CN112682586A

CN112682586A - Flexible pipe for transporting natural gas and/or petroleum fluids submerged in a body of water

Info

Publication number: CN112682586A
Application number: CN201910990767.6A
Authority: CN
Inventors: F·德曼兹; L·鲍米尔; B·森纳维尔; G·佩蒂翁
Original assignee: Technip France SAS
Current assignee: Technip Energies France SAS
Priority date: 2019-10-18
Filing date: 2019-10-18
Publication date: 2021-04-20

Abstract

Flexible pipe for transporting natural gas and/or petroleum fluids submerged in a body of water. The invention relates to a flexible pipe for transporting natural gas and/or petroleum fluids, intended to be submerged in a body of water, the flexible pipe having, from the outside inwards: the sealing outer sleeve is used for limiting water in a water area from entering the flexible pipe; at least one outer reinforcing structure for reinforcing the flexible pipe against internal radial and/or tensile forces; a protective inner sleeve (6); the annular space is limited by the sealing outer sleeve and the protective inner sleeve (6), and the outer reinforcing structural member is arranged in the annular space; a tubular inner reinforcing structure (8) for reinforcing a flexible pipe against external radial forces exerted on the flexible pipe, having at least one helical void (10) and at least one seal (11) for restricting the flow of natural gas and/or petroleum fluids from the inner passage to the annular space, the seal (11) being helically wound within the at least one helical void (10). The invention can reduce the corrosion of the external reinforced structural member.

Description

Flexible pipe for transporting natural gas and/or petroleum fluids submerged in a body of water

Technical Field

The present invention relates to the technical field of flexible pipes for transporting natural gas and/or petroleum fluids in a body of water.

The technical field of the present invention relates in particular to flexible tubes of the unbonded (in english terminology "unbonded") type.

Background

Generally, flexible pipes for transporting natural gas and/or petroleum fluids in a subsea environment are submerged in water at depths that may exceed 3000 meters. It is particularly advantageous to carry natural gas and/or petroleum fluids between subsea equipment and surface equipment. It can also be used to connect two subsea devices. Some flexible pipes may also be used to connect two pieces of surface equipment.

The construction of Flexible pipes is well known in the art and is described, inter alia, in the American Petroleum institute published Standard documents API RP 17B (Recommended Practice for Flexible pipes) and API 17J (Specification for Unbonded Flexible pipes).

Flexible tubes are generally formed from a set of stacked concentric layers. The flexible pipe is considered to be of the "non-bonded" type in that at least one of the layers of the flexible pipe is capable of moving longitudinally relative to the adjacent layer when the flexible pipe is bent. In particular, a non-bonded flexible pipe is a flexible pipe without bonding material connecting the layers forming the flexible pipe.

Flexible pipe typically has from the inside out an inner reinforcing structure, commonly referred to as a carcass or endoskeleton, an inner sealing polymer jacket, at least one outer reinforcing structure, and an outer sealing polymer jacket.

The main function of the inner skeleton is to take up radial compression forces, e.g. related to hydrostatic pressure. The inner frame is made of a profiled metal strip wound at a short pitch to form helical coils that snap into each other. The expression "with a short pitch" characterizes a helical disc winding having a helix angle with an absolute value between 70 ° and 90 °. The absolute value of the helix angle of the endoskeleton is typically close to 85. Generally, the metal strip is S-shaped in cross-section. Thus, each coil of the metal strip cooperates with an adjacent coil to form a snap fit of the inner reinforcing structure.

The inner sealing polymer sleeve, more commonly referred to as a "pressure resistant sleeve" (english term) or "inner sleeve", is a sleeve extruded around the inner reinforcing structure. Its main function is to confine the gas and/or oil fluid inside the flexible pipe. Thus, the sealing polymer inner sleeve defines an internal passage for the circulation of natural gas and/or petroleum fluids. The inner sleeve is arranged on the inner side of the outer reinforcing structural member.

The outer reinforcing structure serves to reinforce the flexible pipe against radial and/or axial forces. Flexible pipes generally have two reinforcing structures. For example, flexible pipes have from the inside outwards a pressure-resistant armor and tensile armour layers. Pressure armour (the english term "pressure armor") is generally formed by a metallic type wire wound in a short pitch around an inner jacket of sealing polymer in a jointed helical turn. Thus, the pressure armour may take up radial forces related to the pressure of the fluid circulating in the flexible pipe. The pressure armour has a helix angle with an absolute value typically close to 85 °. The tensile armour layer is arranged to take up tensile forces exerted on the flexible pipe. These tensile armour layers are formed by armour elements wound around the pressure armour at a long pitch. The expression "in long pitch" characterizes a helical winding having a helix angle with an absolute value less than or equal to 60 °. Flexible pipe typically has one or two pairs of crossed tensile armour layers, the absolute value of the helix angle of these layers typically being between 20 ° and 60 °, advantageously between 25 ° and 55 °. The armour, commonly referred to as armouring wires, is generally made of a metallic material or a composite material. The sealed polymer jacket, commonly referred to as a jacket, is a jacket extruded around the outer reinforcing structure. The purpose of this outer jacket is in particular to protect the outer reinforcing structure against corrosion, in particular when the flexible pipe is submerged in the water bottom.

Although the pressure resistant jacket is sealed against hydrocarbons and other transported fluids, such as water, small amounts of gas can slowly escape through it, especially when the temperature and pressure are high. This phenomenon is mainly related to small size molecules, especially gaseous water, and carbon dioxide (CO)₂) Hydrogen sulfide (H)₂S) and methane (CH)₄). Thus, when the natural gas and/or petroleum fluid contains one or more of these gases, one or more of these gases may escape through the unsealed inner skeleton and then through the pressure jacket and accumulate in the annular space between the pressure jacket and the outer jacket. Due to the presence of water in the annular space, which may originate, for example, from the accidental rupture of the outer casing or from the condensation of gaseous water escaping through the pressure-resistant casing, these gases may cause corrosion of the metal elements and chemical ageing of the possibly present composite parts of the outer reinforcing structure. Corrosion of the metal elements of the outer reinforcing structure may then lead to premature rupture of the flexible pipe.

There is therefore a need to provide a flexible pipe for transporting natural gas and/or petroleum fluids submerged in a body of water with a limited risk of rupture.

Disclosure of Invention

To this end, the invention proposes a flexible pipe for transporting natural gas and/or petroleum fluids, intended to be submerged in a body of water, said flexible pipe having from the outside inwards thereof:

a sealing jacket for restricting water from the body of water from entering the flexible tube,

at least one outer reinforcement structure for reinforcing the flexible pipe against internal radial and/or tensile forces,

-a protective inner sleeve,

an annular space defined by a sealing outer sleeve and a protective inner sleeve, an outer reinforcement structure being arranged in the annular space,

-a tubular inner reinforcing structure for reinforcing the flexible pipe against external radial forces exerted on the flexible pipe, the tubular inner reinforcing structure having:

-a profiled strip helically wound to form a tubular inner reinforcing structure, adjacent helical turns of the profiled strip being snapped into each other, the profiled strip defining at least one helical void.

The invention is characterized in that the tubular internal reinforcing structure further comprises:

-at least one seal for restricting the flow of gas and/or oil fluid from the inner passage to the annular space, the seal being helically wound in the at least one helical void.

The internal reinforcing structure has helical gaps and small gas molecules such as carbon dioxide (CO) contained in the natural gas and/or petroleum fluid₂) Hydrogen sulfide (H)₂S) or methane (CH)₄) Or gaseous water molecules may enter through these helical gaps and then escape through the sealing polymer inner jacket. According to the invention, the seal closes at least some of these helical gaps to prevent the passage of gas and/or oil fluids through the internal reinforcing structure. In this way, the inner reinforcing structure no longer allows the passage of gas and/or oil fluids, thus creating a sealed structure that greatly limits the amount of gas that may escape from the flexible pipe into the annular space. Thus, by means of the invention, the amount of corrosive gas present in the annular space is kept extremely low, below a threshold value that may cause deterioration of the outer reinforcement structure.

According to one embodiment of the invention, the cross-section of the profiled strip has:

a first end zone having a lower bearing free end, an upper bearing branch connected to the lower bearing free end by a first transverse connecting branch,

a second end region having a lower bearing branch, an upper bearing free end connected to the lower bearing branch by a second transverse connecting branch,

a central zone having a third transverse branch connecting the upper support branch of the first end zone to the lower support branch of the second end zone,

and the upper support free end of the second end region of a first coil is inserted between the lower support free end of the first end region of an adjacent coil and the upper support leg to form a snap fit of the tubular inner reinforcing structure.

The inner reinforcing structure is configured to take up external radial forces, typically those related to hydrostatic pressure exerted on the flexible pipe, which may reach 300 bar or even higher. The snap thus forms between each helical turn a separation zone (joint) of variable axial amplitude, allowing the flexible tube to bend. The axial extent of the separation zone is defined in particular by the second transversely connected branch of each helical turn. Thus, the inner reinforcing structure is sufficiently flexible and strong for flexible pipe applications.

According to one embodiment of the invention, the helical void is radially defined by the lower support branch of the second end region of a first helical turn and by the lower support free end of the first end region of an adjacent helical turn,

and/or radially defined by an upper support free end of the second end region of a first helical turn and by a lower support free end of the first end region of an adjacent helical turn,

and/or radially by the upper support free end of the second end region of a first helical turn and by the upper support branch of the first end region of an adjacent helical turn.

Advantageously, this embodiment may improve the sealing of the inner reinforcing structure. In fact, between each helical turn, there is one axial separation zone leading to the inside of the flexible tube and one axial separation zone leading to the inner sleeve of the sealing polymer. The amplitude of the inner and outer axial separation zones changes when the flexible tube is bent, thereby ensuring the flexibility of the flexible tube. In contrast, the variation in the amplitude of the axial separation zones makes the insertion of the seal difficult, since the seal cannot adapt to the variation in the amplitude of the axial separation zones in order to ensure a sufficient sealing function. Advantageously, therefore, the helical void in which the seal is helically wound has a substantially constant amplitude in the radial direction relative to the axis of the flexible pipe. Thus, the sealing of the inner reinforcing structure is maintained despite the axial movement of the coil to accommodate bending of the flexible pipe.

According to one embodiment of the invention, the lower bearing free end of the first end region of a helical turn has a first section extending from a first transverse connecting branch to a second section having a concavity directed toward the lower bearing branch of the second end region of an adjacent helical turn.

By means of this concavity, the thickness of the wall of the tubular inner reinforcing structure is greater than or equal to four times the thickness of the profiled strip. This improves the strength of the internal reinforcing structure against internal and external pressure.

According to one embodiment of the invention, the helical void is radially defined by the lower support leg of one helical turn and by the second segment of the lower support free end of an adjacent helical turn.

Advantageously, this embodiment may ensure the stability of the seal within the inner reinforcing structure. In fact, the concavity of the lower bearing free end mechanically secures the seal within the helical void. In addition, in this configuration, the pressure present inside the flexible tube enhances the tightness of the inner reinforcing structure, since it will increase the contact pressure between the seal and the profiled strip. Thus, in this configuration, under the effect of the pressure existing within the flexible tube, the seal tends to deform to increase the volume occupied by the seal in the helical void, thereby also enhancing the tightness of the internal reinforcing structure.

According to one embodiment of the flexible pipe, the upper bearing free end of the second end region of a helical turn has a first section extending from the second transverse connecting branch to a second section having a concavity directed towards the upper bearing branch of the first end region of an adjacent helical turn; and the helical void is further defined by the second section of the upper support free end and by the upper support branch of the first end region of the adjacent helical turn.

According to one embodiment of the flexible pipe, the inner reinforcing structure has a plurality of seals.

The plurality of seals may fill a plurality of gaps within the inner reinforcing structure. This may therefore enhance the sealing of the inner reinforcing structure to the transported natural gas and/or petroleum fluids, thereby limiting the escape of small molecules of gas, such as carbon dioxide (CO), through the inner sealing polymer jacket₂) Hydrogen sulfide (H)₂S), methane (CH)₄) Or the amount of gaseous water.

According to an embodiment of the flexible pipe, the sealing member has an elliptical cross-section.

Alternatively, according to the invention, the seal has a rectangular cross section.

The different geometries of the cross-section of the sealing element ensure an optimal tightness of the inner reinforcing structure. In fact, these geometries are adapted to the geometry of the voids.

According to one embodiment of the flexible pipe, the thickness of the sealing element is less than or equal to half the thickness of the profiled strip.

For a seal with a rectangular cross-section, the thickness is advantageously less than or equal to half the thickness of the profiled strip. The smaller the thickness of the spiral seal, the less the gas, such as carbon dioxide (CO)₂) Hydrogen sulfide (H)₂S), methane (CH)₄) The less the flow of gaseous water into the annular space. In addition, such a thickness may minimize the radial extent of the helical gap within the inner reinforcing structure, thereby enhancing its sealing.

According to one embodiment of the flexible pipe, the seal has a body formed of a metal or polymer material.

Such as carbon dioxide (CO)₂) Hydrogen sulfide (H)₂S), methane (CH)₄) Or gaseous water, at a temperature of 80 ℃ and a pressure of 40 bar within the sealed polymer jacket, is about 10^-7Square centimeter per second. The volume flow per unit length in a seal, in particular made of a metallic material, is less than 10 at a temperature of 80 ℃ and a pressure of 40 bar^-7Square centimeter per second. This can therefore significantly reduce the number of these gas molecules inside the annular space.

In addition, the polymer material has a great flexibility, which allows the rigidity of the inner reinforcing structure not to be significantly increased. The flexible tube can then be encouraged to bend without reducing the tightness of the inner reinforcing structure.

For example, according to the invention, the polymeric material is selected from thermoplastics or elastomers or thermoplastic elastomers.

According to one embodiment of the flexible pipe, the material has a filler for reducing the coefficient of friction between the seal and the profiled strip.

According to one embodiment of the flexible pipe, the seal has a polymer coating for enhancing the sealing of said seal against natural gas and/or petroleum fluids.

According to an embodiment of the flexible pipe, the seal has at least one reinforcement for increasing the compressive strength of the seal.

According to one embodiment of the flexible tube, the sealing member is fixed to at least a portion of the profiled strip, for example by gluing.

The sealing element is chemically fixed to at least a portion of the profiled strip of the inner reinforcing structure, which allows the sealing element to be retained in the helical void despite axial movement of the helical coil when the flexible pipe is bent.

Drawings

The invention will be better understood from a reading of the following description, given purely by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a section of flexible pipe according to the present invention;

figure 2 is a half-section through one helical turn of a profiled strip of the inner reinforcing structure of the flexible pipe shown in figure 1 taken along a plane containing the axis of the flexible pipe;

FIG. 3 is a half-sectional view of the inner reinforcing structure and inner sleeve of the flexible pipe shown in FIG. 1 taken along a plane containing the axis of the flexible pipe;

FIG. 4A is a half sectional view of one coil of the inner reinforcing structure snapping over an adjacent coil, taken along a plane containing the axis of the flexible tube, showing a first position with a first inner axial separation zone Ji1 between the coils;

FIG. 4B is similar to FIG. 4A and shows a second position with a second inner axial separation zone Ji2 between the coils;

FIG. 5A is a half-sectional view of one coil of the inner reinforcing structure snapped with an adjacent coil, taken along a plane containing the axis of the flexible tube, with the seal helically wound in the helical void;

fig. 5B to 5D are similar to fig. 5A, showing some implementation variants;

figure 6 is a half-sectional view of an inner stiffening structure according to another embodiment variant taken along a plane containing the axis of the flexible tube.

Detailed Description

A flexible pipe 1 according to the invention is shown for example in a perspective view in fig. 1.

The flexible pipe 1 is intended to be submerged in a body of water for transporting natural gas and/or petroleum fluids.

In particular, the flexible pipe 1 ensures the transport of gas and/or oil fluids between a subsea installation and a surface installation, between two subsea installations, or between two surface installations. The subsea device is, for example, a manifold (in english term "manifold"), a wellhead (in english term "wellhead"), or any other subsea structure to which a flexible pipe can be connected. Sea-surface installations are for example: a fixed platform, such as a jack-up rig (in english terminology "jack-up rig"); or mobile platforms, such as Floating Production Storage and Offloading vessels called FPSOs (english term "Floating Production Storage and Offloading"); alternatively, any other sea surface device to which flexible tubing may be connected.

The water area in which the flexible pipe 1 is submerged is, for example, a lake, sea or ocean. The depth of the water area is between 50 and 5000 meters, and is generally between 100 and 2500 meters. Thus, the hydrostatic pressure exerted on the flexible tube 1 may be as high as 500 bar.

Natural gas and/or petroleum fluids are formed from a multiphase mixture comprising a plurality of liquid phases formed from a plurality of saturated and/or unsaturated, linear and/or cyclic carbon-containing compounds of variable density and water, a gas phase formed from methane, carbon dioxide, hydrogen sulfide and other gas molecules, and a solid phase, which may be present, comprising sand. The temperature of the gas and/or oil fluid at the well outlet is typically between 50 ℃ and 200 ℃, typically between 50 ℃ and 130 ℃. The pressure of the natural gas and/or petroleum fluid is higher than 100 bar, higher than 300 bar, higher than 500 bar, or higher than 1000 bar. The invention is particularly suitable for the following cases: the natural gas and/or petroleum fluid has a partial pressure of carbon dioxide comprised between 50 bar and 100 bar, or even higher than 100 bar, and/or a partial pressure of hydrogen sulphide higher than 10 mbar, higher than 100 mbar, or even higher than 1 bar.

The flexible pipe 1 has a plurality of concentric polymer layers, metal layers and possibly composite layers, which layers are arranged around an axis a-a'.

In the following description, the expression "outer" refers to an axis a-a' radially relatively further away from the flexible pipe 1. The expression "inner" then means radially relatively closer to the axis a-a' of the flexible pipe 1.

The flexible pipe 1 is provided with a sealing outer sleeve 2, an outer reinforcing structural member 3, an inner sleeve 6 and an inner reinforcing structural member 8 from outside to inside.

The sealing outer sleeve 2 is used for limiting water in a water area from entering the flexible pipe 1. The outer casing 2 may also limit wear of the flexible pipe 1, for example during installation.

The jacket 2 is in contact with the water of the body of water. The thickness of the outer jacket 2 is between 5 mm and 15 mm. For example, the jacket is made of a polymeric material, for example selected from polyolefins such as polyethylene, or polyamides such as polyamide 11 or polyamide 12. According to another embodiment, the material of jacket 2 is poly (p-phe nyl) paraphenylene terephthalamide.

The outer jacket 2 is made by extrusion of a tubular sealing structure. According to another embodiment, the jacket 2 is made from a strip extruded and subsequently wound to form a sealed tubular structure.

The outer reinforcing structure 3 serves to reinforce the flexible pipe 1 against internal radial and/or tensile forces.

An outer reinforcing structure 3 is arranged inside the outer casing 2.

In the embodiment shown in fig. 1, the flexible pipe 1 has two outer reinforcing structures 3 formed by a pair of tensile armour layers 4 and a pressure armour layer 5.

The pair of tensile armour layers 4 serve to reinforce the flexible pipe 1 against tensile forces, particularly in relation to the weight of the flexible pipe 1.

The pair of tensile armor layers 4 are formed by spirally winding a plurality of armor pieces 41. These armor elements 41 are wound with a long pitch, which characterizes a helix angle having an absolute value of between 20 ° and 60 °, advantageously between 25 ° and 55 °. To ensure that the pair of tensile armour layers 4 are balanced under internal and external pressure, the armour elements 41 of the first tensile armour layer 4 are wound at a helix angle opposite to the helix angle of the armour elements 41 of the second tensile armour layer 4.

The armor 41 is formed, for example, of a metallic material selected from stainless steel, or carbon steel containing between 0.1% and 0.8% carbon, or low alloy steel, or a mixture of these materials. Low alloy steel characterizes alloys with less than 5% of each alloying element and less than 1% manganese. According to an alternative, the armor 41 is formed from a composite material comprising fibers, such as carbon fibers, embedded in a polymer matrix, such as an epoxy resin. According to another embodiment, the polymer matrix is chosen, for example, from polyolefins, such as polyethylene or polypropylene, or polyaryletherketones, such as polyetheretherketone. The composite material may reduce the weight of the pair of tensile armour layers 4 and thereby reduce the overall weight of the flexible pipe 1.

The flexible pipe 1 may have one or two pairs of tensile armour layers 4.

The pressure armour 5 serves to reinforce the flexible pipe 1 against internal radial forces, in particular in relation to the pressure prevailing inside the flexible pipe 1. Pressure armour 5 is arranged inside the pair of tensile armour layers 4.

The pressure armour 5 has a coil of metal profile wound helically with a short pitch. By "short pitch" is meant a helix angle with an absolute value of between 70 ° and 90 °, advantageously 85 °.

The cross section of the metal profile of the pressure armour 5 is generally U-shaped, T-shaped, K-shaped, Z-shaped or I-shaped.

Depending on the pressure and temperature conditions, the flexible pipe 1 may be free of pressure resistant armour 5.

In addition, the flexible tube 1 has a protective inner sleeve 6.

The inner jacket 6 is arranged inside the reinforcing structure 3. The inner jacket 6 is arranged in particular inside the pressure-resistant armor 5. In case the inner reinforcing structure 8 loses its sealing properties, the inner sleeve 6 gives protection to the flexible tube 1. The inner sleeve 6 also constitutes a bearing member having a smooth surface on which the outer reinforcing structure 3 is formed. In fact, the inner reinforcing structure 8 generally has an irregular surface that may reduce the strength of the outer reinforcing structure 3 against radial and/or axial forces.

The inner sleeve 6 is formed of a polymer material. The polymer material of the inner sleeve 6 is selected from polyolefins such as polyethylene or polypropylene, polyamides such as polyamide 11 or polyamide 12, fluoropolymers such as polyvinylidene fluoride (polyvinylidene fluoride), polyaryletherketones such as polyetheretherketone.

According to another embodiment, the inner jacket 6 is formed from a composite material comprising a reinforcement embedded in a polymer matrix. The reinforcement is for example carbon fibre, the polymer matrix being formed of a material selected for example from the following materials: epoxy resins, polyamides, polyolefins such as polyethylene or polypropylene, polyaryletherketones such as polyetheretherketone.

The inner sleeve 6 has a thickness of between 1 mm and 20 mm, for example. It is generally made by extrusion molding.

The outer jacket 2 and the inner jacket 6 delimit an annular space 7 in which the outer reinforcement structure 3 is arranged.

The flexible pipe 1 may have additional metal and/or polymer layers. For example, the flexible pipe 1 may have an insulating jacket, for example arranged around the outer reinforcing structure 3. Thus, the annular space 7 may have a plurality of sub-annular spaces defined by the inner jacket 6 and by additional polymer or metal layers, and/or by the outer jacket 2 and by additional polymer or metal layers.

Advantageously, according to the invention, the outer reinforcing structure 3 is free to move longitudinally relative to the outer jacket 2 and relative to the inner jacket 6 when the flexible pipe 1 is bent. In other words, the outer reinforcement structure 3 is free of adhesive material. The flexible pipe 1 is of a non-adhesive type.

Regarding the geometry, materials, arrangement and manufacture of the outer jacket 2, the pair of tensile armour layers 4, the pressure armour 5 and possibly also the inner jacket 6, reference may be made, for example, to the standard documents API 17J published by the american petroleum institute in 2014, month 5, version 4, and API 17B published in 2014, month 5, version 5.

In addition, the tubular inner reinforcing structure 8 serves to reinforce the flexible pipe 1 against external radial forces.

The internal reinforcing structure 8 limits the risk of collapse of the flexible tube 1 under hydrostatic pressure, which may in particular be up to 500 bar. The inner reinforcing structure 8 is in contact with the gas and/or oil fluid.

The inner reinforcing structure 8 has a profiled strip 9 which is wound in a helical fashion to form a tubular structure.

By "profiled strip" according to the invention is meant a strip whose initial cross-section has been modified by bending in order to obtain a final cross-section with a different geometry. The cross-section of the profiled strip 9 is understood to be a section taken along a plane perpendicular to the axis a-a' of the flexible pipe 1.

The thickness of the profiled strip 9 is between 0.5 mm and 3.5 mm.

The thickness of the wall of the inner reinforcing structure 8 is for example greater than or equal to four times the thickness of the profiled strip 9. Advantageously, the thickness of the wall of the inner reinforcing structure 8 is between four and six times the thickness of the profiled strip 9. This can improve the strength of the inner reinforcing structure 8 against the internal and external pressures.

The profiled strip 9 is wound helically with a short pitch. By "short pitch" is meant a helix angle with an absolute value of between 70 ° and 90 °, advantageously 85 °.

The profiled strip 9 is formed of a metallic material resistant to the physicochemical characteristics of the natural gas and/or petroleum fluids being transported.

As shown in fig. 3, according to the invention, adjacent turns of the profiled strip 9 snap into each other. By snap-fit it is meant that adjacent turns of the profiled strip 9 fit together so that axial movement of one turn is limited by the adjacent turns.

The snap-fit is used to increase the strength of the inner reinforcing structure 8 under the hydrostatic pressure exerted on the flexible pipe 1 and under the internal pressure.

As shown in fig. 3, the adjacent helical turns of the profiled strip 9 snap into each other, defining an inner axial separation zone Ji, open to the inside of the flexible tube 1, and an outer axial separation zone Je, open to the outside of the flexible tube 1. The inner sleeve 6 disposed on the inner reinforcing structural member 8 tends to creep locally into the outer axial separation zone Je. In addition, the inner axial separation zone Ji defines a rough inner surface. The flexible tube 1 is then of the type known in the art as a non-smooth channel (english term "rough bore").

The inner axial separation region Ji and the outer axial separation region Je ensure the flexibility of the inner reinforcing structural member 8. In fact, the flexible pipe 1 is subjected to bending effects during storage, installation and operation of the flexible pipe 1. The amplitude of the inner axial separation zone Ji and the outer axial separation zone Je allows to adapt the radius of curvature of the flexible tube 1. Measured along the axis of the flexible pipe 1 between two adjacent regions of adjacent helical turns.

For example, fig. 4A shows a first inner axial separation zone Ji1 at the extrados, resulting from a large bending of the flexible tube 1, i.e. from a small radius of curvature of the flexible tube 1. In fig. 4B, the flexible tube 1 is subjected to less bending than in fig. 4A, resulting in a second inner axial separation zone Ji2 that is smaller than Ji 1. In fig. 4B, the radius of curvature of the flexible pipe 1 is larger than that of the flexible pipe in fig. 4A.

In addition, the profiled strip 9 has an S-shaped cross-section.

Advantageously, as shown in fig. 2, the cross-section of the profiled strip 9 has a first end region 12, a second end region 13 and a central region 14.

First end region 12 has a lower support free end 15, an upper support branch 16 connected to lower support free end 15 by a first transverse connecting branch 17.

According to a particularly advantageous embodiment, the lower bearing free end 15 of the first end region 12 is formed with a first section 22, said first section 22 extending from the first transverse connecting branch 17 to a second section 23. The second section 23 has a concave surface. The concave surface increases the thickness of the wall of the inner reinforcing structure 8, thereby increasing the strength thereof against internal and external pressure. As shown in fig. 3, the concavity is toward the lower support leg 18 of the second end region 13 of the adjacent coil. Advantageously, the free end of the second section 23 of one helical turn bears against and extends over at least a portion of the lower support branch 18 of an adjacent helical turn (not shown). This ensures the stability of the profile strip 9 structure, for example under internal or external pressure.

According to another embodiment, not shown, the concavity of the second section 23 faces the upper support branch 16 of the first end region 12 of the adjacent helical turn.

In addition, advantageously, the concave second section 23 has a straight top with a width greater than or equal to half the width of the second section 23.

Advantageously, first section 22 and upper support branch 16 are straight. Advantageously, the upper support branch 16 and the first section 22 are parallel to the axis of the flexible pipe 1. The first transverse connecting branch 17 is advantageously curved.

Thus, the first end region 12 forms an open first enclosure when the coils are not snapped onto each other.

The second end region 13 has a lower supporting branch 18, an upper supporting free end 19 connected to the lower supporting branch 18 by a second transverse connecting branch 20.

Advantageously, lower bearing branch 18 and upper bearing free end 19 are straight. The second transverse connecting branch 20 is advantageously curved.

Thus, the second end region 13 forms an open second enclosure when the coils are not snapped onto each other.

Central region 14 has a third transverse connecting branch 21 which connects upper support branch 16 of first end region 12 to lower support branch 18 of second end region 13.

Advantageously, the third transversal connecting branch 21 is curved.

As shown in fig. 3, the upper bearing free end 19 of the second end region 13 of one coil is advantageously inserted between the lower bearing free end 15 and the upper bearing branch 16 of the first end region 12 of an adjacent coil to form a snap-fit of the inner reinforcing structure 8.

Thus, the upper bearing free end 19 of one coil is inserted into the first housing at the first end region 12 of the adjacent coil. Thus, upper support free end 19 and upper support branch 16 overlap. Thus, after snapping, the side wall of the cabinet opposite the first transverse connecting branch 17 is closed by the second transverse connecting branch 20 of the adjacent spiral turn.

In addition, as shown in fig. 3, the profiled strip 9 defines at least one helical void 10.

The helical void 10 according to the present invention is defined as a gap radially defined by two adjacent regions of two adjacent helical turns. The expression "radial" is with respect to the flexible pipe 1, i.e. along a radius of the flexible pipe 1. The amplitude of the helical void 10 is measured radially between two adjacent regions of two adjacent helical turns. Advantageously, the amplitude of the helical void 10 is substantially constant, independent of the radius of curvature of the flexible pipe 1.

The helical void 10 is radially defined by the lower support leg 18 of the second end region 13 of one helical turn and by the lower support free end 15 of the first end region 12 of an adjacent helical turn.

According to another embodiment, the helical void 10 is radially defined by the lower support branch 18 of the second end region 13 of one helical turn and by the second section 23 of the lower support free end 15 of an adjacent helical turn.

According to another embodiment, the helical void 10 is radially defined by the lower support branch 18 of the second end region 13 of one helical turn and by the first section 22 of the lower support free end 15 of an adjacent helical turn. Alternatively, the helical void 10 is radially defined by the second section 23 of the upper support free end 19 and by the upper support branch 16 of the first end region 12 of the adjacent helical turn.

According to another embodiment, the helical void 10 is radially defined by the upper support free end 19 of the second end region 13 of one helical turn and by the lower support free end 15 of the first end region 12 of an adjacent helical turn.

According to another embodiment, the helical void 10 is radially defined by the upper support free end 19 of the second end region 13 of one helical turn and by the upper support branch 16 of the first end region 12 of an adjacent helical turn.

The profiled strip 9 may have a plurality of helical gaps 10. These embodiments of the spiral-shaped void 10 can be employed according to all possible combinations.

For example, the profiled strip 9 may have four helical gaps 10, wherein each helical gap is radially defined by the lower support branch 18 of the second end region 13 of a helical turn and by the second section 23 of the lower support free end 15 of an adjacent helical turn, by the lower support branch 18 of the second end region 13 of a helical turn and by the first section 22 of the lower support free end 15 of an adjacent helical turn, by the upper support free end 19 of the second end region 13 of a helical turn and by the lower support free end 15 of the first end region 12 of an adjacent helical turn, by the upper support free end 19 of the second end region 13 of a helical turn and by the upper support branch 16 of the first end region 12 of an adjacent helical turn, respectively.

The helical void 10 represents a path for gas and/or oil fluid to flow from the inner passage of the flexible pipe 1 to the inner jacket 6. At high pressure and temperature, gas molecules contained in the natural gas and/or petroleum fluid, such as methane, carbon dioxide, hydrogen sulfide, and gaseous water, may escape through the inner jacket 6 and accumulate in the annular space 7. The fugacity of the carbon dioxide in the annular space 7 is then generally greater than or equal to 50 bar. The fugacity of the hydrogen sulphide in the annular space 7 is then typically between 1 bar and 2 bar.

These gases, in combination with water which may result from the rupture of the outer jacket 2 or from the condensation of water dissipated through the inner jacket 6, may cause corrosion of the outer reinforcing structure 3 and/or its chemical ageing, causing the rupture of the flexible tube 1.

In order to limit the risk of rupture of the flexible pipe 1, the inner reinforcing structure 8 is, according to the invention, further provided with a seal 11 helically wound in the helical interspace 10 for limiting the flow of gas and/or oil fluid from the inner passage to the annular space 7.

According to the embodiment shown in fig. 5A, the seal 11 is helically wound within the helical void 10 radially defined by the lower support branch 18 of the second end region 13 of one helical turn and by the second section 23 of the lower support free end 15 of an adjacent helical turn.

According to another embodiment shown in fig. 5B, the seal 11 is helically wound in the helical void 10 radially defined by the upper bearing free end 19 of the second end region 13 of one helical turn and the lower bearing free end 15 of the first end region 12 of an adjacent helical turn.

According to another embodiment shown in fig. 5C, the seal 11 is helically wound in the helical void 10 radially defined by the upper support free end 19 of the second end region 13 of one helical turn and by the upper support branch 16 of the first end region 12 of an adjacent helical turn.

According to another embodiment shown in fig. 5D, the seal 11 is helically wound in the helical void 10 radially defined by the lower support branch 18 of the second end region 13 of one helical turn and by the first segment 22 of the lower support free end 15 of an adjacent helical turn.

The invention makes it possible to maintain the tightness of the reinforcing structure 8 against the natural gas and/or petroleum fluids transported, independently of the radius of curvature of the flexible pipe 1. In fact, as shown in fig. 4A and 4B, the inner axial separation zone Ji varies with the radius of curvature of the flexible tube 1. According to the invention, the seal 11 is helically wound in the interspace 11 with only a significant variation in amplitude measured radially with respect to the axis of the flexible pipe 1. The seal 11 thus ensures its function in a constant manner. The flexible pipe 1 is then suitable for both static and dynamic applications.

In order to increase the tightness of the inner reinforcing structure 8, the latter advantageously has a plurality of sealing elements 11.

The inner reinforcing structure 8 has, for example, between two and four sealing elements 11, each of which is wound in a spiral in, for example, the aforementioned spiral gap 10.

Advantageously, the inner reinforcing structure 8 has four seals 11, each of which is wound helically in the helical gap 10, for example, as described above.

Advantageously, the seal 11 fills at least 50% of the volume of the helical void 10.

The seal 11 has a polygonal cross-section, for example rectangular, square, hexagonal.

Advantageously, the seal 11 has a rectangular cross section. This embodiment is particularly suitable for the geometry of the helical interspace 10 defined by the straight branches of the cross section of the profiled strip 9, so that the tightness of the inner reinforcing structure 8 can be improved.

Preferably, the width of the cross section of the seal 11 is greater than or equal to half the width of the upper support branch 16 along axis a-a', or greater than or equal to half the width of the top of the second section 23 of the lower support free end 15. Advantageously, the width of the seal 11 is greater than 2 mm. Preferably, the thickness of the seal 11 is greater than half the thickness of the profiled strip 9. Advantageously, the thickness of the seal 11 is greater than 1.5 mm.

Alternatively, the seal 11 has an elliptical cross-section. This cross section is particularly suitable for the geometry of the helical void 10 radially defined by the lower support branch 18 of a helical turn and by the second section 23 of the adjacent helical turn, the second section 23 having a concavity directed towards the lower support branch 18. Thus, the sealing element 11 may substantially fill the entire volume of the helical void 10 to improve the tightness of the inner reinforcing structure 8.

Alternatively, the seal 11 has a circular cross-section or any other geometry suitable for the present invention.

When the inner reinforcing structure 8 has a plurality of seals 11, each seal 11 may have a different cross-section to accommodate the geometry of each helical void 10.

The seal 11 has a body formed of one material. Such as a polymer or a metal.

The metallic material of the body is for example selected from stainless steel, copper alloys, or any other material having chemical properties resistant to the natural gas and/or petroleum fluids transported under the conditions of transport pressure and temperature. An additional advantage of the seal 11 having a body formed from a metallic material is that the electrical conductivity can be measured on the seal 11. This allows, in particular, to detect possible breakages of the seal 11 after the manufacture of the inner reinforcing structure 8.

According to an alternative, the material of the body of the seal 11 is formed by glass fibres. This also controls the integrity of the seal 11.

The polymeric material is chosen, for example, from thermoplastics such as polyaryl diketones (polyaryl thc lane), in particular polyetheretherketones. Advantageously, the polymeric material is chosen from fluoropolymers such as polyvinylidene fluoride, polyolefins such as polyethylene or polypropylene, polyamides, or polyarylene sulfides (polyarylene sulfides), elastomers such as silicone, fluorosilicones, chloroprene, copolymers of butadiene and acrylonitrile (NBR: the English term "nitrile butadiene rubber"), chloroprene rubber, isobutylene-isoprene copolymer, ethylene-propylene-diene monomer (EPDM), or thermoplastic elastomers such as thermoplastic silicones or styrene thermoplastic elastomers.

Alternatively, the body is formed from a composite or hybrid material.

Advantageously, the polymeric material of the body is for example chosen from polymers having an elastic modulus greater than or equal to 2500 mpa, measured at 20 ℃.

The body material may also have a filler for reducing the coefficient of friction between the seal 11 and the profiled strip 9. The material of the filler is, for example, polytetrafluoroethylene.

Advantageously, the seal 11 comprises a polymer coating for improving the tightness of the seal 11 against natural gas and/or petroleum fluids. The polymeric coating is formed, for example, from a material having a modulus of elasticity, measured at 20 ℃, of less than or equal to 2000 megapascals.

Preferably, the permeability of the polymer coating to hydrogen sulphide and/or carbon dioxide at a pressure of 40 bar and a temperature of 80 ℃ is lower than the permeability of the body of the seal 11 to hydrogen sulphide and/or carbon dioxide under the same conditions.

The seal 11 may have at least one reinforcement for increasing the compressive strength of the seal 11. The reinforcement is inserted for example inside the body of the seal 11. The reinforcement is formed, for example, of a metallic material, or of poly-paraphenylene terephthalamide, or of another thermoplastic polymer, for example selected from the polyaryletherketone family, such as polyetheretherketone, or of a composite material. According to an alternative, the reinforcement is arranged around the seal 11.

A reinforcement formed of a metallic material is also used to control the integrity of the seal 11. In fact, by measuring, for example, an electric signal inside the seal 11, it is possible to determine whether the seal 11 is broken or not.

According to an alternative or in combination with a reinforcement, the seal 11 has optical fibres arranged in the body of the seal 11. The optical fibres may for example control the temperature along the flexible tube 1.

Advantageously, the metal reinforcement is electrically energized, generating thermal energy by joule effect, to solve the possible problem of blockage of hydrates that can be generated when the temperature of the gas and/or oil fluid is lowered.

According to one embodiment, the body of the seal 11 is porous. Advantageously, the porosity of the body is between 0.5% and 10%. This may facilitate the manufacture of the inner reinforcing structure 8, since the snapping of the profiled strip 9 is not restricted by the presence of the seal 11, which can be deformed to allow such snapping.

According to one embodiment, the seal 11 is fixed to at least a portion of the profiled strip 9. The fixation is for example performed by gluing. This allows the seal 11 to be retained in the helical void 10 under pressure or after the flexible pipe 1 has been bent.

According to one embodiment shown in fig. 6, the inner reinforcing structure 8 has a sealing resin 24, and the sealing resin 24 is used to improve the sealing property of the inner reinforcing structure 8. The sealing resin 24 is, for example, disposed in at least a part of the volume of a first casing of a coil, which is closed laterally by the second transverse connecting branch 20 of the adjacent coil. Advantageously, a sealing resin 24 is disposed in at least a portion of the volume of the first housing of each coil.

The sealing resin 24 is, for example, an epoxy or cyanoacrylate or silicone type resin.

The sealing resin 24 is injected in liquid form, for example, by injection holes 25 made through the profiled strip 9. An injection hole 25 is made, for example, through the upper support branch 16 of the first end region 12 of one coil and the upper support free end 19 of the adjacent coil in the stack, preferably through each coil.

Advantageously, at least one inspection hole (not shown) is also made through the profiled strip 9. The inspection hole can control the amount of the sealing resin 24 inputted. The inspection holes are holes made through the profiled strip 9 on the same spiral with the injection holes 25, or on adjacent spirals.

For example, after the profiled strip 9 has been wound and snapped on, injection holes 25 and possibly also inspection holes are made through the profiled strip 9. This embodiment allows positioning of the injection holes 25 and the inspection holes along the inner reinforcing structure 8. According to another embodiment, injection holes 25 and possibly also inspection holes are made through the profiled strip 9 before the profiled strip 9 is wound. According to another embodiment, the injection holes 25 and possibly also the inspection holes are made before shaping the metal strip to form the profiled strip 9.

The polymerization temperature of the sealing resin 24 is higher than or equal to 10 ℃, preferably between 10 ℃ and 35 ℃.

Advantageously, the sealing resin 24 also closes the injection holes 25 to limit the leakage path of the natural gas and/or petroleum fluid.

A method of manufacturing a flexible pipe 1 for transporting natural gas and/or petroleum fluids submerged in a body of water will now be described.

The method of manufacturing the flexible pipe 1 comprises the steps of:

(a) the profiled strip 9 is helically wound to form a tubular inner reinforcing structure 8 for reinforcing the flexible pipe 1 against external radial forces applied to the flexible pipe 1, adjacent helical turns of the profiled strip 9 snap into each other, the profiled strip 9 defining at least one helical void 10,

(b) a protective inner jacket 6 is provided around the inner reinforcing structure 8,

(c) around the polymeric sealing liner 6, there is provided a metallic outer reinforcing structure 3, which serves to reinforce the flexible pipe 1 against internal radial and/or tensile forces,

(d) around the outer reinforcing structure 3, a polymer sealing jacket 2 is provided for restricting water from a body of water from entering the flexible pipe 1, the jacket 2 and the inner jacket 6 defining an annular space 7, the outer reinforcing structure 3 being arranged in the annular space,

step (a) further comprises the steps of: at least one seal 11 is helically wound in the helical void 10 for restricting the flow of gas and/or oil fluid from the internal passage to the annular space 7.

For example, the precursor tape is loaded onto a first bobbin.

Advantageously, the precursor strip has one or more injection holes 25 and optionally also one or more inspection holes.

The seal 11 is loaded onto the second bobbin.

The tape was unwound and inserted into a molding machine (profileuse). The precursor strip is bent in a forming machine to form a profiled strip 9.

The profiled strip 9 is then advantageously wound helically around the mandrel at a short pitch. By "short pitch" is meant a helix angle with an absolute value of between 70 ° and 90 °, advantageously 85 °. The wound profiled strip 9 defines a helical void 10.

The seal 11 is unwound and, simultaneously with the winding of the profiled strip 9, is wound helically in the helical interspace 10. This facilitates the insertion of the seal 11 into the spiral-shaped interspace 10.

The spiral turns of the profiled strip 9 are then snapped together by a pressing mechanism arranged around the mandrel, which applies a pressing force on the spiral turns of the profiled strip 9.

Advantageously, after this step, one or several injection holes 25 and possibly also one or several inspection holes are made through the profiled strip 9. According to another embodiment, the injection hole 25 is made before the precursor strip is inserted into the molding machine.

An inner sleeve 6 is formed around the inner reinforcing structure 8. For example, the inner sleeve 6 is extruded directly around the inner reinforcing structure 8.

Then, at least one outer reinforcing structure 3 is arranged around the inner sleeve 6. Advantageously, two outer reinforcing structures 3 are arranged, for example one pressure armour 5 and then a pair of tensile armour layers 4.

For example, a metal profile is loaded onto the bobbin. The metal profile is then spread out so that it is arranged helically around the inner jacket 6 with a short pitch to form the pressure-resistant armor 5. By "short pitch" is meant a helix angle with an absolute value of between 70 ° and 90 °, advantageously 85 °.

Next, some of the armour 41 are loaded onto a plurality of bobbins, the armour is unrolled and arranged helically at long pitches around the pressure armour 5 simultaneously to form pairs of tensile armour layers 4. By "long pitch" is meant a pitch angle having an absolute value of between 20 ° and 60 °, advantageously between 25 ° and 55 °.

Subsequently, the jacket 2 is formed. For example, the extruded jacket 2 is directly wrapped around the tensile armour layer 4. Alternatively, some of the strips are extruded and then wound around the outer reinforcing structure 3.

Thus, an annular space 7 is formed between the inner jacket 6 and the outer jacket 2, in which the outer reinforcing structure 3 is arranged.

Thus, a flexible tube is formed with a limited risk of breakage.

Advantageously, the integrity of the inner reinforcing structure 8 according to the invention is verified by injecting a fluid into, for example, the reinforcing structure 8 at a pressure generally higher than the working pressure, in particular the pressure determined in the standard documents of the american petroleum institute.

The fluid is for example a liquid, such as water or oil. According to another embodiment, the fluid is a gas, such as compressed air.

The fluid may be injected after the inner reinforcing structure 8 is manufactured. The sealing member is then mounted at the end of the inner reinforcing structure 8.

According to another embodiment, the fluid is injected after the inner jacket 6 is formed. According to this embodiment, the fluid is injected into the reinforcing structure 8, or in the volume between the inner jacket 6 and the reinforcing structure 8.

According to one embodiment, the volume between the inner sleeve 6 and the inner reinforcing structure 8 is filled with a fluid, such as methanol or water, to reduce the pressure difference between the inner channel of the flexible tube 1 and the outside of the flexible tube 1. The volume is filled through a hole in the end of the flexible pipe 1 communicating with the volume during installation of the flexible pipe 1 into the water, or during manufacture of the flexible pipe 1.

This volume is filled with water from the body of water during installation of the flexible pipe 1, which may lead to corrosion of the inner reinforcing structure 8. In order to limit corrosion and at the same time facilitate pressure equalization between the inner channel and the outside of the flexible pipe 1, a device for desalinating water of a body of water is arranged, for example, in the head. The desalination device is, for example, an ion exchanger, or a reverse osmosis membrane.

Claims

1. A flexible pipe (1) for transporting natural gas and/or petroleum fluids, for submersion in a body of water, said flexible pipe (1) having from the outside inwards thereof:

-a sealing jacket (2) for restricting the ingress of water from a body of water into the flexible pipe (1),

-at least one outer reinforcing structure (3) for reinforcing the flexible pipe (1) against internal radial and/or tensile forces,

-a protective inner sleeve (6),

-an annular space (7) delimited by a sealing outer sleeve (2) and a protective inner sleeve (6), an outer reinforcement structure (3) being arranged within the annular space (7),

-a tubular inner reinforcing structure (8) for reinforcing the flexible pipe (1) against external radial forces exerted on the flexible pipe (1), the tubular inner reinforcing structure having:

-a profiled strip (9) helically wound to form a tubular inner reinforcing structure (8), adjacent helical turns of the profiled strip (9) being snapped into each other, the profiled strip (9) defining at least one helical void (10),

characterized in that the tubular inner reinforcing structure (8) further comprises:

-at least one seal (11) for restricting the flow of gas and/or oil fluid from the inner passage to the annular space (7), the seal (11) being helically wound in the at least one helical void (10).

2. Flexible pipe (1) according to claim 1, characterized in that the cross section of the profiled strip (9) has:

-a first end zone (12) having a lower bearing free end (15), an upper bearing branch (16) connected to the lower bearing free end (15) by a first transverse connecting branch (17),

-a second end region (13) having a lower support branch (18), an upper support free end (19) connected to the lower support branch (18) by a second transverse connecting branch (20),

-a central zone (14) having a third transverse branch (21) connecting the upper support branch (16) of the first end zone (12) to the lower support branch (18) of the second end zone (13);

and the number of the first and second electrodes,

the upper bearing free end (19) of the second end region (13) of a first coil is inserted between the lower bearing free end (15) and the upper bearing branch (16) of the first end region (12) of an adjacent coil to form a snap fit of the tubular inner reinforcing structure (8).

3. Flexible pipe (1) according to claim 2, characterized in that the helical interspace (10) is radially delimited by a lower supporting branch (18) of the second end region (13) of a first helical turn and by a lower supporting free end (15) of the first end region (12) of an adjacent helical turn,

and/or radially by an upper bearing free end (19) of the second end region (13) of a first helical turn and by a lower bearing free end (15) of the first end region (12) of an adjacent helical turn,

and/or radially by the upper bearing free end (19) of the second end region (13) of a first coil and by the upper bearing branch (16) of the first end region (12) of an adjacent coil.

4. Flexible pipe (1) according to claim 2 or 3, characterized in that the lower support free end (15) of the first end region (12) of a spiral turn has a first section (22) extending from the first transverse connecting branch (17) to a second section (23) having a concavity directed towards the lower support branch (18) of the second end region (13) of an adjacent spiral turn.

5. Flexible pipe according to claim 4, characterized in that the helical interspace (10) is radially delimited by the lower bearing branch (18) of a helical turn and by the second segment (23) of the lower bearing free end (15) of the adjacent helical turn.

6. Flexible pipe (1) according to claim 2 or 3, characterized in that the upper bearing free end (19) of the second end region (13) of a spiral turn has a first section (22) extending from the second transverse connecting branch (20) to a second section (23) having a concavity facing the upper bearing branch (16) of the first end region (12) of an adjacent spiral turn; and the helical void (10) is further defined by said second section (23) of the upper bearing free end (19) and by the upper bearing branch (16) of the first end region (12) of the adjacent coil.

7. Flexible pipe (1) according to any of the preceding claims, characterized in that the inner reinforcing structure (8) has a plurality of seals (11).

8. Flexible pipe (1) according to any of the preceding claims, characterized in that the seal (11) has an oval cross-section.

9. Flexible pipe (1) according to any of claims 1 to 7, characterized in that the seal (11) has a rectangular cross section.

10. Flexible pipe (1) according to claim 9, characterized in that the thickness of the sealing (11) is less than or equal to half the thickness of the profiled strip (9).

11. Flexible pipe (1) according to any of the preceding claims, characterized in that the seal (11) has a body formed of a metal or polymer material.

12. Flexible pipe (1) according to claim 11, characterized in that the polymer material is selected from thermoplastics or elastomers or thermoplastic elastomers.

13. Flexible pipe (1) according to claim 11 or 12, characterized in that said metal or polymer material has a filler for reducing the coefficient of friction between the seal (11) and the profiled strip (9).

14. Flexible pipe (1) according to any of the preceding claims, characterized in that the seal (11) has a polymer coating for enhancing the tightness of the seal (11) against natural gas and/or petroleum fluids.

15. Flexible pipe (1) according to any of the preceding claims, characterized in that the seal (11) has at least one reinforcement for increasing the compressive strength of the seal (11).

16. Flexible pipe (1) according to any of the preceding claims, characterized in that the sealing (11) is fixed to at least a part of the profiled strip (9), for example by gluing.