Method and apparatus for carcass smoothing

Abstract

A tape element, a method of forming a tape element and a strip element are disclosed. The tape element has an overall cross section profile comprising: a primary tape portion that has a primary tape cross section that is profiled in a shape of an open simple curve and a cover tape portion that has a cover tape cross section that is straight and that has a first cross section end that extends away from a centre of the overall cross section profile beyond a lateral extent of a closest one end region of the primary tape cross section that ends in an end of the cross section closest to the cover tape portion. An end region of the cover tape cross section at a remaining end of the cover tape cross section is secured to or maintained proximate to a connector region of the primary tape cross section.

Description

[0001] METHOD AND APPARATUS FOR CARCASS SMOOTHING

[0002] The present invention relates to a method and apparatus for helping to smooth a bore of a flexible pipe for transporting production fluids. In particular, but not exclusively, the present invention relates to forming a tape element for winding as a carcass layer of flexible pipe body from a straight elongate cover strip joined to a primary elongate strip, whereby the geometry of the tape element both helps to form an interlocked carcass layer and helps to smooth a radially inner surface of the carcass layer.

[0003] T raditionally flexible pipe is utilised to transport production fluids, such as oil and / or gas and / or water, from one location (such as a Christmas tree at a wellhead) to another location (such as a subsea or topside device). Flexible pipe is particularly useful in connecting a sub-sea location (which may be deep underwater, say 1000 metres or more) 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). A flexible pipe is generally formed as an assembly of flexible pipe body and one or more end fittings. The 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. There are different types of flexible pipe such as unbonded flexible pipe which is manufactured in accordance with API 17J or composite type flexible pipe or the like. The pipe body is generally built up as a combined structure including polymer layers and / or composite layers and / or metallic layers. For example, pipe body may include polymer and metal layers, or polymer and composite layers, or polymer, metal and composite layers. Layers may be formed from a single piece such as an extruded tube or by helically winding one or more wires at a desired pitch or by connecting together multiple discrete hoops that are arranged concentrically side-by-side. Depending upon the layers of the flexible pipe used and the type of flexible pipe some of the pipe layers may be bonded together or remain unbonded.

[0004] Some flexible pipe has been used for deep water (less than 3,300 feet (1 ,005.84 metres)) and ultra-deep water (greater than 3,300 feet) developments. It is the increasing demand for oil which is causing exploration to occur at greater and greater depths (for example in excess of 8202 feet (2500 metres)) where environmental factors are more extreme. Increased depths increase the pressure associated with the environment in which the flexible pipe must operate. For example, a flexible pipe may be required to operate with external pressures ranging from 0.1 MPa to 30 MPa acting on the pipe. Equally, transporting oil, gas or water may well give rise to high pressures acting on the flexible pipe from within, for example with internal pressures ranging from zero to 140 MPa from bore fluid acting on the pipe. As a result the need for high levels of performance from certain layers such as a pipe carcass or a pressure armour or a tensile armour layer of the flexible pipe body is increased. It is noted for the sake of completeness that flexible pipe may also be used for shallow water applications (for example less than around 500 metres depth) or even for shore (overland) applications.

[0005] Conventionally flexible pipe body may be constructed with a carcass layer as a radially innermost layer, in so-called “rough bore” operation. Radially outside the carcass layer is a fluid retaining layer, usually called a barrier layer when the carcass is present. Inside the barrier layer, bore fluid is transported along the flexible pipe through a central bore. The carcass layer is thus a reinforcing layer that helps to support the barrier layer from collapsing inwards due to the large crushing pressures and provides mechanical protection against abrasive particles and pigging tools passing through the central bore. The carcass layer is typically manufactured from a carcass tape that is helically wound on a mandrel such that neighbouring windings of the tape overlap and interlink. However, this approach for manufacturing the carcass layer introduces helical gaps between neighbouring carcass tape windings. Therefore, walls of the carcass layer are not smooth, instead having successive gaps. These gaps interfere with the smooth, laminar flow of the bore fluid along the central bore of flexible pipe body, introducing regions of turbulent flow. The resulting turbulence in bore fluid can significantly increase the friction factor of a bore of flexible pipe and is particularly acute for smaller diameter bores. Thus, head pressure loss is higher over a length of flexible pipe body with a carcass layer. Further, the gaps can cause production fluid flow rates to decrease because the speed of the fluid at the radially outer limit of the bore is slowed by fluid entering and escaping these gaps. Likewise adjacent repeats of the gap along a length of the pipe body can cause flow induced pulsation (FLIP) which can give rise to “Singing” under certain circumstances, for instance when the fluid is dry gas flowing at certain velocities. Such FLIP is a vector for energy vibrations through the fluid along the pipe and result in fatigue of topside and subsea equipment.

[0006] Folded tape inserts or multi component inserts have been proposed to help cover the gap and may thus be used to help alleviate this. However, due to the size and shape of such folded tapes, fluid may still breach past these inserts into the gaps between carcass windings and impact of fluid flow. Additionally, some proposed inserts are difficult and / or costly to manufacture on an industrial scale. Often a whole new manufacturing process is required to wind the carcass layer whilst inserting and aligning the insert tape relative to adjacent windings of a tape forming the carcass layer. A still further problem is that a mechanism is needed to “fix” the relative position of windings of the insert tape with respect to the carcass windings or else the insert tape may become displaced in use and cause a catastrophic failure to the flexible pipe.

[0007] WO 2015 / 169322 (‘322) discloses a flexible metal tube having a length and a longitudinal axis suitable for forming a carcass of a flexible pipe. One embodiment disclosed in ‘322 and illustrated in Figure 6 shows a metal strip 2 which has various folded parts 6, 7 joined by a folded portion 8 (together effectively forming a traditional carcass tape profile) and a cover flange 9 which is adapted to cover the gap 5 between two adjacent windings 3 and 4 when the metal strip is wound to form a tube.

[0008] However, this embodiment has numerous weaknesses. Firstly, because of manufacturing limitations, the cover flange is joined at an end extremity to the remainder of the metal strip and is cantilevered over the gap 5. The join is therefore likely to be a stress concentrator and prone to failure. Also, the joining location of the cover flange, along the folded portion 8, forces the cover flange to jut out of the gap 5 at an odd angle. This necessitates the cover flange having a curved profile, and yet despite the curved profile the angle at which the cover flange protrudes causes the cover flange to disrupt the flow of fluid in the bore region of the tube. This reduces the effectiveness of the cover flange at mitigating the effects of FLIP.

[0009] Still further, the cover flange merely partially closes the gap 5 thus enabling further disturbance of flow. Most significantly, the cover flange has to be manually attached to rest of the metal strip 2 once the strip has been folded, measurably increasing the manufacturing complexity and duration. This weakness is due to the perceived difficulties in folding the metal strip after the cover flange has been attached which ‘322 does not attempt to address. It will be appreciated that attaching thousands of metres of cover flange to a complex folded metal strip 2 is both time consuming and prone to error. Thus, the embodiment is in no way able to be used to provide flexible pipe for transport of production fluids and provides no apparent benefits compared to other known tape inserts.

[0010] Figures 13 and 14 of ‘322 illustrate an alternative embodiment, in which a single metal strip 2 with an extended kink (protrusion 34) is folded to have effectively a traditional carcass tape profile (first and second laterally folded parts 35, 36) except that the protrusion 34 acts as a cover flange. The cover flange is thus an integral part of the metal strip 2. A variation to the alternative embodiment is also shown in Figures 10 and 11. Interestingly, the priority application to ‘322, PA 2014 70276 (‘276), also includes an embodiment that was not pursued further in ‘322. Figures 9 and 10 of ‘276 illustrate a second alternative embodiment, which includes a multilayered tape 2 having three layers 21 , 22, 23. There is almost no discussion on how this tape is used or made.

[0011] For example, there is no disclosure teaching how to fold the two other layers 22, 23 without disturbing the protruding layer 21 (see Figure 9) using a manufacturing process. Also, the shear force exerted on the join between the two other layers 22, 23 when they are bent during folding causes them to separate. Further, the repeated folding of the protruding Iayer21 makes it liable to failure. The layer 21 would also be liable to interfere with a neighbouring winding when the metal strip was later attempted to be wound into a tube, causing catastrophic failure. None of these issues are addressed in ‘322 and the disclosure is effectively non enabled in consequence.

[0012] It is likely that the second alternative embodiment was not pursued further in ‘322 because the inventors realised by the international filing ‘322 that they were unable to implement the second alternative embodiment. For these reasons - and provided solely with the very limited disclosure of ‘276 - the second alternative embodiment was not enabled in ‘276. Its disclosure would have been readily dismissed as a possible / workable solution by those skilled in the art.

[0013] It is an aim of the present invention to at least partly mitigate one or more of the above- mentioned problems.

[0014] It is an aim of certain embodiments of the present invention to provide a tape element that can be helically wound to form a carcass layer of flexible pipe body which does not present radially inward facing gaps between neighbouring windings.

[0015] It is an aim of certain embodiments of the present invention to help mitigate the effects of flow induced pulsations (FLIP) in a bore of flexible pipe body.

[0016] It is an aim of certain embodiments of the present invention to provide apparatus for covering carcass cavities.

[0017] It is an aim of certain embodiments of the present invention to provide apparatus for helping to prevent the development of turbulent flow in a rough bore flexible pipe. It is an aim of certain embodiments of the present invention to provide apparatus for smoothening an inner bore of flexible pipe body, thus decreasing an equivalent friction factor compared to existing solutions and reducing overall pressure losses.

[0018] It is an aim of certain embodiments of the present invention to simplify the process of manufacturing a carcass layer of flexible pipe body from a helically wound tape element in which gaps between adjacent windings of the carcass layer are covered.

[0019] It is an aim of certain embodiments of the present invention to provide simpler and more reliable apparatus for smoothening the bore of unbonded flexible pipe body.

[0020] It is an aim of certain embodiments of the present invention to facilitate the manufacture of tape elements with new geometries including features such as a joined additional layer, bends in a cross section with a constant radius of curvature, and the like.

[0021] It is an aim of certain embodiments of the present invention to provide a manufacturing apparatus for forming a tape element that involves fewer steps than previous solutions.

[0022] It is an aim of certain embodiments of the present invention to broaden the range of possible tape element cross sections that can be manufactured.

[0023] According to a first aspect of the present invention there is provided a tape element for providing a helically wound layer in flexible pipe body of an unbonded flexible pipe, the tape element being configured for an incoming winding of the tape element to be interlocked with an immediately preceding winding of the tape element wound in a helical manner to form a flexible pipe body layer, wherein the tape element has an overall cross section profile comprising: a primary tape portion that has a primary tape cross section that is profiled in a shape of an open simple curve; and a cover tape portion that has a cover tape cross section that is straight and that has a first cross section end that extends away from a centre of the overall cross section profile beyond a lateral extent of a closest one end region of the primary tape cross section that ends in an end of the cross section closest to the cover tape portion; wherein an end region of the cover tape cross section at a remaining end of the cover tape cross section is secured to or maintained proximate to a connector region of the primary tape cross section.

[0024] Aptly the open simple curve has a hooked end that extends from a free end of the open simple curve into an intermediate region that extends into a remaining end region, that includes a bend extending towards a further free end of the open simple curve, that turns in a direction opposed to a direction associated with the hooked end.

[0025] Aptly the primary tape cross section is S-shaped.

[0026] Aptly the overall cross section profile is a profile in a plane orthogonal to a primary length-wise axis associated with the tape element.

[0027] Aptly the tape element has a common overall cross section along a whole axial length or at least 90% of a whole axial length of the tape element.

[0028] Aptly the primary tape portion has a primary tape portion cross section in which the primary tape has a uniform thickness that is a first thickness; the cover tape portion has a cover tape cross section in which the cover tape portion has a uniform thickness that has a further thickness; and the first thickness is greater than the further thickness.

[0029] Aptly the first thickness is between 1 ,8mm and 2.2mm and optionally is 2.0mm and the further thickness is between 0.7 and 0.82mm and optionally is 0.76mm.

[0030] Aptly the primary tape portion has a primary tape portion cross section in which the primary tape portion cross section has a length that is a first length; the cover tape portion has a cover tape cross section in which the cover tape portion cross section has a length that is a further length; and the first length is greater than the further length.

[0031] Aptly the unbonded flexible pipe is for transporting fluids from a deep-water subsea location that is a location where a depth of water is at least 1500m below a local water surface level. Aptly the tape element is an elongate tape element having a length to width ratio of greater than 10:1 and optionally greater than 100:1 and optionally greater than 1000:1.

[0032] Aptly each incoming winding is interlockable with a respective immediately preceding winding at a winding station that comprises a plurality of winding roller elements.

[0033] Aptly each winding roller element rotates about a respective winding roller axis and all winding roller elements are circumferentially spaced apart about a common centre point aligned with an inline manufacturing axis used for forming a helically wound collapse resistant layer in flexible pipe body.

[0034] Aptly the winding roller elements all simultaneously and constantly rotate about the inline manufacturing axis as a helically wound layer that is collapse resistant is provided.

[0035] According to a second aspect of the present invention there is provided a method of forming a tape element for providing a helically wound layer in flexible pipe body, comprising the steps of: providing a strip element that comprises a primary strip and a cover strip secured to the primary strip, to a pinch point between a first set of opposed roller elements of a plurality of sets of opposed roller elements; consecutively deforming a cross section of the strip element via opposed roller elements of the sets of opposed roller elements as the strip element is urged consecutively between roller elements of the plurality of sets; and at each of at least one set of opposed roller elements, via at least one separation element that is disposed proximate to an interface region between opposed roller elements of the at least one set, separating an edge region of the cover strip away from the primary strip thereby providing a tape element having a primary tape portion provided from the primary strip and a cover tape portion provided from the cover strip respectively.

[0036] Aptly the method further comprises: for each at least one set, separating the edge region by urging an abutment surface of a roller member that rotates about a respective pivot axis that is orthogonal to or oblique to respective pivot axes of roller elements of a respective set of roller elements proximate to the separation element. Aptly the method further comprises: for each at least one set, separating the edge region by urging a sharp edge of a blade element, that is located at a location between opposed roller surfaces of the roller elements of a respective set of roller elements, between the primary strip and the cover strip.

[0037] Aptly the method further comprises: for each at least one set, separating the edge region by urging an abutment surface of an abutment member, that comprises the separation element, against an edge of the primary strip as the primary strip is deformed at a respective set of roller elements proximate to the separation element thereby buckling the primary strip and responsive thereto urging a region of the primary strip away from a region of the cover strip.

[0038] Aptly the method further comprises: providing said strip element constantly for at least five minutes to the pinch point and, via the plurality of sets of opposed roller elements, constantly providing a tape element with a desired overall cross section from a last set of the plurality of sets of opposed roller elements.

[0039] Aptly the method further comprises: providing the strip element comprises providing the primary strip and the cover strip in an abutting side-by-side relationship in which the cover strip is axially and transversely affixed to the primary strip.

[0040] Aptly the method further comprises: providing the strip element comprises providing a primary flat strip having a common primary cross section along a primary strip length and providing a secondary flat strip as the cover strip that has a common cover strip cross section along a cover strip length and that is secured to the primary flat strip at a root region that extends axially and in a predetermined relative transverse position along an axial length of both the primary strip and cover strip.

[0041] According to a third aspect of the present invention there is provided a strip element, comprising: a primary strip that comprises a first side and a further side and that has a common primary strip cross section along a primary strip length of the primary strip and a first primary strip edge at a first end of the common primary strip cross section and a remaining primary strip edge that is spaced apart from the first primary strip edge and is disposed at a remaining end of the common primary strip cross section; and a cover strip that has a common cover strip cross section along a cover strip length of the cover strip and a first cover strip edge at a first end of the common cover strip cross section of the cover strip and a remaining cover strip edge that is spaced apart from the first cover strip edge and is disposed at a remaining end of the common cover strip cross section of the cover strip; wherein an edge region of the cover strip is welded continuously or repeatedly along the cover strip length to a side of the primary strip and the first cover strip edge of the cover strip that is a most proximate edge of the cover strip to the first primary strip edge is spaced apart from the first primary strip edge by a predetermined common distance along said a primary strip.

[0042] Aptly the strip element consists of the primary strip and the cover strip.

[0043] Aptly the primary strip and the cover strip each consist of a respective single layer strip manufactured from a strip material.

[0044] Aptly the edge region comprises a region of the cover strip inset from a nearest edge of the cover strip and the nearest edge of the cover strip to a weld line remains free or the edge region comprises a region that extends from and includes the nearest edge and a portion of the cover strip proximate to the nearest edge.

[0045] Certain embodiments of the present invention provide a tape element which includes a welded insert that can be helically wound to form a carcass layer of flexible pipe body wherein the carcass layer presents an effectively a smooth inner bore surface to fluid flowing without gaps showing between adjacent windings.

[0046] Certain embodiments of the present invention provide a tape element which includes a welded insert that can be helically wound to form a carcass layer of flexible pipe body using existing flexible pipe body designs and / or existing winding machinery. Certain embodiments of the present invention provide a continuous cover strip that is fixed to an inner diameter of a carcass layer, covering internal cavities between successive windings of a primary tape portion that are wound to form the carcass layer. The cover strip can optionally be welded, bonded and / or mechanically fastened to the inner diameter of the carcass layer. The method of fixture can be applied to an elongate strip before or during the forming process that produces the tape element. It is a much simpler method for covering the carcass cavity for FLIP mitigation and flow assurance compared to existing attempts.

[0047] Certain embodiments of the present invention provide methods for fixing a cover strip to a carcass layer that have not been developed or attempted before. Certain embodiments of the present invention differ from known attempts which typically involve inserting additional layers during manufacture of the carcass layer that are free to move, introducing a possible source of failure and additional complexities.

[0048] Certain embodiments of the present invention provide a tape element helically windable to form a carcass layer of flexible pipe body that mitigates flow induced vibration and helps reduce overall pressure losses in a length of flexible pipe body.

[0049] Certain embodiments of the present invention provide a tape element that is helically windable to form a carcass layer of flexible pipe body where flow induced pulsations is otherwise a concern and that enables smaller diameter flexible pipe body to be manufactured. This may provide cost reductions in many areas of flexible pipe body manufacture such as flexible pipe design, types and amount of materials required & weight reduction.

[0050] Certain embodiments of the present invention provide a tape element that may be helically windable to form a carcass layer of flexible pipe body that simplifies the carcass layer winding process and can use a traditional manufacturing setup, i.e. not introduce further manufacturing steps and quality checks.

[0051] Certain embodiments of the present invention provide a helically wound tape element that is used to provide a carcass layer of flexible pipe body, whereby each winding of the tape element has a cover tape portion that bridges a clear span gap in the winding that would otherwise be presented along an internal bore of the carcass layer. This may reduce flow disruption in the internal bore whilst simplifying manufacturing and reducing costs, when compared to previous, known attempts. Certain embodiments of the present invention provide manufacturing apparatus that facilitates the forming of previously difficult or unfeasible tape element cross sections.

[0052] Embodiments of the present invention will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which:

[0053] Figure 1 illustrates flexible pipe body;

[0054] Figure 2 illustrates certain uses of flexible pipe body;

[0055] Figure 3A illustrates a cross-section of a carcass layer of flexible pipe body;

[0056] Figure 3B illustrates an axial cross-section of interlocked windings of the carcass layer;

[0057] Figures 4A-G illustrate an axial cross-section of certain stages of deformation of a strip element, eventually forming a tape element that is windable to form the carcass layer;

[0058] Figure 5 illustrates a forming process for deforming a strip element to produce a tape element;

[0059] Figures 6 to 11 illustrate individual stages in the forming process;

[0060] Figure 12 illustrates a segment of the tape element;

[0061] Figure 13 illustrates an overview of how the tape element is wound to provide the carcass layer;

[0062] Figure 14 illustrates an isometric view of a winding process for providing the carcass layer;

[0063] Figures 15A-B illustrate a cross-section of two stages of the winding process illustrated in Figure 14;

[0064] Figure 16 illustrates a carcass winding machine;

[0065] Figures 17A-C illustrate joining strips to provide the strip element;

[0066] Figures 18A-F illustrate joining strip elements to provide an elongate strip element; Figures 19A-B illustrate an alternative method for forming a tape element;

[0067] Figures 20A-D illustrate another alternative method for forming a tape element;

[0068] Figure 21 illustrates another method for forming an alternative tape element; and

[0069] Figures 22A-B illustrate another alternative embodiment for providing a strip element.

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

[0071] Throughout this description, reference will be made to a flexible pipe. It is to be appreciated that certain embodiments of the present invention are applicable to use with a wide variety of flexible pipe. For example certain embodiments of the present invention can be used with respect to flexible pipe body and / or associated end fittings of the type which is manufactured according to American Petroleum Institute (API) 17J. Such flexible pipe is often referred to as unbonded flexible pipe. Other embodiments are associated with other types of flexible pipe.

[0072] It will be understood that the illustrated flexible pipes are an assembly of a portion of flexible pipe body and one or more end fittings (not shown) in each of which a respective end of the pipe body is terminated. Figure 1 illustrates how pipe body 100 containing a central bore 105 is formed from a combination of layered materials that form a pressure-containing conduit. Although a number of particular layers are illustrated in Figure 1 , it is to be understood that certain embodiments of the present invention are broadly applicable to coaxial pipe body structures including two or more layers manufactured from a variety of possible materials. Pipe body may include one or more layers containing composite materials, forming a tubular composite layer. 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.

[0073] A tubular composite layer is thus a layer having a generally tubular shape formed of composite material. Alternatively, a tubular composite layer is a layer having a generally tubular shape formed from multiple components one or more of which is formed of a composite material. The layer or any element of the composite layer may be manufactured via an extrusion, pultrusion or deposition process, or by a winding process in which adjacent windings of tape which themselves have a composite structure are consolidated together with adjacent windings. The composite material, regardless of manufacturing technique used, may optionally include a matrix or body of material having a first characteristic in which further elements having different physical characteristics are embedded. That is to say elongate fibres which are aligned to some extent or smaller fibres randomly orientated can be set into a main body or spheres or other regular or irregular shaped particles can be embedded in a matrix material, or a combination of more than one of the above. Aptly the matrix material is a thermoplastic material, aptly the thermoplastic material is polyethylene or polypropylene or nylon or PVC or PVDF or PFA or PEEK or PTFE or alloys of such materials with reinforcing fibres manufactured from one or more of glass, ceramic, basalt, carbon, carbon nanotubes, polyester, nylon, aramid, steel, nickel alloy, titanium alloy, aluminium alloy or the like or fillers manufactured from glass, ceramic, carbon, metals, buckminsterfullerenes, metal silicates, carbides, carbonates, oxides or the like.

[0074] The pipe body 100 illustrated in Figure 1 includes an internal pressure sheath 110 which acts as a fluid retaining layer and has a polymer layer that ensures internal fluid integrity. The layer provides a boundary for any conveyed (bore) fluid that passes through the bore 105. It is to be understood that this layer may itself comprise a number of sub-layers. It will be appreciated that when a carcass layer 120 is utilised the internal pressure sheath 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 may be referred to as a liner. A barrier layer 110 is illustrated in Figure 1.

[0075] It is noted that a carcass layer 120 is a pressure resistant layer that provides an interlocked construction that can be used as the innermost layer to prevent, totally or partially, collapse of the internal pressure sheath 110 due to pipe decompression, external pressure, and tensile armour pressure and mechanical crushing loads. The carcass is a crush resistant layer. It will be appreciated that certain embodiments of the present invention are thus applicable to ‘rough bore’ applications (with a carcass). Aptly the carcass layer is a metallic layer. Aptly the carcass layer is formed from stainless steel, corrosion resistant nickel alloy or the like. The carcass layer is radially positioned within the barrier layer.

[0076] The carcass layer is a “layer” in the sense that a radially innermost and outermost surface are created in single pass at a single manufacturing node. The single manufacturing node may include multiple tape handling sections axially close together so that they are effectively a single node. The node aptly extends over an axial distance of less than 2.5m. Aptly the node has a length of 1m or less. Manufacture of the carcass layer will be discussed in more detail hereinbelow.

[0077] The pipe body includes a pressure armour layer 130 that is a pressure resistant layer that provides a structural layer that increases the resistance of the flexible pipe to internal and external pressure and mechanical crushing loads. The layer also structurally supports the internal pressure sheath. Aptly as illustrated in Figure 1 the pressure armour layer is formed as a tubular layer. Aptly for unbonded type flexible pipe the pressure armour layer which provides an interlocked construction of wires with a lay angle close to 90°. Aptly in this case the pressure armour layer is a metallic layer. Aptly the pressure armour layer is formed from carbon steel, aluminium alloy, stainless steel or the like. Aptly the pressure armour layer is formed from a pultruded composite interlocking layer. Aptly the pressure armour layer is formed from a composite formed by extrusion or pultrusion or deposition. A pressure armour layer is positioned radially outside an underlying barrier layer.

[0078] The flexible pipe body also includes a first tensile armour layer 140 and a second tensile armour layer 150. Each tensile armour layer is used to sustain tensile loads and optionally also internal pressure. Aptly for some flexible pipes the tensile armour windings are metal (for example steel, stainless steel or titanium or the like). For some composite flexible pipes the tensile armour windings may be polymer composite tape windings (for example provided with either thermoplastic, for instance nylon, matrix composite or thermoset, for instance epoxy, matrix composite). For unbonded flexible pipe the 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°. Aptly the tensile armour layers are counter-wound in pairs. Aptly the tensile armour layers are metallic layers. Aptly the tensile armour layers are formed from carbon steel, stainless steel, titanium alloy, aluminium alloy or the like. Aptly the tensile armour layers are formed from a composite, polymer, or other material, or a combination of materials.

[0079] Aptly the flexible pipe body includes optional layers of tape 160 which help contain underlying layers and to some extent prevent abrasion between adjacent layers. A tape layer may optionally be a polymer or composite or a combination of materials, also optionally comprising a tubular composite layer. Tape layers can be used to help prevent metal-to-metal contact to help prevent wear. Tape layers over tensile armours can also help prevent “birdcaging” of the tensile armour wires. The flexible pipe body also includes optional layers of insulation 165 and an outer sheath 170, which comprises a polymer layer used to protect the pipe against penetration of seawater and other external environments, corrosion, abrasion and mechanical damage. Any thermal insulation layer helps limit heat loss through the pipe wall to the surrounding environment. An annulus region 180 is defined as the space between the internal pressure sheath 110 and the outer sheath 170. In other words, in the flexible pipe body illustrated in Figure 1 , the pressure armour layer 130, the first tensile armour layer 140, the further tensile armour layer 150, the optional layers of tape 160, and the optional layers of insulation 165 are located in the annulus region 180. It will be appreciated that in some embodiments, the annulus region 180 may contain any or none of the layers present in the flexible pipe body illustrated in Figure 1.

[0080] Figure 2 illustrates a riser assembly 200 suitable for transporting production fluid such as oil and / or gas and / or water from a sub-sea location 221 to a floating facility 222. Aptly production fluid may refer to the product of a subsea well outputted at high pressure via a wellhead. In Figure 2 the sub-sea location 221 includes a sub-sea flow line 225. The flexible flow line 225 comprises a flexible pipe, wholly or in part, resting on the sea floor 230 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 Figure 2, a ship. The riser assembly 200 is provided as a flexible riser composing three flexible pipes 240 connecting the ship to the sea floor installation.

[0081] Each flexible pipe 240 has a segment of the flexible pipe body 100 terminated at each end by respective end fittings 245. The end fittings 245 are joined end to end providing an uninterrupted path for bore fluid to be transported along. Aptly each flexible pipe includes at least one portion, referred to as a segment or section, of pipe body 100 together with the end fitting 245 located at at least one end of the flexible pipe. A respective end fitting 245 may be used to terminate each end of the flexible pipe body 100. The end fitting 245 may be a mechanical device that forms the transition between the flexible pipe body and a connector. The different pipe layers as shown, for example, in Figure 1 are terminated in the end fitting in such a way as to transfer the load between the flexible pipe and the connector.

[0082] It will be appreciated that there are different types of riser, as is well-known by those skilled in the art. Certain embodiments of the present invention may be used with any type of riser, such as a freely suspended (free-hanging, catenary riser), a riser restrained to some extent (buoys, chains), totally restrained riser or enclosed in a tube (I or J tubes). Some, though not all, examples of such configurations can be found in API 17J. Figure 2 also illustrates how portions of flexible pipe can be utilised as a jumper 250.

[0083] Turning to Figure 3A, a cross-section of the carcass layer 120 of the flexible pipe body 100 is illustrated. Aptly the cross-section is in a plane parallel to a longitudinal axis extending along the bore 105 of the flexible pipe body 100. It will be appreciated that the carcass layer 120 may be an example of a collapse resistant layer of the flexible pipe body. As previously mentioned the carcass layer 120 is a rigid (but flexible) tubular layer. The carcass layer 120 may help to support the internal pressure sheath 110 in providing the bore 105 for bore fluid (such as production fluids from a wellhead) to flow through. The carcass layer 120 is provided by a length of elongate tape element that has been helically wound providing interlocked windings 310. The interlocking structure of the carcass layer 120 provides some movement between interlocked windings 310, which help the carcass layer to flex and bend to some degree when an external force is applied. Figure 3A shows six interlocked windings 310I-6 of the tape element that forms the carcass layer 120, but it will be appreciated that the carcass layer 120 may contain more (or alternatively less) than six interlocked windings 310. In some instances the flexible pipe 240, and thus the layers that make up the flexible pipe 240 (including the carcass layer 120) may extend to over 500 metres, 1000 metres, or more in length. The interlocked windings 310 are self-interlocked in the sense that they do not require additional interlocked windings of an interlock tape or equivalent. Aptly adjacent interlocked windings 310 may be held together by the grip that a given locked winding 310 of the tape element provides on a neighbouring locked winding 310 due to its geometry. It will be appreciated that other embodiments may be applicable to any interlocked windings that form a collapse resistant layer.

[0084] As illustrated in Figure 3A, the carcass layer 120 has a relatively smooth radially inner surface 320 that does not leave exposed gaps 330 between windings 310. There is a gap 330 between each pair of adjacent interlocked winding of a primary tape portion due to the geometry of the cross-sectional profile of the tape element. The gaps 330 between the interlocked primary tape portion of the tape element may help to make the carcass layer 120 more flexible by providing more freedom for neighbouring interlocked windings 310 to move relative to one another. The relatively smooth radially inner surface 320 may reduce the effect of fluid induced vibrations as fluid flows along the bore 105 and / or may reduce the head pressure needed to drive the fluid along a given length of the bore 105. Each interlocked winding 310 includes the wound cover tape portion 315 that bridges the radially inwards facing gap 330 between primary tape portion windings. Aptly the wound cover tape portion 315 provides a beam bridge extending horizontally (as shown in Figure 3A, at a common radius) across the gap 330. Aptly the gap 330 is an example of a clear span distance between predetermined locations. It will be appreciated that in use, the size of the gap 330 may vary. This is because the carcass layer 120 formed of the interlocked windings 310 is able to flex as the flexible pipe body 100 containing the carcass layer 120 flexes. It will be appreciated that the wound cover tape portion 315 is part of the interlocked windings 310. Aptly the wound cover tape portion 315 is a fixed element of the interlocked windings 310. Details about the shape of the cross section of the tape element, which forms the interlocked windings of the carcass layer 120, will be discussed in more detail later.

[0085] Figure 3B illustrates an axial cross-section of two interlocked windings 310i ,2 that form part of the carcass layer 120. That is to say, the interlocked windings 310 each have a constant longitudinal profile illustrated in Figure 3B. The interlocked windings 310 shown originate from joined sheets of stainless steel that are folded and / or bent to provide the profile illustrated in Figure 3B. This process will be described in more detail with respect to Figure 4. Alternatively, the interlocked windings 310 may be formed from a metal, alloy, polymer, composite, or the like. As mentioned previously the interlocked windings 310 are part of a tape element that has been helically wound thus self-interlocking neighbouring windings 310.

[0086] The interlocked winding 310 is formed from a wound primary tape portion 340 that has a constant wound primary tape thickness ti along its length joined to a wound cover tape portion 315 that similarly has a constant wound cover tape thickness t2 along its length. Aptly h is about 2mm. Aptly h is between about 1.8mm and 2.2mm, or between 1 mm and 3mm, or between about 0.5mm and 5mm. Aptly t2 is about 0.76mm. Aptly t2 is between about 0.7mm and 0.82mm, or between about 0.5mm and 1mm, or between about 0.25mm and 2mm. Aptly the constant wound primary tape thickness h and / or the constant wound cover tape thickness t2 extend along a majority of an axial length, that is perpendicular to the cross section shown in 3B, of the interlocked winding 310. Aptly the axial cross section of the wound cover tape portion 315 is straight, as shown in Figure 3B.

[0087] The interlocked winding 310 has a first hook 350 extending from a first end region 355 that extends through a central body portion 360 to a second hook 370 extending from a second end region 375. Aptly the interlocked winding 310 is generally “S” shaped in cross-section. The first hook 350 is curved in an anticlockwise direction relative to the central body portion 360. The second hook 370 is curved in a clockwise direction relative to the central body portion 360. That is to say the first hook 350 and the second hook 370 are curved in opposite directions. Aptly the first hook 350 may be curved in a clockwise direction relative to the central body portion 360 and the second hook 370 may be curved in an anticlockwise direction. In the region where adjacent interlocked windings 310 are joined, the second hook 370 of the first interlocked winding 310i is engaged with the first hook 350 of the second interlocked winding 3102. That is to say the second end region 375 of the first interlocked winding 310i is enclosed by the first hook 350 of the second interlocked winding 3102 and the first end region 355 of the second interlocked winding 3102 is enclosed by the second hook 370 of the first interlocked winding 310i. The interlocked windings 310 are thus at least partially prevented from being separated.

[0088] The wound cover tape portion 315 of each interlocked winding 310 extends from a joint 380 that is located at a first predetermined location which is between the first end region 350 and the central body portion 360 of the wound primary tape portion 340. An extreme end 390 of the wound cover tape portion 315 opposite the joint 380 extends outwards from the central body portion 360 beyond a lateral extent 395 of the first end region 355 and / or the first hook 350. The wound cover tape portion 315 of a given interlocked winding 3102 extends straight across the clear span gap 330 between a given winding of the wound primary tape portion 340 and an adjacent interlocked winding such that said wound cover tape portion 315 contacts the adjacent winding of the wound primary tape portion 340 at a second predetermined location. Aptly the second predetermined location is between the first hook 350 and the central body portion 360 of the wound primary tape portion 340. The radially inwards facing gap 330 is thus completely covered (and thus bridged) by the wound cover tape portion 315. Aptly the wound cover tape portion has a width that may be wide enough to contact either side of the radially inwards facing gap 330 in the wound primary tape portion 340 when the adjacent windings are at their furthest apart but not so wide that adjacent cover tape portions of adjacent windings of the tape element crash together when windings are at their closest in use.

[0089] The following description of Figures 4 to 18 will now outline how the carcass layer 120 may be manufactured.

[0090] Figures 4A-G illustrate forming stages for the cross-section of a tape element 400 from an elongate strip element 410. It will be appreciated that the elongate strip element 410 may be created by joining multiple individual segments of strip element end-to-end. One such example is illustrated in Figures 18A-E. The tape element 400 may be for providing a helically wound layer in the flexible pipe body 100. It will be appreciated that each of the shapes shown in Figures 4A-G represent a cross-section of an elongate element. That is to say each elongate element has the same cross-section shown in Figures 4A-G along its longest dimension. It will also be appreciated that the tape element 400 has a similar cross-section to the cross-section of one interlocked winding 310, except that in the tape element 400 the second hook 370 has not yet been fully formed. Also, whilst the interlocked winding 310 is helically wound, the tape element 400 is not, though it is windable. Aptly the tape element 400 may be elongate. It will be appreciated that in the following description, where there is reference to a continuous process for forming the carcass layer 120 (see Figure 16 for example), “the tape element” may be one segment of an extended elongate element within the continuous forming and winding process. For example, one early part of the extended elongate element (prior to a tape element forming process) may be a strip element, whilst another further processed segment of the same extended elongate element subsequent to a forming process and a winding process may have interlocked windings of a wound tape element. The stages of forming the tape element 400 illustrated in Figures 4A-G correspond to consecutive stages of deformation provided by opposed rollers in Figures 6 to 12. It will be appreciated that in other embodiments (including but not limited to those illustrated in Figures 19 to 21), the stages of forming the tape element 400 may be provided with different roller configurations, single-axis rollers, or any suitable forming process. Intermediate rollers that introduce little or no deformation may be inserted between opposed rollers that create a desired respective deformation. Such intermediate rollers may help guide a pathway.

[0091] Figure 5 illustrates a diagrammatic representation of how the tape element 400 can be formed continuously from a strip element 410. A tape forming assembly 500 is shown which provides various forming states between the incoming elongate strip element 410 to the outgoing tape element 400. At an entry region 505 the strip element 410 is urged between a pinch point of a first group of roller elements 510i . These have rolling surfaces that are opposed. The incoming strip element 410 is consecutively deformed as it is urged through a second group of roller elements 5102; then a third group of roller elements 5103; then a fourth group of roller elements 5104; then a fifth group of roller elements 510s; then a sixth group of roller elements 510e. The resultant tape element 400 is provided by the sixth group of roller elements 510e. Figure 5 also shows how some rollers in the groups of roller elements 5101-2 have rollers that are aligned with a first axis only. Other groups of roller elements 5103-6 have some rollers that are aligned with a first axis and at least one additional roller that is aligned to a second axis. In different groups of roller elements 510 the respective first axes may not necessarily be parallel, and / or the respective second axes may not necessarily be parallel. In the present illustration the respective first axes and the respective second axes are parallel. Some rollers in a given group of roller elements 510 have an axis of rotation that is perpendicular to a primary plane 520. That is to say some rollers are aligned with the primary plane 520. Other rollers, which are in some of the groups of roller elements 510, each have an axis of rotation that is perpendicular to a secondary plane 530. That is to say some rollers are aligned with the secondary plane 530. The secondary plane 530 is perpendicular to the primary plane 520. Aptly the secondary plane 530 is oblique to the primary plane 520. Each group of roller elements has a pinch point provided by the two or three rollers in that group. Aptly the pinch point is a narrow region between the rollers in a group which is designed to effect deformation.

[0092] It will be appreciated that alternatively a different number of groups of roller elements 510 may be used. Aptly different roller profiles may be used. Aptly different configurations of each group of roller elements may be used, for example, containing rollers operating in one, two or more axes or including one or more separation elements. Figures 19 to 21 illustrate some examples of alternatives.

[0093] In some embodiments, individual rollers belonging to a different group of roller elements 510 may not all lie on the primary plane 520 and / or the secondary plane 530. Instead each pair of opposing first-axis rollers and / or each second-axis roller may be so orientated as desired for that group of roller elements 510. Aptly the primary plane 520 may be angled at about 30, 40, 50, 60, 70, 80 or 90 degrees relative to the secondary plane 530.

[0094] Turning first to Figure 4A, a cross-section of the elongate strip element 410 is shown. The elongate strip element provides a primary strip 420 (extending into the page) joined to a cover strip 430 (also extending into the page). The primary strip 420 and the cover strip 430 are both thin tape-like structures with respective generally regular rectangular cross-sections. The edges may of course alternatively be rounded or otherwise treated to achieve a desired cross section in a resultant tape element. The primary strip 420 and the cover strip 430 are the same length and contact each other along their length via a top face of the primary strip 420 contacting a bottom face of the cover strip 430. In this sense they are disposed in an abutting face-to-face relationship. Aptly, as an alternative, the primary strip 420 and the cover strip 430 are not the same length. The primary strip 420 illustrated is thicker than the cover strip 430 although in some embodiments this may not be the case. Additionally, the cover strip 430 is horizontally positioned on top of the primary strip 420 such that the primary strip 420 extends further to a horizontal extreme than the cover strip 430. That is to say an end of a cross section of the primary strip 420 extends further in a given direction from a central line of the elongate strip element 410 than an end of a cross section of the cover strip 430 does in the same direction. Aptly the primary strip 420 always overhangs the cover strip 430. The width of the cover strip 430 may be chosen to be sufficient to cover a gap 330 between interlocked windings of the wound primary portion 340 in the carcass layer 120 without being too wide as to interfere / clash with the cover strip 430 of neighbouring windings of the tape element 400.

[0095] Aptly the primary strip 420 has a thickness of about 2mm. Aptly the primary strip 420 has a thickness of between about 0.5mm and 10mm. Aptly the cover strip 430 has a thickness of about 0.76mm. Aptly the cover strip 430 has a thickness of between about 0.1mm and 2mm. Aptly the primary strip 420 has a width (left-to-right in Figure 4A) of about 82mm. Aptly the primary strip 420 has a width of between about 10mm and 150mm. Aptly the cover strip 430 has a width (left-to-right in Figure 4A) of about 19.6mm. Aptly the cover strip 430 has a width of between about 5mm and 50mm.

[0096] The primary strip 420 is joined to the cover strip 430 at a root region 435. The root region 435 is shown at a proximal end of the cover strip 430 that is proximal to the primary strip. Alternatively the root region 435 may merely be near the proximal end of the cover strip 430. The primary strip 420 is joined to the cover strip 430 at the root region 435 by a series of welds each separated by a regular interval. It will be appreciated that the root region 435 does not cover the whole contact surface between the primary strip 420 and the cover strip 430. Aptly the weld may provided by a TIG welding process, a plasma arc welding process, a resistance welding process, or the like. Aptly as an alternative the primary strip 420 is joined to the cover strip 430 by one long continuous weld. Aptly the primary strip 420 is joined to the cover strip 430 by another joining technique. Some example methods for creating the elongate strip element 410 are illustrated in Figures 17 and 22.

[0097] Figure 4B illustrates a first state deformed strip element 440. The first state deformed strip element 440 is produced by applying a first forming step to the incoming elongate strip element 410. Aptly the first state deformed strip element 440 is formed by urging the strip element 410 through a pinch point between opposed roller elements (see Figure 6). Aptly said opposed roller elements include a pair of rollers rotatable about parallel spaced apart respective axes. The first state deformed strip element 440 has the same overall profile as the strip element 410 which includes the primary strip 420 and the cover strip 430, except that the first state deformed strip element 440 has a step-shaped profile. Moving from left to right along the profile, the first state deformed strip element 440 has a clockwise bend forming an acute angle between a first end segment 442 and a central segment 444 and an anticlockwise bend forming an equally sized acute angle between the central segment 444 and a second end segment 446 opposite the first end segment 442. The pair of acute angles thus provide a “step” at the central segment 444 of the first state deformed strip element 440. Aptly the “step” has rounded corners.

[0098] Referring to Figures 5 and 6, the first state deformed strip element 440 is formed as follows. Firstly, the strip element 410 is inserted at the entry region 505 into a pinch point between rollers in the first group of roller elements 510i. The first group of roller elements 510i includes a first upper roller 610i , which rotates about a first upper roller axis 620i and has a first upper roller profile 630i. The first group 510i also includes a first lower roller 640i, which rotates about a first lower roller axis 650i and has a first lower roller profile 66O1. Aptly the upper roller profile 630 and the lower roller profile 660 are examples of abutment surfaces. It will be appreciated that an upper roller profile 630 may correspond to a shape of an upper roller 610 when directly facing part of its curved surface. Similarly a lower roller profile 660 may correspond to a shape of a lower roller 640 when directly facing part of its curved surface. As shown in Figure 6, the upper roller axis 620 and the lower roller axis 640 are both perpendicular to the primary plane 520. Also, the first upper roller axis 620i is spaced apart from the first lower roller axis 640i. The first upper roller profile 630I-6 corresponds to the first lower roller profile 66O1. The first upper roller profile 630I-6 may thus abut, along its whole length, the first lower roller profile 66O1 at once. Figure 6 illustrates an interface region 665 between the first upper roller profile 630i and the first lower roller profile 66O1. The first upper roller profile 630i has a pair of parallel surfaces 670I,2 inclined at a first angle 0i relative to the first roller axes 620i, 650i. A first parallel surface 670i left of the primary plane 520 is connected, by an adjoining surface 680 which is inclined at a second angle 02 relative to the first roller axes 620i, 650i, to a second parallel surface 6702 right of the primary plane 520 as shown in Figure 6. The first angle 01 is shallower than the second angle 02 (i.e. , 01 < 62). Aptly 01 > 02. Aptly 01 = 02. Each parallel surface 670 is joined at a respective distal end to a vertical surface 690i, 6902. A first vertical surface 690i is shown on the left (laterally outside) of the first parallel surface 670i. Aptly the first roller profiles 630i, 66O1 correspond to the profile of the first state deformed strip element 440. Aptly the first upper roller profile 630i is rotationally symmetric about a central point on the primary plane. The surfaces 670, 680 thereby help to deform the strip element 410 to provide the first state deformed strip element 440. It will be appreciated that corresponding surfaces of the first lower roller profile 66O1 also assist in this process.

[0099] Figure 4C illustrates a second state deformed strip element 450. The second state deformed strip element 450 is produced by applying a second forming step to the incoming first state deformed strip element 440. Aptly the second state deformed strip element 450 is formed by urging the first state deformed strip element 440 through a pinch point between opposed roller elements (see Figure 7). Aptly said opposed roller elements include a pair of rollers rotatable about parallel spaced apart respective axes. The second state deformed strip element 450 has the same profile as the first state deformed strip element 440 except the first end segment 442 has been deformed. In particular, the first end segment 442 has a ridged feature 455. The ridged feature 455 includes a U-shaped bend that protrudes from a flat surface and extends to an end of the second state deformed strip element 450. Aptly the ridged feature 455 may be spaced apart from the end. The U-shaped bend is comparatively small in width and depth compared to the overall profile of the second state deformed strip element 450. Aptly the U- shaped bend may have an open rectangular profile, or a V-shaped profile, or the like.

[0100] Referring now to Figures 5 and 7, the second state deformed strip element 450 is formed as follows. Firstly, the incoming first state deformed strip element 440 is output from the pinch point between rollers in the first group of roller elements 510i into a pinch point between rollers in the second group of roller elements 5102. The second group of roller elements 5102 includes a second upper roller 6102. The second upper roller 6102 rotates about a second upper roller axis 62O2 and has a second upper roller profile 6302. The second group of roller elements 5102 also includes a second lower roller 6402, which rotates about a second lower roller axis 6502 and has a second lower roller profile 66O2. Aptly the upper roller profile 630 and the lower roller profile 660 are examples of abutment surfaces. Further, as discussed with respect to Figure 6, the upper roller axis 620 and the lower roller axis 650 are both perpendicular to the primary plane 520 and spaced apart from one another, and the second upper profile 6302 also corresponds to the second lower profile 66O2.

[0101] The second state deformed strip element 450 is formed by compressive forces applied by the second upper profile 6302 and the second lower profile 66O2, as illustrated in Figure 7, due to the shape of the respective profiles 6302, 66O2. The interface region 665 is thus provided between the respective profiles 6302, 66O2. The second upper profile 6302 has the parallel surfaces 670i ,2, the adjoining surface 680, and the vertical surfaces 690 previously described. The first parallel surface 670i additionally has a raised lip 710 that protrudes above the rest of the first parallel surface 670i. The raised lip 710 is located a distance from an end of the first parallel surface 670i that adjoins the vertical surface 690. Aptly the raised lip 710 helps to provide the ridged feature 655 of the second state deformed strip element 450. The raised lip 710 thereby helps to deform the first state deformed strip element 440 to provide the second state deformed strip element 450. It will be appreciated that corresponding surfaces of the second lower roller profile 66O2 also assist in this process. Figure 4D illustrates a third state deformed strip element 460. The third state deformed strip element 460 is produced by applying a third forming step to the incoming second state deformed strip element 450. Aptly the third state deformed strip element 460 is formed by providing the second state deformed strip element 450 to a pinch point between opposed roller elements (see Figure 8). Aptly said opposed roller elements include a pair of rollers rotatable about parallel spaced apart respective axes and another roller rotatable about a perpendicular or oblique axis relative to the said respective axes. The third state deformed strip element 460 has the same profile as the second state deformed strip element 450, except for additional deformations to a main body 465 around the first end segment 442 and the second end segment 444. A first end segment bend 466 has been introduced in the first end segment 442 such that a left side expanse 467 nearest a free end of the first end segment 442 is bent at an obtuse bend angle p relative to a right side length of the first end segment 442. Additionally, a second end segment bend 468 has been introduced in the second end segment 446. At the bend 468 at the root region 435 the cover strip 430 begins to diverge from the main body 465 of the third state deformed strip element 460. Relative to the second state deformed strip element 450 the cover strip 430 remains unchanged whilst the main body 465 has been deformed away from the cover strip 430. There is an acute separation angle a between a portion of the second end segment nearest a free end and a lateral plane of the cover strip 430.

[0102] Referring now to Figures 5 and 8, the third state deformed strip element 460 is formed as follows. Firstly, the second state deformed strip element 450 is output from the pinch point between rollers in the second group of roller elements 5102 into a pinch point between rollers in the third group of roller elements 5103. The third group of roller elements 5103 includes a third upper roller 6103, a third lower roller 6403 and a first perpendicular roller 810i. It will be appreciated that the first perpendicular roller 810i is an example of a separation element. The third upper roller 6103 rotates about a third upper roller axis 62O3 and has a third upper roller profile 6303. The third lower roller 6403 rotates about a third lower roller axis 6503 and has a third lower roller profile 66O3. The first perpendicular roller 810i rotates about a first perpendicular roller axis 820i and has a first perpendicular roller profile 830i. The third upper roller axis 62O3 and the third lower roller axis 6503 are both perpendicular to the primary plane 520 and spaced apart from one another. The first perpendicular roller axis 820i is perpendicular to the secondary plane 530. Aptly the first perpendicular roller axis 820i has an orientation angle yi of around 90 degrees with the third upper roller axis 6203. Aptly the first perpendicular roller axis 820i has an orientation angle 72 of around 90 degrees with the third lower roller axis 6503. Aptly the first perpendicular roller axis 820i may be at an oblique angle to the third upper roller axis 62O3 and the third lower roller axis 6503. It will be appreciated that any pair of perpendicular roller axis 820 and upper roller axis 620 may have a different orientation angle yi relative to other pairs. Similarly, any pair of perpendicular roller axis 820 and lower roller axis 650 may have a different orientation angle 72 relative to other pairs. In some embodiments, perpendicular rollers 810 belonging to different groups of roller elements 510 may not all lie on the secondary plane 530. In other words, each perpendicular roller axis 820 may, in some embodiments, differ in alignment from any one or more other perpendicular roller axes 820. Furthermore in some embodiments, upper rollers 610 and lower rollers 640 in a given group of roller elements 510 may not be aligned to one primary plane 520 and / or may not be aligned to the same plane 520 as upper rollers 610 and lower rollers 640 in a different group of roller elements 510.

[0103] The third state deformed strip element 460 is formed by compressive forces applied by the third upper roller profile 6303, the third lower roller profile 66O3, and the first perpendicular roller profile 830i, as illustrated in Figure 8, due to the shape of the respective profiles 6303, 66O3, 830i. Aptly the upper roller profile 630, the lower roller profile 660, and the perpendicular roller profile 830 are examples of abutment surfaces. The interface region 665 is thus provided between the respective profiles 6303, 66O3, 830i. The third upper profile 6303 has, from left to right as shown in Figure 8, an inset region 840, an upper angled surface 845, an upper stepped surface 850, and an upper horizontal surface 855. The third lower profile 66O3 has, from left to right as shown in Figure 8, a first upwards protruding region 86O1 having a first lower angled surface 865i, a lower stepped surface 870, a second upwards protruding region 86O2 having a second lower angled surface 8652 and a lower horizontal surface 875. The first perpendicular roller profile 830i has an angled surface 880 joining a horizontal surface 885 at a radially outermost point 890.

[0104] The upper angled surface 845 of the third upper roller 6103 and the first lower angled surface 865i of the third lower roller 6403 cooperate to help form the first end segment bend 466, having the obtuse bend angle p, in the first end segment 442 of the third state deformed strip element 460. Also, the first perpendicular roller 810i helps to diverge the cover strip 430 from the main body 465 in three roughly concurrent actions. The radially outermost point 890 of the first perpendicular roller 810i introduces a wedge between the cover strip 430 and the main body 465. Effectively the point 890 of the first perpendicular roller 810i drives a free end (away from the root region 435) of the cover strip 430 apart from a free end (at the second end segment 446) of the main body 465. The cover strip 430 is maintained in its previous shape by contact between the upper horizonal surface 855 of the third upper roller 6103 on one side and the horizontal surface 885 of the first perpendicular roller 8101 on the other side. The second end segment bend 468 is formed, having the acute separation angle a, by contact between the angled surface 880 of the first perpendicular roller 810i and the second lower angled surface 8652 of the third lower roller 6403. The inset region 840 of the third upper roller 6103 enables the left side of the first end segment 442 of the third state deformed strip element 460 to be maintained with its previous shape.

[0105] Figure 4E illustrates a fourth state deformed strip element 470. The fourth state deformed strip element 470 is produced by applying a fourth forming step to the incoming third state deformed strip element 460. Aptly the fourth state deformed strip element 470 is formed by providing the third state deformed strip element 460 to a pinch point between opposed roller elements (see Figure 9). Aptly said opposed roller elements include a pair of rollers rotatable about parallel spaced apart respective axes and another roller rotatable about a perpendicular or oblique axis relative to the said respective axes. The fourth state deformed strip element 470 has the same profile as the third state deformed strip element 460 except that the first end segment 442 and the second end segment 446 have been further shaped, effectively increasing the overall magnitude of the acute separation angle a and decreasing the overall magnitude of the obtuse bend angle p.

[0106] Referring now to Figures 5 and 9, the fourth state deformed strip element 470 is formed as follows. Firstly, the third state deformed strip element 460 is output from the pinch point between rollers in the third group of roller elements SlOs into a pinch point between rollers in the fourth group of roller elements 5104. The fourth group of roller elements 5104 includes a fourth upper roller 6104, a fourth lower roller 6404 and a second perpendicular roller 8102. Aptly the second perpendicular roller 8102 is an example of a separation element. The fourth upper roller 6104 rotates about a fourth upper roller axis 62O4 and has a fourth upper roller profile 6304. The fourth lower roller 6404 rotates about a fourth lower roller axis 6504 and has a fourth lower roller profile 66O4. The second perpendicular roller 8102 rotates about a second perpendicular roller axis 8202 and has a second perpendicular roller profile 8302. Aptly the upper roller profile 630, the lower roller profile 660, and the perpendicular roller profile 830 are examples of abutment surfaces. The fourth upper roller axis 62O4 and the fourth lower roller axis 6404 are both perpendicular to the primary plane 520 and spaced apart from one another. The second perpendicular roller axis 8202 is perpendicular to the secondary plane 530. The second perpendicular roller axis 8202 is orthogonal to the fourth upper roller axis 62O4 and the fourth lower roller axis 6504. Aptly the second perpendicular roller axis 8202 may be at an oblique angle to the fourth upper roller axis 62O4 and the fourth lower roller axis 6504.

[0107] The fourth state deformed strip element 470 is formed by compressive forces applied by the fourth upper roller profile 6304, the fourth lower roller profile 66O4, and the second perpendicular roller profile 8302, as illustrated in Figure 9, due to the shape of the respective profiles 6304, 66O4, 8302. The interface region 665 is thus provided between the respective profiles 6304, 66O4, 8302. The fourth upper profile 6304 has, from left to right as shown in Figure 9, a first upper horizontal surface 910i, a downwards protruding region 915, an upper angled surface 920, and a second upper horizontal surface 9102. The fourth lower profile 66O4 has, from left to right as shown in Figure 9, a curved surface 925, a lower angled surface 930, an upwards protruding region 935, and a lower horizontal surface 940. The second perpendicular roller profile 8302 has a vertical surface 945 connected at an upper end, via an outwardly projecting angled surface 950, to a horizontal surface 955.

[0108] The curved surface 925 of the fourth lower roller 6404 cooperates with the downwards protruding region 915 of the fourth upper roller 6104, reducing the bend angle p of the fourth state deformed strip element 470 without crushing the ridged feature 455. Also the upwards protruding region 935, which has a slanted upper surface, cooperates with the horizontal surface 955 of the second perpendicular roller 8102 to increase the separation angle a of the fourth state deformed strip element 470 beyond 90 degrees. Meanwhile the slanted upper surface of the upwards protruding region 935 and the upper angled surface 920 help to maintain the cover strip 430 and part of the central segment 444 in a straight, undeformed shape.

[0109] Figure 4F illustrates a fifth state deformed strip element 480. The fifth state deformed strip element 480 is produced by applying a fifth forming step to the incoming fourth state deformed strip element 470. Aptly the fifth state deformed strip element 480 is formed by providing the incoming fourth state deformed strip element 470 to a pinch point between opposed roller elements (see Figure 10). Aptly said opposed roller elements include a pair of rollers rotatable about parallel spaced apart respective axes and another roller rotatable about a perpendicular or oblique axis relative to the said respective axes. The fifth state deformed strip element 480 has the same profile as the fourth state deformed strip element 460 except that the first end segment 442 and the second end segment 446 have been further shaped. Effectively there has been an increase in the overall magnitude of the separation angle a (which is no longer acute), a decrease in the overall magnitude of the bend angle p (which is no longer obtuse) and further curvature of the left side expanse 467 of the first end segment 442.

[0110] Referring now to Figures 5 and 10, the fifth state deformed strip element 480 is formed as follows. Firstly, the incoming fourth state deformed strip element 470 is output from the pinch point between rollers in the fourth group of roller elements 5104 into a pinch point between rollers in the fifth group of roller elements 5105. The fifth group of roller elements 5105 includes a fifth upper roller 6105, a fifth lower roller 640s and a third perpendicular roller 8103. Aptly the third perpendicular roller 8103 is an example of a separation element. The fifth upper roller 6105 rotates about a fifth upper roller axis 620s and has a fifth upper roller profile 630s. The fifth lower roller 640s rotates about a fifth lower roller axis 650s and has a fifth lower roller profile 66O5. The third perpendicular roller 8103 rotates about a third perpendicular roller axis 82O3 and has a third perpendicular roller profile 8303. Aptly the upper roller profile 630, the lower roller profile 660, and the perpendicular roller profile 830 are examples of abutment surfaces. The fifth upper roller axis 620s and the fifth lower roller axis 640s are both perpendicular to the primary plane 520 and spaced apart from one another. The third perpendicular roller axis 82O3 is perpendicular to the secondary plane 530. The third perpendicular roller axis 82O3 is orthogonal to the fifth upper roller axis 620s and the fifth lower roller axis 650s. Aptly the third perpendicular roller axis 82O3 may be at an oblique angle to the fifth upper roller axis 620s and the fifth lower roller axis 650s.

[0111] The fifth state deformed strip element 480 is formed by compressive forces applied by the fifth upper roller profile 630s, the fifth lower roller profile 66O5, and the third perpendicular roller profile 8303, as illustrated in Figure 10, due to the shape of the respective profiles 630s, 66O5, 8303. The interface region 665 is thus provided between the respective profiles 630s, 66O5, 8303. The fifth upper profile 630s has, from left to right as shown in Figure 10, an upper horizontal surface 1005, an upper angled surface 1010, a downwards protruding region 1020 and a gently sloping surface 1030. The fifth lower profile 66O5 has, from left to right as shown in Figure 10, a first lower horizontal surface 1040i, a first upwards protruding region 1050i with trapezoidal sides, a second lower horizontal surface 10402, a second upwards protruding region 10502 with rounded edges and a third lower horizontal surface 10403. The third perpendicular roller profile 8303 has an angled surface 1060 joined at an upper end to a horizontal surface 1070.

[0112] The first upwards protruding region 1050i of the fifth lower roller 640s cooperates with the upper angled surface 1010 and the downwards protruding region 1020 of the fifth upper roller 61 Os, which cause the first end segment bend 466 to cave inwards, reducing the bend angle P and introducing some curvature. The separation angle a between the cover strip 430 and main body 465 is driven wider by the angled surface 1060 of the third perpendicular roller 8103 pressing part of the fifth state deformed strip element 480 against a right side of the downwards protruding region 1020. Overhang of the second end segment 446 helps allow the segment 446 to bend without being guided by the second upwards protruding region 10502. It will be appreciated that any bend formed by applying bending moments at a distance away from a bend and allowing the strip to deform freely at the bend may not produce a bend with a constant radius of curvature. Such constant radius bends are discussed in respect of Figure 20. As previously discussed the cover strip 430 is maintained in a flat configuration, due to cooperation between the horizontal surface 1070 of the third perpendicular roller 8103 and the gently sloping surface 1030.

[0113] Figure 4G illustrates a final state deformed strip element. The final state deformed strip element is the tape element 400. The tape element 400 is produced by applying a sixth forming step to the incoming fifth state deformed strip element 480. Aptly the tape element 400 is formed by providing the fifth state deformed strip element 480 to a pinch point between opposed roller elements (see Figure 11). Aptly said opposed roller elements include a pair of rollers rotatable about parallel spaced apart respective axes and another roller rotatable about a perpendicular or oblique axis relative to the said respective axes. The tape element 400 has the same profile as the fifth state deformed strip element 470 except that the first end segment 442 and the second end segment 446 have been further shaped. Effectively there has been an increase in the overall magnitude of the separation angle a and further curvature of the left side expanse 467 of the first end segment 442.

[0114] Referring now to Figures 5 and 11 , the tape element 400 is formed as follows. Firstly, the incoming fifth state deformed strip element 480 is output from the pinch point between rollers in the fifth group of roller elements 510s into a pinch point between rollers in the sixth group of roller elements 510e. The sixth group of roller elements 510e includes a sixth upper roller 610e, a sixth lower roller 640e and a fourth perpendicular roller 8104. Aptly the fourth perpendicular roller 8104 is an example of a separation element. The sixth upper roller 610e rotates about a sixth upper roller axis 620e and has a sixth upper roller profile 630e. Aptly the upper roller profile 630, the lower roller profile 660, and the perpendicular roller profile 830 are examples of abutment surfaces. The sixth lower roller 640e rotates about a sixth lower roller axis 650e and has a sixth lower roller profile 660e. The fourth perpendicular roller 8104 rotates about a fourth perpendicular roller axis 82O4 and has a fourth perpendicular roller profile 8304. The sixth upper roller axis 620e and the sixth lower roller axis 640e are both perpendicular to the primary plane 520 and spaced apart from one another. The fourth perpendicular roller axis 8204 is perpendicular to the secondary plane 530. The fourth perpendicular roller axis 82O4 is orthogonal to the sixth upper roller axis 620e and the sixth lower roller axis 650e. Aptly the fourth perpendicular roller axis 82O4 may be at an oblique angle to the sixth upper roller axis 620e and the sixth lower roller axis 650e.

[0115] The tape element 400 is formed by compressive forces applied by the sixth upper roller profile 630e, the sixth lower roller profile 660e, and the fourth perpendicular roller profile 8304, as illustrated in Figure 11 , due to the shape of the respective profiles 630e, 660e, 8304. The interface region 665 is thus provided between the respective profiles 630e, 660e, 8304. The sixth upper profile 630e has, from left to right as shown in Figure 11 , a first upper horizontal surface 1110i, an upper angled surface 1120 and a downwards protruding region 1130 curving towards a second upper horizontal surface 11102. The sixth lower profile 660e has, from left to right as shown in Figure 11 , a first lower horizontal surface 1140i , a lower angled surface 1050, a second lower horizontal surface 11402, an upwards protruding region 1160 and a third lower horizontal surface 11403. The fourth perpendicular roller profile 8304 has an angled surface 1170 joined at an upper end to a horizontal surface 1180.

[0116] The first upper horizontal surface 1110i and the lower angled surface 1150 cooperate to help further curve the first end segment 442 producing a C-shaped first end segment bend 466, whilst the downwards protruding region 1130 and the upwards protruding region 1160 help to grip the tape element 400 in position. The separation angle a is further increased by abutting an overhanging portion of the second end segment 446 against the angled surface 1170 of the fourth perpendicular roller 8104 whilst gripping part of the second end segment 446 between the second upper horizontal surface 111O2 and the upwards protruding region 1160.

[0117] It will be appreciated that cooperating here may refer to the close alignment of opposing surfaces such that any material urged therebetween is deformed. In some instances, cooperating may refer to two or more surfaces acting to deform material by causing buckling, bending, or the like.

[0118] Figure 12 illustrates part of the tape element 400 mentioned above. The tape element 400 may be helically wound to form the carcass layer 120. It will be appreciated that the tape element 400 may extend in an axial direction perpendicular to a uniform cross-section by any length. In some instances the tape element 400 may have a length of 10m, 100m, 1000m or more and be stored on a spool. In other instances the tape element 400 may have a length of 10m or less and / or exist between a first manufacturing node where the tape element 400 is formed (see Figure 5 for example) and a second manufacturing node where the tape element 400 is helically wound (see Figure 14 for example).

[0119] The tape element 400 has a primary tape portion 1210 having a primary tape cross section 1215 joined to a cover tape portion 1220 having a cover tape cross section 1225 at an intermediate region 1230 of the primary tape portion 1210. It will be appreciated that the primary tape portion 1210 may in some instances be similar to carcass tapes known in the art. As is shown in Figure 12 the primary tape portion 1210 and the cover tape portion 1220 both form part of the cross-section of the tape element 400 and extend along its axial length. The cover tape cross section 1225 is generally flat, having a rectangular cross-section with rounded corners that extends in a horizontal direction as shown in Figure 12. The cover tape portion 1220 has a uniform thickness across its width and / or along its length. Aptly the thickness of the cover tape cross section 1225 is, along at least most of its length, defined by a constant cover thickness t2. Aptly t2 is about 0.76mm. Aptly t2 is between about 0.7mm and 0.82mm, or between about 0.5mm and 1mm, or between about 0.25mm and 2mm. At one end of the cover tape cross section 1225 is a free cross section end 1240. The cross section end 1240 of the cover tape cross section 1225 protrudes outwards from the tape element 400 cross section. Along an end region near the opposite end of the cover tape cross section 1225 is a root region 1245. At the root region 1245 the cover tape portion 1220 is in contact with the primary tape 1210. It will be appreciated that the root region 1245 continues along the axial length of the tape element 400. The cover tape portion 1220 is generally rigid and formed from steel. Aptly the cover tape portion 1220 may be formed from any alloy metal, polymer, composite, or the like.

[0120] The primary tape portion 1210 has a roughly S-shaped cross section. Aptly the primary tape cross section 1215 is S-shaped. The primary tape portion 1210 has a uniform thickness across its width and / or along its length. Aptly the thickness of the primary tape cross section 1215 is, along at least most of its length, defined by a constant primary thickness ti. Aptly ti is about 2mm. Aptly ti is between about 1.8mm and 2.2mm, or between 1 mm and 3mm, or between about 0.5mm and 5mm. The primary tape cross section 1215 has an open hooked end region 1260 extending from a first free end 1265. Moving along the primary tape cross section 1215 away from the first free end 1265, there is a first bend 1267 which curves in an anticlockwise direction relative to the open hooked end region 1260. The first bend 1267 and the intermediate region 1230 define a first enclosed space 1270 in the primary tape cross section 1215. The first bend 1267 continues towards the intermediate region 1230, which has a pair of oppositely-curving bends of equal magnitude that may form a stretched-out and flipped “Z” shape. Further along the primary tape cross section 1215, after the root region 1245, along which the primary tape portion 1210 is joined to the cover tape portion 1220, is a second bend 1275. The second bend 1275 straightens at a leg region 1280 that terminates in a second free end 1285. A second enclosed space 1290 is defined in the primary tape cross section 1215 by the second bend 1275 and the intermediate region 1230. A lateral extent 1295 defines a laterally outermost part of the primary tape cross section 1215 on the side of the leg region 1280. Aptly the lateral extent 1295 is defined by an outer side of the second bend 1275. Alternatively, depending on the angle of the second bend 1275, the lateral extent 1295 may alternatively be defined by the second free end 1285, should this protrude further laterally than the second bend 1275. It will be appreciated that the first enclosed space 1270 and the second enclosed space 1290 help make one winding of a length of the tape element 400 interlockable with a neighbouring, overlapping winding of the length of the tape element 400. It will further be understood that interlocking may refer to secure restraint provided between two elements without requiring an additional locking element.

[0121] A curved length h is defined along a surface extending from the second free end 1285 to a join between the cover tape portion 1220 and the primary tape portion 1210, at the root region 1245. A straight length l2is defined along a surface extending from the first cross section end 1250 of the join between the cover tape portion 1220 and the primary tape portion 1210. The curved length h is longer than the straight length l2(h > l2). Aptly in an alternative embodiment the curved length h and the straight length l2could be of equal length (h = l2) or even the straight length l2could be longer than the curved length h. It will be appreciated that this determination of lengths may depend on a method of manufacturing used to form the tape element 400. It will further be appreciated that the straight length l2should be large enough that the cover portion 1220 is able to bridge the gap 330 between neighbouring interlocked windings of the wound primary tape portion 340. Aptly the straight length l2should not be so large that the cover portion 1220 of adjacent interlocked windings of the wound primary tape portion 340 are in contact or overlapping.

[0122] It will be appreciated that whilst the tape element 400 has a specific shape as illustrated in Figure 12, in alternative embodiments any tape-like element that is windable into a tubular layer of the flexible pipe body 100 and which includes the cover tape portion 1220 could be used instead. Figure 13 illustrates how the carcass layer 120 is manufactured through a winding process using a mandrel 1310. In particular the tape element 400 is wrapped on a curved outer surface 1320 of the mandrel 1310. Aptly the winding process may be continuous. Aptly the wound cover tape portion 315 may be continuously or repeatedly secured to the wound primary tape portion 340. The curved outer surface 1320 of the mandrel 1310 is optionally composed of a cylindrical surface 1322 and / or a frustoconical surface 1324. Aptly the majority of the curved outer surface 1320 is the cylindrical surface 1322. Aptly at least 80% (or alternatively between 60% and 95%) of the curved outer surface 1320 is the cylindrical surface 1322. The frustoconical surface 1324 helps to release interlocked windings 310 from the mandrel 1310 after they are wound. The mandrel may also comprise spiral grooves or channels or protrusions to assist the advance of the formed carcass layer in an output direction 1325, the spiral pitch being suitable for the carcass layer being helically wound, and the interaction between the interlocked windings 310 and the mandrel 1310 urging the carcass layer in the output direction 1325.

[0123] The mandrel 1310 is centred on a winding axis A. The tape element 400 is helically wound around the mandrel 1310. Aptly, as the tape element 400 is wrapped around the mandrel 1310, a fixed relative axial relationship and a fixed relative lateral relationship is maintained between the primary tape portion 1210 and the cover tape portion 1220. As windings of the tape element 400 are wrapped around the mandrel 1310 near the right side of Figure 13, fully formed carcass layer 120 exits the outer surface 1320 near the left side of Figure 13 in an output direction 1325. It will be appreciated that only the cross-section of the tape element 400 and windings are shown, although in fact the windings would extend around the curved outer surface 1320 of the mandrel. Aptly the mandrel 1310 may instead have a flat cylindrical outer surface 1320. Aptly the mandrel outer surface 1320 may have features such as ridges, grooves, holes, or the like (not shown in Figure 13) for lubricant application. The frustoconical surface 1324 tapers towards a front face 1327 of the mandrel 1310. The front face 1327 is substantially circular. It will be appreciated that the winding process illustrated in Figure 13 for manufacturing carcass layer 120 is a continuous process. In other embodiments, a layer of another type of pipe could be wound from the tape element 400 using the mandrel 1310.

[0124] During the manufacturing process an incoming winding 1330 of the tape element 400 is urged towards and wrapped around the mandrel 1310. The incoming winding 1330 is aligned with a previous winding 1340 of a partially deformed section of the tape element. The incoming winding 1330 first contacts the curved outer surface 1320 at a touchdown region 1345. Aptly the touchdown region 1345 may be a desired region whereby the incoming winding 1330 should first contact the surface 1320 of the mandrel. The previous winding 1340 is itself interlocked with a still previous interlocked winding 310s. The incoming winding 1330 is positioned so that its cover portion 1220 is facing towards the mandrel outer surface 1320. The open hooked end region 1260 of the incoming winding 1330 is located in the second enclosed space 1290 of the previous winding 1340. The process of aligning and interlocking neighbouring windings 310 will be described in more detail in respect of Figures 15A-B. It will be appreciated that Figure 13 merely shows part of the winding process and the carcass layer 120 may extend over a longer distance than illustrated. Aptly the carcass layer 120 may have more than six interlocked windings 31Oo-s.

[0125] Optionally the profile of the curved outer surface 1320 of the mandrel 1310 may have one or more grooves, ridges, openings to a channel, or the like. Figure 13 illustrates an optional groove 1350 positioned near the touchdown region 1345. The groove 1350 helps to align the incoming winding 1330 (discussed in more detail in Figure 15B).

[0126] Figure 14 illustrates an isometric view of the winding process for manufacturing the carcass layer 120. In the context of the present illustration, elongate tape 400 is fed into one end (left side in Figure 14) of a carcass layer winding device 1400, and carcass layer 120 is released from the opposite free end (right side in Figure 14) of the device. Aptly the carcass layer winding device may be an example of a carcass winding machine. The winding device 1400 includes the mandrel 1310 and a series of circumferentially spaced-apart winding rollers 1410 located around the periphery of the mandrel 1310 (three shown). It will be appreciated that there may be one, two, three, four or more winding rollers 1410 in alternative embodiments. The winding rollers 1410 are broadly cylindrical and have a smaller radius than any radius of the curved outer surface 1320 of the mandrel 1310. Aptly the winding rollers 1410 may have an equally sized or larger radius than any radius of the curved outer surface 1320. Each winding roller 1410 has a respective axis of rotation that is parallel to the winding axis A of the carcass layer winding device 1400. The winding rollers 1410 are positioned near the outer surface 1320 of the mandrel 1310 so that windings of elongate tape 400 are pressed between opposed surfaces.

[0127] A first winding roller 1410i helps to position the incoming winding 1330 as it meets the curved outer surface 1320. The first winding roller 1410i thereby helps to align the incoming winding 1330 to partially overlap the previous winding 1340 (shown in more detail in the next Figure). As the winding process continues the incoming winding 1330 and the previous winding 1340 will eventually become interlocked windings 310. The second winding roller 14102 and / or the third winding roller 1410a may further help to interlock the incoming winding 1330 with the previous winding 1340. Aptly the winding rollers 1410 may, in cooperation with the mandrel 1310, deform and / or restrain the incoming winding 1330, the previous winding 1340 and / or the interlocked windings 310. As part of the tape element 400 is fed onto the curved outer surface 1320, the mandrel 1310 may rotate in an anticlockwise direction to help aid the winding process. It will be appreciated that the primary tape portion 1210 and the cover tape portion 1220 may be maintained in a fixed relative axial and / or lateral relationship as the tape element 400 is helically wound.

[0128] Aptly each winding roller 1410 may not necessarily be commonly axially aligned along its respective axis of rotation relative to other winding rollers 1410. The winding rollers 1410 may be circumferentially positioned around the mandrel 1310 to guide and / or deform the tape element 400 - and particularly the incoming winding 1330 - as it is helically wound over the previous winding 1340 on the mandrel 1310. As such in some instances the first winding roller 1410i may be axially displaced along its axis of rotation further from the front face 1327 of the mandrel 1310 than the second winding roller 14102. Aptly the second and further winding rollers 14102,3,4 may also be displaced from the previous winding roller 14101,2,3 (although not necessarily to the same degree).

[0129] Figures 15A and 15B help illustrate a longitudinal axis section view of stages of the winding process shown in Figure 14. It will be appreciated that Figures 15A-B are merely diagrammatic and not to scale.

[0130] Figure 15A also shows certain dimensions of each interlocked winding 310. The interlocked winding 310 has a wound primary tape portion which has a total depth x and a wound cover tape portion which has a total depth fc. It will be appreciated that the total depth of the wound cover tape portion may be the constant wound cover tape thickness illustrated in Figure 3B. It will be appreciated that the total depth of the wound primary tape portion represents the total thickness of an interlocked winding 310 minus the cover tape thickness. Aptly the total depth x of the wound primary tape portion may be around 6mm to 10mm or 3mm to 20mm or the like. Aptly the total depth of the wound cover tape portion may be around 0.76mm or 0.5mm to 5mm or the like.

[0131] Also shown in Figure 15A is a pivot axis A-A of the mandrel 1310 and a pivot axis B-B of the winding roller 1410. Although the pivot axes are illustrated in Figure 15A as being parallel, it will be appreciated that they could be at oblique angles. Additionally, the curved outer surface 1320 of the mandrel 1310 has an overall mandrel radius Ri of about 150mm or 50mm to 500mm or the like. Aptly the mandrel radius Ri may be bounded by the cylindrical surface 1322 of the curved outer surface 1320. It will be appreciated that the mandrel radius Ri depends on a desired bore radius of the flexible pipe body 100. The winding roller 1410 has an overall winding roller radius R2 bounded by a majority cylindrical outer surface of the winding roller surface 1510. There is a separation distance d between the pivot axis A-A of the mandrel 1310 and the pivot axis B-B of the winding roller 1410. The separation distance d may be calculated as follows: d = R1+ R2+ x + t (equation 1)

[0132] Wherein Ri represents the mandrel radius of the curved outer surface 1320 of the mandrel 1310, R2 represents the winding roller radius of the curved outer surface 1510 of the winding roller 1410, x represents the total depth of the wound primary tape portion 340, and t represents the total depth of the wound cover tape portion 315.

[0133] Figure 15A illustrates a first stage of the winding process in which the previous winding 1340 is urged to interlock with the still previous winding 310s. Part of the mandrel 1310, including its outer surface 1320 and its front face 1327 can be seen from the side. Also shown is a side profile of the first winding roller 1410i . The first winding roller 1410i has a winding roller surface 1510. In Figure 15 the winding roller surface 1510 has two curved protrusions which help to align and shape the windings of the tape element 400. It will be appreciated that the protrusions are arranged to deform and thus urge the previous winding 1340 and the still previous winding 310s into position. For example, the first free end 1265 of the still previous interlocked winding 310s is urged into the second enclosed space 1290 defined by the second bend 1275 (forming a hook) of the previous winding 1340. Aptly the winding roller surface 1510 may have any number of protrusions of any desired shape.

[0134] The previous winding 1340 is then crushed by the opposing surfaces of the mandrel 1310 and the first winding roller 1410i . As such the leg region 1280 of the still previous winding 310s is pressed against the intermediate region 1230 of the previous winding 1340. The hooked end region 1260 of the previous winding 1340 is also pressed against the intermediate region 1230 of the still previous winding 310s. Meanwhile the cover tape portion 1220 aligns parallel to and eventually abuts with the mandrel outer surface 1320. The first bend 1267 of the previous winding 1340 is deformed and its angle is reduced. Similarly, the second bend 1275 of the still previous winding 310s is deformed and its angle is reduced. The cover tape portion 1220 provides a beam bridge that entirely closes the gap 330 between adjacent windings of the primary tape portion 340. Effectively, the cover tape portion 1220 bridges a clear span between predetermined locations on adjacent windings of the primary tape portion 340. Once the windings have become fully interlocked, the interlocked windings 3103,4 are provided. The previous interlocked winding 1340 is interlocked with the still previous winding 310s and presents its outwardly facing leg region 1280 ready to receive the incoming winding 1330.

[0135] Aptly the winding roller surface 1510 may have any number of protrusions and / or the protrusions may have a different shape. Aptly the winding roller surface 1510 may have grooves. The curved outer surface 1320 of the mandrel 1310 and / or the winding roller surface 1510 may be lubricated (not shown). Aptly the curved outer surface 1320 and / or the winding roller surface 1510 may have one or more openings connected to respective fluid communication passageways for delivering lubrication fluid to the surface.

[0136] After the previous winding 1340 has been seated and interlocked with the still previous winding 31 Os, as illustrated in Figure 15B, a section of the tape element 400 may then be wound to produce part of the carcass layer 120 as. It will be appreciated that the cross-section view shown in Figure 15B represents a slightly different location along the circumference of the mandrel 1310 shown in Figure 14, at which point the incoming tape element has contacted the first winding roller 1410i .

[0137] The cross section of the incoming winding 1330 is presented at an oblique angle 0ato the curved outer surface 1320 of the mandrel 1310 so that the hooked end region 1260 is closer to the surface 1320 than the radially outwardly extending leg region 1280. The hooked end region 1260 of the incoming winding 1330 is guided into the second enclosed space 1290 of the previous winding 1340 as the tape element 400 is wound around the mandrel 1310. The open hooked end region 1260 of the incoming winding 1330 is partially restrained by the leg region 1280 of the previous (preceding) winding 1340. As the incoming winding 1330 pivots about the open hooked end region 1260, a leading edge of the carcass tape portion 1220 approaches the groove 1350. As such the carcass tape portion 1220 is seated at the touchdown position 1345. The groove 1350 thus helps to maintain a desired spacing between successive interlocked windings 310.

[0138] The leg region 1280 of the previous winding 1340 is positioned partially in the first enclosed space 1270 of the incoming winding 1330. It will be appreciated that careful timing and placement of the incoming winding 1330 relative to the previous winding 1340 may be beneficial for successful winding. It will further be appreciated that the geometry of the tape element 400 is such that the cover tape portion 1220 remains clear and may not contact any surface during the winding process, except the curved outer surface 1320. As shown in Figure 15B, the oblique angle 0aof the incoming windings 1330 may be determined. Aptly the oblique angle 0amay be defined by the angle between the width dimension of the cross section of the incoming winding 1330 and the cylindrical surface 1322 of the mandrel 1310. Aptly the oblique angle 0amay be between zero and 60 degrees.

[0139] As the winding process continues, the incoming winding 1330 is drawn inwards towards the mandrel 1310 and left (as shown in Figure 15B) in the output direction 1325. Continually, new incoming windings 1330 are provided on the right of the mandrel 1310 shown in Figure 15 and interlocked windings 310, producing the carcass layer 120, are released at a lift-off region 1520 on the left of the mandrel 1310 in accordance with the output direction 1325. Aptly release may be assisted by the optional frustoconical surface 1324 as part of the outer surface 1320 of the mandrel 1310. It will be appreciated that in other embodiments the tape element 400 may be wound in a different direction, or with additional secondary elements or the like.

[0140] Figure 16 illustrates a carcass winding machine 1600. It will be appreciated that the carcass winding machine 1600 is for manufacturing the carcass layer 120. Aptly manufacturing the carcass layer 120 is a continuous process. Aptly manufacturing the carcass layer 120 is alternatively completed in stages. The carcass winding machine 1600 rotates in an anticlockwise winding direction 1605. Aptly the winding direction 1605 may alternatively be clockwise. The carcass winding machine 1600 rotates about a main rotor pivot axis 1610 in the anticlockwise winding direction 1605. The carcass winding machine 1600 has a main rotor member with a front face 1620 that is rotatable about the main rotor pivot axis 1610. Aptly the front face 1620 may be an example of a rotor. A spool 1630 is rotatably mounted to the front face 1620 of the machine 1600 at a distance from the main rotor pivot axis 1610. The spool 1630 holds one (1) kilometre of the elongate strip element 410. That is to say the elongate strip element is pre prepared to include the primary strip and cover strip secured together. It will be appreciated that in alternative embodiments the spool 1630 may hold a length of the elongate strip element 410 that is 10m, 100m, 2km, or more. The elongate strip element may be pre-prepared using a process such as the welding process illustrated in Figures 17A-C. It will be appreciated that alternative methods may also be applied to pre-prepare the spool 1630 of the elongate strip element 410 (e.g., laser welding, friction welding, bonding, localised treatment, or the like). Alternatively, the spool 1630 may be mounted behind the front face 1620. Optionally the spool may be wound into a drum or container (not shown) where multiple lengths of the elongate strip may be wound in series into the drum or container, connected end-to-end by welding or another suitable means, and thereby a longer length of elongate strip may be supplied to the front face without interruption to the manufacturing process.

[0141] In some alternative embodiments, instead of using a pre manufactured elongate strip element, a length of the strip element 410 having a cross section similar to the previously described elongate strip element may be used. This may be manufactured from a length of primary strip 420 and a length of cover strip 430 during the manufacture of the carcass layer 120 instead of being prepared before. For example, in the embodiment illustrated in Figures 22A-B below, the elongate strip element 410 having the desired cross-section and elements may be manufactured using TIG welding almost at the point of the strip element being input to the series of forming rollers 500.

[0142] The elongate strip element 410 illustrated in Figure 16 is fed from the spool 1630 via a first guide roller 1640i and a second guide roller 16402 to the tape forming assembly 500. The guide rollers 1640 are fixed to the periphery of the front face 1620 at suitable locations to guide the strip element 410. Aptly there may be one, two, three or more guide rollers 1640. The elongate strip element 410 is formed via the tape forming assembly 500 into the elongate tape element 400. The tape element 400 is fed into the carcass layer winding device 1400 where it is wrapped around the curved outer surface 1320 of the mandrel 1310. As discussed previously, winding rollers 14101-4 help to guide and shape windings of the tape element 400. Thereby, interlocked windings 310 are created, collectively providing the carcass layer 120. In Figure 16, the carcass layer 120 extends out of the page. Aptly the carcass layer 120 is formed as the main rotor member of the winding machine 1600 rotates in winding direction 1605.

[0143] Figures 17A-C illustrate how the elongate strip element 410 may be manufactured from the primary strip 420 and the cover strip 430. In Figure 17A the primary strip 420 is illustrated. The primary strip 420 may have dimensions of about 82mm wide, 2mm thick, and extend lengthwise (top side in Figure 17A). Only a small section of an overall length of the primary strip 420 is illustrated in Figure 17A, which can extend by up to more than 1000m. Aptly the primary strip 420 may have a width of between 10mm and 200mm. Aptly the primary strip 420 may have a thickness of between 0.5mm and 5mm. Figure 17B illustrates the cover strip 430. The cover strip 430 may have dimensions of about 19.6mm wide, 0.76mm thick, and extend lengthwise (top side in Figure 17B). Whilst only a small section of an overall length of the cover strip 430 is shown in Figure 17B, the cover strip 430 may extend by up to more than 1 km lengthwise. Aptly the cover strip may have a width of between 5mm and 50mm. Aptly the cover strip 430 may have a thickness of between 0.1 mm and 2mm.

[0144] Figure 17C illustrates a continuous welding process. The elongate cover strip 430 and the elongate primary strip 420 are urged past a tungsten inert gas (TIG) welder 1710 along an inside edge 1715 of the elongate cover strip 430 nearest the root region 435. The TIG welder 1710 is located at a fixed position. Aptly the elongate primary strip 420 and / or the elongate cover strip 430 are urged past the TIG welder 1710 by applying a tensile force to a respective front edge of the elongate primary strip 420 and / or the elongate cover strip 430. Aptly the front edge is nearest the bottom of Figure 17C. Aptly the inside edge 1715 of the elongate cover strip 430 is nearest a proximal region of the elongate primary strip 420. A welding rod 1720 is fed into an electrical arc (welding region) 1730 provided by the TIG welder 1710 as the welder passes slowly along the length of the root region 435 (from front to back in Figure 17C). Molten steel from the welding rod 1720 is continuously deposited at the welding region 1730 as the TIG welder 1710 passes along the inside edge 1715 of the elongate cover strip 430. In this way a continuous (unbroken) weld 1740 is provided along the length of the elongate cover strip 430 at the root region 435 as the resulting elongate tape element 410 is drawn in an output direction 1750 (towards the bottom of Figure 17C). Aptly the welding rod 1720 may be formed from any suitable alloy metal. Alternatively welding spots or lines may be provided at intervals along the root region 435, as will be discussed in more detail in respect of Figure 21 below. Aptly said intervals may be periodically or non-periodically separated. According to either approach, the elongate strip element 410 is produced including the elongate cover strip 430 attached near one cross-sectional end to the elongate primary strip 420. Aptly the elongate cover strip 430 may be joined to the elongate primary strip 420 at the root region 435 but away from the inside edge 1715. Aptly the elongate cover strip 430 does not need to be edge-welded to the elongate primary strip 420. In a yet further alternative, the TIG welder 1710 could itself be moved past stationary elongate primary and cover strips.

[0145] According to some embodiments, a length of the elongate strip element 410 could be wound around a spool 1630 for storage, later deployment, immediate use in manufacturing the carcass layer 120, or the like. It will be appreciated that the length of primary strip 420 is about the same length as the length of cover strip 430. Aptly the primary strip 420 may have a thickness of between 1.8mm and 2.2mm and optionally is 2.0mm and the cover strip 430 a thickness of between 0.7 and 0.82mm and optionally is 0.76mm. It will further be appreciated that any suitable type of welder may be used instead of the TIG welder 1710, such as a MIG welder, flux-cored arc welder, or using other techniques such as resistance welding, laser welding, friction welding, pressure welding, or the like.

[0146] Turning to Figures 18A-F, a method of joining lengths of strip element together to form the elongate strip element 410 is illustrated. In Figure 18A, a first pre-manufactured segment of strip element 1810i and a second pre-manufactured segment of strip element 18102 are shown. In Figure 18F a single elongate strip element 410 is shown. It will be appreciated that segments of strip element 1810 may be joined using alternative methods as well.

[0147] The welding of one length of elongate strip to the next length of elongate strip may be done by automatic, semi-automatic or manual MIG or TIG welding, or using other suitable welding processes, utilizing filler rod in the welding process as would be normal for welding of different types of stainless steel or corrosion resistant alloy.

[0148] As illustrated in Figures 18A-F, the pre manufactured segments of strip element 1810i,2 may optionally be welded in a sequence to ensure the primary strip 420 and cover strip 430 remain only welded at one location.

[0149] As shown in Figures 18A-B, an end section 1820 of the cover strip 430i of the first premanufactured segment 1810i may be removed (for instance by abrasive grinding, cutting, or the like). The end section is approximately 25mm in length. That is to say, approximately 25mm (or alternatively between 5mm and 100mm) of material is removed from one end of the cover strip 430i. An end section of the cover strip 4302 of the second pre-manufactured segment I8IO2 nearest the first pre-manufactured segment 1810i is similarly removed.

[0150] Next (see Figure 18C), a butt weld 1830 is performed between the opposing ends of a primary strip 420i of the first pre-manufactured segment 1810i and a primary strip 4202 of the second pre-manufactured segment I8IO2. Any imperfections near the weld area 1830 (e.g. extra weld protrusion, geometric anomalies, or the like) may be corrected (for example by abrasive grinding).

[0151] A short section of replacement cover strip 430a is then placed on the primary strips 420I,2 in the gap created by removal of the end sections 1820I,2 (see Figure 18D). It will be appreciated that in the present example the replacement cover strip 430a is about 50mm in length although its size will depend on the matter removed at the end sections 1820. The replacement cover strip 4303 is welded via a continuous weld 1840 to the primary strips 420I,2 in the gap (see Figure 18E). Thereby a continuation of the cover strip 430 across the welded primary strips 420I,2 is created.

[0152] Next (see Figure 18F) the opposed ends of the cover strips 430I,2 of the pre-manufactured elongate strips 1810I,2 are at least partially welded via a continuous weld 1840 to the replacement cover strip 4303. Thereby, continuity is provided in the cover strip 430 along the joined lengths of elongate strip 410.

[0153] Figures 19A-B illustrate an alternative tape forming assembly 1900. The alternative tape forming assembly 1900 provides a method of forming elongate tape 400 using a series of rollers that are all parallel to one axis by also using a sharp-edged wedge (bladed element) 1910. The wedge 1910 may be fixed in position relative to the rollers. Figure 19A illustrates a diagrammatic representation of the overall alternative process of forming the tape element 400 continuously from the strip element 410. The strip element 410 passes between a pinch point provided by upper rollers 1920, corresponding lower rollers 1930, and the sharp-edged wedge 1910. Figure 19B illustrates diagrammatically a cross-section through the path taken by the strip element 410 as it passes towards a last set of rollers 1920e, 1930e. It will be appreciated that other tape element shapes, with or without the cover tape portion 1220, may be formed using this technique.

[0154] Turning back to Figure 19A, it will be appreciated that the alternative tape forming assembly 1900 is similar to the previously described tape forming assembly 500, except the perpendicular rollers 810 have been replaced by the sharp-edged wedge 1910. The sharp- edged wedge 1910 may be an example of a separation element. Aptly the sharp-edged wedge 1910 may be an example of a blade element. Also, the strip element 410 is deformed such that it has the same cross sections shown in Figures 4A-G. The strip element 410 is fed into a pinch point between a first upper roller 1920i and a first lower roller 1930i. The product of this is fed into a pinch point between a second upper roller 19202 and a second lower roller 19302, then between a third upper roller 1920a, a third lower roller 1930a and the sharp-edged wedge 1910, and so on as illustrated in Figure 19A. At each of the six stages illustrated in Figure 19A, the strip element 410 is successively deformed until the tape element 400 is eventually formed.

[0155] In Figure 19B, the third state deformed strip element 460 is shown between a third upper roller 1920a, a third lower roller 1930a, and part of the sharp-edged wedge 1910. The third upper roller 1920a and the third lower roller 1930a each have a respective axis of rotation. The third upper roller 19202 has a third upper roller profile 1940a and the third lower roller 1930a has a third lower roller profile 1950a. The third upper roller profile 1940a broadly corresponds to the third upper roller profile 630a and will not be described again here. The third lower roller profile 1950a also broadly corresponds to the third lower roller profile 66O3, except for a slanted surface 1955 near a right side of the third lower roller profile 1950a (as shown in Figure 19B). To form the third state deformed strip element 460, the third upper roller profile 1940a presses against the third lower roller profile 1950a and surfaces of the sharp-edged wedge 1910 thus deforming the element. Effectively a sharp edge 1960 of the sharp-edged wedge 1910 is urged between the cover strip 430 and the main body 465 of the third state deformed strip element 460, separating the first cross section end (edge region) 1240 of the cover strip 430 from the primary strip 420.

[0156] Figures 20A-D illustrate how the tape element 400 may be formed using an alternative forming process. According to the alternative forming process, the elongate strip element 410 is first fed through the first group of roller elements 510i followed by the second group of roller elements 5102, as illustrated in Figure 5. Then, deviating from the forming process 500 illustrated in Figure 5, the partially deformed strip element is fed through a third group of alternative roller elements 20103, a fourth group of alternative roller elements 20104, a fifth group of alternative roller elements 20105 and lastly a sixth group of alternative roller elements 2010e. Effectively in the alternative forming process, the third, fourth, fifth and sixth groups of roller elements 5103-6 in the previously described forming process 500 are replaced with the third, fourth, fifth and sixth groups of alternative roller elements 2OIO3-6 respectively.

[0157] Compared to the forming process 500 illustrated in Figure 5, it will be appreciated that all groups of roller elements contain opposed rollers that rotate about the same axis (i.e., the respective axes of rotation are parallel). As illustrated in Figures 20A-D, at each stage of the alternative forming process provided by the groups of alternative roller elements 2OIO3-6, the strip element is progressively deformed to have the same shape at the corresponding stage of the previously described groups of roller elements 5103-6.

[0158] Referring first to Figure 20A, the third group of alternative roller elements 20103 has a third upper roller 2020a having a third upper roller profile 2025a and rotating about a third upper roller axis 2030a. That is to say the third upper roller 2020a is rotatable about an axis of rotation defined by the third upper roller axis 2030a. The third group 20103 also has a third lower roller 20403 having a third lower roller profile 2045a and rotating about a third lower roller axis 2050a. It will be appreciated that the third lower roller 2040a is rotatable about an axis of rotation defined by the third lower roller axis 2050a. The upper roller profile 2025 is part of a curved outer surface of the upper roller 2020 in axial cross-section. The lower roller profile 2045 is part of a curved outer surface of the lower roller 2040 in axial cross-section. The upper roller axis 2030 is parallel to the lower roller axis 2050, although in some embodiment the upper roller axis 2030 may be oblique to the lower roller axis 2050. In either case, where the upper roller axis 2030 and the lower roller axis 2050 have a relative skew of between about 0 degrees (as shown in Figure 20A for example) and 45 degrees, the group of alternative roller elements 2010 may be considered to be a pair of single-axis rollers. It will be appreciated that corresponding features, such as the upper and lower rollers, their profiles and axes of rotation, also exist in each of the fourth, fifth, and sixth groups of alternative roller elements 20104-6, as illustrated in Figures 20B, 20C and 20D respectively.

[0159] Figure 20A shows how the third upper roller 2020a opposes the third lower roller 2040a. The rollers 2020, 2040 are thus opposed roller elements providing a pinch point therebetween. The second state deformed strip element 450 is output by the second group of roller elements 5102 and urged into the pinch point between the third rollers 2020s, 2040s. Thus the third state deformed strip element 460 is formed.

[0160] In more detail, in reference to Figures 20A and 4D the third upper roller profile 2025s cooperates with the opposing third lower roller profile 2045s to urge the second state deformed strip element 450 into an axial cross section shape of the third state deformed strip element 460. A sharp point 2060 of the third upper roller profile 2025s helps to separate the cover strip 430 from the deformed primary strip 420 creating the bend 468 in the second end segment 446 as the segment is pressed against a rounded protrusion 2062 of the third lower roller profile 20453. Effectively the sharp point 2060 and its neighbouring sides act as a sharp edge of a blade element. Meanwhile the cover strip 430 abuts a flat portion of the third upper roller profile 2025s, preventing the cover strip from deforming. The free end of the cover strip 430 is held in a V-shaped valley 2064 of the third upper roller profile 2025s. At about the same time, another bend 466 is formed in the first end segment 442 by a roughly semicircular feature 2065 in the third upper roller profile 2025s which presses the first end segment 442 against a corresponding depression in the third lower roller profile 2045s.

[0161] Turning to Figure 20B, (also in reference to Figure 4E) the fourth upper roller 20204 opposes the fourth lower roller 20404. The third state deformed strip element 460 is output by the third group of alternative roller elements 20103 and urged into the pinch point between the fourth rollers 20204, 20404. Thus the fourth state deformed strip element 470 is formed. The fourth upper roller profile 20254 squashes the third state deformed strip element 460 against the fourth lower roller profile 20454, urging the element 460 into an axial cross section shape of the fourth state deformed strip element 470. A broad wedge feature 2070 of the fourth upper roller profile 20254 drives the cover strip 430 further from the second end segment 446 of the fourth state deformed strip element 470, thereby increasing the separation angle a. The second end segment 446 is also pinched between the broad wedge feature 2070 of the fourth upper roller profile 20254 and a narrow wedge feature 2072 of the fourth lower roller profile 20454. Similarly, the first end segment 442 of the fourth state deformed strip element 470 is pinched between a squared jaw 2074 of the fourth upper roller profile 20254 and a corresponding feature of the fourth lower roller profile 20454. The pinched portions, combined with a central chamber 2076 between the profiles 20254, 20454, cause the second end segment bend 468 to become more rounded and the bend angle p to decrease.

[0162] Turning to Figure 20C, (also in reference to Figure 4F) the fifth upper roller 2020s opposes the fifth lower roller 2040s. The fourth state deformed strip element 470 is output by the fourth group of alternative roller elements 20104 and urged into the pinch point between the fifth rollers 2020s, 2040s. Thus the fifth state deformed strip element 480 is formed. The fifth upper roller profile 2025s presses the fourth state deformed strip element 470 against the fifth lower roller profile 2045s, urging the element 470 into an axial cross section shape of the fifth state deformed strip element 480. A rounded jaw 2080 of the fifth upper roller profile 2025s pinches the central segment 444 against a corresponding feature of the fifth lower roller profile 2045s. The central segment 444 is thus held in position as free ends of the first end segment 442 and the second end segment 446 are urged towards the central element 444. A pointed lip 2082 of the fifth lower roller profile 2045s and an angled portion 2084 of the fifth upper roller profile 2025s collectively bend the first end segment 442 inwards, causing the bend angle p to decrease. Meanwhile an obtuse edge 2086 of the fifth lower roller profile 2045s further drives the cover strip 430 (which is itself supported by an abutting portion of the fifth upper roller profile 2025s) away from the second end segment 446 of the fifth state deformed strip element 480.

[0163] Lastly, as shown in Figure 20D, where the sixth upper roller 2020s opposes the sixth lower roller 2040s, the tape element 400 is formed. The fifth state deformed strip element 480 is output by the fifth group of alternative roller elements 2010s and urged into the pinch point between the sixth rollers 2020s, 2040s. Referring also to Figure 4G, the sixth upper roller profile 2025s squashes the fifth state deformed strip element 480 against the sixth lower roller profile 2045s, urging the element 480 into an axial cross section shape of the tape element 400. Compared to the previous state strip element 480, the first end segment bend 446 of the first end segment 442 is rounded into an arcuate shape to form the open hooked end region 1260 of the tape element 400 and the second end segment bend 468 of the second end segment 446 is increased to form the leg region 1280 of the tape element 400. As with the previous group of rollers, the central segment 444 is pinched, holding it in position. A wide valley feature 2090 of the sixth upper roller profile 2025e cooperates with an opposing groove 2092 of the sixth lower roller profile 2045e, causing the first end segment 442 to curl inwards. An obtuse edge 2094 of the sixth lower roller profile 2045e (which has a greater angle than the obtuse edge 2086 of the previous lower roller profile 2045s) further increases the separation angle a between the central segment 444 and the cover strip 430.

[0164] Thus the tape element 400 may alternatively be formed as indicated above.

[0165] Figure 21 illustrates how an alternative tape element 2100 cross-section may be deformed in a forming step using opposed first-axis rollers 2110i,2 and a second-axis roller 2120. Aptly a first axis of the first-axis rollers 2110i ,2 may be perpendicular to a second axis of the second- axis roller 2120. It will be appreciated, as mentioned previously, that the second axis may be oriented relative to the first axis at any angle, for example, 30, 60, 80, or 90 degrees. The alternative tape element 2100 has a constant radius of curvature R throughout a bend 2130 formed near a tape end region 2135 along its cross-section. In the present example R is 2mm, although alternatively R could be any value in proportion to the scale of the alternative tape element 2100. The bend 2130 is formed by cooperating surfaces of the lower first-axis roller 21 IO2 and the second-axis roller 2120. The second-axis roller 2120 has a first curved feature 2140 that has an arcuate shape with a larger radius of curvature than R. The lower first-axis roller 21 IO2 has a corresponding second curved feature 2150 that has an arcuate shape with a smaller radius of curvature than R. It will be appreciated that successive opposed rollers like the first-axis rollers 2110 and the second axis roller 2120 may be used to gradually determine the radius of curvature R so desired for the alternative tape element 2100. In this way, the precise shape and curvature of regions of the alternative tape element 2100 cross-section can be determined. A bend of a predetermined constant radius of curvature can be provided, instead of a bend with a varying radius of curvature.

[0166] Figures 22A-B illustrate an alternative method of forming the strip element 410 using a repetitive welding process. Compared to the method illustrated in Figures 17A-C, in the present Figure the welding tool is held in a fixed position and spaced-apart spot welds are applied whilst the primary strip 420, cover strip 430, and the strip element 410 are moved. Figure 22A illustrates a side view of the repetitive welding process that is moving in a rightwards forward direction 2205. Thus, details further to the left of Figure 22A are earlier in the repetitive process and details further to the right are later in the repetitive process. Figure 22B illustrates a top view of the same repetitive process once a weld has been applied to the primary strip 420.

[0167] As shown in Figure 22A, primary strip 420 and cover strip 430 is fed towards a joining region 2210 along with a welding rod 2220. Aptly the welding rod 2220 may be formed from any suitable alloy metal. At the joining region 2210, the welding rod 2220 is melted by an electrical arc 2230 produced by a TIG welder 2240. Material from the welding rod 2220 is melted at a weld zone 2250 along the root region 435 adjoining the primary strip 420 and the cover strip 430. The TIG welder 2240 is periodically energised and subsequently de-energised forming spaced-apart spot welds 2260 in the weld zone 2250. Aptly the spot welds 2260 may be circular, pill shaped, elongate lines, or the like. Aptly the spot welds 2260 may each be separated by a predetermined distance. Aptly the spot welds 2260 may have varying gaps between one another. It will be appreciated that spot welds 2260 may use less welding rod 2220 material with no appreciable (or an acceptable) decline in joining strength. After welding, the finished strip element 410, which includes the primary strip 420 joined at the root region 435 to the cover strip 430, continues moving in the forward direction 2205. Figure 22B illustrates how the strip element 410 leaves the welding process for subsequent use. This method may therefore be beneficial for manufacturing long segments of the strip element 410 or for manufacturing the strip element 410 directly before forming the strip element 410 into the tape element 400. Aptly any suitable type of welder may be used instead of the TIG welder 2230, such as a MIG welder, flux-cored arc welder, or the like. It will be appreciated that other welding methods and other joining methods may otherwise be used to join the cover strip 430 to the primary strip 420. The manufactured strip element 410 may be subsequently stored. Aptly the manufactured strip element 410 may be formed into the elongate tape element 400 as part of a continuous manufacturing process.

[0168] In alternative unillustrated embodiments, the continuous welding process illustrated in Figures 17A-C or the periodic welding process illustrated in Figures 22-B could be used to manufacture a strip element having a cross section similar to the previously described elongate strip element 410 from spools of the primary strip 420 and the cover strip 430 during the manufacturing process for producing the carcass layer 120. In one example, the apparatus providing the periodic welding process illustrated in Figures 22A-B is mounted on the front face 1620 of the carcass welding machine. Spools of the primary strip 420 and the cover strip 430, which are also mounted on the front face 1620, are fed through the periodic winding process providing the strip element having a cross section similar to the previously described elongate strip element 410 for near-immediate entry into the tape forming assembly 500. Such applications may be beneficial because they enable off-the-shelf components to be manufactured into the carcass layer 120 without an initial manufacturing stage (e.g., where the elongate strip element 410 could be pre-prepared).

[0169] 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.

[0170] Features, integers, characteristics 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 the features and / or steps are mutually exclusive. The invention is not restricted to any details of any foregoing embodiments. The invention extends to any novel one, or 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.

[0171] 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

CLAIMS:

1. A tape element for providing a helically wound layer in flexible pipe body of an unbonded flexible pipe, the tape element being configured for an incoming winding of the tape element to be interlocked with an immediately preceding winding of the tape element wound in a helical manner to form a flexible pipe body layer, wherein the tape element has an overall cross section profile comprising: a primary tape portion that has a primary tape cross section that is profiled in a shape of an open simple curve; and a cover tape portion that has a cover tape cross section that is straight and that has a first cross section end that extends away from a centre of the overall cross section profile beyond a lateral extent of a closest one end region of the primary tape cross section that ends in an end of the cross section closest to the cover tape portion; wherein an end region of the cover tape cross section at a remaining end of the cover tape cross section is secured to or maintained proximate to a connector region of the primary tape cross section.

2. The tape element as claimed in claim 1 , further comprising; the open simple curve has a hooked end that extends from a free end of the open simple curve into an intermediate region that extends into a remaining end region, that includes a bend extending towards a further free end of the open simple curve, that turns in a direction opposed to a direction associated with the hooked end and / or the primary tape cross section is S-shaped.

3. The tape element as claimed in claim 1 or claim 2, further comprising; the overall cross section profile is a profile in a plane orthogonal to a primary length-wise axis associated with the tape element.

4. The tape element as claimed in any preceding claim, further comprising: the tape element has a common overall cross section along a whole axial length or at least 90% of a whole axial length of the tape element.

5. The tape element as claimed in any preceding claim, further comprising:the primary tape portion has a primary tape portion cross section in which the primary tape has a uniform thickness that is a first thickness; the cover tape portion has a cover tape cross section in which the cover tape portion has a uniform thickness that has a further thickness; and the first thickness is greater than the further thickness.

6. The tape element as claimed in claim 5, further comprising: the first thickness is between 1.8mm and 2.2mm and optionally is 2.0mm and the further thickness is between 0.7 and 0.82mm and optionally is 0.76mm.

7. The tape element as claimed in any preceding claim, further comprising: the primary tape portion has a primary tape portion cross section in which the primary tape portion cross section has a length that is a first length; the cover tape portion has a cover tape cross section in which the cover tape portion cross section has a length that is a further length; and the first length is greater than the further length.

8. The tape element as claimed in any one of claims 1 to 7, further comprising: the tape element is an elongate tape element having a length to width ratio of greater than 10:1 and optionally greater than 100:1 and optionally greater than 1000:1.

9. The tape element as claimed in any one of claims 1 to 8, further comprising: each incoming winding is interlockable with a respective immediately preceding winding at a winding station that comprises a plurality of winding roller elements.

10. The tape element as claimed in claim 9, further comprising: each winding roller element rotates about a respective winding roller axis and all winding roller elements are circumferentially spaced apart about a common centre point aligned with an inline manufacturing axis used for forming a helically wound collapse resistant layer in flexible pipe body and optionally the winding roller elements all simultaneously and constantly rotate about the inline manufacturing axis as a helically wound layer that is collapse resistant is provided.

11. A method of forming a tape element for providing a helically wound layer in flexible pipe body, comprising the steps of:providing a strip element that comprises a primary strip and a cover strip secured to the primary strip, to a pinch point between a first set of opposed roller elements of a plurality of sets of opposed roller elements; consecutively deforming a cross section of the strip element via opposed roller elements of the sets of opposed roller elements as the strip element is urged consecutively between roller elements of the plurality of sets; and at each of at least one set of opposed roller elements, via at least one separation element that is disposed proximate to an interface region between opposed roller elements of the at least one set, separating an edge region of the cover strip away from the primary strip thereby providing a tape element having a primary tape portion provided from the primary strip and a cover tape portion provided from the cover strip respectively.

12. The method as claimed in claim 11 , further comprising: for each at least one set, separating the edge region by urging an abutment surface of a roller member that rotates about a respective pivot axis that is orthogonal to or oblique to respective pivot axes of roller elements of a respective set of roller elements proximate to the separation element.

13. The method as claimed in claim 11 , further comprising: for each at least one set, separating the edge region by urging a sharp edge of a blade element, that is located at a location between opposed roller surfaces of the roller elements of a respective set of roller elements, between the primary strip and the cover strip.

14. The method as claimed in claim 11 , further comprising: for each at least one set, separating the edge region by urging an abutment surface of an abutment member, that comprises the separation element, against an edge of the primary strip as the primary strip is deformed at a respective set of roller elements proximate to the separation element thereby buckling the primary strip and responsive thereto urging a region of the primary strip away from a region of the cover strip.

15. The method as claimed in any one of claims 11 to 14, further comprising: providing said strip element constantly for at least five minutes to the pinch point and, via the plurality of sets of opposed roller elements, constantly providing atape element with a desired overall cross section from a last set of the plurality of sets of opposed roller elements.

16. The method as claimed in anyone of claims 11 to 14, further comprising: providing the strip element comprises providing the primary strip and the cover strip in an abutting side-by-side relationship in which the cover strip is axially and transversely affixed to the primary strip and optionally providing the strip element comprises providing a primary flat strip having a common primary cross section along a primary strip length and providing a secondary flat strip as the cover strip that has a common cover strip cross section along a cover strip length and that is secured to the primary flat strip at a root region that extends axially and in a predetermined relative transverse position along an axial length of both the primary strip and cover strip.

17. A strip element, comprising: a primary strip that comprises a first side and a further side and that has a common primary strip cross section along a primary strip length of the primary strip and a first primary strip edge at a first end of the common primary strip cross section and a remaining primary strip edge that is spaced apart from the first primary strip edge and is disposed at a remaining end of the common primary strip cross section; and a cover strip that has a common cover strip cross section along a cover strip length of the cover strip and a first cover strip edge at a first end of the common cover strip cross section of the cover strip and a remaining cover strip edge that is spaced apart from the first cover strip edge and is disposed at a remaining end of the common cover strip cross section of the cover strip; wherein an edge region of the cover strip is welded continuously or repeatedly along the cover strip length to a side of the primary strip and the first cover strip edge of the cover strip that is a most proximate edge of the cover strip to the first primary strip edge is spaced apart from the first primary strip edge by a predetermined common distance along said a primary strip.

18. The strip element as claimed in claim 17 wherein the strip element consists of the primary strip and the cover strip.

19. The strip element as claimed in claim 17 or claim 18 wherein the primary strip and the cover strip each consist of a respective single layer strip manufactured from a strip material.

20. The strip element as claimed in any one of claims 17 to 19, further comprising: the edge region comprises a region of the cover strip inset from a nearest edge of the cover strip and the nearest edge of the cover strip to a weld line remains free or the edge region comprises a region that extends from and includes the nearest edge and a portion of the cover strip proximate to the nearest edge.

Images