DK201670448A1 - Connection end-fitting of a flexible conduit, and associated flexible conduit and method - Google Patents

Abstract

This end-fitting (14) comprises at least one end segment (34) of each armor element (29), an end arch (50) with central axis (A-A') and a cover (51) fastened on the end arch (50). The end-fitting (14) comprises at least one ring (57, 58) circumferentially outwardly covering the armor elements (29) of each armor layer and an adhesive layer (59) inserted between an inner peripheral surface of the ring (57, 58) and the outer surface of each armor element (29). The adhe-sive layer (59) fixes each armor element (29) on the ring (57, 58).

Description

Connection end-fitting of a flexible conduit, and associated flexible conduit and method

The present invention relates to a connection end-fitting of a flexible conduit for transporting fluid, the flexible conduit comprising at least one tubular sheath and at least one tensile armor element positioned outwardly relative to the tubular sheath, the armor layer comprising a plurality of filiform armor elements, the end-fitting comprising: - at least one end segment of each armor element, - an end arch with a central axis and a cover fastened on the end arch, the end arch and the cover defining a chamber between them for receiving each end segment.

The conduit is in particular a flexible conduit of the unbonded type designed to transfer hydrocarbons through an expanse of water, such as an ocean, sea, lake or river.

Such a flexible conduit is for example made according to normative documents API 17J (Specification for Unbonded Flexible Pipe) and API RP 17B (Recommended Practice for Flexible Pipe) established by the American Petroleum Institute.

The conduit is generally formed by a set of concentric and superimposed layers. It is considered "unbonded" within the meaning of the present invention when at least one of the layers of the conduit is able to move longitudinally relative to the adjacent layers when the conduit is bent. In particular, an unbonded conduit is a conduit with no bonding materials connecting the layers forming the conduit.

The conduit is generally positioned through an expanse of water, between a bottom assembly, designed to collect the fluid mined in the bottom of the expanse of water, and a floating or stationary surface assembly designed to connect and distribute the fluid. The surface assembly may be a semisubmersible platform, an FPSO or another floating assembly.

In some cases, for the exploitation of fluids in deep water, the flexible conduit has a length exceeding 800 m. The ends of the conduit have end-fittings for connecting to the bottom assembly and the surface assembly, as well as for intermediate connections.

These conduits undergo very high axial tensile forces, in particular when the expanse of water in which the conduit is positioned is very deep.

In that case, the upper end-fitting connecting the conduit to the surface assembly must react a very significant axial tension, which may reach several hundreds of tons. These forces are transmitted to the end-fitting by means of layers of tensile armor extending along the conduit.

The axial tension not only has a high average value, but also permanent variations depending on the vertical movements of the surface assembly and the conduit, under the effect of the agitation of the expanse of water caused by the swell or by the waves.

The axial tension variations may reach several tens of tons and repeat continually throughout the lifetime of the conduit. In 20 years, the number of cycles may thus reach more than 20 million.

It is therefore necessary to ensure particularly robust fastening between the tensile armor layers and the body of the end-fitting.

To that end, in the known end-fittings, the anchoring of the armors is generally provided by the friction between the armor yarns and an epoxy resin poured in the chamber defined by the arch and the cover.

Furthermore, the winch effect related to the spiral trajectory of the armor yarns also contributes to anchoring the armors, this effect being able to be increased by modifying the diameter of the spiral described by the wires in the end-fitting relative to the diameter of the spiral in running length, for example by gradually increasing the diameter along an ascending cone, then decreasing it along a descending cone.

Furthermore, hook-, wave- or twist-shaped deformations may be formed at the end of each armor yarn to be engaged in the epoxy resin, in order to produce mechanical blocking opposing the applied tension. These deformations initiate the force necessary for the establishment of the winch effect.

Such an end-fitting is not fully satisfactory. Sometimes, over time, the anchoring of the tensile armors becomes faulty through fatigue.

To offset this problem, WO 2004/051131 proposes robustly fastening each end segment in slots arranged in the rear part of the arch before fastening of the end-fitting.

The rear part further has a flared shape making it possible to increase the winch effect.

Such an end-fitting is nevertheless very tedious to produce and very radially cumbersome.

One aim of the invention is to obtain an end-fitting of a flexible conduit reacting axial tension effectively, in which the risk of fatigue failure is greatly decreased, the endfitting being easy to manufacture and compact.

To that end, the invention relates to an end-fitting of the aforementioned type, characterized in that the end-fitting comprises: - at least one ring circumferentially outwardly covering the armor elements of each armor layer, the ring being at least partially fixed in axial translation relative to the cover and/or relative to the end arch; - an adhesive layer inserted between an inner peripheral surface of the ring and the outer surface of each armor element, the adhesive layer fixing each armor element on the ring.

The end-fitting according to the invention may comprise one or more of the following features, considered alone or according to any technically possible combination(s): - the adhesive layer has a radial thickness smaller than the radial thickness of the ring; - the adhesive layer has a maximum thickness smaller than 5 mm, and advantageously comprised between 0.1 mm and 3 mm; - the ring is axially wedged on the cover and/or on an intermediate element wedged on the cover; - the armor elements extend along a cylindrical envelope in the receiving chamber; - the end segments are positioned in a cylindrical envelope defined between a first cylinder of revolution around the central axis and a second cylinder of revolution around the central axis, the radial distance separating the first cylinder from the second cylinder being less than 120% of the thickness of each end segment.

- the ring radially grips the adhesive layer and the armor elements, the ring advantageously comprising a plurality of circumferential segments assembled on one another; - the inner peripheral surface of the ring has a first axial region situated at a first distance from each armor element and a second axial region situated at a second distance from each armor element, the first distance being different from the second distance; the adhesive layer having at least a first axial part positioned across from the first axial region and a second axial part positioned across from the second axial region, the radial thickness of the adhesive layer being different in the first axial part and in the second axial part; - it comprises a cannula positioned radially inside each armor element across from the ring, and an inner adhesive layer, advantageously with a radial thickness smaller than that of the cannula, the inner adhesive layer being inserted between an outer surface of the cannula and an inner surface of each armor layer; - the adhesive layer comprises a first axial part formed with a base of a first, relatively more rigid adhesive and a second axial part formed with a base of a second adhesive that is relatively more flexible than the first adhesive; - the outer surface of each armor element is mechanically, physically or chemically pretreated; - the inner peripheral surface of the or each ring defines at least one annular or helical slot opening across from the armor elements and partially receiving the adhesive layer; - it comprises a front sealing assembly intended to produce sealing around the tubular sheath, the front sealing assembly being axially offset in the forward direction relative to each ring; - the or each ring defines, in the receiving chamber, a front intermediate space and/or a rear intermediate space, the end-fitting comprising a flexible filler material filling the front intermediate space and/or the rear intermediate space; - the or each ring defines, in the receiving chamber, a front intermediate space and/or a rear intermediate space, the end-fitting comprising a watertight seal filling the front intermediate space and/or the rear intermediate space; - it comprises a first group of end segments of armor elements of a first armor layer and a second group of end segments of armor elements of a second armor layer, the endfitting comprising a first ring and circumferentially outwardly covering the armor elements of the first group, and a second ring circumferentially outwardly covering the armor elements of the second group, the second ring being axially offset relative to the first ring, the adhesive layer being inserted between an inner annular surface of each of the first ring and the second ring and the outer surface of each armor element, the adhesive layer fixing each armor element on the first ring and on the second ring, respectively; - the ring is fixed in axial translation relative to the cover and/or relative to the end arch independently of the concentric layers of the flexible conduit.

The invention also relates to a flexible conduit for conveying a fluid, advantageously unbonded,, comprising: - at least one tubular sheath; - at least one tensile armor element positioned outwardly relative to the tubular sheath, the armor layer comprising a plurality of filiform armor elements; and - an end-fitting as defined above.

The invention also relates to a method for assembling an end-fitting of a flexible conduit for transporting fluid, the flexible conduit comprising at least one tubular sheath and at least one tensile armor element positioned outwardly relative to the tubular sheath, the armor layer comprising a plurality of filiform armor elements, the end-fitting [sic] comprising the following steps: - freeing at least one end segment of each armor element, - arranging an end arch with a central axis and fastening a cover on the end arch, the end arch and the cover defining a chamber between them for receiving each end segment; characterized in that the method comprises: - placing an adhesive layer on the outer surface of each armor element, - positioning at least one ring to circumferentially outwardly cover the armor elements of each armor layer, the ring being next at least partially fixed in axial translation relative to the cover and/or relative to the end arch; - Inserting an adhesive layer inserted between an annular inner surface of the ring and the outer surface of each armor element, the adhesive layer fixing each armor element on the ring.

The invention will be better understood upon reading the following description, provided solely as an example and done in reference to the appended drawings, in which: - figure 1 is a partial cutaway perspective view of a central segment of a first flexible conduit according to the invention; - figure 2 is a partial sectional view along an axial median plane of an end-fitting of the conduit of figure 1; - figure 3 is a view similar to figure 2 of the end-fitting of a second flexible conduit according to the invention; - figure 4 is a view similar to figure 2 of the end-fitting of a third flexible conduit according to the invention; - figure 5 is a view similar to figure 2 of the end-fitting of a fourth flexible conduit according to the invention; - figure 6 is a view similar to figure 2 of the end-fitting of a fifth flexible conduit according to the invention; - figure 7 is a view similar to figure 2 of the end-fitting of a sixth flexible conduit according to the invention; - figure 8 is a view similar to figure 2 of the end-fitting of a seventh flexible conduit according to the invention; - figure 9 is a view similar to figure 2 of a subassembly of the end-fitting of an eighth flexible conduit according to the invention; and - figure 10 is a view similar to figure 2 of a subassembly of the end-fitting of an ninth flexible conduit according to the invention.

In the rest of this document, the terms "outer" and "inner" are generally to be understood radially relative to an axis A-A' of the conduit, the term "outer" being understood as being relatively radially further from the axis A-A' and the term "inner" being understood as being relatively radially closer to the axis A-A' of the conduit.

The terms "front" and “rear" are to be understood axially relative to an axis A-A' of the conduit, the term "front" being understood as being relatively further from the middle of the conduit and closer to one of its ends, the term "rear" being understood as being relatively closer to the middle of the conduit and further from one of its ends. The middle of the conduit is the point of the conduit situated at equal distances from the two ends thereof.

A first flexible conduit 10 according to the invention is partially illustrated in figure 1.

The flexible conduit 10 comprises a central segment 12 illustrated partially in figure 1. It comprises, at each of the axial ends of the central segment 12, an end end-fitting 14 (not shown in figure 1), the relevant parts of which are shown in figure 2.

In reference to figure 1, the conduit 10 delimits a central passage 16 for the flow of a fluid, advantageously an oil fluid. The central passage 16 extends along an axis A-A', between the upstream end and the downstream end of the conduit 10. It emerges through the end-fittings 14.

The flexible conduit 10 is designed to be positioned through an expanse of water (not shown) in a fluid exploitation facility, in particular for hydrocarbons.

The expanse of water is for example a sea, lake or ocean. The depth of the expanse of water at the fluid exploitation installation is for example comprised between 500 m and 3000 m.

The fluid exploitation installation comprises a surface assembly, in particular floating, and a bottom assembly (not shown), that are generally connected to one another by the flexible conduit 10.

The flexible conduit 10 is preferably an "unbonded" conduit.

At least two adjacent layers of the flexible conduit 10 are free to move longitudinally relative to one another when the conduit bends.

Advantageously, all of the layers of the flexible conduit are free to move relative to one another. Such a conduit is for example described in the normative documents published by the American Petroleum Institute (API), API 17J and API RP 17B.

As illustrated by figure 1, the conduit 10 delimits a plurality of concentric layers around the axis A-A', which extend continuously along the central segment 12 up to the end-fittings 14 situated at the ends of the conduit.

According to the invention, the conduit 10 comprises at least one first tubular sheath 20 with a base of a polymer material advantageously forming a pressure sheath.

The conduit 10 further comprises at least one tensile armor layer 24, 25 positioned outwardly relative to the first sheath 20 forming a pressure sheath.

Advantageously, and depending on the desired use, the conduit 10 further comprises an inner carcass 26 positioned inside the pressure sheath 20, a pressure arch 28 inserted between the pressure sheath 20 and the tensile armor layer(s) 24, 25, and an outer sheath 30, designed to protect the conduit 10.

In a known manner, the pressure sheath 20 is designed to tightly confine the fluid transported in the passage 16. It is made from a polymer material, for example with a base of a polyolefin such as polyethylene, a base of a polyamide such as PA11 or PA12, or a base of a fluorinated polymer such as polyvinylidene fluoride (PVDF).

The thickness of the pressure sheath 20 is for example comprised between 5 mm and 20 mm.

When the carcass 26 is present, it is formed by a profiled metal sheet, wound in a spiral. The turns of the sheet are advantageously stapled to one another, which makes it possible to react the radial crushing forces.

In this example, the carcass 26 is positioned inside the pressure sheath 20. The conduit is then designated by the term "rough bore" due to the geometry of the carcass 26.

In an alternative that is not shown, the flexible conduit 10 has no inner carcass 26, and is then referred to as “smooth bore".

The helical winding of the profiled metal sheet forming the carcass 26 has a short pitch, i.e., it has a spiral angle with an absolute value close to 90°, typically comprised between 75° and 90°.

In this example, the pressure arch 28 is designed to react the forces related to the pressure prevailing inside the pressure sheath 20. It is for example formed by a metal profiled wire wound in a spiral around the sheath 20. The profiled wire generally has a complex geometry, in particular in the shape of a Z, T, U, K, X or I.

The pressure arch 28 is wound in a spiral with a short pitch around the pressure sheath 20, i.e., with a spiral angle with an absolute value close to 90°, typically comprised between 75° and 90°.

The flexible conduit 10 according to the invention comprises at least one armor layer 24, 25 formed by a helical winding of at least one elongated reinforcing element 29.

In the example shown in figure 1, the flexible conduit 10 comprises a plurality of inner armor layers 24, 25, in particular an inner armor layer 24, pressed on the pressure arch 28 (or on the sheath 20 when the arch 28 is absent), and an outer armor layer 25 around which the outer sheath 30 is positioned.

Each armor layer 24, 25 comprises longitudinal armor elements 29 wound with a long pitch around the axis A-A' of the conduit. These elements 29 are visible in figure 2.

"Wound with a long pitch" means that the absolute value of the spiral angle is less than 60°, and typically comprised between 25° and 55°.

The armor elements 29 of a first layer 24 are generally wound by an opposite angle relative to the armor elements 29 of a second layer 25. Thus, if the winding angle of the armor elements 29 of the first layer 24 is equal to +a, a being comprised between 25° and 55°, the winding angle of the armor elements 29 of the second armor layer 25 positioned in contact with the first armor layer 24 is for example equal to -a.

The armor elements 29 are for example formed by metal wires, in particular steel wires, or strips of composite material, for example reinforced carbon fiber strips. In the examples shown in the figures, the armor elements 29 are formed by metal wires.

In reference to figure 2, the armor elements 29 each have an end segment 34 inserted into the end-fitting 14.

The end segment 34 extends to a free end positioned in the end-fitting 14. It advantageously has a spiral trajectory with axis A-A' in the end-fitting 14, the spiral winding on a cylindrical enclosure.

The cylindrical enclosure is defined between a first cylinder of revolution around the central axis and a second cylinder of revolution around the central axis, the radial distance separating the first cylinder from the second cylinder being less than 120% of the thickness of each end segment.

In the example shown in figures 2 and 3, for each layer of reinforcements 24, 25, the end segments 34 of the reinforcing elements 29 extend at a substantially constant distance from the axis A-A’ toward a free front end 36.

This distance is similar to that present in the central segment 12 of the conduit 10.

The end segments 34 of the armor elements 29 have been pretreated during the assembly of the end-fitting 14. In particular, the outer surface of the end segments 34 of each armor element 29 has been stripped and treated mechanically, physically and/or chemically.

For example, degreasing of the outer surface of each end segment 34 is done, for example by wiping with solvent, degreasing with solvent in vapor phase, or cleaning using detergents (alkaline, neutral or acid products) followed by rinsing.

Alternatively, chemical or electrochemical treatments, such as anodization with phosphoric acid or sulfochromic treatment, have been done.

In another alternative, a coating is applied on each end segment 34 to provide the end segment 34 with a layer of primer having a high chemical reactivity.

The primer layer is for example formed from organo-functional silanes, for example those marketed under the Dynasylan® brand by the company Evonik.

In still another alternative, a plasma treatment is done on the outer surface of the end segment 34.

Also alternatively, a mechanical ablation, such as sanding or shot blasting, is done. This mechanical treatment eliminates the layer present on the surface and modifies the morphology of the surface by increasing its roughness and introducing residual compression stresses favorable to fatigue behavior.

The outer sheath 30 is designed to prevent the permeation of fluid from the outside of the flexible conduit 10 toward the inside. It is advantageously made from a polymer material, in particular with a base of a polyolefin, such as polyethylene, or a base of a polyamide.

The thickness of the outer sheath 30 is for example comprised between 5 mm and 15 mm.

As illustrated by figure 2, on the end segments 34, each end-fitting 14 comprises an end arch 50 and an outer connecting cover 51 protruding axially rearwards from the end arch 50. The cover 51 delimits, with the end arch 50, a central chamber 52 for receiving the end segments 34 of the armor elements 29.

The end-fitting 14 further comprises a front sealing assembly 54 around the tubular sheath 20, shown diagrammatically in figure 2, and a rear sealing assembly 56 around the outer sheath 30.

According to the invention, the end-fitting 14 further comprises, for each armor layer 24, 25, a ring 57, 58 axially wedged relative to the end arch 50 and/or relative to the cover 51, and an inner adhesive layer 59 gluing each ring 57, 58 on the end segments 34 of the armor elements 29 of the armor layer 24, 25.

In this example, the end arch 50 is designed to connect the conduit 10 to another connection end-fitting 14 or to terminal equipment, advantageously by means of an end flange (not shown).

The end arch 50 has a central bore intended to receive the end of the first sheath 20 and allow the flow of the fluid circulating through the central passage 16 toward the outside of the conduit 10.

The cover 51 comprises a tubular peripheral wall 70 extending around the axis A-A'. The peripheral wall 70 has a front edge 71 fixed on the end arch 50, radially away from the armor layers 24, 25, and a rear edge 72 extending axially backward past the end arch 50.

The cover 51 delimits the chamber 52 radially toward the outside. A rear face 73 of the end arch 50 axially defines the chamber 52 in the forward direction.

The cover 51 in this example defines an inner shoulder 68 for wedging at least one maintaining ring 57, 58. The inner shoulder 68 is advantageously situated near the rear edge 72, across from the rear sealing assembly 56.

The front sealing assembly 54 is situated in front of the end-fitting 14, in contact with the end arch 50. In the embodiment of figure 2, the front sealing assembly 54 is axially offset in the forward direction relative to each ring 57, 58.

In a known manner, it comprises a front crimping ring 74 (not shown in figure 2, but shown in figure 4), intended to engage on the pressure sheath 20, and a tightening collar 76.

In the example shown in figure 2, in which the conduit 10 comprises a pressure arch 28, the front assembly 54 further comprises an intermediate stop ring 78 for the pressure arch 28 (shown in figure 4). The intermediate stop ring is inserted between the front crimping ring 74 and the gripping collar 76.

The rear sealing assembly 56 is positioned behind each ring 57, 58.

It comprises at least one rear crimping ring 80 crimping the outer sheath 30, and a rear collar 82 for gripping the rear ring 80, fastened on the cover 51, advantageously at the rear edge 72 of the peripheral wall 70.

Each maintaining ring 57, 58 extends radially outside the end segment 34 of the armor elements 29 of an armor layer 24, 25. It advantageously comes into radial contact with an inner surface of the cover 51.

The rear ring 58 is axially wedged against the shoulder 68, which prevents it from moving axially backward. The front ring 57 is axially wedged against the rear ring 58, which also prevents it from moving axially backward.

The length of the rear ring 58, considered parallel to the axis A-A', substantially corresponds to the axial length of the end segments 34 of the outer armor layer 25 in the end-fitting 14, considered parallel to the axis A-A'. The length of the front ring 57, considered parallel to the axis A-A', substantially corresponds to the axial length of the end segments 34 of the inner armor layer 24 that protrudes past the end segment 34 of the outer armor layer 25.

Below each ring 57, 58, the end segments 34 of each armor layer 24, 25 keep the cylindrical configuration that they have in the central segment 12 of the flexible conduit 10.

The end-fitting 14 therefore has a reduced radial bulk. This favors the heat exchanges with the outside environment and limits the temperatures at the end-fitting 14, which is beneficial for the aging properties of the adhesive layer 59, even when the fluid conveyed in the flexible conduit 10 has a high temperature, for example greater than or equal to 130°C.

In this example, the end segments 34 do not protrude axially past the ring 57, 58 below which they are situated.

The end segments 34 therefore do not have fastening members such as a hook or wave at their end. They do not rise on the end arch 50. They therefore do not need to be deformed during the assembly of the end-fitting 14, which is favorable in terms of fatigue behavior.

Furthermore, each ring 57, 58 is positioned completely axially behind the front sealing assembly 54.

Each ring 57, 58 has a cylindrical inner peripheral surface 90, on which the adhesive layer 59 is applied, and an outer peripheral surface 92, positioned across from the cover 51.

In the example illustrated in figure 2, each ring 57, 58 [is] for example formed by a metal ring. This ring has been machined to the desired dimensions.

The adhesive layer 59 is inserted between each ring 57, 58 and the end segments 34 of an armor layer 24, 25.

The adhesive layer 59 glues each end segment 34 in the ring 57, 58 to secure the ring 57, 58 to the end segment 34.

The thickness of the adhesive layer 59 is small. This thickness is advantageously smaller than the thickness of each end segment 34, and than the thickness of each ring 57, 58, the thicknesses being considered radially relative to the axis A-A'.

The thickness of the first part 59 is for example less than 5 mm, in particular less than 3 mm, preferably greater than 0.1 mm and for example comprised between 0.1 mm and 2 mm.

The adhesive layer 59 has a shear strength greater than 1 MPa, in particular greater than 4 MPa, for example comprised between 4 MPa and 20 MPa. This shear strength is for example measured according to standard EN 1465 (Determination of tensile lap-shear strength of bonded assemblies). The test pieces making it possible to carry out the tensile strength tests are chosen from materials respectively making up an end segment 34 and the ring 57, 58.

The adhesive layer 59 is for example formed from glue of the epoxide type with one or two components, polyurethane with one or two components, thermosetting material with one or two components, cyanoacrylate with one or two components, anaerobic glue, acrylic glue with one or two components, hot melt glue, polyurethane and/or plastisol.

In this example, no filler material other than the adhesive layer 59 is positioned in the chamber 52.

In particular, the front and rear intermediate spaces situated in the chamber in front of and behind the ring(s) 57, 58 have no filler material.

Each ring 57, 58 glued on the end segment 34 reacts all of the tension experienced by the end-fitting 14, without significantly increasing the anchor length.

Furthermore, the thickness of the adhesive layer 59 being small, the formation of bubbles or cracks that cause water infiltrations and armor corrosion is minimized.

The assembly of the end-fitting 14 according to the invention is done as follows.

Initially, the different layers of the conduit 10 are cut to the correct length to expose, on the arch 28, a free end segment 34 of each armor element 29 of the armor layers 24, 25.

Each free end segment 34 has no radial deformation, in particular wave- or hookshaped deformation.

The free end segments 34 are kept in the cylindrical configuration that they occupy in the central segment 12 of the flexible conduit 10.

No bending/unbending of each end segment 34 is done, or formation of a fastening member at the end of each end segment 34, which increases the fatigue behavior of each end segment 34.

Advantageously, each end segment 34 is stripped and undergoes a mechanical, physical and/or chemical treatment, as described above. This treatment in particular comprises degreasing, anodization with phosphoric acid, the deposit of a primary coating, a plasma treatment, and/or mechanical ablation, such as sanding or shot blasting.

The adhesive layer 59 is then applied on the outer radial surface of each end segment 34 and/or on the inner surface of each ring 57, 58. The adhesive layer 59 has a small thickness, smaller than that of each end segment 34, as described above.

The rings 58, 57 are next successively inserted from the front to respectively surround the end segment 34 of the armor elements 29 of the second armor layer 25 and the end segments 34 of the armor elements 29 of the first armor layer 24.

Next, the end arch 50 and the front sealing assembly 54 are put into place. The cover 51 is next fastened to the end arch 50. The rear sealing assembly 56 is next placed and fastened to the cover 51.

During operation, when the end-fitting 14 is connected to another end-fitting 14 or to a surface assembly, the axial tension transmitted by the armor layers 24, 25 resulting from the weight of the conduit 10 is reacted by the segments 34 glued on each ring 57, 58. The axial tension is next transmitted from each ring 57, 58 toward the cover 51 and/or toward the end arch 50.

The end-fitting 14 according to the invention therefore very robustly reacts all of the tension experienced, with a relatively small anchor length.

For example, a set of rings 57, 58 measuring one meter long, each ring 57, 58 being glued only on the outer surface of the end segment 34, with a thin layer of glue approximately 1 mm thick, having a shear strength of 4.5 MPa, reacts a tension of 200 t on a structure with a diameter of 145 mm and 420 t on a structure with a diameter of 300 mm.

With a higher performing glue having a shear strength of 15 MPa, the reacted tension is 420 t on a structure with a diameter of 300 mm, with an anchor measuring 300 mm long.

In one alternative of the end-fitting 14, radial crimping is done around each ring 57, 58, after placing the ring 57, 58, to apply a radial pressure on the end segment 34 of the armor elements 29 of each armor layer 24, 25.

The radial pressure is for example greater than 2 MPa.

The radial crimping precisely controls the thickness of the applied adhesive layer 59 to offset the ovalization of the end segments 34 of the armor layers 24, 25.

This ovalization normally complicates the precise adjustment of each armor layer 24, 25 inside the respective ring 57, 58. The radial gripping of the end segments 34 of each armor layer 24, 25 with the respective ring 57, 58 reduces the ovalization and resolves the potential problem of mechanical adjustment.

The end-fitting 14 of a second flexible conduit 100 according to the invention is illustrated by figure 3.

Unlike the end-fitting 14 of the first flexible conduit 10 shown in figure 2, each ring 57, 58 comprises a plurality of separate circumferential segments 102 assembled on one another to form a ring, and assembly and radial gripping members 104 for the circumferential segments 102.

The number of circumferential segments 102 is for example comprised between 2 and 5, advantageously 3 or 4.

The assembly and radial gripping members 104 are for example formed by screw/nut systems.

Advantageously, the radial gripping of the circumferential segments 102 is adjusted via the assembly and radial gripping members 104 to apply a radial pressure oriented toward the axis A-A' on the end segments 34 of the armor elements 29 of each armor layer 24, 25.

The radial pressure is for example greater than 2 MPa.

As previously described, the radial gripping allows precise control of the thickness of the applied adhesive layer 59 to offset the ovalization of the end segments 34 of the armor layers 24, 25.

The presence of several circumferential segments 102 simplifies the assembly of the end-fitting 14. It is no longer necessary to precisely adjust the dimensions of each ring 57, 58 before assembly, since the adjustment is done directly during the assembly.

Furthermore, the glue forming the adhesive layer 59 is easily applied on the inner surface of each circumferential segment 102 and/or on the outer surface of each end segment 34, without creating significant bother during assembly.

The end-fitting 14 of a third flexible conduit 110 according to the invention is illustrated by figure 4.

Unlike the end-fitting 14 illustrated by figure 2, this end-fitting 14 comprises, for each ring 57, 58, a support cannula 112, positioned inside each end segment 34, across from the ring 57, 58.

The end-fitting 14 further comprises an additional adhesive layer 114 inserted between the inner surface of each end segment 34 and the outer surface of the cannula 112.

In this alternative, all of the faces of the end segments 34 of the armor elements 29, comprising the inner face, have advantageously been pretreated during the assembly of the end-fitting 14. Thus, the inner and outer surfaces of the end segments 34 of each armor element 29 have been stripped and treated mechanically, physically and/or chemically according to the surface preparation methods described above.

The cannula 112 comprises a cylindrical body 116 advantageously having a beveled rear free edge 118. It comprises a front collar 120, placed bearing against a front surface of the ring 57, 58. Owing to the front collar 120, the cannula 112 is axially wedged on the ring 57, 58, which prevents it from moving axially backward.

The cylindrical body 116 of the cannula 112 defines, with the ring 57, 58, an intermediate space for receiving each end segment 34, and adhesive layers 59, 114, the intermediate space being closed in the forward direction by the collar 120.

The cylindrical body 116 has a small radial thickness, advantageously smaller than the radial thickness of each end segment 34 and advantageously smaller than the radial thickness of each ring 57, 58.

The additional adhesive layer 114 is thin. Its radial thickness [is] advantageously smaller than the radial thickness of each end segment 34 and advantageously smaller than the radial thickness of each ring 57, 58.

This radial thickness is similar to that of the adhesive layer 59.

In this example, the front ring 57 further defines, in its inner surface 90, a rear housing 122 receiving the collar 120 of the rear cannula 112 positioned across from the rear ring 58.

The assembly of the end-fitting 14 shown in figure 4 differs from that of the endfitting 14 illustrated by figure 3 in that the cannulas 112 are inserted below the end segment 34 of the armor elements 29, before the placement of the rings 57, 58.

The presence of the cannulas 112 increases the adhesion surface of the end segments 34, without increasing the length of the end-fitting 14. Thus, for example, if the cannulas 112 have a length substantially equal to that of the rings 57, 58, the adhesion surface is substantially doubled due to the presence of the cannulas 112, which doubles the axial tensile strength of the end-fitting 14. The axial tensile forces reacted by each cannula 112 via the additional adhesive layer 114 are transmitted to the rings 57, 58 owing to the front collars 112 that are positioned bearing on the rings 57, 58.

The end-fitting 14 of a fourth flexible conduit 130 according to the invention is illustrated by figure 5.

Unlike the end-fitting 14 shown in figure 2, the inner peripheral surface 90 of at least one ring 57, 58 has a first axial region 132 situated at a first radial distance D1 from each armor element 29 and a second axial region 134 situated at a second radial distance D2 from each armor element 29, the first radial distance D1 being different from the second radial distance D2.

Preferably, the first radial distance D1 from the first axial region 132 situated further forward is smaller than the second radial distance D2 from the second axial region 134 situated further backward.

In the example shown in figure 5, the inner peripheral surface 90 further has a third axial region 136, situated behind the second axial region 132. The third axial region 136 is situated at a third radial distance D3 from each armor elements 29. The third radial distance D3 is larger than the second distance D2.

Thus, the inner peripheral surface 90 defines a step whereof the radial spacing with the end segment 34 of the armor elements 29 increases moving axially from front to back.

The adhesive layer 59 thus has a first axial part 138 positioned across from the first axial region 132, a second axial part 140 positioned across from the second axial region 134, and advantageously, a third axial part 142 positioned across from the third axial region 136. The radial thickness of the adhesive layer 59 is different and increases from one axial part 138, 140, 142 to the other from front to back.

Behind the ring 57, 58, the adhesive layer 59 thus has an increased shear flexibility and provides greater freedom of movement to the end segment 34 of the armor elements 29, relative to the front of the ring 57, 58 where the end segments 34 are completely blocked.

Figure 6 illustrates the end-fitting 14 of a fifth flexible conduit 150 according to the invention.

Unlike the end-fitting 14 shown in figure 3, the adhesive layer 59 arranged opposite each ring 57, 58 comprises a first axial part 138 formed with a base of a first, relatively more rigid adhesive and a second rear axial part 140 formed with a base of a second adhesive that is relatively more flexible than the first adhesive.

The rigidity of the adhesive is characterized by its elasticity modulus, as measured on a tensile strength test of a glued assembly made according to standard EN 1465.

Examples of relatively more rigid adhesives are epoxides with one or two components, thermosetting materials, cyanoacrylates with one or two components. Examples of relatively more flexible adhesives are polyurethanes with one or two components, acrylics with one or two components, polyurethane hot melt glues, plastisols.

In the example shown in figure 6, the thickness of the adhesive layer 59 is constant along the rings 57, 58. Alternatively, this thickness varies, as illustrated by figure 5.

The end-fitting 14 of a sixth flexible conduit 160 according to the invention is illustrated by figure 7.

Unlike the end-fitting 14 shown in figure 3, the intermediate spaces 162, 164 of the receiving chamber 52 respectively situated axially in front of and behind each ring 57, 58 are filled with a filler material.

This filler material is preferably more flexible than the glue forming the adhesive layer 59. The filler material blocks the armor elements 29 gradually in the rear intermediate space 164 and wedges the rings 57, 58 in the front intermediate space 162.

Advantageously, at least the rear intermediate space 164 is filled with a polyurethane. The presence of this material ensures sealing, limits the lateral movements of the end segments 34 and favors their embedding.

The end-fitting 14 of a seventh flexible conduit 170 according to the invention is illustrated by figure 8.

Unlike the end-fitting 14 of the sixth conduit 160 shown in figure 7, the front intermediate space 162 and/or the rear intermediate space 164 is filled with a seal defining the water migration.

This seal is for example formed by an oil bath, a silicone and/or a polyurethane.

The seal is further advantageously positioned in an annular space 172 inside the end segments 34 of the armor elements 29, between the pressure arch 28 and the armor elements 29.

The seal prevents the water from penetrating the chamber 52 and reaching the adhesive layer 59. This increases the aging and fatigue behavior of the end-fitting 14.

Figure 9 illustrates a subassembly of an end-fitting of an eighth flexible conduit according to the invention, and constitutes an alternative of the second conduit shown in figure 2.

In this alternative, the inner peripheral surface 90 of the ring 57, 58 is not cylindrical, the inner surface of the ring 57, 58 defines a central slot 203. The inner peripheral surface 90 has three cylindrical axial regions, i.e., two lateral axial regions 200, 202 situated at a first radial distance from the longitudinal axis of the ring 57, 58, and a central axial region 201 situated at a second radial distance greater than the first radial distance. The difference E between the second and first radial distance defines the depth of the central slot 203.

The depth E of the central slot 203 is advantageously comprised between 1 mm and 2 mm. The adhesive layer 59 positioned between the end segment 34 and the inner peripheral surface 90 therefore has a greater radial thickness in light of the central slot 90 than in light of the two lateral axial regions 200, 202.

Thus, even if the two axial regions are in direct contact with the end segment 34, the thickness of the adhesive layer 59 in light of the central slot 203 still remains greater than E, which guarantees an adequate thickness of the adhesive layer 59 to obtain a good quality gluing in light of the central slot 203.

This embodiment may be generalized by using several slots with the same depth instead of only one, or by using a helical slot with a constant depth.

The spiral shape of the slot 203 facilitates the insertion of the adhesive in the slot 203, in particular when the ring 57 is engaged around the end segments 34 of the armor elements 29 while pivoting it around its axis from front to back.

Figure 10 illustrates a subassembly of an end-fitting of a ninth flexible conduit according to the invention, and constitutes an alternative of the fourth conduit shown in figure 5.

In this alternative, the inner face of the ring 57, 58 has three slots, i.e., a front slot 205 with depth E1, a central slot 209 with depth E2 and a rear slot 212 with depth E3.

Outside these three slots, the inner peripheral surface 90 of the ring 57, 58 has four cylindrical axial regions 204, 207, 210, 211 that are coaxial and have the same radius. Furthermore, the depth E1 is smaller than the depth E2, which in turn is smaller than the depth E3.

In this way, even if the four axial cylindrical regions 204, 207, 210, 211 are in direct contact with the end segments 34, the thickness of the adhesive layer 59 at the slots 205, 209, 212 still remains both greater than E1, E2, E3, respectively, and increasing from the front to back of the ring 57, 58.

This improves the reproducibility of the gluing while preventing the adhesive layer 59 from having local spots that are too thin, and provides gluing with a shear flexibility increasing from the front to the back of the ring 57, 58.

This embodiment may be generalized by increasing the number of slots, or by using a helical slot whose depth increases gradually from the front to the back of the ring 57, 58.

According to another embodiment not shown in figures, the end-fitting is equipped with a cooling system for the rings 57, 58 serving to lower the temperature of the adhesive layer 59. This allows the adhesive layer to keep its mechanical properties lastingly, even when the fluid conveyed by the flexible conduit 10 has a high temperature, for example greater than or equal to 130°C.

Furthermore, advantageously, the surface pretreatment prior to the gluing step is done not only on the faces of the end segments 34 of the armor elements 29, but also in the inner face of the rings 57, 58, and optionally on the outer face of the cannulas 112.

In the embodiments previously described, the axial tensile force exerted by the conduit 10 is first transmitted from the armor elements 29 of the armor layers 24, 25 to the rings 57, 58 via the adhesive layer 59. The axial tensile force is next transmitted from the rings 57, 58 to the cover 51 and/or to the end arch 50 via fastening means completely independent from the flexible conduit, for example, an adhesive layer, and/or by axial wedging on a mechanical stop formed on the cover 51, or by another ring 58. Thus, the rings 57, 58 are fixed in axial translation relative to the cover 51 and/or relative to the end arch 50 independently of the concentric layers of the flexible conduit 10.

Claims (17)

1. A connection end-fitting (14) of a flexible conduit (10) for conveying fluid, the flexible conduit (10) comprising a plurality of concentric layers comprising at least one tubular sheath (20) and at least one tensile armor element (24, 25) positioned outwardly relative to the tubular sheath (20), the armor layer (24, 25) comprising a plurality of filiform armor elements (29), the end-fitting (14) comprising: - at least one end segment (34) of each armor element (29), - an end arch (50) with central axis (A-A’) and a cover (51) fastened on the end arch (50), the end arch (50) and the cover (51) defining a chamber (52) between them for receiving each end segment (34); characterized in that the end-fitting (14) comprises: - at least one ring (57, 58) circumferentially outwardly covering the armor elements (29) of each armor layer (24, 25), the ring (57, 58) being at least partially fixed in axial translation relative to the cover (51) and/or relative to the end arch (50), the ring (57; 58) being formed by a metal annulus; - an adhesive layer (59) inserted between an inner peripheral surface of the ring (57, 58) and the outer surface of each armor element (29), the adhesive layer (59) fixing each armor element (29) on the ring (57, 58).

2. The end-fitting (14) according to claim 1, characterized in that the adhesive layer (59) has a radial thickness smaller than the radial thickness of the ring (57, 58).

3. The end-fitting (14) according to any one of the preceding claims, characterized in that the adhesive layer (59) has a maximum thickness smaller than 5 mm, and advantageously comprised between 0.1 mm and 3 mm.

4. The end-fitting (14) according to any one of the preceding claims, characterized in that the ring (57, 58) is axially wedged on the cover (51) and/or on an intermediate element wedged on the cover (51).

5. The end-fitting (14) according to any one of the preceding claims, characterized in that the armor elements (29) extend along a cylindrical envelope in the receiving chamber (52).

6. The end-fitting (14) according to any one of the preceding claims, characterized in that the ring (57, 58) radially grips the adhesive layer (59) and the armor elements (29), the ring (57, 58) advantageously comprising a plurality of circumferential segments (102) assembled on one another.

7. The end-fitting (14) according to any one of the preceding claims, characterized in that the inner peripheral surface (90) of the ring (57, 58) has a first axial region (132) situated at a first distance (D1) from each armor element (29) and a second axial region (134) situated at a second distance (D2) from each armor element (29), the first distance (D1) being different from the second distance (D2), the adhesive layer (59) having at least a first axial part (138) positioned across from the first axial region (132) and a second axial part (140) positioned across from the second axial region (134), the radial thickness of the adhesive layer (59) being different in the first axial part (138) and in the second axial part (140).

8.

The end-fitting (14) according to any one of the preceding claims, characterized in that it comprises a cannula (112) positioned radially inside each armor element (29) across from the ring (57, 58), and an inner adhesive layer (114), advantageously with a radial thickness smaller than that of the cannula (112), the inner adhesive layer (114) being inserted between an outer surface of the cannula (112) and an inner surface of each armor layer (29). 9. -The end-fitting (14) according to any one of the preceding claims, characterized in that the adhesive layer (59) comprises a first axial part (138) formed with a base of a first, relatively more rigid adhesive and a second axial part (140) formed with a base of a second adhesive that is relatively more flexible than the first adhesive.

10. The end-fitting (14) according to any one of the preceding claims, characterized in that the outer surface of each armor element (29) is mechanically, physically or chemically pretreated.

11. The end-fitting (14) according to any one of the preceding claims, characterized in that the inner peripheral surface of the or each ring (57, 58) defines at least one annular or helical slot (203, 205, 209, 212) opening across from the armor elements (29) and partially receiving the adhesive layer (59).

12. The end-fitting (14) according to any one of the preceding claims, characterized in that it comprises a front sealing assembly (54) intended to produce sealing around the tubular sheath (20), the front sealing assembly (54) being axially offset in the forward direction relative to each ring (57, 58).

13. The end-fitting (14) according to any one of the preceding claims, characterized in that the or each ring (57, 58) defines, in the receiving chamber (52), a front intermediate space (162) and/or a rear intermediate space (164), the end-fitting (14) comprising a flexible filler material filling the front intermediate space (162) and/or the rear intermediate space (164).

14. The end-fitting (14) according to any one of the preceding claims, characterized in that the or each ring (57, 58) defines, in the receiving chamber (52), a front intermediate space (162) and/or a rear intermediate space (164), the end-fitting (14) comprising a watertight seal filling the front intermediate space (162) and/or the rear intermediate space (164).

15. The end-fitting (14) according to any one of the preceding claims, characterized in that (57, 58) is fixed in axial translation relative to the cover (51) and/or relative to the end arch (50) independently of the concentric layers of the flexible conduit (10).

16. A flexible conduit (10) for conveying a fluid, advantageously unbonded, comprising: - a plurality of concentric layers comprising: • at least one tubular sheath (20); • at least one tensile armor element (24, 25) positioned outwardly relative to the tubular sheath (20), the armor layer (24, 25) comprising a plurality of filiform armor elements (29); and - an end-fitting (14) according to any one of the preceding claims;

17. A method for assembling an end-fitting (14) of a flexible conduit (10) for conveying fluid, the flexible conduit (10) comprising at least one tubular sheath (20) and at least one tensile armor layer (24, 25) positioned outwardly relative to the tubular sheath (20), the armor layer (24, 25) comprising a plurality of filiform armor elements (29), the end-fitting (14) comprising the following steps: - freeing at least one end segment (34) of each armor element (29), - arranging an end arch (50) with central axis (A-A’) and fastening a cover (51) on the end arch (50), the end arch (50) and the cover (51) defining a chamber (52) between them for receiving each end segment (34); characterized in that the method comprises: - placing an adhesive layer (59) on the outer surface of each armor element (29), - arranging at least one ring (57, 58) to circumferentially outwardly cover the armor elements (29) of each armor layer (24, 25), the ring (57, 58) being next at least partially fixed in axial translation relative to the cover (51) and/or relative to the end arch (50); - inserting an adhesive layer (59) between an annular inner surface of the ring (57, 58) and the outer surface of each armor element (29), the adhesive layer (59) fixing each armor element (29) on the ring (57, 58).