Method of terminating a flexible pipe body, an apparatus for terminaton and flexible pipe

Abstract

A method of terminating flexible pipe of a flexible pipe body, apparatus for terminating an end region of flexible pipe body and a flexible pipe are disclosed. The method comprises providing flexible pipe body comprising an inner fluid retaining layer, a permeation retarding layer radially outside of the inner fluid retaining layer, a polymer layer radially outside of the permeation retarding layer and a pressure armour layer radially outside of the polymer layer; and via a respective end fitting, at a first sealing location, providing a fluid tight seal against a radially outer surface of at least one end region of said a polymer layer thereby providing at least a portion of a further fluid retaining layer radially outside the inner fluid retaining layer along at least a portion of the flexible pipe body extending from said a respective end fitting.

Description

[0001] METHOD OF TERMINATING A FLEXIBLE PIPE BODY, AN APPARATUS FOR TERMINATON AND FLEXIBLE PIPE

[0002] The present invention relates to terminating flexible pipe body of a flexible pipe in an end fitting, and also to a flexible pipe. In particular, but not exclusively, the present invention relates to terminating a segment of flexible pipe body, that includes a permeation retarding layer located between a radially innermost fluid retaining layer and a further fluid retaining layer of the flexible pipe body, in an end fitting such that the radially innermost fluid retaining layer, the further fluid retaining layer, and a radially outermost fluid retaining layer are fluidly sealed at respective positions in the end fitting.

[0003] Flexible pipes are widely used in the oil and gas industry in offshore applications for the transportation of oil, gas, water, or other fluids from one location to another. Flexible pipe is particularly useful in connecting sea-level supporting structures and subsea locations (which may be deep underwater, say 1000 metres or more), where the pipe may act as a riser. A flexible pipe is generally formed as an assembly of flexible pipe body and one or more end fittings. Flexible pipe body 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). Due to their location, flexible pipes are exposed to a range of challenging conditions that may have high pressures, seawater, high tensile strain, and corrosive environments. Flexible pipe body is therefore composed of several concentric polymeric, metallic, and / or composite 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. The polymeric layers generally provide sealing from fluid ingress and the metallic layers structural rigidity.

[0004] Some flexible pipes have 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. For example, in such deep and ultra-deep water environments, ocean floor temperature increases the risk of production fluids cooling to a temperature that may lead to pipe blockage. In practice, flexible pipes are conventionally designed to perform at operating temperatures of -30°C to +130°C and pipe body are being developed for even more extreme temperatures. Increased depths also 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 and environmental resilience 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] The innermost layers of flexible pipe body often include an inner sheath which can be an extruded non-porous polymer layer that confines a bore fluid to its internal circumference, and often a carcass, a spirally wound interlocking metal structure which forms the very innermost layer. The carcass prevents the collapse of the inner liner and also protects the liner from abrasive particles. When a carcass layer is present in the flexible pipe body, the inner sheath is referred to as a barrier layer. When a carcass layer is not present in the flexible pipe body, the inner sheath is referred to as a liner.

[0006] The outermost sealed or fluid tight layer of a flexible pipe is typically the outer sheath, an extruded non-porous polymer layer that protects the pipe’s structural elements from the environment around the flexible pipe and prevents the ingress of seawater. A flexible pipe can however include additional layers located radially outside of the other sheath. These additional layers can for example include insulation layers and / or an outermost protective layer that often helps protect the outer sheath (and any insulation layers) from abrasion related damage due to contact with rough or sharp substances in the environment. The layers that are disposed radially outside of the outer sheath are typically not sealed (or fluid tight) in order to reduce the axial compression experienced by a flexible pipe in use.

[0007] Flexible pipes sometimes include an outer and an inner polymer layer. An annulus of such a flexible pipe is typically a region between the innermost fluid containing layer and the outermost fluid containing layer. The innermost layers in the annulus region are typically pressure armour layers, which are often made of helically wound flattened metallic wires arranged at a lay angle close to 90°. Neighbouring wound wires in the pressure armour layer often interlock to control the gap between windings. Pressure armour is designed to withstand hoop stress in the pipe wall, which is caused by the bore fluid pressure. Pairs of tensile armour layers are typically also located in the annulus, and these are often cross-wound radially outside the pressure armour layer. Tensile armour layers are often made of slightly flattened rectangular metallic wires arranged at a lay angle of about 25 - 55°. Tensile armour layers support the weight of all internal pipe layers and transfer the resulting tensile stress to the sealevel supporting structures. The annulus may also have other layers such as anti-wear and anti-birdcaging tapes, and thermally insulating layers. Carbon steel wires in the annulus are thus often a feature of flexible pipes for subsea environments.

[0008] Conventionally in the end fitting, flexible pipe body is typically terminated by sealing and securing ends of some polymer or composite layers and securing any pressure armour windings and securing the tensile armour wires. The annulus which extends along the flexible pipe body segment thus extends into a region within the end fitting. In configurations where two flexible pipes are joined end-to-end to form a pipeline there is typically no fluid connection between the annulus in one flexible pipe and the annulus in the other flexible pipe.

[0009] T raditionally flexible pipe is utilised to transport production fluids, such as oil and / or gas and / or water, from one location to another. Flexible pipe is particularly useful in connecting a sub-sea location to a sea level location. Flexible pipe is generally formed as an assembly of a portion of flexible pipe body and one or more end fittings. The pipe body is typically formed as a composite of layered materials that form a pressure-containing conduit. The pipe structure allows large deflections without causing bending stresses that impair the pipe's functionality over its lifetime. The pipe body is generally built up as a composite structure including metallic and polymer layers.

[0010] The end fittings of a flexible pipe may be used for connecting segments of flexible pipe together or for connecting them to terminal equipment such as a rigid sub-sea structures or floating facilities. As such amongst other varied uses, flexible pipe can be used to provide a riser assembly for transporting fluids from a sub-sea flowline to a floating structure. In such a riser assembly a first segment of flexible pipe may be connected to one or more further segments of flexible pipe. Each segment of flexible pipe typically includes at least one (for example two) end fitting(s). It is well-known that there are many varied problems associated with the provision of end fittings for ends of flexible pipe body. The end fittings must ensure both good fastening and good sealing. Particular problems occur when the various specific layers of the multi layer flexible pipe body are terminated. The flexible pipe body may include layers having very different material characteristics such as single polymer layers and / or interlocked metallic layers. The termination of each of these layers in an end fitting brings with it characteristic problems. For example, flexible pipe body typically includes an internal barrier layer formed generally as a polymer sheath or inner pressure sheath. Such a layer operates as a primary liquid retaining layer. To prevent rupture of such a layer or indeed any underlying layer under high pressure caused by the pressure of the transported fluid, an interlocked wire layer is often located outside the barrier layer. Armour layers formed by layers of wire may also be provided to sustain tensile loads and internal pressure. If a pressure armour layer is not supported along its length, it is possible for portions of the barrier layer or other such underlying layer to burst through under pressure and cause failure of the terminating structure.

[0011] It is known that gasses from fluid in a flexible pipe bore in use can permeate through the respective layers of the flexible pipe and can intrude into an annulus of the flexible pipe. Sometimes these gasses can be harmful for particular layers of the flexible pipe. For example, gasses such as carbon dioxide and hydrogen sulphide can aberrantly affect metallic layers such as armouring layers that are often located in a pipe annulus and can for example increase rates of corrosion and the like, and can generally reduce the structural stability of such armouring layers. This can result in a reduced fatigue life of a flexible pipe and can increase the need for repairs and pipe downtime which can be costly and complex. Furthermore, there is a problem, with implementing non-sealed layers that aim to prevent or reduce permeation of such harmful gases into the pipe annulus as gas will find a preferential flow route that often is located in a pipe end fitting where such a non-sealed layer is terminated. This can sometimes result in regions of high gas flow at the end fitting and thus can result in gas rich regions of a pipe annulus at or proximate to the end fitting. Armouring layers sometimes experience significantly high forces / loads at or proximate to end fittings due to differences in rigidity of pipe components at such a location and thus a gas rich region (which may harm the structural integrity of pipe armour layers) at or proximate to end fittings can be problematic.

[0012] It is an aim of the present invention to at least partly mitigate one or more of the above- mentioned problems. It is an aim of certain embodiments of the present invention to provide a sealed intermediate polymer layer of a flexible pipe that helps prevent a preferential gas flow at or proximate to a flexible pipe end fitting.

[0013] It is an aim of certain embodiments of the present invention to provide a method of terminating a segment of flexible pipe body that includes sealing an intermediate polymer layer, that is located radially within the outer sheath but radially outside of the inner pressure sheath, at a sealing position in the end fitting.

[0014] It is an aim of certain embodiments of the present invention to provide a flexible pipe that includes an inner pressure sheath that is a radially innermost fluid retaining layer, a permeation retarding layer that is radially outside of the radially innermost fluid retaining layer, an intermediate sealed fluid retaining layer that is arranged radially outside of the permeation retarding layer, a pressure armour layer that is arranged radially outside of the intermediate sealed fluid retaining layer, and an outermost fluid retaining layer that is arranged radially outside of the pressure armour layer, one or more further amour layers (for example tensile armour layers) optionally being arranged between the intermediate sealed fluid retaining layer and the outermost fluid retaining layer.

[0015] Certain embodiments of the present invention provide an intermediate sealed fluid retaining layer that is further fluid retaining layer.

[0016] Certain embodiments of the present invention provide an intermediate sealed fluid retaining layer that is also a protective layer that helps protect the permeation retarding layer from abrasion with one or more armour layer such as a pressure armour layer.

[0017] It is an aim of certain embodiments of the present invention to provide a flexible pipe that includes a sealed inner annulus, in which a permeation resistant layer is located, and a sealed outer annulus, that includes one or more armour layers, and optionally a first fluid communication passageway through an end fitting of the flexible pipe that is fluidly connected to the inner annulus and / or a further fluid communication passageway through the end fitting that is fluidly connected to the outer annulus. It is an aim of certain embodiments of the present invention to provide a permeation retarding layer located in an inner annulus of a flexible pipe and that includes one or a plurality of surface features such as undulations or corrugations or the like to promote gas flow longitudinally through the inner annulus and towards a vent pathway in a flexible pipe end fitting.

[0018] According to a first aspect of the present invention there is provided a method of terminating flexible pipe body of a flexible pipe, comprising the steps of: providing flexible pipe body comprising an inner fluid retaining layer, a permeation retarding layer radially outside of the inner fluid retaining layer, a polymer layer radially outside of the permeation retarding layer and a pressure armour layer radially outside of the polymer layer; and via a respective end fitting, at a first sealing location, providing a fluid tight seal against a radially outer surface of at least one end region of said a polymer layer thereby providing at least a portion of a further fluid retaining layer radially outside the inner fluid retaining layer along at least a portion of the flexible pipe body extending from said a respective end fitting.

[0019] Aptly the method further comprises, via a respective end fitting at each end of the flexible pipe body, sealing each of two end regions of said a polymer layer, thereby providing a sealed fluid retaining layer between respective sealing locations in respective end fittings and providing a radially inner annulus region between a radially outside surface of the inner fluid retaining layer and a radially inner surface of said a sealed fluid retaining layer that comprises said a polymer layer.

[0020] Aptly the method further comprises sealing each end region of the polymer layer at a respective sealing location by energising an annular seal element of a respective end fitting at the sealing location, during a termination process.

[0021] Aptly the method further comprises providing a further annulus region between a radially outer surface of said a polymer layer and a radially inner surface of an outer sheath of the flexible pipe body, that provides a still further fluid retaining layer, whereby the pressure armour layer and at least one tensile armour layer of the flexible pipe body are disposed in the further annulus region.

[0022] Aptly the method further comprises providing the permeation retarding layer by helically winding a tape element over the inner fluid retaining layer whereby adjacent windings of the tape element overlap or by providing an extruded layer over the inner fluid retaining layer, and subsequently providing the polymer layer over overlapped windings of the tape element or the extruded permeation retarding layer thereby providing the inner fluid retaining layer radially inside the polymer layer.

[0023] Aptly the method further comprises providing said an extruded layer by extruding a layer of polyamide and / or polyethylene and / or polyvinylidene fluoride, said a layer optionally having a thickness of 0.52 to 10 mm, the thickness optionally being 2 mm to 7 mm, the thickness optionally being 3 mm to 6 mm.

[0024] Aptly the method further comprises providing the permeation retarding layer by helically winding a PEEK tape or PEEK-based tape or metal tape around the inner fluid retaining layer with adjacent windings of a wound tape optionally overlapping by between 10% to 70%16%, optionally between 20% and 60%, optionally around 50%.

[0025] Aptly the method further comprises providing a standoff between pressure armour windings of the pressure armour layer and an outer surface of the permeation retarding layer via the polymer layer.

[0026] Aptly the method further comprises preventing, wholly or at least in part, permeating gas from permeating through a sacrificial layer comprising the polymer layer disposed between the pressure armour layer and the permeation retarding layer and radially outside a barrier layer or liner that comprises the inner fluid retaining layer, thereby partially reducing cracking and / or fracture of armour windings in a further annulus region, comprising a primary annulus region, of the flexible pipe body.

[0027] According to a second aspect of the present invention there is provided apparatus for terminating an end region of flexible pipe body, comprising: a first elongate body comprising a connection flange at a first elongate body end and an open mouth at a remaining elongate body end, a radially inner facing surface proximate to the remaining body end extending from said open mouth; a first annular seal element locatable between a portion of the inner facing surface and an outer surface of an inner fluid retaining layer of an end region of flexible pipe body; an intermediate collar securable to the first elongate body around the inner fluid retaining layer, a permeation retarding layer of the flexible pipe body disposed over the inner fluid retaining layer and a polymer layer of the flexible pipe body disposed over the permeation retarding layer; and a further annular seal element locatable between a region of a radially inner facing surface of the intermediate collar and an outer surface of the polymer layer; wherein the further annular seal element is locatable against the region of the radially inner facing surface of the intermediate collar and a region of the outer surface of the polymer layer to provide at least a portion of a further fluid retaining layer, radially outside the inner fluid retaining layer, that extends along at least a portion of the flexible pipe body away from the first elongate body when said an end region of the flexible pipe body is terminated via an end fitting comprising the first elongate body.

[0028] Aptly the flexible pipe body further comprises a pressure armour layer radially outside said polymer layer.

[0029] Aptly the flexible pipe body further comprises an outer sheath, radially outside the polymer layer, that provides a still further fluid retaining layer of the flexible pipe body.

[0030] Aptly the permeation retarding layer comprises a helically wound tape wound over the first fluid retaining layer or an extruded layer over the first fluid retaining layer.

[0031] Aptly the first elongate body comprises at least one fluid communication passageway that extends through the first elongate body from a location between the first annular seal element and the further annular seal element.

[0032] According to a third aspect of the present invention there is provided a flexible pipe, comprising: a segment of flexible pipe body comprising an inner fluid retaining layer, a permeation retarding layer radially outside of the inner fluid retaining layer, a polymer layer radially outside of the permeation retarding layer and a pressure armour layer radially outside of the polymer layer; a first end fitting disposed at a first terminal end region of the segment of flexible pipe body and in which the segment of flexible pipe body is terminated; wherein at a first sealing location, a fluid tight seal of the first end fitting is disposed against a radially outer surface of a first end region of said a polymer layer.

[0033] Aptly the flexible pipe further comprises a further end fitting disposed at a further terminal end of the flexible pipe body and in which the segment of flexible pipe body is terminated wherein a fluid tight seal of the further end fitting is disposed against a radially outer surface of a further end region of said a polymer layer. Aptly said a polymer layer provides a further fluid retaining layer radially outside the inner fluid retaining layer along at least a portion of the segment of flexible pipe body.

[0034] Aptly the flexible pipe further comprises at least one fluid communication passageway that extends at least partly through a body of the first end fitting from a location between said a polymer layer and the inner fluid retaining layer.

[0035] Aptly the flexible pipe further comprises an inner annulus of the flexible pipe disposed radially between an outer surface of the inner fluid retaining layer and an inner surface of the polymer layer, and a further annulus of the flexible pipe body disposed between an outer surface of the polymer layer and an inner surface of a still further fluid retaining layer disposed radially outside of the pressure armour layer.

[0036] Aptly the inner annular is fluidly connected to said at least one fluid communication passageway.

[0037] Aptly the permeation retarding layer comprises at least one fluid transport promoting region for promoting or directing transport of fluid axially along the inner annulus and towards said at least one fluid communication passageway.

[0038] Aptly the fluid transport promoting region comprises a corrugated surface of the permeation retarding layer, or a plurality of spaced apart ridges disposed on a surface of permeation retarding layer, or at least one fluid passageway or lumen.

[0039] Certain embodiments of the present invention provide an inner annulus region of a flexible pipe provided by a sealed inner barrier sheath and a sealed intermediate polymer layer wherein a permeation resistant layer is provided in the inner annulus.

[0040] Certain embodiments of the present invention provide a flexible pipe arrangement which limits permeation of gasses from an inner bore of the flexible pipe to an outer annulus of the flexible pipe in which one or more armour layers of the flexible pipe are located.

[0041] Certain embodiments of the present invention reduce build-up of gas rich regions in a flexible pipe annulus region that is within or proximate to an end fitting of the flexible pipe. Certain embodiments of the present invention provide a vent or test port for an inner annulus of a flexible pipe that includes a permeation retarding layer which reduces permeation of gas from a flexible pipe inner bore to an outer annulus of the flexible pipe.

[0042] Embodiments of the present invention will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which:

[0043] Figure 1 illustrates a flexible pipe body;

[0044] Figure 2 illustrates certain uses of a flexible pipe;

[0045] Figure 3 illustrates a schematic view of how some layers of a flexible pipe body can be sealed in an end fitting;

[0046] Figure 4 illustrates a cross sectional view of an end region of a flexible pipe terminated in an end fitting;

[0047] Figure 5a illustrates a portion of the end fitting of Figure 4 in more detail;

[0048] Figure 5b illustrates a different portion of end fitting of Figure 4 in more detail;

[0049] Figure 5c illustrates another portion of the end fitting of Figure 4 in more detail;

[0050] Figure 5d illustrates how an intermediate polymer layer can be sealed in the end fitting of Figure 4 in more detail;

[0051] Figure 5e illustrates another portion of the end fitting of Figure 4 in more detail;

[0052] Figure 5f illustrates how an outer collar member of an end fitting can be secured to a body of the end fitting;

[0053] Figure 5g illustrates a further portion of the end fitting of Figure 4 in more detail;

[0054] Figure 5h illustrates a still further portion of the end fitting of Figure 4 in more detail; Figure 6 illustrates how a segment of flexible pipe body can be terminated in a further end fitting;

[0055] Figure 7a illustrates a portion of the end fitting of Figure 6 in more detail;

[0056] Figure 7b illustrates a further portion of the end fitting of Figure 6 in more detail;

[0057] Figure 7c illustrates a still further portion of the end fitting of Figure 6 in more detail;

[0058] Figure 7d illustrates another portion of the end fitting of Figure 6 in more detail;

[0059] Figure 7e illustrates yet another portion of the end fitting of Figure 6 in more detail;

[0060] Figure 7f illustrates how an intermediate polymer layer of a segment of flexible pipe body is sealed in the end fitting of Figure 6;

[0061] Figure 7g illustrates a further view of how an intermediate polymer layer of the segment of flexible pipe body can be sealed in the end fitting of Figure 6;

[0062] Figure 7h illustrates a further view of how an intermediate polymer layer of the segment of flexible pipe body can be sealed in the end fitting of Figure 6;

[0063] Figure 7i illustrates how an outer collar member can be secured to a body of the end fitting of Figure 6;

[0064] Figure 8 illustrates a perspective view of a test assembly for testing annulus pressure of a Pipe;

[0065] Figure 9a illustrates the test assembly of Figure 8 in cross section;

[0066] Figure 9b illustrates a portion of the test assembly of Figure 8 in more detail;

[0067] Figure 9c illustrates a further portion of the test assembly of Figure 8 in more detail; Figure 10 illustrates results from monitoring the annulus pressure of a first pipe (that does not include a low permeation system and an inner annulus) and the outer annulus pressure of a further pipe (that includes a low permeation system and an inner annulus); and

[0068] Figure 11 illustrates results from monitoring the inner and outer annulus respectively in a pipe that includes a low permeation system.

[0069] In the drawings like reference numerals refer to like parts.

[0070] 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 associated end fittings of the type which is manufactured according to API 17J. Such flexible pipe is often referred to as unbonded flexible pipe. Other embodiments are associated with other types of flexible pipe.

[0071] 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 in each of which a respective end of the pipe body is terminated. Figure 1 illustrates how pipe body 100 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. The pipe body may include one or more layers comprising 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.

[0072] 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.

[0073] The pipe body 100 illustrated in Figure 1 includes an inner pressure sheath 110 which acts as a fluid retaining layer. Optionally the inner pressure sheath is an internal pressure sheath. The inner pressure sheath of Figure 1 comprises a polymeric material. Optionally the inner pressure sheath may comprise any other suitable material. It will be appreciated that the inner pressure sheath ensures internal fluid integrity. The inner pressure sheath of Figure 1 is a polymer layer, however the internal pressure sheath may optionally be any other suitable layer. The layer provides a boundary for any conveyed fluid. 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 inner 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 inner pressure sheath may be referred to as a liner. A barrier layer 110 is illustrated in Figure 1 .

[0074] 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 inner 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. Aptly the carcass layer is formed from a composite, polymer, or other material, or a combination of materials and components. The carcass layer is usually radially positioned within the barrier layer. 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.

[0075] The pipe body of Figure 1 further includes a permeation retarding layer 122 that is disposed radially outside of the inner pressure sheath 110. The permeation retarding layer 122, or low permeation layer, of Figure 1 is a layer of helically wound tape with windings that overlap with adjacent windings of the tape. It will be understood that the permeation retarding layer is made from a material that is substantially resistant to the permeation of gasses that can pass through the inner pressure sheath 110 during use of the pipe body, such as carbon dioxide and / or hydrogen sulphide for example. It will be appreciated how the permeation retarding layer may be made from a suitable material that is substantially resistant to permeation of such gasses, for example a polymeric material and / or a metallic material and / or a composite material or the like. The permeation retarding layer 122 could instead of course be a nonwound layer, for example an extruded polymeric layer or the like.

[0076] Disposed radially outside of the permeation retarding layer 122 is a further polymer layer 124. The polymer layer 124 is a sealed layer and thus is a further sealed fluid retaining layer. The polymer layer is sealed at respective sealing points in respective end fittings. It will be appreciated how the polymer layer and the inner pressure sheath 110 provide an inner annulus region of the flexible pipe body. That is to say that an inner annulus region is provided between the radially outer surface of the inner pressure sheath 110 and a radially inner surface of the polymer layer. The permeation retarding layer 122 is located in the inner annulus region. The polymer layer of Figure 1 is an extruded layer however it will be appreciated that any other suitable fluid retaining polymer layer could instead be utilised.

[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 inner 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 consists of 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 illustrated also includes a first tensile armour layer 140 and 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 have a microstructure that consists of orientated lamellae. 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 metal 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.

[0080] The flexible pipe body shown in Figure 1 also includes optional layers of insulation 165 and an outer sheath 170, which comprises a polymeric material. Optionally the outer sheath is a polymer layer. Optionally the outer sheath is made from any other suitable material. It will be understood that the outer sheath helps 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. It will be appreciated that insulation layers may be arranged radially outside of the outer sheath. Such insulation layer external to the outer sheath can also add protection to outer sheath. It will be appreciated that the outer sheath is a sealed fluid retaining layer that optionally is an outermost sealed (or fluid tight) layer. An annulus is a region associated with the space between fluid retaining layers of the pipe. For example, an annulus region is located between the inner pressure sheath 110 and the outer sheath 170 if the inner pressure sheath and the outer sheath are the only two fluid retaining layers. However, as is the case of the pipe of Figure 1 , a pipe can include multiple annulus regions between fluid retaining layers when more than two fluid retaining layers are included in a flexible pipe. In the pipe of Figure 1 , a first (or inner) annulus is located between the inner pressure sheath and the further (or intermediate) fluid retaining polymer layer. A further (or outer) annulus is located between the further or intermediate fluid retaining layer (the polymer layer) and the outer sheath. 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 further or outer annulus region. It will be appreciated that in some embodiments, the annulus region may contain any or none of the layers present in the flexible pipe body illustrated in Figure 1.

[0081] Each flexible pipe comprises at least one portion, referred to as a segment or section, of pipe body 100 together with an end fitting located at least one end of the flexible pipe. A respective end fitting may be used to terminate each end of the flexible pipe body. An end fitting provides a mechanical device which forms the transition between the flexible pipe body and a connector. The different pipe layers as shown, for example, in 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] 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. For example, 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, that is to say a flexible pipe 240 connecting the ship to the sea floor installation. The flexible pipe may be in segments of flexible pipe body with connecting end fittings.

[0083] 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.

[0084] Figure 3 illustrates a schematic representation of how some layers of flexible pipe body can be sealed in an end fitting. Figure 3 illustrates a schematic view of an end region 304 of a segment of flexible pipe body 302. It will be appreciated that the segment of flexible pipe body 302 shown in Figure 3 is a portion of the flexible pipe body 100 described with respect to Figure 1 and is connected between two end fittings 312 at respective terminal end regions of the segment of flexible pipe body 100. Figure 3 helps illustrate how the segment of flexible pipe body 302 includes an outer sheath 170 that is a radially outermost sealed layer of the segment of flexible pipe body 302. Figure 3 also helps illustrate how the segment of flexible pipe body includes a sealed polymer layer 124 that is an intermediate sealed layer of the segment of flexible pipe body 302. As shown in Figure 3, a pressure armour layer 130 and two tensile armour layers 140, 150 are disposed between the sealed polymer layer 124 and the outer sheath 170. As shown in Figure 3, the tensile armour layers each include a plurality of helically wound tensile armour wires 316 that are made from a metallic material. It will be appreciated that different tensile armour layers may include helically counter-wound wires. Optionally, the tensile armour wires may be made from a composite material or the like. The pressure armour layer 130 is disposed radially within the tensile armour layers 140, 150 and includes interlocking windings. The pressure armour layer 130 of Figure 3 is made from a metallic material however optionally the pressure armour layer may be made from any other suitable material. Figure 3 also shows how respective anti-wear tape layers or anti-birdcaging tape layers or anti-abrasion tape layers 160 are arranged between and over the two tensile armour layers 140, 150 and also between the radially innermost tensile armour layer 140 and the pressure armour layer 130. Optionally, one, two, three, four or more anti-wear tape layers may be included in the flexible pipe body. Optionally the anti-wear layers may be a wound tape or may be extruded or the like. It will be appreciated that these anti-wear tape layers 160 help prevent the tensile armour layers 140, 150 and the pressure armour layer 130 from abrasion and other damage relating to direct contact between these layers. It will be appreciated that the anti-wear tape layers 160 are made from a polymeric material and are not sealed within the end fittings 312.

[0085] Figure 3 shows only a single end fitting 312 located at an end region 304 of the segment of flexible pipe body. It will be understood that the remaining end region of the segment of flexible pipe body 302 will also be terminated in an end fitting. An end fitting 312 is a metallic structure in which various layers of a segment of flexible pipe body 312 can be terminated. Figure 3 schematically shows how the outer sheath 170 of the flexible pipe body 302 is sealed in the end fitting via a fluid tight seal 320. Figure 3 also shows how the sealed polymer layer 124 is sealed in the end fitting 312 via a further (intermediate) fluid tight seal 324. It will thus be appreciated how the area between the radially outer surface 328 of the polymer layer and the radially inner surface 332 of the outer sheath 170 is an outer annulus region 336 of the segment of flexible pipe body 302. It will be understood that the tensile armour wire layers and pressure armour layer of the segment of flexible pipe body is located within the outer annulus region.

[0086] Figure 3 also shows how the segment of flexible pipe body includes a permeation retarding layer 122 disposed radially inside of the sealed polymer layer 124. Disposed radially within the permeation retarding layer is the inner pressure sheath 110 that is sealed in the end fitting 312 via an inner fluid tight seal 340. It will be appreciated that, due to the sealed polymer layer 124 and the sealed inner pressure sheath 110, an inner annulus region 344 is located between a radially outer surface of the inner pressure sheath 110 and a radially innermost surface of the polymer layer 124. Thus, the permeation retarding layer is disposed in the inner annulus. It will be appreciated that, although not shown in Figure 3, that the segment of flexible pipe body includes a carcass layer 120 radially within the inner pressure sheath 110. Optionally no carcass layer is included.

[0087] Although the fluid tight seals 320, 324, 340 are shown schematically in Figure 3, it will be appreciated that the fluid tight seals of Figure 3 each include one or more swagable ring elements in the end fitting 312 which can be energised to sealingly engage with the outer sheath, the polymer layer, and the inner pressure sheath respectively. Energising of the seals 320, 324, 340 may include urging a deformable portion of the respective ring element radially inwardly and into biting engagement with the outer sheath, polymer layer and inner pressure sheath respectively.

[0088] Figure 3 also helps illustrate how the end fitting includes two fluid communication passageways 348, 352 extending through the end fitting 312. Optionally only one or more than two fluid communication passageways may be included in the end fitting 312. Optionally The end fitting 312 may include no fluid communication passageways. Figure 3 shows how a first fluid communication passageway 348 of the two fluid communication passageways is connected to (or extends from) the inner annulus region 344 of the segment of flexible pipe body. Thus, the first fluid communication passageway helps vent gasses located in the inner annulus that have permeated, from the bore of the pipe, through the inner barrier layer in use. A further fluid communication passageway 452 of the two fluid communication passageways that extends from the outer annulus region 336 which consequently is fluidly connected to the further fluid communication passageway 452. Thus, the further fluid communication passageway helps vent gasses located in the outer annulus region and that have permeated from the pipe bore radially outwardly through the inner pressure sheath 110, the permeation retarding layer 122, and the sealed polymer layer 124. It will be understood that the fluid communication passageways 348, 352 may also function as test ports to allow testing of the pressure and fluid composition of the inner and outer annulus regions respectively.

[0089] It will be understood that Figure 3 illustrates a segment of flexible pipe body that includes a low permeation system (that includes the permeation retarding layer and the fluid tight / sealed polymer layer that is an intermediate polymer layer).

[0090] It will be appreciated that by creating the inner annulus between the inner pressure sheath and the intermediate sealed polymer layer underneath the pressure armour, the risks associated with preferential gas flow through a non-sealed sacrificial layer that can be located beneath a pressure armour layer and a permeation retarding layer in the vicinity of the end fittings is reduced. That is to say, preferential gas flow through non-sealed regions of such a sacrificial layer are reduced.

[0091] By creating an inner annulus between the inner pressure sheath 110 and the intermediate sealed layer 124 underneath the pressure armour, should an outer annulus be flooded by an outer sheath breach for example, the original characteristics of the low permeation system provided by the permeation retarding layer will remain preserved as the intermediate sealed polymer layer will avoid water ingress into the inner annulus.

[0092] As discussed, the flexible pipe body described with respect to Figures 1 and 3 includes a sealed intermediate sheath radially outside the pressure armour layer 130, and radially inside the tensile armour layers 140, 150, creating a pressure armour annulus. It is noted that the absence of a sealed polymer layer 124 radially inwards of the pressure armour in combination with a permeation retarding layer 122 thereunder, can result in the pressure armour being exposed to higher levels of permeated fluids in the pressure armour annulus (in the radially outer annulus shown in Figure 3), and therefore the pressure armour layer 130 may be at higher risk of damage and failure, even when that pressure armour annulus is vented.

[0093] The adoption of a sealing element on the intermediate sealed polymer layer will allow the execution of factory acceptance tests to assure the sealing effectiveness and the integrity of the intermediate sealed polymer layer to pressures significantly higher than the ones adopted for conventional annulus integrity tests which normally are meant to demonstrate the integrity of the outer sealed layer / outer sheath.

[0094] It will be appreciated that the sealed intermediate polymer layer 124 will, by virtue of manufacturing care necessary when providing sealed or fluid tight layers, have more controlled thickness. This minimises the risks of damage to or in the sacrificial layer and can support the inner pressure sheath in the control of permeation of gases through the annular regions of the flexible pipe (mainly in the extremities of the pipe). Inclusion of such a layer can also increase the benefits of any additional low permeation layer, if any such layer is included, and can help protect the inner barrier layer against excess creep into the gaps of the pressure armour.

[0095] Figure 4 illustrates a cross sectional view of a segment of flexible pipe body 100 that is terminated in an end fitting 312. The end fitting shown in Figure 4 may be usable to terminate flexible pipe body that has a diameter of around 6 inches or the like. It will be appreciated that end fittings 312 can be connected in a back-to-back arrangement. The end fitting 312 terminates an end of a segment of flexible pipe body 100. It will be appreciated that a further end fitting 312 can be utilised to terminate a respective end of a further segment of flexible pipe body. It will be also understood that a still further end fitting may terminate a remaining end of the segment of flexible pipe body 100 illustrated in Figure 4. The end fitting 312 can be connected to a further end fitting via respective flanges 404. These can be bolted together via bolts (not shown in Figure 3) and can include matching seal ring grooves on opposing flange faces.

[0096] As shown in Figure 4, an outer jacket 408 is secured to the flange 404 and an outer collar 426 is secured to the jacket 408 which, via a radially inner surface of the jacket, seals against an outer surface of an outer sheath 170 of the flexible pipe body 100 via at least one seal ring 320 that is an example of the fluid tight seal discussed in Figure 3. Optionally, the end fitting 312 may instead include a central flange that is connected or secured to the jacket 408 and a separate connector flange (for connecting the end fitting 312 to a further end fitting) via a neck region. In such an embodiment the flange 404 would become the central flange of the end fitting 312 and axially distil to the central flange, at the other end of the neck region, the separate connector flange would be configured, comprising a longitudinal terminal end region with flange-to-flange sealing features (similar to those shown in Figures 4, 5a, 5b, 6, 7a, and 7e in relation to the flange 404). As shown in Figure 4, a radially innermost surface of the jacket 408 is spaced apart from a radially outer surface of a generally cylindrical but slightly flared outwards end of a first elongate end fitting body 416 of the end fitting. The end fitting 312 also includes a further elongate end fitting body 418 that is securable to the first elongate end fitting body 416, optionally via other elements of the end fitting. Optionally the end fitting 312 includes a single end fitting body. An open mouth 420 of the end fitting body faces an associated end region 304 of flexible pipe body. Tensile armour wires 316 are terminated in the tapered space 424 between the outer casing and the end fitting body. Aptly epoxy is located in the tapered space to entomb the ends of the tensile armour wires 316. The end fitting 312 is associated with a central longitudinal axis A-A and the central longitudinal axis of each end fitting is aligned along a common axis when the end fittings are arranged in a back- to-back configuration. During use production and injection fluids are transported along a bore provided by the barrier layer or liner of the flexible pipe body and the inner surface of each end fitting 312.

[0097] Figure 4 helps illustrate how the segment of flexible pipe body 100 includes an inner pressure sheath 110 that is sealed via at least one seal ring 340 that is an example of the inner fluid tight seal described with respect to Figure 3. Figure 4 further helps illustrate how the segment of flexible pipe body 100 includes a permeation resistant layer 122 radially around the inner pressure sheath 110 and a sealed polymer layer 124 disposed radially around the permeation resistant layer 122. Figure 4 also helps show how the polymer layer is sealed in the end fitting 312 via at least one seal ring 324 that is an example of a further fluid tight seal. It will be appreciated how due to the respective sealing of the inner pressure sheath, the polymer layer and the outer sheath, two annulus regions are located in the segment of flexible pipe body 100. As described with respect to Figure 3, an inner annular region is located between the inner pressure sheath and the polymer layer, and an outer annular region is located between the polymer layer and the outer sheath.

[0098] As shown in Figure 4, one or more optional diagonal fluid port / ports 450, 490 can be arranged to extend through the inner collar from behind the inner seal ring. This port communicates with a fluid communication passageway (not shown in Figure 4 but detailed in various forms in Figures 5e, 7d and 9b) which passes through the body of the end fitting 416 to a venting region at an external surface of the end fitting. Thus, the inner annulus can be vented via this port and fluid communication passageway.

[0099] The outer annulus can be vented via a horizontal port which passes through the jacket and a through-hole in the outer collar 426, and exits to the front to the end fitting proximate to where the flexible pipe body enters the end fitting (as also shown in Figures 5b, 6, 7b, and 7c).

[0100] Figure 5a illustrates a cross sectional view of a portion of the flange 404 of the end fitting 312 of Figure 4 in more detail. Figure 5a helps illustrate how a fluid communication passageway may extend from a radially outermost surface of the flange 404 to a terminal end of the flange. This can help test the sealing integrity of a gasket type seal ring (for instance an API 6A type BX gasket seal ring) installed into the annular seal ring recesses provided between the two flange faces of opposing flanges 404 connecting end fittings together or connecting an end fitting and a subsea or topside structure pipe connection.

[0101] Figure 5b illustrates a cross section view of a portion of the flange 404 of the end fitting 312 of Figure 4 in more detail. Figure 5b illustrates how the flange of the end fitting includes a longitudinal gas venting port for connecting to the outer annulus via tubing (not shown) which extends alongside the tensile armour wires in the end fitting 312 to ensure a through passage for fluid from the outer annulus 336 to the vent valve arrangement.

[0102] Figure 5c illustrates a cross section view of a portion of the flange 404 of the end fitting 312 of Figure 4 in more detail. Figure 5c helps illustrate how various components of the end fitting 312 can be secured together via fastening elements for example bolts and the like.

[0103] Figure 5d illustrates how respective seal rings, that are further fluid tight seals 324, engage in a sealing manner against a radially outer surface of the polymer layer 124 to thereby provide a sealed fluid retaining layer disposed between the outer sheath and the inner barrier layer (that themselves also constitute fluid retaining layers). It will be understood that Figure 5d illustrates an end region 304 of a segment of flexible pipe body 100 that is terminated in the end fitting of Figure 4. As shown in Figure 5d, the seal rings 324 include a deformable portion 540 that is urged radially inwardly thus into intimate contact (that optionally is biting engagement) with the radially outer surface of the sealed polymer layer 124. It will be appreciated that each deformable portion is urged radially inwardly such that an abutment or sealing surface disposed on a radially inner surface of the deformable portion is urged into intimate contact (that optionally is biting engagement) with the polymer layer 124. Figure 5d helps illustrate how the deformable portion 540 of the respective seal rings 324 is urged inwardly via abutment of the deformable portion of each seal ring with a respective intermediate collar member 544 of the end fitting 312. As shown, each intermediate collar member includes a radially innermost facing abutment surface which is urged against a cooperating tapered collar abutment surface disposed on a radially outer surface of each deformable portion. Thus, as the intermediate collar members are urged against each of the seal rings, the deformable portion is urged radially inwardly due to the mating abutment surfaces of the respective intermediate collar members and seal rings.

[0104] Figure 5e illustrates how a fluid communication passageway 560 is disposed in the end fitting of Figure 4. Figure 5e helps illustrate how the fluid communication passageway extends longitudinally along the end fitting (parallel with a longitudinal axis of the end fitting), from a position proximate to between the inner seal ring 340 and at least one intermediate seal ring 324, to ensure a through passage for fluid from the inner annulus 344 to the vent valve arrangement. It will be appreciated that in the arrangement shown in Figure 5e, the vent valve arrangement is located at the radially outer surface of the end fitting 312. This is similar to that shown in Figure 7d.

[0105] Figure 5f helps illustrate how the outer collar member 426 of the end fitting 312 of Figure 4 is secured to a jacket 408 by means of a fastening element 570, securing and retaining the outer seal 320. It will be appreciated that the fastening element may be one or more screws or bolts of the like. It will be appreciated that securement of the collar and the jacket urged the outer seal radially inwards to seal against the outer sheath.

[0106] Figure 5g helps illustrate how a fastener / fastening element 570 (that is an example of a securing element) can extend through a first intermediate collar member 544i and into a further collar member 5442 to thereby secure the intermediate collar members to a body 418 of the end fitting.

[0107] Figure 5h helps illustrate how a fastener / fastening element 570 (that is an example of a securing element) can extend through a first intermediate collar member 544i and into a further collar member 5442 to thereby secure respective body portions 416, 418 of the end fitting together via the intermediate collar members.

[0108] Figure 6 illustrates a cross section view of an end region of a segment of flexible pipe body that is terminated in a further end fitting 612. It will be appreciated that the end fitting illustrated in Figure 6 is usable to terminate segments of flexible pipe body with an 8-inch bore diameter (that is the internal diameter of the internal carcass layer in a rough bore pipe or the internal diameter of the liner in a smooth bore pipe) or the like. It will be appreciated that the end fitting illustrated in Figure 6 is similar to the end fitting illustrated in Figure 4. With similarity to the end fitting 312 described with respect to Figure 4, the end fitting 612 of Figure 6 is arranged around an end segment 602 of flexible pipe body 100. As described with respect to Figures 1 , 3 and 4 it will be understood that the flexible pipe body includes an inner pressure sheath 110 (that is a first fluid retaining layer), a permeation retarding layer 122 located radially outside of (and radially around) the inner pressure sheath 110, a polymer layer 124 (that is a further fluid retaining layer) radially outside of the permeation retarding layer 122, a pressure armour layer 130 located radially outside of the polymer layer 124, tensile armour layers 140, 150 located radially outside of the pressure armour layer 130 and an outer sheath 170 (that is a still further, and radially outermost, fluid retaining layer) located radially outside of the tensile armour layers 140, 150. The respective layers of the segment of flexible pipe body 100 are terminated in the end fitting 612 in a similar manner as described with respect to Figure 4. In particular, the inner pressure sheath 110 is sealing in the end fitting via at least one first (inner) seal ring 640 (that is an example of a fluid tight seal) that is compressed and urged into abutment with an outer surface of the inner pressure sheath 110. It will be appreciated that a tapered radially inner surface region of a first elongate body 616 of the end fitting 612 is urged against a tapered outer surface region of the first seal ring 640 to thereby energise the seal ring 640 by driving at least a deformable portion of the first seal ring 640 radially inwardly and into intimate contact (to sealingly engage) with the inner pressure sheath 110.

[0109] The polymer layer 124 is sealed, at a sealing location that is associated with the polymer layer sealing (and is a location at which a sealing effect is provided on the polymer layer), in the end fitting 612 via at least one further sealing ring 624 (that is an example of a fluid tight seal). The two further sealing rings 624i, 6242 are illustrated in Figure 6 however it will be appreciated that any other suitable number of further sealing rings could be utilised. As shown in Figure 6, the further sealing rings are each located between respective intermediate collar members 644 and the sealed polymer layer 124. As illustrated in Figure 6, the intermediate collar members 644 are located radially inside of an end fitting jacket 608 that is secured to a radially extending flange 636 of the first elongate body 616. It will be understood that the end fitting 612 additionally includes a further elongate body 618 that is connected to the first elongate body 616 via the intermediate collar members 644, such that the first elongate body 616, the intermediate collar members 644, and the further elongate body 618 substantially extend along the longitudinal axis 648 (or the A-A axis) of the flexible pipe. Figure 6 helps illustrate how, when the end fitting 612 is properly assembled, a radially outer tapered surface region of the right most (from the perspective view of Figure 6) further seal ring 620 abuts against a radially inner tapered surface region of the right most (from the perspective view shown in Figure 6) intermediate collar member 644 to thereby urge at least a portion of the ring 624 radially inwardly to seal against the outer surface of the sealed polymer layer 124. Similarly, the left-most (from the perspective view of Figure 6) intermediate collar member 644 includes a tapered radially inner surface region that, when the end fitting 612 is assembled as shown in Figure 6, abuts against a complimentary tapered radially outwardly facing surface region of the left-most (from the perspective view of Figure 6) further seal ring 624 thereby urging at least a portion of the further ring 624 radially inwardly to seal against the outer surface of the sealed polymer layer 124.

[0110] Figure 6 also illustrates how the outer sheath 170 (of the segment of flexible pipe body 100 is sealed in the end fitting 612 of Figure 6 via at least one outer seal ring 320 (that is an example of a fluid tight seal). Figure 6 helps illustrate how a radially inner facing tapered surface region of the jacket 608 abuts against a corresponding tapered radially outwardly facing surface region of the outer seal ring 320 to urge at least a portion the outer seal ring 320 radially inwardly into intimate contact with, and sealing against, a radially outer surface of the outer sheath 170.

[0111] Due to the fluid tight sealing of the inner pressure sheath 110, the sealed polymer layer 124 and the outer sheath 170 of the segment of flexible pipe body in the end fitting 612, it will be appreciated how an inner annulus is provided between the inner pressure sheath 110 and the sealed polymer layer 124. It will also be appreciated how an outer annulus 336 is provided between polymer layer 124 and the outer sheath 170. At least one test fluid passageway 652 is provided in the end fitting 612. As illustrated in Figure 6 the test fluid passageways may extend from the radially outer surface of the first elongate body 616 and / or the radially outer surface of an intermediate collar member 644 and pass radially through the respective components to a position between pairs of fluid seals, which may be sealing rings 640, 624, or may be pairs of o-rings which provide additional sealing between end fitting components. The test fluid passageway may therefore provide means to test the integrity of the seal pairs during fit-up and assembly. It will also be appreciated that when the test fluid passageway 652 extends through a portion of the first elongate body 616 it may fluidly connect to the inner annulus 344 thereby providing means to test the integrity of the inner seal 640 and further sealing ring 624. It will further be appreciated that such a fluid passageway 652 may subsequently also be connected to a longitudinally extending fluid communication passageway 716 (see Figure 7c) through which gasses from the inner annulus can pass towards associated vent pathways 660 to thereby vent gasses from the inner annulus via respective vent valves located on the end fitting exterior. The end fitting 612 also includes an epoxy fill passageway 664 that extends through the end fitting jacket 608 from the epoxy cavity 656 to a port on the outer surface of the end fitting . It will be appreciated that the end fitting may not include such fluid communication passageways, may include different fluid communication passageways or may include additional fluid communication passageways. It will be appreciated that the epoxy fill passageway 664 may be utilised to pump or provide epoxy into the end fitting cavity 656 during terminating the segment of flexible pipe body 100 in the end fitting 612 and may then be drilled into to provide a fluid communication passageway subsequent to curing the epoxy in the cavity.

[0112] Figure 7a helps illustrate how additional fluid communication passageways can be arranged in the end fitting 612 of Figure 6. It will be understood that Figure 7 illustrates the radially extending flange 636 in cross section and shows how an additional fluid communication passageway 704, that is non-straight and substantially forms a right-angle, extends from a radially outermost surface of the flange 636 to a longitudinal terminal end region 708 of the end fitting 612 proximate to the flange 636. It will be appreciated that one or more of the additional fluid communication passageways 704 may be arranged at different radial positions around the end fitting 612.

[0113] Figure 7b helps illustrate how another fluid communication passageway can be arranged in the end fitting 612 of Figure 6. Figure 7b illustrates a cross sectional view of a portion of the end fitting 612 of Figure 6. Figure 7b helps illustrate how the end fitting 612 of Figure 6 includes one or more fluid communication passageways 712, extending at an oblique angle to the longitudinal axis 648, between the cavity 656 to an outer surface region of the flange 636. Thus, the passageway 712 extends radially through the flange 636. It will be appreciated that more than one of these fluid communication passageways 712 may be arranged at different radial positions around the end fitting 612.

[0114] Figure 7c helps illustrate how yet another fluid communication passageway is included in the end fitting 612 of Figure 6. It will be understood that Figure 7c illustrates a portion of the end fitting 612 of Figure 6 in cross section. Figure 7c illustrates how a generally longitudinally extending fluid communication passageway 716 (that is to say that most of the passageway extends substantially parallel to the longitudinal axis 648 of the end fitting) extends from a point within the epoxy filled cavity 656 of the end fitting 612 proximate to the point 626 where the armour wires 140, 150 enter the epoxy filled cavity, to a radially external surface of the end fitting 612. It will be understood that this fluid communication passageway 716 can be utilised as a vent path subsequent to filling or partially filling the epoxy filled cavity to allow gas present in the outer annulus 336) to be vented. It will be noted that gas originating from the outer annulus 336 may also be able to pass or permeate through the epoxy in the cavity 656 and be vented via the substantially longitudinal fluid communication pathway 716 irrespective of the open terminal end of the fluid communication passageway.

[0115] Figure 7d helps illustrate how another fluid communication pathway is included in the end fitting 612 of Figure 6. It will be understood that Figure 7b illustrates a portion of the end fitting 612 of Figure 6. Figure 7d shows how a fluid communication pathway 720 extends through the first elongate body 616. In particular, the Figure 7d illustrates how the fluid communication pathway 720 includes a first portion 760 that is a radially extending portion which extends radially outwardly in a direction along the flange 636 and a further portion that extends longitudinally and substantially parallel with the longitudinal axis 648 of the flexible pipe. Figure 7d illustrates how the fluid communication passageway 720 extends beneath the cavity 656 of the end fitting 612. It will be understood that the fluid communication pathway 720 extends towards the intermediate collar members 644, and is fluidly connected to the inner annulus via a fluid pathway extending at least partially around and between the collar member 644 and the first elongate body 616.

[0116] Figure 7e helps illustrate how the radially extending flange 636 of the first elongate body 616 is secured to the end fitting jacket 608 via bolts 724 that are examples of securing elements. It will be appreciated that Figure 7e illustrates a portion of the end fitting 612 of Figure 6 in cross section. Figure 7f helps illustrate how the further elongate body 618 of the end fitting 612 can be secured to an intermediate collar member 644 via bolts 724 and the like. It will be appreciated that securing the intermediate collar member to the further elongate body acts to urge the intermediate collar against a respective seal ring 624 to thereby seal the polymer layer 124 of the segment of flexible pipe body.

[0117] Figure 7g illustrates how a securing element 724 can extend through a first intermediate collar member 644 and into a further intermediate collar member 644 to thereby connect two intermediate collar members to the further elongate body. It will be appreciated that such securement of multiple intermediate collar members acts to energise multiple seal rings 624 to seal against the polymer layer of the segment of flexible pipe body.

[0118] Figure 7h illustrates how a securing element 724 can extend between the first and further elongate bodies (respectively 616 and 618) of an end fitting 612 and through a series of intermediate collar members 644 to thereby secure the first and further elongate bodies together and also to energise respective seal rings 624 and 640 against the polymer layer 124 and the inner pressure sheath 110 of a flexible pipe.

[0119] Figure 7i helps illustrate how an outer collar member 626 can be secured to a terminal end of the jacket 608 of the end fitting 612 of Figure 6 via respective securing elements 724.

[0120] Figure 8 illustrates a test assembly 804 that can be utilised to monitor or test annular pressure / gas composition. As illustrated in Figure 8 the test assembly 804 includes a flared- out body portion 8O81, 8O82 at each end of the assembly 804. The test assembly includes a narrowed tubular region 802 located between each of the flared-out regions. It will be understood that the test assembly 804 simulates or approximates a segment of flexible pipe body terminated at each end in a respective end fitting.

[0121] Figure 9a illustrates how the test assembly 804 in cross section. Figure 9a illustrates how the test assembly includes a representative segment of flexible pipe body that includes an inner fluid retaining layer 110 (that is an inner pressure sheath), a permeation resistant / retarding layer 122 that is disposed radially around the inner fluid retaining layer 110, a sealed polymer layer 124 (that is an further fluid retaining layer) located radially around the permeation retarding layer and a pressure armour layer 960 disposed radially around the polymer layer. As shown in Figure 9a, respective seal rings 940, 924 provide fluid tight seals on outer surface regions of the inner fluid retaining layer and the polymer layer respectively. It will thus be appreciated how the test assembly 804 of Figure 8 simulates a terminated segment of flexible pipe body including an inner annulus (in which a permeation retarding layer is located) between a sealed inner pressure sheath and a sealed intermediate polymer layer, and an outer annulus radially outside of the intermediate polymer layer.

[0122] Figure 9b illustrates how a test port 952 is fluidly connected to the inner annulus of the test assembly 804. It will be appreciated that the test port is fluidly connected to the inner annulus (between the inner pressure sheath 110 and intermediate polymer layer 124) of the assembly. It will be appreciated that the test port 952 is connected to the inner annulus via a fluid communication passageway that extends through a portion of the test assembly. It will be appreciated that the test port can be utilised to determine the pressure and / or fluid composition of gasses or other fluid in the inner annulus. That is to say that pressure build-up in the inner annulus can be measured by the dedicated port 952 which might be used not only to monitor the pressure build-up but also to test the inner annulus and pure accumulated gases accumulated in the inner annulus.

[0123] Figure 9c illustrates how the test assembly 804 is made from a number of parts that are secured together. Figure 9c shows how a main body 970 of the test assembly 804 is secured to respective end caps by securing a respective radially outwardly extending flange 978 located at a respective terminal ends of the main body 970 to the end caps via an intermediate collar or sleeve portion 982. Figure 9c shows how the endcap and main body portion can be secured via fastening elements 986 (for example screws or bolts or the like) that extend through the flange, through the intermediate collar portion and into the end cap. It will be understood how securing the main body portion, the intermediate collar portion and the end cap together urges respective seal rings inwardly to thereby seal against layers of the test pipe located in the test assembly 804.

[0124] Figure 10 illustrates results of a midscale permeation test of a first pipe 1004 (that does not include a low permeation system) and a further pipe 1008 (including a low permeation system as described with respect to Figure 3). Figure 10 illustrates a plot of annulus pressure (that is an outer annulus of the further pipe and the single annulus of the first pipe) against elapsed time of the test. It will be appreciated that the further pipe includes a sealed inner annulus between a fluid tight inner pressure sheath and a fluid tight intermediate polymer layer in which a permeation retarding layer is located. It will be understood that the further pipe thus includes an outer annulus that generally corresponds to the single annulus of the first pipe. The first pipe does not include a permeation retarding layer or a fluid tight intermediate polymer layer. The results shown in Figure 10 indicate that a measured pressure in the single annulus of the first pipe is around 18 times higher than a measured pressure in the outer annulus of the further pipe after 100 days of testing. Furthermore, the pressure data recorded in respect of the first pipe indicates a gradual increase in annulus pressure (in the single annulus of the first pipe that is located between the fluid tight inner pressure sheath and the outer sheath) over the 100-day test period shown in Figure 10. By contrast the recorded date of the further pipe indicate a substantially constant annulus pressure (in the outer annulus that is located between the intermediate polymer layer and the outer sheath of the further pipe) compared to the recorded pressure data for the first pipe.

[0125] The results illustrated in Figure 10 indicate that the permeation retarding layer disposed between the inner pressure sheath and the intermediate polymer layer of the further pipe (and thus in the inner annulus of the first pipe) greatly reduces the permeation of gas from the inner bore of the pipe (that is located within the inner pressure sheath) into the measured annulus region that includes the pipe armouring layers (such as tensile armour layers and pressure armour layers). It is noted that the results obtained in Figure 10 were measured from test ports disposed at an end region of the respective pipes and thus at a region that represents an end fitting of a flexible pipe. Thus, the results of Figure 10 also indicate that the sealed intermediate polymer layer of the further pipe also helps reduce the build-up of gas rich regions in the measured annulus located at terminal end regions of a pipe (or at regions where a pipe is terminated in an end fitting). Thus, including the low permeation system described in Figure 3 in a flexible pipe helps reduce gas permeation into the outer annulus thereby reducing armour layer exposure to harmful gasses which reduce the fatigue life of such armour layers. That is to say that the intermediate seals implemented to seal the intermediate polymer layer of the further pipe help avoid the preferential flow of potentially harmful gasses (such as carbon dioxide) through an end fitting region pf a flexible pipe.

[0126] Figure 11 illustrates results of a midscale permeation test between an inner annulus (located between a sealed inner pressure sheath and a sealed intermediate polymer layer and that includes a permeation retarding layer) and an outer annulus (located between the sealed further polymer layer and the sealed outer sheath and that includes a pressure armour layer and one or more tensile armour layers) of a flexible pipe including a low permeation system (as described with respect to Figure 3). In particular, Figure 11 illustrates pressure data / pressure build-up data (that is to say a plot of annulus pressure against elapsed time of the test) for the inner annulus 1144 and the outer annulus 1136 respectively.

[0127] When the pressure build-up data for both the pipe outer annulus and inner annulus presented in Figure 11 are compared, it is can be observed that not only the rate of pressure build-up in each annulus vary, the absolute pressure after 100 days of testing in each respective annulus is significantly different. As shown in Figure 11 , the pressure measured in the inner annulus is around 2.5 times higher than the pressure measured in the outer annulus (that includes the armour wires). This is a clear indication the intermediate fluid tight seal(s) that provide respective fluid tight seals on the further polymer layer (that optionally is an intermediate fluid retaining polymer layer) reduce gas flow into the outer annulus and also that the permeation retarding layer (in the inner annulus) reduces permeation of gasses into the outer annulus of the flexible pipe. It is noted that if the intermediate fluid tight seal(s) were not present to seal the further polymer layer (to provide a sealed further fluid retaining layer), a higher pressure would be recorded in the outer annulus of the pipe as gas flow into the outer annulus would come from a preferential gas path in the end fitting region at a region where a non-sealed further polymer layer would be terminated.

[0128] 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.

[0129] 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 method of terminating flexible pipe body of a flexible pipe, comprising the steps of: providing flexible pipe body comprising an inner fluid retaining layer, a permeation retarding layer radially outside of the inner fluid retaining layer, a polymer layer radially outside of the permeation retarding layer and a pressure armour layer radially outside of the polymer layer; and via a respective end fitting, at a first sealing location, providing a fluid tight seal against a radially outer surface of at least one end region of said a polymer layer thereby providing at least a portion of a further fluid retaining layer radially outside the inner fluid retaining layer along at least a portion of the flexible pipe body extending from said a respective end fitting.

2. The method as claimed in claim 1 , further comprising: via a respective end fitting at each end of the flexible pipe body, sealing each of two end regions of said a polymer layer, thereby providing a sealed fluid retaining layer between respective sealing locations in respective end fittings and providing a radially inner annulus region between a radially outside surface of the inner fluid retaining layer and a radially inner surface of said a sealed fluid retaining layer that comprises said a polymer layer.

3. The method as claimed in claim 1 or claim 2, further comprising: sealing each end region of the polymer layer at a respective sealing location by energising an annular seal element of a respective end fitting at the sealing location, during a termination process.

4. The method as claimed in any preceding claim, further comprising: providing a further annulus region between a radially outer surface of said a polymer layer and a radially inner surface of an outer sheath of the flexible pipe body, that provides a still further fluid retaining layer, whereby the pressure armour layer and at least one tensile armour layer of the flexible pipe body are disposed in the further annulus region.

5. The method as claimed in any preceding claim, further comprising:providing the permeation retarding layer by helically winding a tape element over the inner fluid retaining layer whereby adjacent windings of the tape element overlap or by providing an extruded layer over the inner fluid retaining layer, and subsequently providing the polymer layer over overlapped windings of the tape element or the extruded permeation retarding layer thereby providing the inner fluid retaining layer radially inside the polymer layer.

6. The method as claimed in claim 5, further comprising: providing said an extruded layer by extruding a layer of polyamide and / or polyethylene and / or polyvinylidene fluoride, said a layer optionally having a thickness of 0.5 to 10 mm, the thickness optionally being 2 mm to 7 mm, the thickness optionally being 3 mm to 6 mm.

7. The method as claimed in claim 5, further comprising:Providing the permeation retarding layer by helically winding a PEEK and / or PEEK-based tape or metal tape around the inner fluid retaining layer with adjacent windings of a wound tape optionally overlapping by between 10% to 70%, optionally between 20% and 60%, optionally around 50%.

8. The method as claimed in any preceding claim, further comprising: providing a standoff between pressure armour windings of the pressure armour layer and an outer surface of the permeation retarding layer via the polymer layer.

9. The method as claimed in any preceding claim, further comprising: preventing, wholly or at least in part, permeating gas from permeating through a sacrificial layer comprising the polymer layer disposed between the pressure armour layer and the permeation retarding layer and radially outside a barrier layer or liner that comprises the inner fluid retaining layer, thereby partially reducing cracking and / or fracture of armour windings in a further annulus region, comprising a primary annulus region, of the flexible pipe body.

10. Apparatus for terminating an end region of flexible pipe body, comprising:a first elongate body comprising a connection flange at a first elongate body end and an open mouth at a remaining elongate body end, a radially inner facing surface proximate to the remaining body end extending from said open mouth; a first annular seal element locatable between a portion of the inner facing surface and an outer surface of an inner fluid retaining layer of an end region of flexible pipe body; an intermediate collar securable to the first elongate body around the inner fluid retaining layer, a permeation retarding layer of the flexible pipe body disposed over the inner fluid retaining layer and a polymer layer of the flexible pipe body disposed over the permeation retarding layer; and a further annular seal element locatable between a region of a radially inner facing surface of the intermediate collar and an outer surface of the polymer layer; wherein the further annular seal element is locatable against the region of the radially inner facing surface of the intermediate collar and a region of the outer surface of the polymer layer to provide at least a portion of a further fluid retaining layer, radially outside the inner fluid retaining layer, that extends along at least a portion of the flexible pipe body away from the first elongate body when said an end region of the flexible pipe body is terminated via an end fitting comprising the first elongate body.

11. The apparatus as claimed in claim 10, further comprising: the flexible pipe body further comprises a pressure armour layer radially outside said polymer layer.

12. The apparatus as claimed in claim 10 or claim 11 , further comprising: the flexible pipe body further comprises an outer sheath, radially outside the polymer layer, that provides a still further fluid retaining layer of the flexible pipe body.

13. The apparatus as claimed in anyone of claims 10 to 12, further comprising: the permeation retarding layer comprises a helically wound tape wound over the first fluid retaining layer or an extruded layer over the first fluid retaining layer.

14. The apparatus as claimed in anyone of claims 10 to 13, further comprising:the first elongate body comprises at least one fluid communication passageway that extends through the first elongate body from a location between the first annular seal element and the further annular seal element.

15. A flexible pipe, comprising: a segment of flexible pipe body comprising an inner fluid retaining layer, a permeation retarding layer radially outside of the inner fluid retaining layer, a polymer layer radially outside of the permeation retarding layer and a pressure armour layer radially outside of the polymer layer; a first end fitting disposed at a first terminal end region of the segment of flexible pipe body and in which the segment of flexible pipe body is terminated; wherein at a first sealing location, a fluid tight seal of the first end fitting is disposed against a radially outer surface of a first end region of said a polymer layer.

16. The flexible pipe as claimed in claim 15, further comprising: a further end fitting disposed at a further terminal end of the flexible pipe body and in which the segment of flexible pipe body is terminated wherein a fluid tight seal of the further end fitting is disposed against a radially outer surface of a further end region of said a polymer layer.

17. The flexible pipe as claimed in claim 16, further comprising: said a polymer layer provides a further fluid retaining layer radially outside the inner fluid retaining layer along at least a portion of the segment of flexible pipe body.

18. The flexible pipe as claimed in any one of claims 15 to 17, further comprising: at least one fluid communication passageway that extends at least partly through a body of the first end fitting from a location between said a polymer layer and the inner fluid retaining layer.

19. The flexible pipe as claimed in any one of claims 15 to 18, further comprising: an inner annulus of the flexible pipe disposed radially between an outer surface of the inner fluid retaining layer and an inner surface of the polymer layer, and a further annulus of the flexible pipe body disposed between an outer surface of the polymerlayer and an inner surface of a still further fluid retaining layer disposed radially outside of the pressure armour layer.

20. The flexible pipe as claimed in claim 19 when dependent on claim 18, further comprising: the inner annular is fluidly connected to said at least one fluid communication passageway.

Images