A method of securing a pipe end section of an unbonded flexible pipe to an end-fitting and an unbonded flexible pipe assembly

Abstract

The invention relates to a method of securing a pipe end section of an unbonded flexible pipe (1) to an end-fitting (8) comprising an inner casing (7). The method comprises applying a fixation ring (11) to cover an end region of pressure armor (4) of the pipe end section, the fixation ring having one or more fixation ring recesses. A locking collar (12) is applied to surround the pressure armor (4), and a support collar (13) is applied adjacent to the fixation ring. The locking collar (12) is moved to cover at least a part of said fixation ring (11) and at least a part of said support collar (13) so that the support collar (13) is engaged with the fixation ring (11) and the inner casing collar (9), respectively, at opposite end surfaces of the support collar (13). The locking collar (12) is anchored to said inner casing collar (9). The invention further relates to an unbonded flexible pipe assembly.

Description

[0001] A METHOD OF SECURING A PIPE END SECTION OF AN UNBONDED FLEXIBLE

[0002] PIPE TO AN END-FITTING AND AN UNBONDED FLEXIBLE PIPE ASSEMBLY

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to a method of securing a pipe end section of an inner pipe portion of an unbonded flexible pipe to an end-fitting comprising an inner casing. The invention also relates to an unbonded flexible pipe assembly comprising an inner pipe portion of an unbonded flexible pipe and an end-fitting comprising an inner casing.

[0005] BACKGROUND OF THE INVENTION

[0006] Unbonded flexible pipes for transferring fluids, such as petrochemical fluids, are well known in the art. Unbonded flexible pipes are especially suitable for offshore and / or underwater applications. A general description of unbonded flexible pipes may be found in the standard documents API 17J (Specification for Unbonded Flexible Pipe) and API RP 17B (Recommended Practice for Flexible Pipe) established by the American Petroleum Institute.

[0007] An unbonded flexible pipe comprises a number of concentric and superimposed layers comprising polymeric layers and reinforcement layers, wherein at least one of the layers is not interracial ly bonded to at least one other of the layers and accordingly this at least one layer of the pipe is able to move longitudinally relative to the at least one other of the layers when the pipe is bent. Due to this construction, the unbonded flexible pipe may be optimized with respect to strength and flexibility and the unbonded flexible pipe may be transported in long lengths on reels or carousels.

[0008] A typical unbonded flexible pipe comprises from the inside and outwards an optional inner armor layer known as the carcass or the pressure vault or merely the vault, an internal pressure sheath comprising an extruded polymer layer surrounded by one or more armor layers and an outer sheath (also referred to as external protective polymer sheath), such as an extruded polymer layer. The unbonded pipe may comprise additional layers, such as intermediate polymer layers, insulation layers, additional armor layers, and wound tape layers. Since two or more, such as a plurality thereof or even all of the respective layers are not interracial ly bonded, it is well known to secure the respective layers in an end-fitting at each end of the unbonded flexible pipe.

[0009] Due to the high flexibility and the use of the unbonded flexible pipe for transporting fluids at high pressure and / or where the pipe is subjected to high and varying hydrostatic pressures, the layers, and in particular the pressure armor layer, need to be secured to the end-fitting with a very high or durable strength. For example, a typical requirement for an unbonded flexible pipe is that it should have a lifetime of 20 years in its intended use.

[0010] The load on the securement between the end-fitting and the layers of the unbonded flexible pipe may be extremely high especially where the flexible pipe is applied at relatively deep water, such as below 50 m from the sea surface or deeper, such as 500 m or deeper, such as 1000 m or deeper, such as 2000 m or deeper, and where the pressure in the bore may vary e.g. due to temperature variations, production variations, or blockages in the pipe etc. There is therefore a very high requirement for the strength of a securement of the pressure armor in the end-fitting.

[0011] The pressure armor forms part of an inner pipe portion comprising a pressure sheath sealing against outflow of the fluid to be transported and thereby defining a bore of the unbonded flexible pipe. The pressure armor usually comprises helically wound armor wires which may be interlocked or not. When the armor wires are interlocked, they may be referred to as interlocked armor wires. The pressure armor has the purpose of providing the pressure sheath with collapse resistance, also referred to as burst resistance. The inner pipe portion may often comprise a carcass located inside the pressure sheath.

[0012] An end-fitting usually comprises an inner casing and an outer casing, where each casing may be formed from one or more elements. The inner pipe portion is usually secured to the inner casing of the end-fitting followed by securing the layers externally to the pressure armor to the outer casing or between the inner casing and the outer casing.

[0013] Several methods of mechanical securing of the pressure armor in the end-fitting have been suggested. A possible method for ensuring a high strength securement of the pressure armor in the end-fitting comprises filling the space around the end region of the pressure sheath with epoxy resin in order to fasten the pressure armor wires and support the pressure sheath at areas where the pressure sheath is not covered by the pressure armor to avoid creep of the pressure sheath.

[0014] US10690275 describes a connection end-fitting for a flexible line used for fluid transport. The flexible line includes a pressure sheath, an interlocked pressure vault arranged outwardly relative to the pressure sheath and at least one traction armor layer arranged outwardly relative to the interlocked pressure vault and comprising a plurality of armor elements. The end-fitting comprises an end region of the interlocked pressure vault, at least one end segment of each armor element, an end vault, and a cover fastened on the end vault, the end vault and the cover defining a chamber between them for receiving each end segment of the armor elements, a front crimping flange of the pressure sheath attached on the end vault and arranged outwardly relative to the end region of the interlocked pressure vault, and a locking system configured to lock the interlocked pressure vault relative to the end vault, wherein the locking system comprises a curved holding assembly radially mounted between the end region of the interlocked pressure vault and the front crimping flange.

[0015] However, none of the prior art solutions for mechanical securement of the pressure armor in the end fitting has been satisfactory, since they are generally difficult to establish to provide the desired high strength securement, which simultaneously ensures a desired support of the pressure sheath thereby ensuring a low risk of undesired creep of the pressure sheath.

[0016] There is a substantial need for alternative or improved methods of securing a pressure armor of an inner pipe portion of an unbonded flexible pipe in an end-fitting.

[0017] DISCLOSURE OF THE INVENTION

[0018] An objective of the invention is to provide an alternative or improved method of mechanically securing a pipe end section of an inner pipe portion of an unbonded flexible pipe in an end-fitting. In an embodiment, it is an objective of the invention to provide a method of mechanically securing a pipe end section of an inner pipe portion of an unbonded flexible pipe in an end-fitting, which method can be performed relatively fast without the need for nondestructive testing (NDT), such as electromagnetic inspection.

[0019] In an embodiment, it is an objective of the invention to provide a method of mechanically securing a pipe end section of an inner pipe portion of an unbonded flexible pipe in an end-fitting which method provides a high strength securement of the pressure armor to an inner casing of the end-fitting while simultaneously ensure a relatively low risk of creep of the pressure sheath in the end-fitting.

[0020] In an embodiment, it is an objective of the invention to provide a method of mechanically securing a pipe end section of an inner pipe portion of an unbonded flexible pipe in an end-fitting with which method it is possible to eliminate the risk of damaging the pressure sheath during any cutting and / or the welding step, when applicable.

[0021] In an embodiment, it is an objective of the invention to provide an unbonded flexible pipe assembly comprising an inner pipe portion of an unbonded flexible pipe and an end-fitting, wherein the inner pipe portion is mechanically secured to an inner casing collar of the end fitting in a relatively high strength securement and wherein the securement simultaneously provides that a potential risk of creep of the pressure sheath in the end-fitting is relatively low.

[0022] In an embodiment, it is an objective of the invention to provide a method of mechanically securing a pipe end section of an inner pipe portion of an unbonded flexible pipe to an end-fitting with which method it is possible to eliminate the risk of having air bubbles, impurities and other defects that arise from other pressure armor anchoring processes such as epoxy casting and / or welding.

[0023] These and other objects have been solved by the invention or embodiments thereof as defined in the claims and as described herein below.

[0024] It has been found that the invention or embodiments thereof have a number of additional advantages, which will be clear to the skilled person from the following description. The inventors of the present invention have realized and enabled a relatively simple method for effectively mechanically securing a pipe end section of an inner pipe portion of an unbonded flexible pipe to an end-fitting, which method is relatively fast and wherein a potential risk of creep of the pressure sheath in the end-fitting is relatively low. Thanks to the invention, an attractive solution of the abovementioned objectives has thereby been provided.

[0025] It should be emphasized that the term “comprises / comprising” when used herein is to be interpreted as an open term, i.e. it should be taken to specify the presence of specifically stated feature(s), such as element(s), unit(s), integer(s), step(s) component(s) and combination(s) thereof, but does not preclude the presence or addition of one or more other stated features.

[0026] Reference made to “some embodiments” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with such embodiment(s) is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in some embodiments” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment(s). Further, the skilled person will understand that particular features, structures, or characteristics may be combined in any suitable manner within the scope of the invention as defined by the claims.

[0027] The term “substantially” should herein be taken to mean that ordinary product variances and tolerances are comprised.

[0028] Throughout the description or claims, the singular encompasses the plural unless otherwise specified or required by the context.

[0029] All features of the invention and embodiments of the invention as described herein, including ranges and preferred ranges, may be combined in various ways within the scope of the invention, unless there are specific reasons not to combine such features.

[0030] Other term definitions may be found in API17B and API17J. In a first aspect, the invention relates to a method of securing a pipe end section of an inner pipe portion of an unbonded flexible pipe to an end-fitting comprising an inner casing with a front end and a rear end and with an inner casing collar located at the front end, wherein the inner pipe portion comprises a pressure sheath surrounded by a pressure armor comprising pressure armor windings of one or more pressure armor wires, the method comprises,

[0031] • at the pipe end section, exposing an outer surface of an end region of the pressure sheath;

[0032] • applying a fixation ring to cover an end region of the pressure armor adjacent the exposed end region of the pressure sheath, wherein the fixation ring has one or more fixation ring recesses, and preferably wherein the fixation ring is applied to cover at least 2 pressure armor windings;

[0033] • cutting an end portion of each of the one or more pressure armor wires to provide one or more wire termination recesses, wherein the cutting is performed such that the one or more fixation ring recesses correspond to and form overlaying one or more recesses pairs with said one or more wire termination recesses;

[0034] • applying a locking collar to surround the pressure armor next to said end region of the pressure armor;

[0035] • applying a support collar adjacent to the fixation ring wherein the support collar comprises one or more collar protrusions and wherein the support collar is configured and applied such that each of the one or more collar protrusions engages with a respective of said one or more overlaying recesses pairs;

[0036] • inserting a portion of the exposed pressure sheath of said inner pipe portion through an opening of the inner casing collar;

[0037] • moving the locking collar to cover at least a part of said fixation ring and at least a part of said support collar so that the support collar is engaged with the fixation ring and the inner casing collar, respectively, at opposite end surfaces of the support collar; and

[0038] • anchoring the locking collar to said inner casing collar.

[0039] As will be further explained below, the locking collar connects the fixation ring to the inner casing and supports the support collar so that the support collar holds the pressure sheath in place and thereby reduces, such as prevents, deformation of the pressure sheath also when the flexible pipe is in use. Such deformation could otherwise lead to damage and possible burst of the pressure sheath and thereby leakage of the fluid flowing through the pipe.

[0040] The term “recess” refers to a, typically abrupt, change in the outer geometry of the fixation ring and armor wires. An example will be shown in the figures. The fact that “the one or more fixation ring recesses correspond to and form overlaying one or more recesses pairs with said one or more wire termination recesses” as cited above means that the number of fixation recesses and the number of wire termination recesses are typically the same.

[0041] In some embodiments of the invention, the inner casing collar forms part of the inner casing prior to inserting the portion of the exposed pressure sheath of said inner pipe portion through the opening of the inner casing collar, or the method comprises fixing the inner casing collar to form part of the inner casing after inserting the portion of the exposed pressure sheath of said inner pipe portion through the opening of the inner casing collar. Which of these options to use may be determined during the design process and may e.g. depend on the dimensions and the mechanical properties of the components. It may also depend on the overall design of the inner casing and how it has been manufactured.

[0042] The pressure armor may comprise interlocked pressure armor windings of two or more pressure armor wires, such as of an even number of four or more pressure armor wires.

[0043] In some embodiments of the invention:

[0044] - the pressure armor comprises radially outwards facing helical gaps between the pressure armor windings,

[0045] - the fixation ring has a fixation ring radially inwards face comprising one or more helical ribs corresponding to the helical gaps between the pressure armor windings, and

[0046] - the step of applying the fixation ring to cover the end region of the pressure armor comprises inserting the helical ribs into the helical gaps between the covered pressure armor windings.

[0047] By such a design, the resulting mechanical engagement between the helical gaps of the pressure armor windings and the ribs of the fixation ring facilitates the correct positioning of the fixation ring during both the assembling process and the subsequent use of the unbonded flexible pipe. In alternative embodiments, the fixation ring has a fixation ring radially inwards face free of protruding helical ribs, preferably the fixation ring radially inwards face is smooth. Such embodiments may provide more flexibility with respect to the arrangement of the fixation ring relative to the pressure armor.

[0048] The fixation ring may be threaded along at least a part of a fixation ring radially outwards face. Such a threading may be used for engagement with the locking collar as will be shown in the figures.

[0049] The fixation ring may be applied to cover at least 3 pressure armor windings, such as at least 4 pressure armor windings, such as up to 20 pressure armor windings. The dimensions of the fixation ring and thereby also how many pressure armor windings it covers for a given size and arrangement of the pressure armor windings will be determined as part of the design process. The design process will typically include a combination of computer simulations and physical testing.

[0050] The fixation ring may have a first edge adjacent the exposed end region of the pressure sheath, wherein the first edge has a first edge periphery comprising said one or more fixation ring recesses. An example of such a design will be shown in the figures.

[0051] In some embodiments of the invention, the fixation ring has a first edge adjacent the exposed end region of the pressure sheath, wherein the pressure armor end region has a terminating edge with a terminating edge periphery, wherein the first edge of the fixation ring has a first edge periphery matching the terminating edge periphery. An example of such a design will be shown in the figures.

[0052] The cutting of an end portion of each of the one or more pressure armor wires may comprise performing the cutting using the fixation ring as a jig, and the method may comprise applying a shield between the end portion of the respective armor wires to be cut, performing the cutting, and removing the shield. Hereby the cutting process is supported by the fixation ring, and a desired match between the geometries of the fixation ring recess and the armor wires is easier to obtain. Preferably the cutting is performed after application of the fixation ring to cover the end region of the pressure armor adjacent the exposed end region of the pressure sheath. The cutting of an end portion of each of the one or more pressure armor wires may comprise cutting the end portion of each of the respective one or more pressure armor wires in a cutting line perpendicular to the that pressure armor wire. Hereby it is possible to bend the armor wire and use a shield underneath the armor wire to protect the pressure sheath during the cutting step so that the risk of damaging it is reduced.

[0053] In some embodiments, the fixation ring is in the form of a single ring-shaped unit.

[0054] In some embodiments, the fixation ring is in the form of a single open ring-shaped unit or in the form of two ring sections which can be connected into a ring-shaped unit.

[0055] The fixation ring may be of metal, optionally coated with a corrosion protection coating. However, any material that can withstand the mechanical and chemical conditions during manufacturing, installation, and use of the unbonded flexible pipe is covered by the scope of protection.

[0056] In some embodiments, the method comprises fixing the fixation ring to the end region of the pressure armor, preferably the method comprises mechanically fixing the fixation ring to the end region of the pressure armor, wherein the mechanical fixation preferably comprises fixing by use of at least one metallic fastener for each wire. Hereby it can be ensured that the fixation ring remains at the desired location both during the subsequent steps of securing the pipe end section to the end-fitting and during installation and use of the unbonded flexible pipe.

[0057] In some embodiments, the locking collar has a locking collar axis, a locking collar length along the locking collar axis, a first end face adapted to face towards the inner casing collar, and an opposite second end face, wherein the locking collar at least in a threaded length section comprises a threaded radially inwards face, wherein the threaded radially inwards face preferably is adapted to engage with a threaded portion of the radially outwards face of said fixation ring. Alternatively, or in combination therewith, the fastening of the locking collar comprises fastening with a bolted connection.

[0058] The threaded length section may be located farther from the first end face of the locking collar than from the second end section of the locking collar, preferably the threaded length section has a length of from 20 % to 80 % of the locking collar length, such as 20 % to 50 % of the locking collar length. The threaded length section preferably has a length corresponding to 1-10 times the pressure armor pitch, such as 1-5 times the pressure armor pitch, such as 2-5 times the pressure armor pitch. The length for a given application and design will be determined as a part of the design process, typically by a combination of computer simulations and physical testing.

[0059] In embodiments wherein the locking collar comprises a threaded length section, the threaded length section may be adapted for rotationally mating with the threaded radially outwards face of the fixation ring.

[0060] In some embodiments, the locking collar has a locking collar axis, a locking collar length along the locking collar axis, a first end face adapted to face towards the inner casing collar, and an opposite second end face, wherein the locking collar at least in a beveled length section comprises a beveled radially inwards face, wherein the beveled length section preferably is beveled to provide a narrowing locking collar diameter in a direction towards the second end face of the locking collar. Such a beveled shape of at least a part of the locking collar may be configured to engage with a mating shape of one or more other parts used for the securing steps. The figures illustrate an embodiment in which the beveled length section engages with a mating beveled outer surface of the support collar.

[0061] In embodiments wherein the locking collar comprises a beveled length section, the beveled length section may be located closer to the first end face of the locking collar than to the second end face of the locking collar, preferably the beveled length section has a length of from 20 % to 80 % of the locking collar length, such as 30 % to 70 % of the locking collar length.

[0062] The above-described moving of the locking collar to cover at least a part of said fixation ring and at least a part of said support collar may comprise rotationally mating at least a length portion of said threaded length section of said locking collar with at least a portion of a length section of said threaded radially outwards face of the fixation ring.

[0063] In some embodiments of the invention, the support collar is a split support collar comprising at least one collar split between two neighboring collar split edges, and the method comprises separating the two collar split edges to provide a gap there between, applying the support collar through said gap and reassembling the two collar split edges. The split support collar may e.g. be a single split support collar or double split support collar meaning that it can be split into two or three parts, respectively. Alternatively, the support collar has a one-piece design without such collar split.

[0064] In embodiments comprising a split support collar, the two collar split edges may be fixed to each other by a fastener, such as a screw, and the method may comprise unfastening said fastener prior to separating the two collar split edges and refastening said fastener simultaneously with or after reassembling the two collar split edges.

[0065] In some embodiments, the support collar has a first end face adapted to face towards the inner casing collar and an opposite second end face, and the application of said support collar comprises applying said support collar between the inner casing collar and the fixation ring with the first end face of the support collar facing the inner casing collar and the second end face of the support collar facing the fixation ring. An example of such a design will be shown in the figures.

[0066] In embodiments as just described, the support collar may have an outward facing surface, and at least a sloping length section of the support collar may be sloping upwards towards the first end face of the support collar, with a sloping angle of from 1 degree to 45 degrees, preferably from 5 degrees to 20 degrees, relative to a central axis of the support collar. Such a sloping length section may be adapted for engagement with a beveled length section of the locking collar as mentioned above.

[0067] The support collar may have an outward facing surface, and at least a sloping length section of the support collar, when present, may be adapted for mating with the beveled radially inwards face of said beveled length section of said locking collar. An example of such an embodiment will be shown in the figures.

[0068] In embodiments wherein the locking collar has a beveled length section as described above, the moving of the locking collar to cover at least a part of said fixation ring and at least a part of said support collar may comprise providing said beveled radially inwards face of said beveled length section of said locking collar to mechanically engage with at least a portion of said sloping length section of the support collar, preferably the mechanically engagement may comprise that the beveled radially inwards face of said beveled length section of said locking collar is pressed against the outwards facing surface of the support collar.

[0069] In some embodiments, the anchoring of the locking collar to said inner casing collar comprises mechanically locking the locking collar directly to said inner casing collar, preferably by using a fastener such as a strap fastener, screw fastener, or bolts.

[0070] In some embodiments, the anchoring of the locking collar to said inner casing collar comprises mechanically locking the locking collar to said support collar, preferably comprising a mechanical engagement between the locking collar and the support collar, comprising that a radially inwards face of said locking collar is pressed against an outward facing surface of the support collar.

[0071] In some embodiments, the anchoring of the locking collar to said inner casing collar comprises mechanically locking the locking collar to said support collar using a fastener such as a strap fastener, screw fastener, or grub screws.

[0072] Which way of fastening to be used for ensuring that the parts remain in place during use will be determined as a part of the design process and may e.g. depend on the dimensions and shapes of the parts as well as the expected stresses during use of the unbonded flexible pipe.

[0073] In some embodiments, the moving of the locking collar to cover at least a part of said fixation ring and at least a part of said support collar and / or the anchoring of the locking collar to said inner casing collar comprises providing the support collar to be in physical contact with the inner casing collar, preferably providing the support collar to be pressed against the inner casing collar. Hereby a reduced risk of deformation, such as creep, of the pressure sheath can be obtained.

[0074] In some embodiments, the moving of the locking collar to cover at least a part of said fixation ring and at least a part of said support collar and / or the anchoring of the locking collar to said inner casing collar comprises providing the fixation ring to be in physical contact with the support collar, preferably providing the fixation ring recesses to be pressed against the support collar. Hereby a reduced risk of deformation, such as creep, of the pressure sheath can be obtained. The application of said support collar may comprise applying said support collar between the inner casing collar and the fixation ring with a first end face of the support collar facing the inner casing collar and an opposite second end face of the support collar facing the fixation ring, and the moving of the locking collar to cover at least a part of said fixation ring and at least a part of said support collar and / or the anchoring of the locking collar to said inner casing collar may comprise providing the fixation ring to be in physical contact with the support collar and may comprise providing said support collar to support the pressure sheath it the surface area between the inner casing collar and the end region of the pressure armor.

[0075] The pressure armor windings may be helical windings having a winding angle in an unloaded condition of from 55 degrees to 89 degrees, preferably in the range from 75 degrees to 85 degrees, in relation to a longitudinal axis of the unbonded flexible pipe. The winding angle will be determined as a part of the design process taking expected loading conditions into account.

[0076] The one or more pressure armor wires may be profiled wires having equal or different cross-sectional profiles preferably selected from a C / U-shaped profile, a Z-shaped profile, a T-shaped profile, a K-shaped profile, an X-shaped profile, or an l-shaped profile.

[0077] The method may further comprise sealing the pressure sheath to the inner casing, preferably comprising applying at least one sealing ring, such as a sealing bushing and / or a pressure sheath expander. Hereby a fluid-tight connection can be established preventing leakage of the fluid flowing through the pipe during use. In other words, the invention can be applied to end fittings with or without an expander, and with a metallic sealing ring or other sealing solutions.

[0078] In embodiments as just described, the sealing of the pressure sheath to the inner casing may be located closer to the rear end of the inner casing than the inner casing collar.

[0079] In addition to the features as described above, the inner pipe may further comprise a carcass located inside the pressure sheath, and the method may further comprise securing the carcass to the inner casing, preferably comprising fixing an end portion of the carcass to a carcass end ring located closer to the rear end of the inner casing than the inner casing collar.

[0080] In embodiments comprising a carcass, the carcass end ring may be located closer to the rear end of the inner casing than the sealing of the pressure sheath to the inner casing, preferably the sealing of the pressure sheath to the inner casing comprises compressing an end portion of the pressure sheath between the carcass and the inner casing optionally via the at least one seal ring.

[0081] In a second aspect, the invention relates to an unbonded flexible pipe assembly comprising an inner pipe portion of an unbonded flexible pipe and an end-fitting, wherein:

[0082] - the end-fitting comprises an inner casing with a front end and a rear end and with an inner casing collar located at the front end,

[0083] - the inner pipe portion comprises a pressure sheath surrounded by a pressure armor comprising, preferably interlocked, pressure armor windings of one or more pressure armor wires, and

[0084] - a pipe end section of the inner pipe portion is secured to the inner casing collar by a method according to the first aspect of the invention.

[0085] In some embodiments of the unbonded flexible pipe assembly:

[0086] - the pipe end section of the inner pipe portion is secured to the inner casing collar by a fixation ring, a locking collar and a support collar,

[0087] - the fixation ring has one or more fixation ring recesses and is located to cover at least two pressure armor windings of an end region of the pressure armor,

[0088] - the covered pressure armor windings comprise one or more wire termination recesses and the fixation ring recesses correspond to and form overlaying recesses pairs with said one or more wire termination recesses,

[0089] - the support collar comprises one or more collar protrusions and is located adjacent to the fixation ring such that the one or more collar protrusions engage with a respective of said overlaying recesses pairs, and

[0090] - the locking collar is anchored to the inner casing collar and is located to cover at least a part of said fixation ring and at least a part of said support collar.

[0091] In some embodiments of the unbonded flexible pipe assembly: - the pressure armor comprises radially outwards facing helical gaps between the pressure armor windings,

[0092] - the fixation ring has a fixation ring radially inwards face comprising one or more helical ribs corresponding to the helical gaps between the pressure armor windings, and

[0093] - the fixation ring is configured to cover the end region of the pressure armor by inserting the helical ribs into the helical gaps between the covered pressure armor windings during the application.

[0094] The fixation ring may be threaded along at least a part of a fixation ring radially outwards face.

[0095] In some embodiments of the unbonded flexible pipe assembly, the locking collar has a locking collar axis, a locking collar length along the locking collar axis, a first end face adapted to face towards the inner casing collar, and an opposite second end face, wherein the locking collar at least in a threaded length section comprises a threaded radially inwards face, wherein the threaded radially inwards face preferably is adapted to engage with a threaded portion of the radially outwards face of said fixation ring.

[0096] In some embodiments of the unbonded flexible pipe assembly, the locking collar has a locking collar axis, a locking collar length along the locking collar axis, a first end face adapted to face towards the inner casing collar, and an opposite second end face, wherein the locking collar at least in a beveled length section comprises a beveled radially inwards face, wherein the beveled length section preferably is beveled to provide a narrowing locking collar diameter in a direction towards the second end face of the locking collar.

[0097] The support collar may be a split support collar comprising at least one collar split between two neighboring collar split edges, and the split support collar may be configured to be separated at the two collar split edges to provide a gap there between, so that it is configured for applying the support collar through said gap and reassembling the two collar split edges.

[0098] In some embodiments of the unbonded flexible pipe assembly, the support collar has an outward facing surface, wherein at least a sloping length section of the support collar is sloping upwards towards the first end face of the support collar, with a sloping angle of from 1 degree to 45 degrees, preferably from 5 degrees to 20 degrees, relative to a central axis of the support collar, preferably wherein at least the sloping length section of the support collar is adapted for mating with the beveled radially inwards face of said beveled length section of said locking collar.

[0099] The inner pipe may further comprise a carcass located inside the pressure sheath and the carcass may be configured to be secured to the inner casing, preferably by fixing an end portion of the carcass to a carcass end ring located closer to the rear end of the inner casing than the inner casing collar.

[0100] The first and second aspects of the present invention may each be combined. In particular, the features mentioned in relation to the first aspect of the invention may also apply to the second aspect of the invention. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0101] BRIEF DESCRIPTION OF THE FIGURES

[0102] The method of securing a pipe end section of an inner pipe portion of an unbonded flexible pipe to an end-fitting according to the invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

[0103] Figures 1 A and 1 B schematically show the overall design of an example of a known unbonded flexible pipe.

[0104] Figure 2A schematically shows a cross-sectional view of an embodiment of an unbonded flexible pipe assembly after it has been assembled and ready for use. The figure shows the region around the front area of an end fitting. Figure 2B shows figure 2A in exploded view.

[0105] Figure 3 schematically shows a partial three-dimensional view of the embodiment in figure 2 with the support collar and the locking collar removed. Figure 4 schematically shows a partial view of the support collar to be arranged in the former free space, seen in figure 3, between the fixation ring and the inner casing collar.

[0106] Figure 5A schematically shows a three-dimensional view of an example of a support collar, and figure 5B is a cross-sectional view thereof.

[0107] Figures 6A, 6B, and 6C schematically and in cross-sectional views illustrate the mounting steps used for assembling the assembly in figure 2A.

[0108] Figures 7A and 7B schematically and in three-dimensional views illustrate the mounting of the assembly in figure 2.

[0109] Figures 8A and 8B schematically show cross-sectional views of the mounting of the inner pipe section to the end-fitting. In the two alternative embodiments in figures 8A and 8B, the support collar and the inner casing collar are integrated as one single piece.

[0110] Figures 9A and Figure 9B schematically and in a three-dimensional view illustrate the mounting of the support collar in engagement with the fixation ring.

[0111] DETAILED DESCRIPTION OF AN EMBODIMENT

[0112] Figures 1A and 1B schematically show the overall design of an example of a known unbonded flexible pipe 1. Figure 1A shows the layers which from the outside comprise: an outer sheath 2, tensile armor windings 3, pressure armor windings 4, a pressure sheath 5, and a carcass 6. In embodiments of the invention comprising a carcass 6 located inside the pressure sheath 5, the method comprises securing the carcass 6 to the inner casing 7 of the end fitting 8, preferably by fixing an end portion of the carcass 6 to a carcass end ring located closer to the rear end of the inner casing 7 than the inner casing collar 9. The pressure armor windings 4 are typically helical windings having a winding angle in an unloaded condition of from 55 degrees to 89 degrees, preferably in the range from 75 degrees to 85 degrees, in relation to a longitudinal axis of the unbonded flexible pipe 1. The pressure armor wires formed into windings are typically profiled wires having equal or different cross-sectional profiles preferably selected from a C / U-shaped profile, a Z- shaped profile, a T-shaped profile, a K-shaped profile, an X-shaped profile, or an l-shaped profile. Detailed description of such a design of unbonded flexible pipes may be found in the standard documents API 17J (Specification for Unbonded Flexible Pipe) and API RP 17B (Recommended Practice for Flexible Pipe) established by the American Petroleum Institute. Figure 1 B shows how an end fitting 8 is arranged at each end of a pipe section of two neighboring unbonded flexible pipes 1 so that longer flexible pipes can be obtained by connecting subsequently arranged pipe sections via their end fittings 8.

[0113] Figure 2A schematically shows a cross-sectional view of an embodiment of an unbonded flexible pipe assembly after it has been assembled and ready for use. The figure shows the region around the front area of an end fitting for unbonded flexible pipe. The end fitting 8 is a structural device for terminating the different pipe layers in such a way as to transfer the load between the flexible pipe and the connector and seal all internal and external fluid containment layers. Figure 2B shows figure 2A in exploded view. In this and some of the following figures, the flexible pipe comprises a carcass 6, but the inventive method would be the same if the flexible pipe did not comprise a carcass. More details of the mounting steps will be given in the description of the following figures. The assembly comprises an inner pipe portion of an unbonded flexible pipe 1 and an end-fitting 8. The end-fitting 8 comprises an inner casing 7 with a front end 10 and a rear end (not shown) and with an inner casing collar 9 located at the front end 10. In the illustrated embodiment, the inner casing collar 9 forms part of the inner casing 7 prior to inserting the portion of the exposed pressure sheath of said inner pipe portion through the opening of the inner casing collar. However, the method may alternatively comprise fixing the inner casing collar 9 to form part of the inner casing 7 after inserting the portion of the exposed pressure sheath 5 of said inner pipe portion through the opening of the inner casing collar 9. The end-fitting 8 also comprises more parts than shown in figure 2, such as an outer casing. These parts are not shown in the figures, as they are not considered necessary for the understanding of the present invention. The inner pipe portion comprises a pressure sheath 5 surrounded by a pressure armor 4 comprising, preferably interlocked, pressure armor windings 4a of one or more pressure armor wires. The pipe end section of the inner pipe portion is secured to the inner casing collar 9 of the end-fitting 8 by a fixation ring 11 , a locking collar 12, and a support collar 13. The fixation ring 11 is preferably fixed to the end region of the pressure armor 4 e.g. by use of at least one metallic fastener (not shown) for each wire 4a. The locking collar 12 has a locking collar axis 12A, a locking collar length 12L along the locking collar axis 12A, a first end face 12FE adapted to face towards the inner casing collar 9, and an opposite second end face 12SE. The locking collar 12 is anchored to the inner casing collar 9 and is located to cover a part of said fixation ring 11 and a part of said support collar 13. In the illustrated embodiment, the locking collar 12 fully covers the support collar 13. In the embodiment in figures 2A and 2B, the fixation ring 11 is threaded along a fixation ring radially outwards face 11 OF, and the locking collar 12 in a threaded length section comprises a threaded radially inwards face 12IF. This threaded radially inwards face 12IF preferably is adapted to engage with a threaded portion of the radially outwards face 110F of said fixation ring 11. In the embodiment in figures 2A and 2B, the locking collar 12 in a beveled length section comprises a beveled radially inwards face 12BIF, wherein the beveled length section is beveled to provide a narrowing locking collar diameter in a direction towards the second end face 12SE of the locking collar 12. The support collar 13 has an outward facing surface 13OS, wherein at least a sloping length section of the support collar 13 is adapted for mating with the beveled radially inwards face 12BIF of said beveled length section of said locking collar 12 as shown in figures 2A and 2B.

[0114] Figure 3 schematically shows a partial three-dimensional view of the embodiment in figure 2 with the support collar 13 and the locking collar 12 removed. The threaded part is the fixation ring 11 arranged around and covering the pressure armor windings 4 as will be explained in further details below. The figure shows how the pressure sheath 5 is not covered by the pressure armor 4 at all the way to the inner casing 7. This un-covered part of the pressure sheath 5 is referred to as an exposed end region. Figure 4 schematically shows a partial view of the support collar 13 arranged in the former free space, seen in figure 3, between the fixation ring 11 and the inner casing collar 9. Hereby the support collar 13 supports the pressure sheath 4 and prevents deformation, such as creep, thereof.

[0115] Figure 5A schematically shows a three-dimensional view of an example of a support collar 13, and figure 5B is a cross-sectional view thereof. The support collar 13 has a first end face 13FE adapted to face towards the inner casing collar 9 as shown in figure 2 and an opposite second end face 13SE. In this embodiment, the support collar 13 is in the form of a double split support collar comprising two collar splits 14 between two neighboring collar split edges. The support collar 13 is typically mounted by first disassembling it into two half support collars by unfastening screws (not shown) and then reassembling the two collar split edges.

[0116] As shown in figure 3, the fixation ring 11 has one or more fixation ring recesses 15; in this embodiment it has two such fixing ring recesses 15. The fixation ring 11 has a first edge adjacent to the exposed end region of the pressure sheath 5, and this first edge has a first edge periphery comprising the fixation ring recesses 15. The fixation ring 11 is located to cover at least two pressure armor windings of an end region of the pressure armor 4. The covered pressure armor windings comprise one or more wire termination recesses. The fixation ring recesses 15 correspond to and form overlaying recesses pairs with said one or more wire termination recesses 16 (see figure 7A). In the embodiment shown in figures 4, 5A, and 5B, the support collar 13 comprises two collar protrusions 17 and is located adjacent to the fixation ring 11 such that each of the support collar protrusions 17 engage with a respective of said overlaying recesses pairs. In the illustrated embodiments, the cutting of an end portion of each of the pressure armor wires 4a has comprised cutting the end portion of each of the respective pressure armor wires in a cutting line perpendicular to that pressure armor wire. This cutting may preferably be performed by using the fixation ring 11 as a jig, wherein the method comprises applying a shield between the end portion of the respective armor wires to be cut, performing the cutting, and removing the shield. In the embodiment in figures 5A and 5B, the support collar 13 is in the form of two ring sections which can be connected into a ring-shaped unit by means of screws (not shown) via screw holes in the support collar 13. However, the support collar could alternatively be in the form of a single ring-shaped unit. In a corresponding manner, the fixation ring 11 could be made as one or more parts. The fixation ring 11 is typically made of metal optionally coated with a corrosion protection coating.

[0117] Figures 6A, 6B, and 6C schematically and in cross-sectional views illustrate the mounting steps used for assembling the assembly in figure 2A. In figure 6A, the fixation ring 11 has been applied and is arranged so that it covers an end region of the pressure armor 4 adjacent the exposed end region of the pressure sheath 5. The locking collar 12 has been applied to surround the pressure armor 4 and the fixation ring 11 next to the end region of the pressure armor 4. In this figure, a portion of the exposed pressure sheath 5 of the inner pipe portion has been inserted through an opening of the inner casing collar 9, but this may also be performed as a part of the step shown in figure 6B. In figure 6B, the support collar 13 has been applied adjacent to the fixation ring 11. As described above, the support collar 13 comprises one or more collar protrusions 17, and the support collar 13 is configured and applied such that each of the one or more collar protrusions 17 engage with a respective of said one or more overlaying recesses pairs as shown in figure 4. In figure 6C, the locking collar 12 has been moved to cover a part of the fixation ring 11 and the support collar 13 so that the support collar 13 is engaged with the fixation ring 11 and the inner casing collar 9, respectively, at opposite end surfaces of the support collar 13. The locking collar 12 has been anchored to the inner casing collar 9 e.g. with grub screws 18. As illustrated in the figures 6A, 6B, and 6C, the moving of the locking collar 12 to cover at least a part of said fixation ring 11 and at least a part of said support collar 13 comprises providing the beveled radially inwards face 12BIF of the beveled length section of the locking collar 12 to mechanically engage with at least a portion of the sloping length section of the support collar 13. The mechanical engagement preferably comprises that the beveled radially inwards face of the beveled length section of the locking collar 12 is pressed against the outwards facing surface of the support collar 13. The anchoring of the locking collar 12 to said inner casing collar 9 preferably comprises mechanically locking the locking collar 12 to the support collar 13 using a fastener such as a strap fastener, screw fastener, or grub screws. During use of the flexible pipe, the internal pressure in the fluid flowing in the pipe will be transferred through the support collar 13 to the locking collar 12.

[0118] Figures 7A and 7B schematically and in three-dimensional views illustrate the mounting of the assembly from another angle of view than the one in figures 6A, 6B, and 6C. Figure 7A shows the step of arranging the support collar 13, and figure 7B shows the assembled state with the locking collar 12 in engagement with the inner casing collar 9.

[0119] Figures 8A and 8B schematically show cross-sectional views of the mounting of the inner pipe section to the end-fitting 8. In this embodiment, the inner casing 7 and the inner casing collar 9 are integrally formed as one single, solid piece. Figure 8B shows an alternative embodiment to Figure 8A in which an inner liner expander 19 is used between the carcass 6 and the pressure sheath 5. In this configuration, a metallic ring 20 is required between the pressure armor 4 and the pressure sheath 5 to support the pressure sheath 5.

[0120] Figures 9A and Figure 9B schematically and in a three-dimensional view illustrate the mounting of the support collar 13 to be in engagement with the fixation ring 11. The geometry constraints eliminate the risk of support collar rotation during assembly.

[0121] Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms “comprising” or “comprises” do not exclude other possible elements or steps. Also, the mentioning of references such as “a” or “an” etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.

Claims

CLAIMS1. A method of securing a pipe end section of an inner pipe portion of an unbonded flexible pipe (1) to an end-fitting (8) comprising an inner casing (7) with a front end (10) and a rear end and with an inner casing collar (9) located at the front end (10), wherein the inner pipe portion comprises a pressure sheath (5) surrounded by a pressure armor (4) comprising pressure armor windings of one or more pressure armor wires (4a), the method comprises,• at the pipe end section, exposing an outer surface of an end region of the pressure sheath (5);• applying a fixation ring (11) to cover an end region of the pressure armor (4) adjacent the exposed end region of the pressure sheath (5), wherein the fixation ring (11) has one or more fixation ring recesses (16), and preferably wherein the fixation ring (11) is applied to cover at least two pressure armor windings;• cutting an end portion of each of the one or more pressure armor wires (4a) to provide one or more wire termination recesses, wherein the cutting is performed such that the one or more fixation ring recesses (16) correspond to and form overlaying one or more recesses pairs with said one or more wire termination recesses;• applying a locking collar (12) to surround the pressure armor (4) next to said end region of the pressure armor (4);• applying a support collar (13) adjacent to the fixation ring (11) wherein the support collar (13) comprises one or more collar protrusions (17) and wherein the support collar (13) is configured and applied such that each of the one or more collar protrusions (17) engage with a respective of said one or more overlaying recesses pairs;• inserting a portion of the exposed pressure sheath (5) of said inner pipe portion through an opening of the inner casing collar (9);• moving the locking collar (12) to cover at least a part of said fixation ring (11) and at least a part of said support collar (13) so that the support collar (13) is engaged with the fixation ring (11) and the inner casing collar (9), respectively, at opposite end surfaces of the support collar (13); and• anchoring the locking collar (12) to said inner casing collar (9).

2. The method of claim 1 , wherein the inner casing collar (9) forms part of the inner casing (7) prior to inserting the portion of the exposed pressure sheath (5) of said inner pipe portion through the opening of the inner casing collar (9) or wherein the method comprises fixing the inner casing collar (9) to form part of the inner casing (7) after inserting the portion of the exposed pressure sheath (5) of said inner pipe portion through the opening of the inner casing collar (9).

3. The method of claim 1 or claim 2, wherein the pressure armor (4) comprises interlocked pressure armor windings of two or more pressure armor wires (4a), such as of an even number of four or more pressure armor wires (4a).

4. The method of any one of the preceding claims, wherein:- the pressure armor (4) comprises radially outwards facing helical gaps between the pressure armor windings,- the fixation ring (11) has a fixation ring radially inwards face comprising one or more helical ribs corresponding to the helical gaps between the pressure armor windings, and- the step of applying the fixation ring (11) to cover the end region of the pressure armor (4) comprises inserting the helical ribs into the helical gaps between the covered pressure armor windings.

5. The method of any one of the preceding claims 1-3, wherein the fixation ring (11) has a fixation ring radially inwards face free of protruding helical ribs, preferably the fixation ring radially inwards face is smooth.

6. The method of any one of the preceding claims, wherein the fixation ring (11) is threaded along at least a part of a fixation ring radially outwards face.

7. The method of any one of the preceding claims, wherein the fixation ring (11) is applied to cover at least three pressure armor windings, such as at least four pressure armor windings, such as up to 20 pressure armor windings.

8. The method of any one of the preceding claims, wherein the fixation ring (11) has a first edge adjacent to the exposed end region of the pressure sheath (5), wherein the first edge has a first edge periphery comprising said one or more fixation ring recesses9. The method of any one of the preceding claims, wherein the fixation ring (11) has a first edge adjacent the exposed end region of the pressure sheath (5), wherein the pressure armor end region has a terminating edge with a terminating edge periphery, wherein the first edge of the fixation ring has a first edge periphery matching the terminating edge periphery.

10. The method of any one of the preceding claims, wherein the cutting of an end portion of each of the one or more pressure armor wires (4a) comprises performing the cutting using the fixation ring as a jig, wherein the method comprises applying a shield between the end portion of the respective armor wires (4a) to be cut, performing the cutting, and removing the shield, preferably the cutting is performed after application of the fixation ring (11) to cover the end region of the pressure armor (4) adjacent the exposed end region of the pressure sheath (5).

11. The method of any one of the preceding claims, wherein the cutting of an end portion of each of the one or more pressure armor wires (4a) comprises cutting the end portion of each of the respective one or more pressure armor wires (4a) in a cutting line perpendicular to that pressure armor wire.

12. The method of any one of the preceding claims, wherein the fixation ring (11) is in the form of a single ring-shaped unit.

13. The method of any one of the preceding claims 1-11, wherein the fixation ring (11) is in the form of a single open ring-shaped unit or in the form of two ring sections which can be connected into a ring-shaped unit.

14. The method of any one of the preceding claims, wherein the fixation ring (11) is of metal optionally coated with a corrosion protection coating.

15. The method of any one of the preceding claims, wherein the method comprises fixing the fixation ring (11) to the end region of the pressure armor (4), preferably the method comprises mechanically fixing the fixation ring (11) to the end region of the pressure armor (4), wherein the mechanical fixation preferably comprises fixing by use of at least one metallic fastener for each wire.

16. The method of any one of the preceding claims, wherein the locking collar (12) has a locking collar axis (12A), a locking collar length (12L) along the locking collar axis, a first end face (12FE) adapted to face towards the inner casing collar (9), and an opposite second end face (12SE), wherein the locking collar (12) at least in a threaded length section comprises a threaded radially inwards face, wherein the threaded radially inwards face preferably is adapted to engage with a threaded portion of the radially outwards face of said fixation ring (11).

17. The method of claim 16, wherein the threaded length section is located farther from the first end face (12FE) of the locking collar (12) than from the second end section of the locking collar, preferably the threaded length section has a length of from 20 % to 80 % of the locking collar length, such as 20 % to 50 % of the locking collar length.

18. The method of claim 16 or claim 17, wherein the threaded length section is adapted for rotationally mating with the threaded radially outwards face of the fixation ring (11).

19. The method of any one of the preceding claims, wherein the locking collar (12) has a locking collar axis (12A), a locking collar length (12L) along the locking collar axis (12A), a first end face (12FE) adapted to face towards the inner casing collar (9), and an opposite second end face (12SE), wherein the locking collar (12) at least in a beveled length section comprises a beveled radially inwards face (12BIF), wherein the beveled length section preferably is beveled to provide a narrowing locking collar diameter in a direction towards the second end face of the locking collar (12).

20. The method of claim 19, wherein the beveled length section is located closer to the first end face (12FE) of the locking collar (12) than to the second end face (12SE) of the locking collar (12), preferably the beveled length section has a length of from 20 % to 80 % of the locking collar length, such as 30 % to 70 % of the locking collar length (12L).

21. The method of any one of the preceding claims 16-20, wherein the moving of the locking collar (12) to cover at least a part of said fixation ring (11) and at least a part of said support collar (13) comprises rotationally mating at least a length portion of saidthreaded length section of said locking collar (12) with at least a portion of a length section of said threaded radially outwards face of the fixation ring (11).

22. The method of any one of the preceding claims, wherein the support collar (13) is a split support collar comprising at least one collar split (14) between two neighboring collar split edges and wherein the method comprises separating the two collar split edges (14) to provide a gap there between, applying the support collar (13) through said gap and reassembling the two collar split edges.

23. The method of claim 22, wherein the two collar split edges are fixed to each other by a fastener, such as a screw, and wherein the method comprises unfastening said fastener prior to separating the two collar split edges and refastening said fastener simultaneously with or after reassembling the two collar split edges.

24. The method of any one of the preceding claims, wherein the support collar (13) has a first end face (13FE) adapted to face towards the inner casing collar (9) and an opposite second end face (13SE), wherein the application of said support collar (13) comprises applying said support collar (13) between the inner casing collar (9) and the fixation ring (11) with the first end face (13FE) of the support collar (13) facing the inner casing collar (9) and the second end face (13SE) of the support collar (13) facing the fixation ring (11).

25. The method of claim 24, wherein the support collar (13) has an outward facing surface, wherein at least a sloping length section of the support collar (13) is sloping upwards towards the first end face of the support collar, with a sloping angle of from 1 degree to 45 degrees, preferably from 5 degrees to 20 degrees, relative to a central axis of the support collar (13).

26. The method of claim 24 or claim 25, when dependent on claim 19, wherein the support collar (13) has an outward facing surface, wherein at least a sloping length section of the support collar (13) is adapted for mating with the beveled radially inwards face of said beveled length section of said locking collar (12).

27. The method of claim 25 or claim 26, when dependent on claim 19, wherein the moving of the locking collar (12) to cover at least a part of said fixation ring (11) and atleast a part of said support collar (13) comprises providing said beveled radially inwards face (12BIF) of said beveled length section of said locking collar (12) to mechanically engage with at least a portion of said sloping length section of the support collar (13), preferably the mechanically engagement comprising that the beveled radially inwards face (12BIF) of said beveled length section of said locking collar (12) is pressed against the outwards facing surface of the support collar (13).

28. The method of any one of the preceding claims, wherein the anchoring of the locking collar (12) to said inner casing collar (9) comprises mechanically locking the locking collar (12) directly to said inner casing collar (9), preferably by using a fastener such as a strap fastener, screw fastener, or bolts.

29. The method of any one of the preceding claims, wherein the anchoring of the locking collar (12) to said inner casing collar (9) comprises mechanically locking the locking collar (12) to said support collar (13), preferably comprising a mechanical engagement between the locking collar (12) and the support collar (13), comprising that a radially inwards face of said locking collar (12) is pressed against an outward facing surface of the support collar (13).

30. The method of any one of the preceding claims, wherein the anchoring of the locking collar (12) to said inner casing collar (9) comprises mechanically locking the locking collar (12) to said support collar (13) using a fastener such as a strap fastener, screw fastener, or grub screws.

31. The method of any one of the preceding claims, wherein the moving of the locking collar (12) to cover at least a part of said fixation ring (11) and at least a part of said support collar (13) and / or the anchoring of the locking collar (12) to said inner casing collar (9) comprises providing the support collar (13) to be in physical contact with the inner casing collar (9), preferably providing the support collar (13) to be pressed against the inner casing collar (9).

32. The method of any one of the preceding claims, wherein the moving of the locking collar (12) to cover at least a part of said fixation ring (11) and at least a part of said support collar (13) and / or the anchoring of the locking collar (12) to said inner casing collar (9) comprises providing the fixation ring (11) to be in physical contact with thesupport collar (13), preferably providing the fixation ring (11) recesses to be pressed against the support collar (13).

33. The method of any one of the preceding claims, wherein the application of said support collar (13) comprises applying said support collar (13) between the inner casing collar (9) and the fixation ring (11) with a first end face of the support collar (13) facing the inner casing collar (9) and an opposite second end face of the support collar (13) facing the fixation ring (11), and wherein the moving of the locking collar (12) to cover at least a part of said fixation ring (11) and at least a part of said support collar (13) and / or the anchoring of the locking collar (12) to said inner casing collar (9) comprises providing the fixation ring (11) to be in physical contact with the support collar (13) and comprises providing said support collar (13) to support the pressure sheath (5) in the surface area between the inner casing collar (9) and the end region of the pressure armor (4).

34. The method of any one of the preceding claims, wherein the pressure armor windings are helical windings having a winding angle in an unloaded condition of from 55 degrees to 89 degrees, preferably in the range from 75 degrees to 85 degrees, in relation to a longitudinal axis of the unbonded flexible pipe.

35. The method of any one of the preceding claims, wherein the one or more pressure armor wires (4a) are profiled wires having equal or different cross-sectional profiles preferably selected from a C / U-shaped profile, a Z-shaped profile, a T-shaped profile, a K- shaped profile, an X-shaped profile, or an l-shaped profile.

36. The method of any one of the preceding claims, wherein the method further comprises sealing the pressure sheath (5) to the inner casing (7), preferably comprising applying at least one sealing ring, such as a sealing bushing and / or a pressure sheath expander.

37. The method of claim 36, wherein the sealing of the pressure sheath (5) to the inner casing (7) is located closer to the rear end of the inner casing than the inner casing collar (9).

38. The method of any one of the preceding claims, wherein the inner pipe portion further comprises a carcass (6) located inside the pressure sheath (5) and wherein themethod further comprises securing the carcass (6) to the inner casing (7), preferably comprising fixing an end portion of the carcass (6) to a carcass end ring located closer to the rear end of the inner casing (7) than the inner casing collar (9).

39. The method of claim 38, wherein the carcass end ring is located closer to the rear end of the inner casing (7) than the sealing of the pressure sheath (5) to the inner casing (7), preferably the sealing of the pressure sheath (5) to the inner casing (7) comprises compressing an end portion of the pressure sheath (5) between the carcass (6) and the inner casing (7) optionally via the at least one seal ring.

40. An unbonded flexible pipe assembly comprising an inner pipe portion of an unbonded flexible pipe (1) and an end-fitting (8), wherein:- the end-fitting (8) comprises an inner casing (7) with a front end (10) and a rear end and with an inner casing collar (9) located at the front end (10),- the inner pipe portion comprises a pressure sheath (5) surrounded by a pressure armor (4) comprising interlocked pressure armor windings of one or more pressure armor wires (4a), and- a pipe end section of the inner pipe portion is secured to the inner casing collar (9) by a method obtainable by any one of the preceding claims.

41. The unbonded flexible pipe assembly of claim 40, wherein:- the pipe end section of the inner pipe portion is secured to the inner casing collar (9) by a fixation ring (11), a locking collar (12) and a support collar 13),- the fixation ring (11) has one or more fixation ring recesses (15) and is located to cover at least two pressure armor windings of an end region of the pressure armor (4),- the covered pressure armor windings comprise one or more wire termination recesses and the fixation ring recesses (15) correspond to and form overlaying recesses pairs with said one or more wire termination recesses,- the support collar (13) comprises one or more collar protrusions (17) and is located adjacent to the fixation ring (11) such that the one or more collar protrusions (17) engage with a respective of said overlaying recesses pairs, and- the locking collar (12) is anchored to the inner casing collar (9) and is located to cover at least a part of said fixation ring (11) and at least a part of said support collar (13).

42. The unbonded flexible pipe assembly of claim 40 or 41 , wherein:- the pressure armor (4) comprises radially outwards facing helical gaps between the pressure armor windings,- the fixation ring (11) has a fixation ring radially inwards face comprising one or more helical ribs corresponding to the helical gaps between the pressure armor windings, and- the fixation ring (11) is configured to cover the end region of the pressure armor (4) by inserting the helical ribs into the helical gaps between the covered pressure armor windings during the application.

43. The unbonded flexible pipe assembly of any of claims 40 to 42, wherein the fixation ring (11) is threaded along at least a part of a fixation ring radially outwards face.

44. The unbonded flexible pipe assembly of any of claims 40 to 43, wherein the locking collar (12) has a locking collar axis (12A), a locking collar length (12L) along the locking collar axis (12A), a first end face (12FE) adapted to face towards the inner casing collar (9), and an opposite second end face (12SE), wherein the locking collar (12) at least in a threaded length section comprises a threaded radially inwards face, wherein the threaded radially inwards face preferably is adapted to engage with a threaded portion of the radially outwards face of said fixation ring (11).

45. The unbonded flexible pipe assembly of any of claims 40 to 44, wherein the locking collar (12) has a locking collar axis (12A), a locking collar length (12L) along the locking collar axis (12A), a first end face (12FE) adapted to face towards the inner casing collar (9), and an opposite second end face (12SE), wherein the locking collar (12) at least in a beveled length section comprises a beveled radially inwards face (12BIF), wherein the beveled length section preferably is beveled to provide a narrowing locking collar diameter in a direction towards the second end face of the locking collar (12SE).

46. The unbonded flexible pipe assembly of any of claims 40 to 45, wherein the support collar (13) is a split support collar comprising at least one collar split (14) between two neighboring collar split edges, and wherein the split support collar is configured to be separated at the two collar split edges to provide a gap there between, so that it is configured for applying the support collar (13) through said gap and reassembling the two collar split edges.

47. The unbonded flexible pipe assembly of any of claims 40 to 46, wherein the support collar (13) has an outward facing surface, wherein at least a sloping length section of the support collar (13) is sloping upwards towards the first end face of the support collar (13), with a sloping angle of from 1 degree to 45 degrees, preferably from 5 degrees to 20 degrees, relative to a central axis of the support collar, preferably wherein at least the sloping length section of the support collar is adapted for mating with the beveled radially inwards face of said beveled length section of said locking collar.

48. The unbonded flexible pipe assembly of any of claims 40 to 47, wherein the inner pipe further comprises a carcass (6) located inside the pressure sheath (5) and wherein the carcass (6) is configured to be secured to the inner casing (7), preferably by fixing an end portion of the carcass (6) to a carcass end ring located closer to the rear end of the inner casing (7) than the inner casing collar (9).

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