FR3078360A1 - CONDUIT FOR FORMED FLUID OF REVERSIBLE JUNCTION MODULES - Google Patents

Abstract

The present invention relates to a conduit (10) adapted to be traversed by a fluid, comprising a first (24) and a second (26) tubular membranes and a connecting device assembling ends of each of said membranes. The junction device includes a first (64) and a second (66) axial locking member, an inner waistband (60) and an annular outer waistband (62). Each membrane end (40, 42) is folded around one of the axial locking members. The membranes are inserted into each other so as to form a contact interface (96). The inner and outer belts are arranged radially on either side of said interface and fixed (80, 82) to one another. Each axial locking member (64, 66) abuts axially against the inner (60) or outer (62) waistband.

Description

Fluid line formed by modules with reversible junction

The present invention relates to a pipe capable of being traversed by a fluid, of the type comprising first and second tubular membranes connected to each other and aligned along a main axis, each of said first and second membranes being capable of delimiting a interior space, the pipe further comprising a device for joining the first and second membranes, assembling a first end of the first membrane with a second end of the second membrane.

The invention is particularly applicable to water pipes, especially cold water pipes integrated into thermal energy systems of the seas (ETM). Such systems generate electricity, exploiting the temperature difference between surface and deep waters to drive a generator.

These systems require water lines to draw cold water deep down. These water pipes have a significant length, for example more than 600 meters or even more than 1000 meters. In order to obtain such lengths, it is known to produce these pipes directly on site, from sections assembled together, as described for example in documents FR2978979 and FR3017179.

Junctions between sections must be designed to withstand extreme environmental conditions, for example swell and / or currents. Said junctions must in particular have significant resistance to different mechanical stresses, while guaranteeing optimum sealing of the pipe.

Furthermore, the on-site assembly of the pipes generates costly operations, in particular carried out at sea. Thus, it is desirable that the assembly of the sections requires implementation as simple and rapid as possible, taking into account constraints such as the large diameter of the pipes and the large dimensions of the corresponding junctions.

The present invention aims to meet such needs. To this end, the invention relates to a pipe of the aforementioned type, in which the joining device comprises: first and second axial locking elements; an inner belt; an outer belt; and a plurality of fasteners for the interior and exterior belts; each of said first and second axial locking elements and each of said belts having an annular shape arranged around the main axis. Each of the first end of the first membrane and the second end of the second membrane is folded around, respectively, the first and second (66) axial locking members; the first end of the first membrane is inserted into the second end of the second membrane, so as to form a contact interface between said first and second membranes at a non-zero axial height; the inner and outer belts are arranged radially on either side of said interface, respectively in contact with the first and second membranes, said inner and outer belts being fixed to one another by the plurality of elements of fixing distributed around the main axis; and the first and second axial locking elements come into axial abutment against, respectively, the inner belt and the outer belt.

According to other advantageous aspects of the invention, driving comprises one or more of the following characteristics, taken in isolation or in any technically possible combination:

- The first membrane is arranged radially between the second locking element and the inner belt; and / or the second membrane is arranged radially between the first locking element and the outer belt;

- A free edge of the first end of the first membrane is folded inward, so as to be disposed in the interior space delimited by said first membrane; and / or a free edge of the second end of the second membrane is folded outwards, so as to be arranged outside the interior space delimited by said second membrane;

- At least one of the first end of the first membrane and the second end of the second membrane has a plurality of axial notches distributed around the main axis;

- one end of the axial cuts is arranged in the contact interface;

- the inner belt has a crown formed in one piece; and / or the outer belt is formed of segments in arcs of a circle, assembled in a removable manner;

- at least one of the first and second axial locking elements is formed by sectors in arcs of a circle, assembled in a removable manner;

- at least one of the first and second membranes is flexible and deformable, the pipe further comprising holding members maintaining said at least one of the first and second membranes around the interior space.

The invention further relates to a method of mounting a pipe as described above, comprising the following steps: folding the first end of the first membrane around the first axial locking element, then assembling said first membrane with the inner belt, in axial abutment with said first blocking element; folding the second end of the second membrane around the second axial locking element, then inserting the first end of the first membrane into the second end of the second membrane, so as to form the contact interface; then assembling the outer belt with the inner belt, radially on either side of said contact interface, said outer belt coming into axial abutment with the second locking element.

According to a preferred embodiment of the mounting method, before the insertion of the first end of the first membrane into the second end of the second membrane, the holding members are assembled to at least one of said first and second membranes.

The invention also relates to a thermal energy system for the seas comprising at least one pipe as described above.

The invention will be better understood on reading the description which follows, given solely by way of nonlimiting example and made with reference to the drawings in which:

- Figure 1 is a partial perspective view of a pipe according to an embodiment of the invention;

- Figure 2 is a detail view, in longitudinal section, of the pipe of Figure 1;

- Figure 3 is a perspective view, in dissociated configuration, of a first element of the pipe of Figure 1;

- Figure 4 is a top view, in dissociated configuration, of a second element of the pipe of Figure 1;

- Figures 5 and 6 are schematic representations of steps in a method of mounting the pipe of Figure 1; and

- Figure 7 is a schematic representation of a thermal energy system of the seas comprising the pipe of Figure 1.

FIG. 1 represents a pipe 10 according to an embodiment of the invention, capable of being traversed by a fluid such as a liquid or a gas. Line 10 is preferably a cold seawater line. Line 10 is for example integrated into a system 200 for thermal energy of the seas shown diagrammatically in FIG. 7, analogous to the system described in document FR3017179.

In the operating configuration, the pipe 10 extends along a main vertical axis 12. In the following description, the terms "axial" and "radial" are understood with respect to said main axis.

The pipe 10 is formed of a plurality of modules 14, 16, 18 aligned along said main axis 12, two adjacent modules 14, 16, 18 being connected by a junction device 20, 22.

In particular, a first module 14 and a second module 16 of the pipe 10, connected by a junction device 20, are visible in FIG. 1. The second module 16 is also connected to a third module 18, by a device junction 22 similar to device 20.

In the following description, it is considered that the modules 14, 16, 18 and the joining devices 20, 22 of the pipe 10 are substantially identical to each other. The detailed description which follows, of the first 14 and second 16 modules and of the junction device 20, applies respectively to all the modules and to all the junction devices of the pipe 10, with the possible exception of the modules (not shown ) forming ends of the pipe 10.

Each module 14, 16 comprises a tubular membrane 24, 26 and retaining members 28. The tubular membrane 24, 26 is flexible and deformable. Furthermore, the tubular membrane 24, 26 is preferably impermeable to liquids, in particular impermeable to water. The tubular membrane 24, 26 is for example formed of a woven textile material, coated with a waterproofing plastic.

The holding members 28 are fixed to the tubular membrane 24, 26 so as to give said membrane a substantially cylindrical shape of revolution. The tubular membrane 24, 26 thus defines an interior space 29 (FIG. 2) capable of forming a water pipe.

In the embodiment shown, the holding members are rings 28 inserted in the tubular membrane 24, 26. The rings 28 are of substantially circular shape, arranged perpendicular to the main axis 12 and centered on said axis. The rings 28 are for example made of concrete, metal or composite material. By way of example, the rings 28 have an external diameter of between 2 m and 15 m, corresponding substantially to the diameter of the interior space 29.

According to a variant not shown, the holding members comprise for example an inflatable wall, as described in the document FR969566.

FIG. 3 shows the first module 14 in a dissociated configuration, before assembly of the pipe 10. The following description of the first module 14 also applies to the second module 16.

The tubular membrane 24 of the first module 14 extends along the main axis 12 between a first 30 and a second 32 free edges. Over the entire periphery of the membrane 24, a height 34, substantially constant along said main axis, separates said first 30 and second 32 free edges. Said height 34, corresponding substantially to a length of the module 14, is preferably between 2 m and 15 m, preferably between 5 and 6 meters.

At least one end 40, 42 of the tubular membrane 24, near the first 30 or the second 32 free edge, comprises a plurality of axial notches 36, 38 distributed around the main axis. Preferably, as shown in FIG. 3, each of the first 40 and second 42 ends of the tubular membrane 24 comprises a plurality of axial notches, respectively 36 and 38, starting respectively from the first 30 and from the second 32 free edge.

The notches 36 of the first end 40 have a substantially identical length 44 along the main axis 12. Similarly, the notches 38 of the second end 42 have a substantially identical length 46 along the main axis 12. Preferably, the lengths 44 and 46 are substantially equal. The lengths 44 and 46 are much less than the height 34 and are for example between 60 cm and 200 cm.

Preferably, each notch 36, 38 has a substantially triangular shape, a base of the triangle corresponding to the first 30 or to the second 32 free edge and the opposite vertex corresponding to the other end 50, 52 of the notch.

The axial cuts 36 and 38 respectively divide the first 40 and the second 42 ends of the tubular membrane 24 into a series of strips, respectively 56 and 58, of the same axial length 44 or 46. Each strip 56 or 58 is in particular deformable independently of the other strips.

Preferably, a number of axial cuts 36, 38 and strips 56, 58 of the same end 40 or 42 is between ten and fifty.

In the following description, the first free edge 30 and the first end 40 of a module 14, 16 of the pipe 10 relate to the lower free edge and to the lower end of said module, along the vertical. Likewise, the second free edge 32 and the second end 42 of a module 14, 16 relate to the upper free edge and to the upper end of said module of the pipe 10.

Figure 2 shows a sectional view of the pipe 10 at the junction device 20 assembling the first 14 and the second 16 modules. FIG. 4 shows a top view of the joining device 20 in a dissociated configuration, before assembly of the pipe 10.

The joining device 20 comprises: an inner belt 60; an outer belt 62; a first 64 and a second 66 axial locking elements; and a plurality of elements 68 for fixing the interior and exterior belts.

In the operating configuration of the pipe 10, shown in FIGS. 1 and 2, each of the interior 60 and exterior 62 belts and each of the first 64 and second 66 axial locking elements has an annular shape substantially centered on the main axis 12.

The inner belt 60 comprises a crown 70, preferably formed in one piece, as well as gripping reliefs 72. The crown 70 has the shape of a section of cylinder of revolution and has an internal surface and an external surface 74 cylindrical. The gripping reliefs 72 form radial projections, oriented towards the main axis 12, relative to the internal surface of the crown.

Furthermore, at least one edge of the crown 70 forms a substantially planar surface 75, perpendicular to the main axis 12.

The outer belt 62 is formed of several segments 76 in arcs of a circle, which can be assembled with one another in a removable manner, the assembled segments forming an internal surface 78 substantially cylindrical of revolution. In the embodiment shown, the outer belt 62 has four segments 76, each segment corresponding to an arc of 90 ° from the internal surface 78.

Furthermore, at least one edge of the outer belt 62 forms a substantially planar surface 79, perpendicular to the main axis 12.

The inner 60 and outer 62 belts are preferably formed from one or more composite materials, comprising reinforcing fibers in a polymer matrix. Alternatively, the inner belt 60 and / or outer 62 is metallic.

The fastening elements 68 are for example of the screw-nut type, each element comprising in particular a threaded rod 80 and a nut 82. The threaded rods 80 are integral with the inner belt 60, one end of each rod forming a radial projection towards the outside relative to the external surface 74. The threaded rods 80 are distributed over the crown 70, preferably regularly, around the main axis 12.

Furthermore, the outer belt 62 has a plurality of through holes 84, extending radially, able to assemble with the rods 80 as in the operating configuration of the pipe 10. In said configuration, the inner belts 60 and outer 62 are arranged coaxially, the outer belt 62 around the inner belt 60, the flat surfaces 75 and 79 being oriented opposite one another.

Each of the first 64 and second 66 locking elements is formed of sectors 88, 90 identical, in arcs of a circle. The sectors of the same element 64, 66 are assembled to each other in a removable manner, for example by means of pins (not shown). The number of sectors 88, 90 forming the first 64 and / or the second 66 blocking element is for example between eight and thirty-two, an arc length of a sector 88, 90 being for example between 20 cm and 2.5 m. Preferably, an arc length of a sector is of the order of 1 m.

Preferably, the arc length of a sector 88, 90 is greater than the arc length of a strip 56, 58 of the membrane 24. For example, the arc length of each sector corresponds to a number between one and three.

A diameter of the first element 64 is slightly less than a diameter of the second element 66. More specifically, in the operating configuration of the pipe 10, the first blocking element 64 has substantially the same outside diameter as the inner belt 60 and the second element locking 66 has substantially the same inside diameter as the outer belt 62.

Each of the first 64 and second 66 locking elements has a substantially planar surface 92, 94, perpendicular to the main axis 12. Preferably, in a plane passing through said main axis, each sector 88, 90 has a substantially rectangular section or trapezoidal.

The first 64 and second 66 blocking elements are preferably formed from one or more polymer or composite materials. As a variant, the first 64 and / or the second 66 blocking element is metallic.

In the operating configuration of the pipe 10, as visible in FIG. 2, the first end 40 of the membrane 24 of the first module 14 is folded axially around the first blocking element 64. Preferably, said first end 40 is folded inwards, so that the first free edge 30 is substantially in contact with an internal surface of the membrane 24.

In said operating configuration, the second end 42 of the membrane 26 of the second module 16 is folded axially around the second locking element 66. Preferably, said second end 42 is folded outwards, so that the second free edge 32 is substantially in contact with an external surface of the membrane 26.

Furthermore, in said operating configuration, the first end 40 of the membrane 24 is inserted into the second end 42 of the membrane 26. According to a non-zero axial height 95, an external surface of the membrane 24 is in contact with a internal surface of the membrane 26, forming a contact interface 96 between the first 14 and second 16 modules. In order to guarantee the watertightness of the pipe 10, the ends 50, 52 of the notches 36, 38 are preferably arranged inside said interface.

Preferably, the height 44, 46 of the notches 36, 38 is substantially equal to 1.5 times to 2 times the axial height 95 of the contact interface 96. Preferably, the axial height 95 of the contact interface 96 is included between 30 cm and 90 cm. For example, the axial height 95 is of the order of 40 cm for an axial loading of the pipe of approximately 330 tonnes.

In addition, the interior 60 and exterior 62 belts are assembled together. The external surface 74 of the crown 70 and the internal surface 78 of the external belt sandwich the contact interface 96, as well as the strips 56, 58 of the membranes 24 and 26, folded inwards and in respectively. outside. Thus, the interior 60 and exterior 62 belts sandwich four thicknesses of membrane 24, 26 in total. Said four thicknesses are punctually crossed by the rods 80 of the fastening elements 68, each rod being held by a nut 82 screwed in contact with the outer belt 62. Preferably, at least part of the rods 80 passes through the membranes 24 and 26 at level of the notches 36, 38.

According to one embodiment (not shown), the first edge 30 of the membrane 24 and / or the second edge 32 of the membrane 26 are sandwiched between the inner 60 and outer 62 belts. Alternatively, as shown in the figure 2, said first 30 and second 32 edges are projecting axially from said belts.

Finally, in the operating configuration, each of the planar surfaces 92, 94 of the first 64 and second 66 locking elements comes into axial abutment, respectively against each of the planar surfaces 75, 79 of the inner 60 and outer 62 belts. Each stop takes into account sandwich, respectively, the strips 56 of the membrane 24 and the strips 58 of the membrane 26.

Such a junction of the first 14 and second 16 modules allows the pipe 10 to effectively resist radial, axial and shear stresses, while ensuring good sealing. In particular, the contact interface 96, sandwiched between the interior 60 and exterior 62 belts, makes it possible to distribute the stresses over a large area. The first 64 and second 66 locking elements, forming axial stops, prevent the first 14 and second 16 modules from being dissociated from each other by traction.

In addition, the production of the elements of the joining device 20 in polymeric or composite materials allows a significant weight saving compared to a metallic device.

First and second axial ends of the contact interface 96 are disposed at the first 64 and second 66 blocking elements, respectively. Preferably, at said first axial end, the membrane 26 of the second module 16 is radially sandwiched between the first locking element 64 and the outer belt 62. Preferably, at said second axial end of the interface contact 96, the membrane 24 of the first module 14 is radially sandwiched between the second locking element 66 and the inner belt 60. Such a configuration gives better resistance to the junction.

A method of mounting a pipe 10 from the modules 14, 16 and the junction devices 20 will now be described, with the support of Figures 5 and 6. In particular, the assembly of the first module 14 to the second module 16, already assembled in the third module 18, will be described.

The method of mounting the pipe 10 is for example implemented on a platform 100, or a barge, floating on a body of water 102. Said platform 100 comprises a well 104 making it possible to lower the pipe vertically 10, as it is formed, towards the depths of said body of water 102. The platform 100 further comprises an assembly station 105, located above the well 104, and an assembly station 106, preferably located near said well.

The first module 14 is supplied in dissociated form, as in FIG. 3. Likewise, the joining device 20 is supplied in dissociated form.

At the assembly station 106, the membrane 24 is assembled to a cylindrical support 108. Said support, for example an inflatable cylinder section, maintains the membrane 24 in its cylindrical shape of the operating configuration of the pipe 10.

The first free edge 30 of the membrane 24 being oriented upwards, each sector 88 of the first blocking element 64 is presented opposite the corresponding strip or strips 56. Each strip is then folded inwards from the membrane 24, around the corresponding sector 88. The triangular cut of the notches 36 makes it possible to avoid overlapping of the strips 56 at the level of the first edge 30.

The adjacent sectors 88 are then linked together, for example by pins, to form four fragments 110 of the first blocking element 64, each fragment forming an arc of approximately 90 °.

As shown in FIG. 5, the inner belt 60 is then presented facing the first end 40 of the membrane 24, in particular by a lifting device 112 connected to the gripping reliefs 72. The inner belt 60 is then disposed inside said first end 40. The axial position of the first edge 30 is adjusted so that the ends 50 of the notches 36 are covered by the crown 70.

At least some of the fastening elements 68, the rods 80 of which are integral with the crown 70, are then bolted to temporary elements 114 for radial locking (FIG. 6). Said temporary elements 114 have a shape in an arc of a circle, similar to that of the segments 76 of the outer belt 62. Preferably, the temporary elements 114 form an angle less than that of the segments 76, said angle being for example of the order 60 °. Preferably, two temporary elements 114, disposed vis-à-vis the main axis 12, are assembled to the inner belt 60. Said inner belt is thus held in place inside the membrane 24.

The fragments 110 are then connected to each other to form the first blocking element 64.

The support 108 is then removed from the membrane 24, said membrane remaining maintained on the mounting station 106 by gripping the reliefs 72 of the inner belt 60 and / or by gripping the temporary elements 114. The holding members such as the rings 28 are then put in place and connected to said membrane, by known methods. One of said rings 28, for example the closest to the second free edge 32, is then assembled to temporary gripping means 116, arranged outside the membrane 24.

The first module 14 thus formed is then turned vertically, so as to orient the first end 40 downwards. The first module is then brought to the level of the well 104, by means of a displacement machine assembled with the temporary gripping means 116 .

At this stage, the second module 16, assembled with the third module 18 and possibly with the rest of the pipe 10, is maintained at the level of the opening of the well 104, the second free edge 32 oriented upwards. Preferably, a ring 28 of said second module is also connected to temporary gripping means 116 and held in place by gripping of said means.

Each sector 90 of the second blocking element 66 of the joining device 20 is presented opposite the corresponding strip or strips 58 of the second end 42 of the second module 16. Each strip is then folded towards the outside of the membrane 26, around the corresponding sector 90. The adjacent sectors 90 are then linked together, until four fragments 120, 121 of the second blocking element 66 are formed. The fragments 120 and 121 are alternated, each fragment forming an arc of approximately 90 °.

The first end 40 of the first module 14 is then presented opposite the second end 42 of the second module 16. The temporary elements 114 and the temporary gripping means 116, integral with the first module 14, are fixed to the station d 'assembly 105. Each of said temporary elements 114 is arranged opposite a fragment 120, on either side of the main axis 12.

The second module 16 is then moved upwards and a grip is exerted on the other fragments 121 of the second blocking element 66; the second end 42 of said second module is thus threaded around the first end 40 of the first module, at the level of said fragments 121. The contact interface 96 is thus formed at the level of said fragments 121.

Two segments 76 of the outer belt 62 are then assembled to the inner belt 60 by fastening elements 68, said segments 76 coming into axial abutment against the fragments 121 of the second locking element 66. These two segments 76 are then secured to the station assembly 105 to replace the temporary elements 114 for radial locking.

The temporary radial locking elements 114 are then separated from the inner belt 60 and the fragments 120 are joined to the fragments 121, so as to form the second locking element 66. The contact interface 96 between the membranes 24 and 26 is thus fully formed.

The missing segments 76 of the outer belt 62 are then assembled to the inner belt 60 so as to come into axial abutment against the fragments 120. The joining device 20 is thus installed, joining the first 14 and second 16 modules.

The temporary gripping means 116 of the second module 16 are then dissociated from said second module and the pipe 10 is moved down into the well 104, the first module 14 taking the place of the second module 16. Said first module can thus be assembled at an additional module.

Such an assembly method makes it possible to easily produce a pipe 10 of great length and large diameter. The rods 80 of the fastening elements 68 being integral with the inner belt 60, the bolting operations with the nuts 82 are carried out only outside the pipe, which facilitates their implementation.

The joining device 20 can also be dismantled according to a method opposite to the method described above, so as to dissociate the modules 14, 16 from the pipe 10 from one another. The said pipe can thus be easily dismantled for maintenance, repair or assembly on another site.

According to a variant of the embodiment shown in FIG. 7, the pipe 10 is integrated into an air conditioning system with naturally cold water, or SW AC system, or else into a Rankine organic cycle machine, or ORC machine.

Claims (11)

1. - Line (10) capable of being traversed by a fluid, said line comprising a first (24) and a second (26) tubular membranes connected to each other and aligned along a main axis (12), each said first and second membranes being able to delimit an interior space (29), the pipe further comprising a device (20) for joining the first and second membranes, assembling a first end (40) of the first membrane with a second end ( 42) of the second membrane; the pipe being characterized in that the joining device comprises: - a first (64) and a second (66) axial locking elements; - an inner belt (60); - an outer belt (62); and - a plurality of elements (68) for fixing the interior and exterior belts; each of said first and second axial locking elements and each of said belts having an annular shape arranged around the main axis; and in that : - Each of the first end (40) of the first membrane and the second end (42) of the second membrane is folded around, respectively, the first (64) and the second (66) axial locking elements; - The first end of the first membrane is inserted into the second end of the second membrane, so as to form a contact interface (96) between said first and second membranes at a non-zero axial height (95); - the interior (60) and exterior (62) belts are arranged radially on either side of said interface, respectively in contact with the first (24) and second (26) membranes, said interior and exterior belts being fixed to each other by the plurality of fixing elements (68) distributed around the main axis; and the first and second axial locking elements come into axial abutment (75, 92; 79, 94) against, respectively, the inner belt and the outer belt. 2, - Pipe according to claim 1, in which: - The first membrane (24) is arranged radially between the second locking element (66) and the inner belt (60); and or - The second membrane (26) is arranged radially between the first locking element (64) and the outer belt (62). 3. - A pipe according to claim 1 or claim 2, in which: - A free edge (30) of the first end (40) of the first membrane (24) is folded inwards, so as to be disposed in the interior space (29) delimited by said first membrane; and or - a free edge (32) of the second end (42) of the second membrane (26) is folded outwards, so as to be disposed outside the interior space delimited by said second membrane. 4. - Pipe according to one of the preceding claims, wherein at least one of the first end of the first membrane and the second end of the second membrane comprises a plurality of axial notches (36, 38) distributed around of the main axis. 5. - Pipe according to claim 4, wherein one end (50, 52) of the axial cuts is arranged in the contact interface (96). 6. - Operation according to one of the preceding claims, in which: - the inner belt (60) has a crown (70) formed in one piece; and or - The outer belt (62) is formed of segments (76) in arcs of a circle, assembled in a removable manner. 7. - Pipe according to one of the preceding claims, wherein at least one of the first (64) and second (66) axial locking elements is formed of sectors (88, 90) in arcs of a circle, assembled so removable. 8. - Pipe according to one of the preceding claims, wherein at least one of the first (24) and second (26) membranes is flexible and deformable, the pipe further comprising retaining members (28) holding said au minus one of the first and second membranes around the interior space (29). 9. - A method of mounting a pipe according to one of the preceding claims, comprising the following steps: - folding the first end (40) of the first membrane (24) around the first axial locking element (64); then assembling said first membrane with the inner belt (60), in axial abutment with said first locking element; - folding the second end (42) of the second membrane (26) around the second axial locking element (66); then - insertion of the first end (40) of the first membrane (24) in the 5 second end (42) of the second membrane (26), so as to form the contact interface (96); then - Assembling the outer belt (62) with the inner belt (60), radially on either side of said contact interface, said outer belt (62) coming into axial abutment with the second locking element (66). 10. - Method according to claim 9 taken in combination with claim 8, in which, before the insertion of the first end (40) of the first membrane (24) into the second end (42) of the second membrane (26), the holding members (28) are assembled to at least one of said first and second membranes. 11. - A thermal energy system for the seas (200), comprising at least one pipe (10) according to one of claims 1 to 8.