Intermediate coupling for connecting rigid pipe elements for conveying a fluid, and associated pipe network and assembly method

1. An intermediate coupling for connecting rigid pipe elements for conveying a fluid, designed to be submerged in an expanse of water, comprising:

an inner rigid shell, comprising:

an inner section, the inner section delimiting an inner passage for a flow of fluid between a first end and a second end,

at least one inner branch tapped on the inner section between the first end and the second end, the inner branch delimiting an inner aperture for a fluid flow emerging in the inner passage;

at least one electric connecting line, intended to heat the fluid flowing in the inner shell, the electric line being positioned outside the inner shell, the electric line having a first electrical connecting point situated on a first side of the inner branch, and a second electrical connecting point situated on a second side of the inner branch,

a rigid outer shell positioned around the inner shell, the outer shell at least partially covering the inner section on either side of the inner branch, and the inner branch, the outer shell and the inner shell delimiting an intermediate space between them extending around the inner section and the inner branch, the electric line being received in the intermediate space, the coupling comprising a thermally insulating layer positioned in the intermediate space across from the inner section and across from the inner branch,

wherein the electric line is placed in thermal contact with the inner shell to heat the fluid contained in the inner passage, the electric line being placed either directly in contact against the outer surface of the inner shell or on a protective layer of the outer surface of the inner shell.

2. The coupling according to claim 1 , comprising an additional electric line positioned in the intermediate space, the additional electric line having a first line segment extending across from the inner section and a second line segment extending across from the inner branch.

3. The coupling according to claim 1 , wherein the thermally insulating layer fills substantially all of the intermediate space.

4. The coupling according to claim 1 , wherein the thermally insulating layer comprises an aerogel.

5. The coupling according to claim 1 , wherein the inner section has a part protruding outside the outer shell at least at one of the first end and the second end.

6. The coupling according to claim 5 , comprising, for the or each protruding part, a cover attached on the outer shell to cover the protruding part.

7. The coupling according to claim 1 , wherein the length of the inner section is shorter than 10 m.

8. The coupling according to claim 1 , wherein the inner shell is made in a single piece.

9. The coupling according to claim 1 , wherein the outer shell comprises an outer section at least partially covering the inner section on either side of the inner branch and an outer branch tapped on the outer section and at least partially covering the inner branch, the intermediate volume delimited between the inner section and the outer section communicating with the intermediate volume delimited between the inner branch and the outer branch.

10. The coupling according to claim 1 , wherein the outer shell has a shape similar to that of the inner shell.

11. The coupling according to claim 1 , characterized in that the outer shell is made in a single piece from metal.

12. A pipe network for conveying a fluid, designed to be submerged in an expanse of water, comprising:

a coupling according to claim 1 ;

a first rigid pipe element for conveying a fluid, coupled to the first end of the inner section;

a second rigid pipe element for conveying a fluid, coupled to the second end of the inner section;

a third rigid pipe element for conveying a fluid coupled to the inner branch.

13. The pipe network according to claim 12 , wherein the first rigid pipe element and the second rigid pipe element each comprise an inner fluid guide tube coupled to the inner section and an outer tube delimiting an annular space with the inner tube, the annular space receiving a thermally insulating layer and at least one electric line designed to heat the fluid contained in the inner tube, the electric lines of the first rigid pipe element and the second rigid pipe element being electrically coupled to each other by the electric connecting line.

14. The network according to claim 13 , wherein the inner section has a part protruding outside the outer shell at least at one of the first end and the second end, the coupling comprising a cover coupled to the outer shell and the outer tube to cover the protruding part.

15. The network according to claim 14 , wherein the electric connection between the electric line present in at least one of the first rigid pipe element and the second rigid pipe element on the one hand, and the electric connecting line on the other hand, is positioned between the protruding part and the cover.

16. A method for assembling a pipe network for conveying a fluid below an expanse of water, comprising the following steps:

providing a coupling according to claim 1 ;

fastening a first rigid pipe element to a first end of the inner section;

fastening a second rigid pipe element to a second end of the inner section;

connecting a third rigid pipe element to the inner branch;

electrically coupling at least one first electric line designed to heat the fluid present in the first rigid pipe element, and the electric connecting line present in the coupling;

electrically coupling at least one second electric line designed to heat the fluid present in the second rigid pipe element, and the electric connecting line present in the coupling.

17. The coupling according to claim 8 , wherein the outer shell is made in a single piece.