 is radially outward of the wear layer 403 and radially inward of the interlocked armour layer 405.

[0109] The second polymeric permeation-barrier layer 407 is applied to the outer surface of the wear layer 403 and heated, for example using a laser, infra-red radiation, hot gas, or the like, such that at least a portion of the second polymeric permeation-barrier layer material melts and becomes tacky. That portion of the second polymeric permeation-barrier layer impregnates the wear layer 403, thereby forming a melt bond 409. The melt bond 409 is an alloy of the material, for example the polymer, of the wear layer 403 and the second polymeric permeation-barrier layer material.

[0110] In this way, the flexible pipe body 400 includes two continuous polymeric permeation-barrier layers 406, 407 positioned radially outward of the carcass layer 401 and the internal pressure sheath 402. In the example shown, the continuous polymeric permeation-barrier layers 406, 407 are positioned directly adjacent the internal pressure sheath 402 and the wear layer 403. The first continuous permeation-barrier layer 406 is sandwiched between the internal pressure sheath 402 and the wear layer 403.

[0111] Advantageously, the melt bonds 408, 409 ensures that the polymeric permeation-barrier layers 406, 407 provide a continuous permeation-barrier along the flexible pipe body 400 (i.e. with no gaps, even when the pipe bends). Permeation of the undesirable fluids from the production fluids to the pipe annulus through leakage is thereby prevented. In particular, the barrier is a continuous barrier of polymeric material. Permeation of the undesirable fluids from the production fluids to the pipe annulus through transmission is thereby prevented.

[0112] Further advantageously, the permeation-barrier layers have a reduced thickness compared to known permeation-barrier layers and so the layers have a reduced weight and require less material.

[0113] It will be clear to a person skilled in the art that features described in relation to any of the embodiments described above can be applicable interchangeably between the different embodiments. The embodiments described above are examples to illustrate various features of the invention. Throughout the description and claims of this specification, the words “comprise” and “contain” 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.

[0114] Features, integers, characteristics, compounds, chemical moieties or groups 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. 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 is not restricted to the details of any foregoing embodiments. 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.

[0115] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

CLAIMS1. A flexible pipe body for transporting production fluids, the flexible pipe body comprising: an internal pressure sheath; a wear layer positioned radially outward of the internal pressure sheath; and an interlocked armour layer positioned radially outward of the wear layer; wherein a first polymeric permeation-barrier layer is provided between the internal pressure sheath and the wear layer and is at least partially bonded to the internal pressure sheath using a melt consolidation or a melt bond; and wherein a second polymeric permeation-barrier layer is provided radially inward of the interlocked armour layer and is at least partially bonded to one of the first polymeric permeation-barrier layer and the wear layer using a melt consolidation or a melt bond.

2. The flexible pipe body according to claim 1 , wherein the internal pressure sheath has a thickness and the first polymeric permeation-barrier layer impregnates less than or equal to 30% of the internal pressure sheath thickness.

3. The flexible pipe body according to claim 2, wherein the first polymeric permeationbarrier layer impregnates at least 10% of the internal pressure sheath thickness.

4. The flexible pipe body according to any of claims 1 to 3, wherein the wear layer has a thickness and the second polymeric permeation-barrier layer impregnates less than or equal to 30% of the wear layer thickness.

5. The flexible pipe body according to claim 4, wherein the second polymeric permeation-barrier layer impregnates at least 10% of the wear layer thickness.

6. The flexible pipe body according to any of claims 1 to 5, wherein the first polymeric permeation-barrier layer and / or the second polymeric permeation-barrier layer is a tape or a film.

7. The flexible pipe body according to claim 6, wherein the tape or film of the first polymeric permeation-barrier layer and / or the second polymeric-permeation barrier layer has a thickness of at least 0.3 millimetres.

8. The flexible pipe body according to claim 7, wherein the thickness of the tape or film of the first polymeric permeation-barrier layer and / or the second polymeric-permeation barrier layer is less than or equal to 5 millimetres.

9. The flexible pipe body according to any of claims 1 to 8, wherein the first polymeric permeation-barrier layer and / or the second polymeric permeation-barrier layer has a thickness of at least 5 millimetres.

10. The flexible pipe body according to claim 9, wherein the thickness of the first polymeric permeation-barrier layer and / or the second polymeric permeation-barrier layer is less than or equal to 20 millimetres.

11. The flexible pipe body according to any of claims 1 to 10, wherein the first polymeric permeation-barrier layer and / or the second polymeric permeation-barrier layer comprises a low permeation polymer.

12. The flexible pipe body according to claim 11, wherein the low permeation polymer comprises at least one of perfluoroalkoxy alkane (PFA), polyether ether ketone (PEEK), polyetherketoneketone (PEKK), polytetrafluoroethylene (PTFE), polyketone, ethylene-vinyl alcohol co-polymer, polyethylene, polypropylene, polyvinylidene fluoride (PVDF), polyphenylene sulphide (PPS), polyimide.1913. A flexible riser comprising the flexible pipe body of any preceding claim.

14. A method of manufacturing a flexible pipe body, the method comprising: providing an internal pressure sheath; providing a first polymeric permeation-barrier layer radially outward of the internal pressure sheath; heating the first polymeric permeation-barrier layer to at least partially bond the first polymeric permeation-barrier layer to the internal pressure sheath using a melt consolidation or a melt bond; providing a wear layer radially outward of the first polymeric permeation-barrier layer; providing a second polymeric permeation-barrier layer; and heating the second polymeric permeation-barrier layer to at least partially bond the second polymeric permeation-barrier layer to one of the first polymeric permeation-barrier layer and the wear layer using a melt consolidation or a melt bond.

15. The method according to claim 14, wherein the step of providing a first polymeric permeation-barrier layer radially outward of the internal pressure sheath comprises winding a helically wound tape or film of the first polymeric permeation-barrier layer material onto the internal pressure sheath of the flexible pipe body.

16. The method according to claim 14, wherein the step of providing a first polymeric permeation-barrier layer radially outward of the internal pressure sheath comprises extruding the first polymeric permeation-barrier layer material onto the internal pressure sheath of the flexible pipe body.

17. The method according to any of claims 14 to 16, wherein the step of providing a second polymeric permeation-barrier layer comprises winding a helically wound tape or film of the second polymeric permeation-barrier layer material onto the one of the first polymeric permeation-barrier layer and the wear layer of the flexible pipe body.2018. The method according to any of claims 14 to 16, wherein the step of providing a second polymeric permeation-barrier layer comprises extruding the second polymeric permeation-barrier layer material onto one of the first polymeric permeation-barrier layer and the wear layer of the flexible pipe body.

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