Seal ring for sealing a connection between a pipe body of a flexible pipe and an end fitting

Abstract

A seal ring for sealing a connection between a pipe body of a flexible pipe and an end fitting. The seal ring comprises an annular member having a body portion and a wedge portion extending substantially longitudinally from the body portion. The wedge portion comprises a radially outer surface delimiting first and second tapered sealing regions, and an intermediate region separating the first and second tapered sealing regions from one another. The intermediate region is one of not tapered, and tapered to a lesser degree than each of the first and second sealing regions.

Description

[0001] Seal ring for sealing a connection between a pipe body of a flexible pipe and an end fitting

[0002] TECHNICAL FIELD

[0003] The invention relates to a seal ring for sealing a connection between a pipe body of a flexible pipe and an end fitting in which the pipe body is, or is to be, mounted, particularly a flexible pipe for conveying oil and gas field fluids. Moreover, the invention relates to a flexible pipe, and to a method of sealing a connection between a pipe body of a flexible pipe and an end fitting.

[0004] BACKGROUND

[0005] Flexible pipe is widely used in the oil and gas industry in offshore applications for the transportation of various fluids, including oil, gas and water. Flexible pipe is particularly useful in connecting sea-level supporting structures and subsea locations, which may be deep underwater, for example at least 1 ,000 feet (-305 m), where the pipe may act as a riser. A flexible pipe is generally formed as an assembly of a pipe body and one or more end fittings. The pipe body may have an internal diameter of typically up to around 0.6 m, for example diameters may range from 0.05 m up to 0.6 m. Dueto their application, flexible pipes are exposed to a range of challenging conditions that may have high pressures, seawater, high tensile strain, and corrosive environments. The pipe body is therefore typically composed of several concentric polymeric, metallic, and / or composite layers. For example, the 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 connectingtogether multiple discrete hoops that are arranged concentrically side-by-side. Depending upon the layers 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. Some flexible pipes have been used for deep water (up to 5,000 feet (-1 ,500 m)) and ultra-deep water (greater than 5,000 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 (2,500 m), 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 between -30 °C to +130 °C, and various pipe body designs 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 rangingfrom 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 1 ,000 feet (-300 m) depth, or even for shore (overland) applications.

[0006] 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 typically referred to as a barrier layer. When a carcass layer is not present in the flexible pipe body, the inner sheath is typically referred to as a liner. 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 additional, insulation layers, from abrasion related damage due to contact with rough or sharp substances in the environment. 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 pipe sometimes includes 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° to 55°. Tensile armour layers support the weight of all internal pipe layers and transferthe resulting tensile stress to the sea-level supporting structures. The annulus may also have other layers such as anti-wear and so-called anti-birdcaging tapes, and thermally insulating layers (the "birdcaging" refers to deformation of wires where the wires unravel or form a bulge, resembling a birdcage). Carbon steel wires in the annulus are thus often a feature of flexible pipes for subsea environments. The end fitting, or coupling, provides a sealing transition between the pipe body and a connecting component, and transmits normal service loads acting on the pipe without allowing the pipe to fail. End fittings may be used for connecting sections of pipe to one another, orfor connecting a section of pipe to, for example, terminal equipment. A problem that can occur when mounting an end fitting to a section of pipe is galling. Galling is a severe form of adhesive wear that occurs in connecting pipes, particularly in the oil and gas industry. It involves the transfer of material between contacting metal surfaces when they are in relative motion under load. More specifically, high localised pressure between sliding metal surfaces causes asperities (microscopic high points on a material's surface) to plastically deform and micro-weld, leading to material transfer and surface damage. The process escalates with continued sliding, resulting in destruction, or wear and degradation of the metal surfaces.

[0008] Galling can occur particularly when the end fitting forms an interference fit with the pipe body, where the fitting is slightly smaller than the pipe body to create an extremely tight connection. The tight fit increases the risk of galling due to high contact stresses. Ensuring a tight fit in critical in many applications, for example sour service applications, i.e., applications in the oil and gas industry where equipment, including pipes and other infrastructure, is exposed to hydrogen sulphide (H2S) gas. Hydrogen sulphide is a highly corrosive, toxic, and flammable gas commonly found in certain natural gas and petroleum deposits. Even at low concentrations, the gas poses significant health risks to workers, including respiratory issues and eye irritation, and in high concentrations it can be fatal.

[0009] Safeguarding both personnel and the environment against hydrogen sulphide, and other contaminants, includes preventing leaks from pipes. Galling presents a risk in that the damage caused can compromise the integrity of connections, subsequently leading to leaks. It is therefore desirable to prevent and mitigate against the risk of galling to ensure reliable, leak-proof connections in oil and gas applications.

[0010] It is known to provide a seal ring when forming connections, to ensure a fluid tight seal. Seal rings play a critical role in connecting a section of pipe to an end fitting, ensuringthe integrity and reliability of the pipe. Galling can therefore be the result of the seal ring sliding against a surface of the end fitting, under load as the connection is made. Damage can occur on the seal ring and / or the end fitting. Seal rings and end fittings are sometimes made of the same material. When the metals are the same or have similar properties, the microscopic asperities on their surfaces can more easily weld together under pressure and friction, making them more prone to galling.

[0011] It is an object of the invention to provide an improved connection in flexible pipes, more specifically a connection that reduces the risk of leakage caused by galling, and / or at least mitigate one or more problems associated with known arrangements.

[0012] SUMMARY OF THE INVENTION

[0013] According to an aspect of the invention, there is provided a seal ring for sealing a joint between a pipe body of a flexible pipe and an end fitting, the seal ring comprising an annular member having a body portion and a wedge portion extending substantially longitudinally from the body portion, wherein the edge portion comprises a radially outer surface delimiting first and second tapered sealing regions, and an intermediate region separating the first and second tapered sealing regions from one another and which is a) nottapered or b) tapered to a lesser degree than each of the first and second sealing regions. This arrangement provides a two-part, or two-stage, sealing arrangement. The first tapered sealing region creates a seal between the seal ring and a pipe layer, or part thereof, radially inward of the seal ring. The second tapered sealing region creates a seal between the seal ring and an end fitting, or part thereof, radially outward of the seal ring. As contact occurs between the seal ring and the end fitting (e.g., during swaging of the end fitting onto the pipe body), the end fitting deflects the first tapered sealing region into the pipe layer, while the second tapered sealing region is spaced apart from the end fitting. Subsequently (e.g., when swaging of the end fitting is almost complete), the end fitting is pressed against the second tapered sealing region. The arrangement allows that the first tapered sealing region contacts only a first portion, e.g., a length, of the end fitting, and the second tapered sealing region contacts only a second portion, e.g., a further length, of the end fitting that is distinct from the first. This means that contact between the second tapered sealing region and the end fitting occurs over a portion thereof free from any galling caused by contact between the first tapered sealing region and the end fitting. This may improve the efficacy of the seal between the seal ring and the end fitting.

[0014] In certain embodiments, the annular member may be metallic, and optionally the annular member may a nickel-based or nickel-chromium-based alloy.

[0015] In certain embodiments, the wedge portion may comprise a radially inward surface having a plurality of projections. Additionally, or alternatively, the first and / or second tapered sealing regions may taper linearly. Ataper angle of the first tapered sealing region may be at least 7.5° and / or up to 30.0°. The taper angle of the first tapered sealing region may be at least 20°. A taper angle of the second tapered sealing region may be at least 7.5° and / or up to 30.0°. However, the first and / or second tapered sealing regions may taper non-linearly, and optionally the first and / or second tapered sealing regions may comprise a concave or convex cross-section of constant radius. In certain embodiments, the first and / or second tapered sealing regions may comprise a recess in which a secondary sealing member is received, and optionally the secondary sealing member may be an O-ring seal.

[0016] In certain embodiments, the wedge portion may comprises a living hinge, i.e., a relatively more flexible section, proximate the body portion that facilitates flexion of the wedge portion radially inward. The living hinge may be in the form of an annular channel extending about the annular member. The seal ring may comprise an annular band substantially filling the annular channel, the annular band having a lesser stiffness than that of the annular member.

[0017] According to another aspect of the invention, there is provided a flexible pipe comprising: a pipe body comprising a polymeric pipe layer; an end fitting in which an end of the pipe body is mounted, the end fitting comprising a radially inner surface; and a seal ring according to any preceding claim, wherein the first and second tapered sealing regions are in sealing engagement with the polymeric pipe layer of the pipe body and the radially inner surface of the end fitting, respectively. The intermediate region may not be in sealing engagement with the end fitting.

[0018] In certain embodiments, the polymeric pipe layer may have a hardness less than that of the annular member. The radially inner surface of the end fitting may be metallic, and optionally wherein the radially inner surface may a nickel-based or nickel-chromium-based alloy. Additionally, or alternatively, the annular member and the radially inner surface of the end fitting may have substantially the same material properties.

[0019] In certain embodiments, the pipe may be for conveying oil and gas field fluids, and / orthe pipe may be a flexible pipe, such as described above in the background section, for example for use in deep water and / or ultra-deep water applications. The flexible pipe my be unbonded flexible pipe. In certain embodiments, a first seal may extend about an annular surface-to- surface contact of a radially inner surface of the wedge portion at or over the first tapered sealing region against a radially outer surface of the polymeric pipe layer. Additionally, or alternatively, a second seal may extends about an annular surface-to-surface contact of the radially outer surface of the wedge portion at or over the second tapered sealing region against the radially inner surface of the end fitting.

[0020] According to yet another aspect of the invention, there is provided a method of sealinga joint between a pipe body of a flexible pipe and an end fitting, the method comprising: providing a seal ring comprising an annular member having a body portion and a wedge portion extending substantially longitudinally from the body portion, the wedge portion comprising a radially outer surface delimiting first and second tapered sealing regions; disposing the seal ring between a polymeric pipe layer of the pipe body and a radially inner surface of the end fitting; moving the seal ring longitudinally relative to the radially inner surface so thatthe firsttapered sealing region contacts only a first length of the radially inner surface and is consequently urged radially inwardly into sealing engagement with the polymeric pipe layer; and further moving the seal ring longitudinally relative to the radially inner surface so that the second tapered sealing region contacts only a second length of the radially inner surface adjacent to the first length and is subsequently urged into sealing engagement with the radially inner surface.

[0021] In certain embodiments, the wedge portion may comprise an intermediate region separating the first and second sealing regions from one another and which is a) not tapered or b) tapered to a lesser degree than each of the first and second sealing regions. Moving and / or further moving the seal ring may be by swaging or crimping. The swaging may be by using the end fitting to perform the swaging of the seal. A position of the seal ring may be unchanged longitudinally with respect to the polymeric pipe layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Embodiments of the invention will now be described, byway of example only, with reference to the accompanying figures, in which:

[0023] Figure 1 is a cross-sectional view of a pipe accordingto an embodiment of the invention, the pipe including a seal ring;

[0024] Figure 2 is a perspective view of the seal ring of Figure 1 , the seal ring being isolated from the remainder of the pipe;

[0025] Figure 3 is a cross-sectional view of the seal ring of Figure 1 , the seal ring being isolated from the remainder of the pipe; and

[0026] Figures 4A to 4D are a series of cross-sectional views of the seal ring of Figure 1 before, during and after stages of forming a seal within the pipe.

[0027] DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0028] Embodiments of the invention may have particular application for use as an offshore pipe for conveying oil and gas field fluids, such fluids including one or more of gas (e.g., methane, ethane, hydrogen, or CO2), hydrocarbon fluids (e.g., oil), water, or other fluids (e.g., slurry). Moreover, embodiments of the invention may be may have particular application as part of a flexible pipe, including unboned flexible pipe, which may be manufactured as described in API standard 17J. However, other applications are contemplated.

[0029] Figure 1 shows an end of a flexible pipe 10 according to an embodiment of the invention. The pipe 10 comprises a pipe body 12 and an end fitting 14, in which an end 16 of the pipe body 12 is mounted, therebyforming a connection between the pipe body 12 and the end fitting 14. The pipe body 12 includes a polymeric pipe layer 18, which may be one of multiple pipe layers of the pipe 10. In the illustrated embodiment, the polymeric pipe layer 18 is an intermediate pipe layer disposed between an inner pipe layer 20 and an outer pipe layer 22. The inner pipe layer 20 may be a liner layer or a supporting carcass layer, and / or the outer pipe layer 22 may be a protective layer or a pressure armour layer. Moreover, one or each of the inner pipe layer 20 and the outer pipe layer 22 may be a further polymeric pipe layer. In the illustrated embodiment, a length of the outer pipe layer 22 is removed, consequently exposing a length of the polymeric pipe layer 18 adjacent the end 16 of the pipe body 12. The exposed length of the polymeric pipe layer 18 is therefore the radially outmost layer of the pipe body 12 at the end 16 thereof. This is to facilitate formingthe connection between the pipe body 12 and the end fitting 14, as will be described in more detail below.

[0030] The flexible pipe 10 further comprises a seal ring 30. The seal ring 30 is disposed between the pipe body 12 and an end fitting 14 to provide a fluid tight seal therebetween. More specifically, the seal ring 30 may be disposed between the polymeric pipe layer 18 and a radially inner surface 24 of the end fitting 14. Yet more specifically, the seal ring 30 may seal against the polymeric pipe layer 18 and against the radially inner surface 24, to thereby create the fluid tight seal. The radially inner surface 24 of the end fitting 14 may delimit an open end 26 of the end fitting 14 and / or form an internal surface of the end fitting 14. In embodiments where the radially inner surface 24 forms only an internal surface of the end fitting, the open end may be otherwise provided. As shown in the illustrated embodiment (see, in particular, Figures 4A to 4D), in forming the seal, the seal ring 30 may deform, i.e., compress, the polymeric pipe layer 18. The deformation may reduce a thickness of the polymeric pipe layer 18 by at least 10%. In certain embodiments, the deformation may reduce the thickness by at least 20%.

[0031] Figures 2 and 3 show the seal ring 30 in isolation. The seal ring 30 is formed of an annular member 32, having a body portion 34 and a wedge portion 36 (best illustrated in Figure 3). The wedge portion 36 extends substantially longitudinally from the body portion 34, from a first side 34a thereof, and has a radially outer surface 38 delimiting in part first and second tapered sealing regions 40, 42. The first sealing region is a part of the wedge portion 36 for effecting a seal between the seal ring 30 and the flexible pipe 10. The second sealing region is a further, distinct part of the wedge portion 36 for effecting a seal between the seal ring 30 and the end fitting 14.

[0032] The radially outer surface 38 further delimits an intermediate region 44 that separates the first and second tapered sealing regions 40, 42 from one another, i.e., the intermediate region 44 is disposed between the first and second tapered sealing regions 40, 42. The first and second tapered sealing regions 40, 42 and the intermediate region 44togetherform a generally tapered transverse cross-section, or profile, of the wedge portion 36, which tapers away from the body portion 34. Used herein, including in the appended claims, the terms “taper”, “tapered”, “tapers”, etc. are to be given their normal meaning, i.e., to diminish, or reduce in thickness, towards one end. No further limitation is to be understood, unless specified expressly. The wedge portion 36 should be understood to be substantially wedge shaped, i.e., having a cross-section that tapers to a thin edge on one side, a free side of the wedge portion 36, and is thicker on the opposing side, where the wedge portion 36 connects to the body portion 34. The wedge portion 36 may have a overall substantially or approximately triangular crosssection. The body portion 34 may be any suitable shape, which may be polygonal, e.g., at least substantially or approximately square, trapezoidal or hexagonal. The body portion 34 may facilitate the application of a force to the wedge portion 36 when formingthe connection between the pipe body 12 and the end fitting 14.

[0033] Crucially, the purpose of the intermediate region 44 is to space apart the first and second tapered sealing regions 40, 42 in manner such that the second tapered sealing region 42 does not come into contact with any part of the end fitting 14 that has previously been experienced sliding engagement with the first tapered sealing region 40 during forming the connection between the pipe body 12 and the end fitting 14. This can be achieved in different ways, and in certain embodiments may be dependent upon the profile of the radially inner surface 24 of end fitting 14. However, as in the illustrated embodiment, this function of the intermediate section 44 may be achieved by the intermediate section 44 not being tapered or otherwise being tapered to a lesser degree than each of the first and second sealing regions 40, 42. This, in effect, may create a step in the radially outer surface 38 of the wedge portion 36. This arrangement has been found to work particularly well when the radially inner surface 24 of end fitting 14 is frustoconical, providing a linear, gradually increasing diameter for receipt of the pipe body 12 within the end fitting 14, the diameter increasingtoward the open end 26. However, the arrangement works with other configurations of the radially inner surface 24, e.g., the radially inner surface 24 may include a cooperating stepped profile, or some other non-linear profile.

[0034] In the illustrated embodiment, the first and second tapered sealing regions 40, 42 are shown to be tapered substantially linearly, though this need not be the case. When tapered linearly, a taper angle of the first tapered sealing region 40 may at least 7.5° and / or up to 30.0°. In certain embodiments, the taper angle of the first tapered sealing region is at least 20°. The taper angle is measured relative a central, longitudinal axis A-A extending through the centre of seal ring 30. Additionally, or alternatively, a taper angle of the second tapered sealing region may be at least 7.5° and / or up to 30.0°. The intermediate region 44 may or may not be tapered. As shown in the illustrated embodiment, the radially outer surface 38 of the wedge portion 36 extends substantially perpendicularly to an opposing radially inner surface 46 of the wedge portion 36, i.e., a radially inner surface on the opposing side of the wedge portion 36 to the radially outer surface 38. In use, the radially inner surface 46 may contact the polymeric pipe layer 18. The intermediate region 44 may include a non-linear, or curved, profile. The features of the pipe 10 may be made of any suitable material. While the invention may address the problem of galling, a problem arising due to metal-to- metal contact as described above, the seal ring 30 may improve sealing efficacy in arrangements having no metal-to-metal contact, since the two-part design of the seal ring 30 means that contact between the second tapered sealing region 42 and the end fitting 14 occurs over a portion thereof free from any damage caused by contact between the first tapered sealing region 40 and the end fitting 14, and also protects the second tapered sealing region 42 during sliding contact between the first tapered sealing region 40 and the end fitting 40 when forming the sealed connection.

[0035] Of course, in certain embodiments, the end fitting 14 and / or the seal ring 30 may be formed of a metal. Alternatively, at least the contact surfaces forming the interfaces between the first and second tapered sealing regions 40, 42 and the end fitting may be formed of a metal, e.g., the radially inner surface 24 and / or radially outer surface 38 may be formed of a metal. The annular member32 of the seal ring 30 may be formed of a metal. Suitable metals include stainless steels, Hastelloy (RTM) (such as UNS N10276) nickel-based (such as UNS N06625) or nickel-chromium-based alloys (e.g. UNS N06059 or UNS N08031). Hastelloy (RTM) is the trade name given to a group of corrosion-resistant nickel-based alloys manufactured by Haynes International, Inc. The polymeric pipe layer 18 may be made from any suitable polymer, including PP, MDPE, HDPE, XLPE, PE-RT, or modified grades thereof, polyamides (e.g., PA-12, PA-11), thermoplastic elastomers, polyphenylene sulphide (PPS), polyvinylidene fluoride or polyvinylidene difluoride (PVDF), though other polymers or polymer alloys may be used. The polymeric pipe layer 18 may comprise filled polymers where the polymer contains a portion of a filler material, such as fibres or particles, or additives that make the polymeric pipe layer 18 more chemically stable at higher temperatures. Generally, the polymeric pipe layer 18 may have a hardness less than the annular member 18, which may facilitate deformation of the pipe layer 18 when formingthe connection.

[0036] The seal ring 30 may comprise further features, including a plurality of surface projections 48 on the radially inner surface of the wedge portion 36 to facilitate its sealing against the polymeric pipe layer 18. The surface projections 48 may have a sawtooth profile. More specifically, the surface projections 48 may provide a sawtooth profile to the radially inner surface 46 of the wedge portion 36. However, in certain embodiments, alternative projection profiles may be used, as arevaryingdepths of the projection profiles, as appropriate for different polymers, such that notch sensitivity limitations of a given polymer used in the manufacture of the polymeric pipe layer 18 are not reached.

[0037] As shown in the illustrated embodiment, in certain embodiments, the wedge portion 36 may include a living hinge 50. The purpose of the living hinge 50 is to promote flexion of the wedge portion 36 during forming of the connection between the pipe body 12 and the end fitting 14, allowing it to more easily deform and / or deform in a more controlled manner. Therefore, the living hinge 50 provides a relatively more flexible section of the wedge portion 36 — relative to the remainder of the wedge portion 36. The living hinge 50 may be provided in the form of reduced cross-section of the wedge portion 36, e.g. by providing an annular channel 52 extending about the annular member 32, thereby effectively removing material from the cross-section of the wedge portion 36. The living hinge 50 may be provided on a radially inner side of the wedge portion 36. In certain embodiments, the seal ring comprise an annular band 54 substantially filling the annular channel 52, the annular band 54 having a lesser stiffness than that of the annular member 32. Suitable materials for filling the annular channel 52 include a silicone elastomer. However, other formable / mouldable / injectable polymer or elastomeric materials may also be used. This enables the living hinge 50 to function as intended, by providing a relatively more flexible section of the wedge portion 36, while preventing the annular channel 52 becoming filled by some other means, e.g., the polymeric layer 18 being displaced under pressure into the annular channel 52 during forming of the connection, or when the pipe is in service, as this may inhibit the desired flexion of the wedge portion 36 and / or strain the polymer layer 18 undesirably.

[0038] Figures 4A to 4D show a method of forming the sealed connection between the pipe body 12 and the end fitting 14. The forming of the sealed connection is essentially a two-stage process, forming a seal between the seal ring 30 and the polymeric pipe layer 18, and also forming a seal between the seal ring 30 and the radially inner surface 24 of end fitting 14. As the skilled reader will understand, at least in view of the following description, the first stage of forming the seal may include initiatingformingthe seal between the seal ring30 and the polymeric pipe layer 18, e.g., as part of a pre-swaging or swaging operation, which forming is subsequently completed during the second stage, e.g. as part of a swaging operation, while forming the seal between the seal ring 30 and the radially inner surface 24 of end fitting 14.

[0039] Figure 4A shows the arrangement prior to forming the connection, with the seal ring 30 disposed between the polymeric pipe layer 18 of the pipe body 12 and the radially inner surface 24 of the end fitting 14. Prior to forming the connection, there may be no contact between the wedge portion 36 and the end fitting 14, as is shown in the illustrated embodiment. However, in certain embodiments, such contact could be present, though prior to forming the connection there may be relatively low forces exerted by the seal ring 30 against each of the polymeric pipe layer 18 and the end fitting 14. Prior to forming the connection, the wedge portion 36 may contact the polymeric pipe layer 18, since the seal 30 may be installed over and / or about the polymeric pipe layer 18 prior to the pipe body 12 being introduced into the open end 26 of the end fitting 14. The body portion 34 of the seal ring 30 may abut the outer pipe layer 22 and / or the end fitting 14. Such abutment occurs on an opposing second side 34b of the body portion 34, i.e., a side on the opposing side of body portion 34 to the first side 34a.

[0040] Figure 4B shows the first stage of forming the sealed connection, the first stage being shown to be in progress and not yet complete. As shown, during the first stage, the seal ring 30 is moved longitudinally, or axially, relative to the end fitting 14. More specifically, the seal ring 30 is moved toward the radially inner surface 24 of the end fitting 14. As shown in the illustrated embodiment, this movement may occur together with movement of the pipe body 12, such that the pipe body 12 and the seal ring 30 move together longitudinally as one. Alternativity, only the end fitting 14 may move while the pipe body 12 and seal ring 30 remain stationary, the end fitting 14 moving axially towards and over the wedge portion 36. As the seal ring 30 is moved, the first tapered sealing region 40 is forced into contact with the radially inner surface 24 of the end fitting 14. This initial contact results in the first tapered sealing region 40 being urged radially inward and against / into the polymeric pipe layer 18, as the path of the first tapered sealing region 40 is deflected by the radially inner surface 24. As the deflection occurs, sliding contact, e.g., sliding metal-to-metal contact, will occur between the seal ring 30 and the end fitting 14, occurring at the interface between the first tapered sealing region 40 and the radially inner surface 24, over a first length of the radially inner surface 24. Due to the contact pressure, the sliding contact may cause galling, or other damage or deformation, of the radially outer surface 38 of the wedge portion 36 and / or of the radially inner surface 24 of the end fitting 14.

[0041] The contact results in the first tapered sealing region 40 being sealingly engaged with the polymeric pipe layer 18, at least once the forming of the sealed connection is complete. Sealing engagement is effected by surface-to-surface contact of the radially inner surface 46 of the wedge portion 36 at or over the first tapered sealing region 40 against a radially outer surface of the polymeric pipe layer 18. As shown in the illustrated embodiment, as the first tapered sealing region 40 is urged radially inward, the polymeric pipe layer 18 may be compressed to effect sealing engagement. Figure 4-B shows the initial compression of the polymeric pipe layer 18.

[0042] The movement of the seal ring 30 may be caused by any suitable means. In certain embodiments, the movement may be caused by swaging or crimping the end fitting 14 onto the pipe body 12. Generally, such processes may be referred to as energising, which the skilled person will understand as a process for forming a connection, especially one which includes connecting sections of pipe body or connecting a pipe body to an end fitting in a manner that ensures a secure and reliable leak-proof connection, and may include compressing seals or gaskets within the connection. Forms of energising may include tightening clamps, screwing threads or using other mechanical means to urge the seal ring 30 and end fitting 14 into a closer relationship.

[0043] Figure 4C shows the second stage of forming the sealed connection, the second stage being shown to be in progress and not yet complete. As shown, during the second stage, continued longitudinal movement of the seal ring 30 relative to the end fitting 14, forces the second tapered sealing region 42 into contact with the radially inner surface 24 of the end fitting 14. This subsequent contact results in the second tapered sealing region 42 being urged against the inner surface 24. As shown in the illustrated embodiment, continued sliding contact may occur between the seal ring 30 and the end fitting 14, occurring at the interface between the second tapered sealing region 42 and the radially inner surface 24. As in the first stage, the sliding contact may cause galling, or other damage or deformation, of the radially outer surface 38 of the wedge portion 36 and / or of the radially inner surface 24 of the end fitting 14. Crucially, this sliding contact, at least partially, occurs over a second length of the radially inner surface 24, the second length being distinct from the first length over which sliding contact occurs between the first tapered sealing region 40 and the radially inner surface 24. As such, any galling, or other damage or deformation, caused to the radially inner surface 24 of the end fitting 14 due to contact with the first tapered sealing portion 40 occurs over a length of the radially inner surface 24 that does not contact the second tapered sealing region 42 during the second stage. Generally, at least a portion of the sliding contact between the radially outer surface 38 at the first tapered sealing region 40 and the radially inner surface 28 occurs only over the first length, and at least a portion of the sliding between the radially outer surface 38 at the second tapered sealing region 42 and the radially outer surface 28 occurs only over the second length.

[0044] The contact results in the second tapered sealing region 42 being sealingly engaged with the end fitting 14, at least once the forming of the sealed connection is complete. Sealing engagement is effected by surface-to-surface contact of the radially outer surface 38 of the wedge portion 36 at or over the second tapered sealing region 42 against the radially inner surface 24 of the end fitting 14. The continued movement may also cause further urging of the first tapered sealing region 40 radially inward and against / into the polymeric pipe layer 18, as shown in the illustrated embodiment, thereby adding to the sealing effect described above in reference to the first stage. Figure 4-C shows further compression of the polymeric pipe layer 18.

[0045] The movement forces the radially outer surface 38 of the wedge portion 36 and the radially inner surface 24 of the end fitting 14 into intimate contact with one another, creating a high contact pressure at the interface between the second tapered sealing region 42 and the radially inner surface 24, thereby eliminating any gap(s) that may otherwise be present. The contact may cause some deformation, e.g., plastic deformation, of the seal ring 30 and / orthe inner surface 24 of the end fitting 14. This deformation may facilitate the seal ring 30 in conforming to end fitting 14 to form of an effective, leak-proof seal. Figure 4D shows the arrangement after forming the connection. Sealing contact between the seal ring 30 and each of the pipe body 12 and the end fitting 14 is complete, and the two are sealed against one another. A first seal extends about the annular surface-to-surface contact of the radially inner surface 46 of the wedge portion 36 at or over the first tapered sealing region 40 against the radially outer surface of the polymeric pipe layer 18. A second seal extends about the annular surface-to-surface contact of the radially outer surface 38 of the wedge portion 36 at or over the second tapered sealing region 42 against the radially inner surface 24 of the end fitting 14. In certain embodiments, a third seal may extend about the annular surface-to-surface contact of the radially outer surface 38 of the wedge portion 36 at or over the first tapered sealing region 40 against the radially inner surface 24 of the end fitting 14. In certain embodiments, the third seal may not be formed due to the galling, or other damage or deformation, of the radially outer surface 38 of the wedge portion 36 and / or of the radially inner surface 24 of the end fitting 14 inhibiting sealing efficacy. The polymeric pipe layer 18 is fully compressed, i.e., compressed by a desired predetermined amount. In the illustrated embodiment, it is no longer possible to move the seal ring 30 longitudinally toward the end fitting 14. As shown, the body portion 34 of the seal ring 30 may remain in contact with the outer pipe layer 22 and / or the end fitting 14, which may inhibit or limit longitudinal movement that could break the seal. Also as shown, the intermediate region 44 may not be in sealing engagement with the end fitting 14.

[0046] The two stage method and / or the design of the seal ring 30 may limit the severity of galling occurring over a length of the end fitting 14 critical for forming a seal between the seal ring 30 and the end fitting 14, and thereby may improve the sealing efficacy of the seal ring 30.

[0047] The invention is not restricted to the details of any foregoing embodiments, e.g., in certain embodiments, the pipe body 12 may include one or more additional pipe layers, e.g., further pipe body layers may be present outside the outer pipe layer 22. These may be selected from further pressure and / or tensile armour layers comprising metallic or composite armouring elements helically wound around the outer pipe layer 22, tapes for preventing wear or fretting of adjacent layers, anti-birdcaging tapes, composite layers, insulation layers and extruded polymeric sealing or separating sheaths. If sealing on other layers further radially outwards in the flexible pipe body structure, there will be more layers radially inwards of the polymeric pipe layer 18 being sealed, i.e., the polymeric pipe layer 18 may be the outermost layer of the flexible pipe body 12. In such embodiments, there would be no removal of layers outward of the polymeric pipe layer 18 in order to enable the sealing of that layer.

[0048] Moreover, while the polymeric pipe layer 18 is shown in the illustrated embodiment to be an intermediate pipe layer, in certain embodiments, the polymeric pipe layer 18 may be a radially outmost or innermost layer. Consequently, there may be no removal of a pipe layer at the end of the pipe body 12 for forming the connection between the pipe body 12 and the end fitting 14. In certain embodiments, the first and / or second tapered sealing regions 40, 42 may taper non-linearly, i.e., may comprise a concave or convex cross-section. Such concave or convex cross-section may have a constant radius. In certain embodiments, the second tapered sealing region 42 may be provided by a radius, constant or otherwise, that is formed between the body portion 34 and the wedge portion 36. The partially or continually changing taper angle, concave or convex radius, assist to achieve a non-sliding seal and / or lower interfacial sealing force, compared to that between the end fitting 14 and the first tapered sealing region 40, between the second taper sealing region 42 and the end fitting 14. In certain embodiments, the first and / or second tapered sealing regions 40, 42 may comprise a recess in which a secondary sealing member is received. The secondary sealing member may be an O-ring seal. Features and methods described herein in relation to the seal ring 30 may apply equally to a seal design comprising a second, opposing seal wedge portion, for example orientated in the opposite longitudinal direction, and associated with the same body portion 34 but extending from the second side 34b, which may also feature first and second tapered sealing regions.

[0049] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0050] Features, integers, or characteristics described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. In particular, the words “certain embodiments” are to be understood to mean any embodiment described, illustrated, or otherwise disclosed herein, unless expressly stated otherwise. All of the features disclosed in this specification (includingany accompanyingclaims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

CLAIMS1 . A seal ring for sealing a connection between a pipe body of a flexible pipe and an end fitting, the seal ring comprising an annular member having a body portion and a wedge portion extending substantially longitudinally from the body portion, wherein the wedge portion comprises a radially outer surface delimiting first and second tapered sealing regions, and an intermediate region separating the first and second tapered sealing regions from one another and which is a) not tapered or b) tapered to a lesser degree than each of the first and second sealing regions.

2. A seal ring according to claim 1 , wherein the annular member is metallic, and optionally wherein the annular member is a nickel-based or nickel- chromium-based alloy.

3. A seal ring according to claim 1 or 2, wherein the wedge portion comprises a radially inward surface having a plurality of projections.

4. A seal ring according any preceding claim, wherein the first and / or second tapered sealing regions taper linearly.

5. A seal ring according to claim 4, wherein a taper angle of the first tapered sealing region is at least 7.5° and / or up to 30.0°, and optionally wherein the taper angle of the first tapered sealing region is at least 20°.

6. A seal ring according to claim 4 or 5, wherein a taper angle of the second tapered sealing region is at least 7.5° and / or up to 30.0°.

7. A seal ring according to any preceding claim, wherein the first and / or second tapered sealing regions taper non-linearly, and optionally wherein the firstand / or second tapered sealing regions comprise a concave or convex crosssection of constant radius.

8. A seal ring according to any preceding claim, wherein the first and / or second tapered sealing regions comprise a recess in which a secondary sealing member is received, and optionally wherein the secondary sealing member is an O-ring seal.

9. A seal ring according to any preceding claim, wherein the wedge portion comprises a living hinge, i.e., a relatively more flexible section, proximate the body portion that facilitates flexion of the wedge portion radially inward.

10. A seal ring according to claim 9, wherein the living hinge is in the form of an annular channel extending about the annular member.

11. A seal ring according to claim 10, wherein the seal ring comprises an annular band substantially filling the annular channel, the annular band having a lesser stiffness than that of the annular member.

12. A flexible pipe comprising: a pipe body comprising a polymeric pipe layer; an end fitting in which an end of the pipe body is mounted, the end fitting comprising a radially inner surface; and a seal ring accordingto any preceding claim, wherein the first and second tapered sealing regions are in sealing engagement with the polymeric pipe layer of the pipe body and the radially inner surface of the end fitting, respectively.

13. A flexible pipe accordingto claim 12, wherein the polymeric pipe layer has a hardness less than that of the annular member.

14. A flexible pipe according to claim 12 or 13, wherein the radially inner surface of the end fitting is metallic, and optionally wherein the radially inner surface is a nickel-based or nickel-chromium-based alloy.

15. A flexible pipe according to any of claims 12 to 14, wherein the annular member and the radially inner surface of the end fitting have substantially the same material properties.

16. A flexible pipe according to any of claims 12 to 15, wherein the pipe is for conveying oil and gas field fluids.

17. A flexible pipe according to any of claims 12 to 16, wherein the intermediate region is not in sealing engagement with the end fitting.

18. A method of sealing a connection between a pipe body of a flexible pipe and an end fitting, the method comprising: providing a seal ring comprising an annular member having a body portion and a wedge portion extending substantially longitudinally from the body portion, the wedge portion comprising a radially outer surface delimiting first and second tapered sealing regions; disposingthe seal ring between a polymeric pipe layer of the pipe body and a radially inner surface of the end fitting; moving the seal ring longitudinally relative to the radially inner surface so that the first tapered sealing region contacts only a first length of the radially inner surface and is subsequently urged radially inwardly into sealing engagement with the polymeric pipe layer; and further moving the seal ring longitudinally relative to the radially inner surface so that the second tapered sealing region contacts only a second length of the radially inner surface adjacent to the first length and is consequently urged into sealing engagement with the radially inner surface.

19. A method accordingto claim 18, wherein the wedge portion comprises an intermediate region separating the first and second sealing regions from one another and which is a) not tapered or b) tapered to a lesser degree than each of the first and second sealing regions.

20. A method accordingto claim 18 or 19, wherein moving and further moving the seal ring is by swaging or crimping, and optionally using the end fitting to perform the swaging, and optionally wherein a position of the seal ring is unchanged longitudinally with respect to the polymeric pipe layer.

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