OA19040A - Bande composite, et procédés pour former une jonction entre deux conduites. - Google Patents

Abstract

Une bande composite (10) qui s'étend dans une direction principale (P) entre des première et deuxième extrémités (10a, 10b) et qui comprend une bande principale (11) comprenant des premières fibres (11a) noyées dans une matrice (11b). Les premières fibres sont en carbone, matériau conducteur d'électricité, et la matrice est composée d'au moins un polymère. La bande composite (10) comprend en outre une couche de jonction (17) formée d'un matériau de jonction conducteur d'électricité. La couche de jonction est disposée sur la bande principale.

Description

Composite tape, and methods for forming a junction between two conduits

5 .. TECHNICAL FIELD The present invention relates to a band .................... composite ...... to ..... form a ..... junction between ...... two pipes , and ...... to the processes for forming said junction. 10 STATE OF THE PRIOR ART More particularly, the invention relates to a. composite strip extending in a main direction between first and second ends, said strip. composite comprising a main strip comprising 15 first fibers embedded in a matrix, said first ·. fibers being made of carbon, an electrically conductive material, and said matrix being composed of at least one polymer. Furthermore, the object of the invention is to form a junction between two conduits for the transport of a fluid, for example a fluid comprising a hydrocarbon (pipeline). Some of these conduits include an electrically conductive composite layer. This type of pipe is used for example in very cold environments, on land as well as at sea, and sometimes at sea at very great depths. Under these conditions the fluid can either _r bUlL LUdy Llltîl- f UU îCuX-ILL ^ X. paraffin or hydrate deposits. These transformations of the fluid can generate plugs and hinder the transport of the fluid in the pipe. This is why these pipes 30 are sometimes heated to avoid these drawbacks. A known technique is the electric heating of these pipes by conductive copper lines placed around the pipes. Document CN280OO21-Y describes such conduct ' 35 for the transport of a hydrocarbon, having a tube in piêîStX ^ Ue ΓΘΓιίΟχύς; pGX de3 of ν’βΓχβ ;? and A pi βϊΠΧΘΐθ

19040 2 electrically powered carbon fiber layer for warm the tube. However, the lines necessary for the transport of hydrocarbons have very long lengths 5 can go several kilometers. The previous document does not offer any solution, nor to mechanically connect pipes one after the other, nor for electrically connect the layers .............. conductors of electricity of these conduits ............................ ............... ..... - 10 Document FR2958991 describes such a conduct improved for the transport of a hydrocarbon, which further comprises a reinforcing layer suitable for improve mechanical strength. This document further describes means of assembly between pipes further comprising 15 power supply means for the layer of heater. However, these means of connection between conducts are complex. It is therefore necessary to find other solutions for junction or connection of pipes 20 between them. DISCLOSURE OF THE INVENTION The object of the present invention is to improve a composite strip of the aforementioned type, in particular for 25 make the mechanical and electrical junction between carbon heating layers of pipes for the hydrocarbon transport. - Z j. C-, L · · -1— J— v ~ * L * f k- * 11 s-l G * XL Lk-2 '—L U. is l_. G G * -L- —L L- * 11 which it further comprises a junction layer formed 30 of an electrically conductive junction material, said junction layer being disposed on the main strip. Thanks to these arrangements, the composite strip preformed is suitable for immediate use for make the electrical junction between layers of Heating of two pipes placed end to end. In addition, the electrical junction is very efficient

19040 3 because the materials of the heating layers and the composite tape are welded naturally, and because the joint layer of the composite tape has very good Electrical Specifications. The composite strip is then 5 able to form an electrical junction with a weak electrical resistance, which avoids losses electric by Joule effect between each pipe, and which helps prevent local overheating that could damage ............... the assembled Hydrocarbon line ............................. .................................... ......... 10 In addition, the mechanical junction is mechanically very resistant. The assembled hydrocarbon line is almost continuous between the first and second pipes adjacent. This eliminates mechanical weaknesses located at each junction. In various embodiments of the strip composite according to the invention, we can optionally have further use one and / or the other of the provisions following. According to one aspect of the invention, the layer of 20 junction is arranged only at the first and second ends of the composite strip. According to one aspect of the invention, the layer of junction in the form of bands extending along the first and second ends, each of said bands 25 having a width in the upper principal direction to 1 cm, and preferably greater than 5 cm. According to one aspect of the invention, the layer of According to one aspect of the invention, the material of

junction is selected from a list comprising a polymer charged with electrically conductive particles, a polymer charged with metallic particles, a polymer charged with silver particles, a polymer charged with metallized carbon fibers, a polymer charged with copper fibers, a polymer filled with woven copper fibers.

According to one aspect of the invention, the first fibers

19040 4 extend in the main direction. According to one aspect of the invention, the first fibers extend substantially in a fiber direction forming a fiber angle with the principal direction, said angle 5 of fiber being between 0 degrees and 45 degrees, and of preferably between 0 degrees and 10 degrees. According to one aspect of the invention, the composite strip has a trapezoidal shape having two side edges which ....... extend ..... in ... directions ....... parallel to each other .............. - 10 and two end edges that belong to the ends of the composite strip and which extend in directions converging towards each other, the junction layer extending parallel to each end edge. According to one aspect of the invention, the edges 15 end form an angle of convergence between 0.1 degree and 20 degrees, and preferably between 0.1 degree and 5 degrees. According to one aspect of the invention, the composite strip further comprises a lateral portion in one direction 20 secondary substantially perpendicular to the direction main, said lateral portion not comprising said first fibers and comprising second fibers embedded in the matrix, said second fibers being formed from a second material that is not electrically conductive. 25 According to one aspect of the invention, the second material is glass. form a junction between a first pipe and a 30 second line. Each pipe includes a hollow tube internal and a heating layer located in the thickness of said pipe, said heating layer comprising fibers formed from a conductive material. In the process, a composite strip is provided 35 extending in a principal direction between first and second ends, said composite strip comprising

I

5 a main strip comprising first fibers embedded in a matrix, said first carbon fibers, an electrically conductive material, said matrix being composed of at least one polymer, and said composite strip 5 further comprising a junction layer formed of an electrically conductive junction material, said junction layer being disposed on the main strip. In the process, an electrical junction is made ............Between. . the... . first ...... and ...... second ......... conduits ...... by ........ performing ......... .. 10 the next step: apply the composite tape to each heating layer or on a layer previously disposed on said heating layers by wrapping around the tubes, and in which the joint layer of the composite strip is contacted with the heating layer of the first pipe and with the layer of heating of the second pipe. In various embodiments of the method according to the invention, it is optionally possible to have recourse in addition to one and / or other of the following arrangements. According to one aspect of the invention, the layer of joint is disposed only at the ends of the composite strip, and wherein the joint layer of the first end is contacted with the heating layer of the first pipe and the joint layer 25 of the second end is contacted with the heating layer of the second pipe. According to one aspect of the invention, each pipe has - ui-O Un i_ j_ eiLLj-L c ue X * JJ_1LLÇ5 b bl 1 L ¹ _JJ 1 UULU 11_ L-U11 X LJ U. L- UU lll <JXIU dCliTS the thickness of the heating layer, and in which we

chooses a composite strip having a trapezoidal shape having!

a geometry adapted to the shapes of the ends of the pipes so that during the electrical junction step, 'the composite strip forms a junction having a shape substantially complementary to the conical ends of the heating layers of the pipes by winding the composite strip in trapezoidal shape around the tubes.

i i

19040 6 According to one aspect of the invention, the first and second ends of the pipes are first machined to clear a cylindrical portion of each tube and to achieve a conical shape in at least the layer of 5 heating of each tube. According to one aspect of the invention, before the step of electrical junction, a welding step of the tube of the first line with the tube of the second ......... driving ........................................ .................................................. .................................................. . - According to one aspect of the invention, a insulation junction step after welding step and before the electrical junction step, in which we applies an insulating tape comprising second fibers embedded in a matrix, said second fibers being 15 formed of a second material that is not electrically conductive, said second material being for example glass. According to one aspect of the invention, after step application of a composite strip, a step is carried out heating during which the composite strip is heated 20 applied between the first and second pipes for crosslink the matrix of the composite strip. The invention also relates to a method for form a junction between a first pipe and a 25 second pipe, in which each pipe comprises a inner hollow tube and a heating layer located in the thickness of said pipe, said heating layer In the process, a main band is provided 30 comprising first fibers embedded in a matrix, said first fibers being formed of a material conductor of electricity, and said matrix being composed of at least one polymer. In the process, an electrical junction is made 35 between the first and second pipes by carrying out the following steps :

- Applying a junction layer on each heating layer or around a layer previously arranged on said heating layers, each junction layer being composed of an electrically conductive junction material, and the junction layers are placed in contact with the heating layer of the first pipe and with the heating layer of the second pipe, and

..............................- we apply the ...... band, main on said ..... layer- ....... 10 junction by winding around the tubes. BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will become apparent from the following description 15 of at least one of its embodiments, given as non-limiting example, with reference to the accompanying drawings. On the drawings: - Figure la is a view in longitudinal section a composite heating pipe; 20 - figure lb is a side cross view of the conduct of Figure 1a; - Figure 2 is a plan view of a strip composite according to a first embodiment of invention; Figure 3 is a sectional view of Figure 2; - Figure 4 is a plan view of a strip composite according to a second embodiment of 1 'ùnw & n t ion

FIG. 5 is a plan view of a composite strip according to a third embodiment of the invention;

- Figures 6 to 9 show sections similar to Figure 3 of composite band variants which can be applied to each of the embodiments of Figures 2 to 5;

- Figure 10 is a longitudinal sectional view

19040 8 of a composite heating pipe prepared to be joined to another heating pipe; - Figure 11 is a longitudinal sectional view of two heating pipes of the type shown in figure 6, the 5 tubes are butt welded; - Figure 12 is a longitudinal sectional view of two heating pipes of the type shown in figure 6, the ends were joined by a junction having a layer ............ driver .....; ............................... ...........-...................................... .................................................. .................. 10 - figure 13 is an enlarged view of the junction of FIG. 8 showing the plurality of elementary layers formed by the composite strip when wrapped around the tube. In the various figures, the same references Numerals denote identical or similar elements. DETAILED DESCRIPTION OF EMBODIMENTS - In the present description, the terms "before" and "rear" are used in relation to the steering 20 longitudinal X. The terms "higher" or "towards the up ”and“ lower ”or“ down ”are used by relative to the vertical direction Z, upwards, perpendicular to the longitudinal direction X and to the transverse direction Y. The term "conduct" of the present invention should be understood as a device comprising a tube to transport a fluid at least between an inlet and a - t> o.LL ± Lj, aiapouiLii can include and other elements, such as a valve, or multiple branches. 30

Figures la and 1b show a pipe 1 of the heating type and comprising a composite material, shown in longitudinal section along a plane XZ and in cross section along a plane YZ. In these figures, only an upper half above the X axis is shown, the other lower half being substantially identical by

19040 9 symmetry about the X axis. Line 1 comprises a hollow tube 2, extending in the longitudinal direction of axis X between a first and second end 1a, 1b of the pipe. This tube 2 5 comprises an internal surface 2a close to the X axis, and an external surface 2b farther from the X axis. A inside the internal surface 2a extends a cavity 2c between an inlet and an outlet of the cavity located .......... each ..... of the ......... ends. .. The ..... cavity- 2c is ...... suitable ..... for ........... Transporting the fluid between said inlet and outlet. Line 1 has a cross section of substantially cylindrical in the YZ plane, but other shapes could be carried out. Tube 2 can be made with a material 15 electrically conductive, such as steel, like this is shown in the figures for the present mode of realization of the pipe. Tube 2 can be made with a material electrically insulating, for example a polymer. This material 20 can advantageously be a polyamide (PA), or a polyvinylidene fluoride (PVDF). On this tube 2, there are for example the layers following, from the inside (close to the X axis) to outside (away from the X axis): 25 - a first insulation layer 3, - a heating layer 4, and - a second layer of insulation 5. electric 3, 5 are electrically insulating. They are For example made of a polymer or a composite comprising glass fibers embedded in the polymer (matrix) or a composite comprising kevlar fibers embedded in the polymer. The polymer is advantageously adapted to adhere well to other layers: tube 2 and 35 heating layer 4. This polymer is optionally same as used in heating layer 4.

19040 10 and / or in tube 2 as mentioned above. The heating layer 4 is a composite comprising at least carbon fibers embedded in a polymer. This polymer can advantageously be a polyamide (PA), or a 5 polyvinylidene fluoride (PVDF). Carbon fibers are able to conduct a electric current to heat the tube by the Joule effect. The electrical resistance R of such a heating layer 4 .......... between the first ...... and ..... second ends ........ (la, ...... 1b) .... ....of the ..... 10 conduct can be approximated by the following formula: n_ ^{L K} P fiber ₂ AT ". cos a. in which : - Pflbre is a resistivity of carbon fibers, 15 having for example for value p _ftbee = l, 9.10 ~ ^s Ω.ηι to a temperature of 20 ° C, which is appreciably 1100 times more resistive than copper at 20 ° C, - L is a length of the heating layer 4 between the first and second ends (la, lb) according to the 20 longitudinal direction X, - Dmoy is an average diameter of the layer of heating 3, - E _p is a thickness of the heating layer in a transverse direction, and 25 -a is an angle of inclination formed by the carbon fibers with respect to the direction of the X axis. Thanks to the angle of inclination of the carbon fibers in the heating layer 4, it is possible to obtain a

electrical resistance R desired for heating.

Thanks to this heating layer 4 comprising carbon fibers well distributed in the polymer material of this layer, the heating is more homogeneous around the tube 2. In addition, if one or more carbon fibers were broken at one point in the pipe , the electric current can still continue to flow through the

19040 11 other carbon fibers, unbroken. Thus, the electrical characteristics (resistance) are poor degraded. The different layers of pipe 1 can 5 be manufactured by known means using preformed strips of composite, each preformed strip extending in one direction and comprising fibers (carbon, glass or kevlar) embedded in a matrix of .......... polymer ........ The ....... fibers ............ are ....... possibly oriented -in......... Said direction of the preformed strip. The present invention aims to use. also composite bands to perform a mechanical and electrical junction between the layers of two pipes 1 placed end to end. In particular, the object of the invention is to use a particular composite strip 10 for making the junction between the heating layer 4 of the first pipe and the heating layer 4 of the second pipe. In FIG. 2, the composite strip 10 extends in a principal direction P between first and second ends 10a, 10b, the first end being opposite to the first end in principal direction P. Each end 10a, 10b comprises an end edge 13a, 13b, 25 respectively. In a secondary direction S substantially perpendicular to the main direction P, it further comprises two side edges 14a, 14b opposite to each other. two ends 10a, 10b of the composite strip. The composite strip 10 thus has, for example, the general shape of a quadrilateral, which may be a square, a rectangle or a trapezoid.

The composite strip 10 firstly comprises fibers 11a (first fibers) embedded in a matrix 11b.

The matrix 11b and the fibers 11a form an assembly, called the main strip 11, having a substantially planar shape in

19040 12 a plan of P-S directions. The main strip 11 thus has an upper face 15a and a lower face 15b. These first fibers 11a are formed from a first electrically conductive material and extend into a 5 direction of fibers F. The first conductive material is advantageously carbon, as for the fibers of the heating layer 4 of the pipe 1. The matrix 11b is composed of at least one polymer. ......... The polymer can ..... advantageously be ..... a polyamide (PA) ...... or 10 a polyvinylidene fluoride (PVDF), as for the matrix heating layer 4 of pipe 1. The composite strip 10 of the first embodiment of Figure 2 further comprises, near each of the ends or edges of ends 13a, 13b a layer of 15 junction 17 formed of a junction material also electrically conductive. This junction layer 17 is located above the main strip 11, that is to say above the first fibers 11a and the matrix 11b. The purpose of this junction layer 17 is to improve the conduction 20 electrical of the composite strip 10 at its ends, intended to be in contact with a heating layer 4 of a pipe 1. This junction layer 17 is visible in section in FIG. 3. It has the shape of a strip which extends along 25 of each end 10a, 10b, each having a width in the main direction P, for example by 1 cm or more, and for example greater than 5 cm. It has a thickness included 11 L -L V -D IL LL LL LJ L _L IL LL LL * This composite strip 10 is therefore a ready-to-use compound. 30 use to make the junction between the heating layers 4 of two pipes 1.

The junction material is advantageously a polymer charged with electrically conductive particles, or a polymer charged with metallic particles, or a polymer charged with silver particles, or a polymer charged with metallized carbon fibers, or a polymer charged with carbon fibers. coppers, or a polymer loaded with woven copper fibers.

Particles are small elements of spherical, elliptical or any other shape. They have a size (greater distance) for example less than 0.1 mm, and preferably less than 0.01 mm. These particles can thus be mixed or loaded into a polymer without too much affecting its viscosity. These particles ...... are ..... therefore in powder form ............................... .........................................-........ ..

During a step of transforming the composite strip by heating, the junction material of the junction layer 17 will bond intimately with the matrix and with the first fibers 11a, to improve the electrical conduction of an area around said junction layer 17 at the end of the composite strip 10. The contact and the electrical conduction with a heating layer 4 of a pipe 1 are thus greatly improved.

The first fibers 11a possibly extend in the main direction P of the composite strip 10. The composite strip is thus easier to produce.

The first fibers 11a advantageously extend in a fiber direction F inclined relative to the main direction P, with a predetermined fiber angle β. The angel of fiber β is for example between 0 degrees and 45 degrees. Advantageously, it is between 0 degrees and 10 degrees.

L-La-ng-i-e --- de --- f-i-b-re — β — de --- 1-a --- band — eempc-eite --- e-s-t

eventually different of The angle tilt at of 30 carbon fibers the layer of heating 4 of pipes 1. Especially, 1 'angle β fiber is advantageously inferior at The angle tilt at. The linear electric resistance ic in the direction of x axis

of 'junction 6 is then less than the linear electrical resistance of the pipe. Heating at the junction is thus reduced, and can even be eliminated.

According to the embodiment of Figure 2, the composite strip 10 has a rectangular shape.

According to the embodiment of Figure 4, the composite strip 10 has a trapezoidal shape: the end edges 13a, 13b extend in directions converging towards each other, forming an angle of convergence χ for example between 0.1 degrees ...... and 20 degrees, and preferably -between 0.1 degrees and 5 degrees. This angle of convergence is advantageously adapted to the shapes of the heating layers 4 of the pipes 1 intended to be attached.

According to the embodiment of FIG. 5, the composite strip 10 comprises:

- a main portion 18 corresponding to the composite strip 10 of the embodiments of Figures 2 to 4, that is to say comprising first conductive fibers 11a, and

a secondary portion 19 which extends in the secondary direction S from the side edge 14a of the main portion 18, said secondary portion 19 not comprising said first fibers and comprising second fibers 20 embedded in the matrix 11b, said second fibers 20 being formed of a second electrically non-conductive material.

The second material is for example glass.

Composite web 10 is a continuous set of raw and juxtaposed raw material and material. second portions 18, 20. This composite strip 10 is thus ready for use to form a junction between two heating layers 4 and a junction between two insulation layers 3 or 5.

Thanks to this composite tape, it is possible to achieve a junction of several or all the layers by a single winding of the specific composite tape 10, and in particular the production of a junction of an insulating layer and a layer of heating (between two pipes).

According to another embodiment (not shown), the composite strip comprises a main portion 18 and two secondary portions 19 on either side of said main portion 18, in the secondary direction.

Thanks to this composite strip, it is possible to make a junction of several or all the layers by .................. a single winding of the specific composite strip · 10, and in particular the realization of a junction of the heating layer 4 and the two insulation layers 3 and 5 on either side of the heating layer (between two pipes).

According to variants of all the previous embodiments of the composite strip, the junction layer 17 can be located in various places on (or in contact with) the main strip 11. FIGS. 6 to 9 show sections similar to the section. of figure 3, and which explain these various places.

In the variant of Figure 6, the junction layer 17 is located at each of the ends 10a, 10b, according to bands extending along the end edges, and disposed on the upper face 15a and under the lower face 15b of the main strip 11. The junction layer 17 thus comprises four strips.

In the variant of FIG. 7, the junction layer is located at each of the ends 10a, 10b, according to ----- des — bands — s ^ -é-be-nda-nt — 1-e — long — de. The edges of the top face 15a and the end edge 13a, 13b are covered and covered. The junction layer 17 thus comprises two strips of "L" shaped section.

In the variant of Figure 8, the junction layer 17 is located at each of the ends 10a, 10b, in strips extending along the end edges, on the upper face 15a, under the lower face 15b, and on the end edge 13a, 13b to connect the strips of

19040 16 lower and upper faces. Junction layer 17 therefore comprises two bands of section in the shape of "C" which includes each end edge. In the variant of FIG. 9, the layer of 5 junction 17 is located over the entire surface of the face upper 15a (and / or lower face 15b). It thus connects each end 10a, 10b. The junction layer 17 covers therefore all of said surface of the main strip 11. .......................... In ......- each ........ of ...... ..... these ......... variants, ....... conduction - 10 electrically achievable in a junction between two pipes with such a composite strip is thus reduced. A process for forming a junction between two pipes 1 of the type in figure 1 will now be 15 explained. These pipes 1 include a hollow tube 2 . internal and successive layers of materials. One of the layers is a heating layer 4 allowing the heating of the pipe by electrical conduction. This heating layer 4 is located in the thickness of the 20 driving, i.e. within a radial distance range with respect to the X axis of the pipe. The heating layer 4 comprises fibers of conductive material, such as carbon fibers. This method uses one of the composite bands 10 25 previously described to connect the heating layers 4 of two pipes 1 placed end to end. In particular, the method comprises a process of - i u / 11 u -L x i _i_ u- u * u _L d. u * d 11 u * L4 d u * u * 11 u * i— .u u * Kx u d b * d d i im ** 11. —l. u. u u * u * next : 30 - We apply the composite strip 10 on each heating layer 4 or on an arranged layer previously on said heating layers by winding around the tubes 2. The junction layer 17 of the composite strip 10 is then brought into contact with the

heating layer 4 of the first pipe and with the heating layer 4 of the second pipe.

Figures 10 to 13 show a more detailed example of the implementation of this method.

In FIG. 10, the second end lb of a pipe 1 is formed for example with the shape presented either in the factory or at the time of the junction between two successive (adjacent) pipes.

A cylindrical portion 2d of the outer surface 2b of the tube is released (without a layer above), and the layers

........ - above the tube 2 are formed - conically in the direction of the end lb of the pipe. _____________________

This second end lb is for example formed by machining a completely cylindrical pipe as shown in Figure 1.

In FIG. 11, two pipes 1 each having its ends formed as explained above are brought together until they are coaxial with axis X and in contact by their ends in a median plane M: The second end lb of the first pipe is in contact with the first end of the second pipe. The two tubes 2 of each pipe are then welded together in a welding step to form a continuous inner tube 2 for the transport of the hydrocarbon fluid. A tube junction 2j is therefore formed by welding between the two tubes 2 of the pipes 1.

In FIG. 12, layers of junctions are then produced on the tube junction 2j to join the respective layers of each pipe 1. Thus, ------- 1-es — é-ta-pe-s— is carried out. sui-va-n-te-s -: --------------------------------------- ------------------------ a) a first insulation junction step in which an insulating tape is applied comprising second fibers embedded in a matrix of polymer, said second fibers being formed from a second electrically non-conductive material, such as glass; a first insulation layer junction 3j is thus produced and joins the first insulation layers 3 of the two pipes 1 above the tube junction 2j;

b) an electrical junction step in which a composite tape 10 is applied by winding around the insulation layer 3j, the joint layers 17 of each end of the composite tape being in contact with each heating layer 4 of the two pipes 1; a heating layer junction 4j is thus produced and joins said heating layers 4 above the insulation layer junction 3j; and

............................. c) a second stage of insulation junction in which an insulating tape of the same type as 'at the _________ first insulation junction step, above the heating layer junction 4j; a second insulation layer junction 5j is thus produced and joins the second insulation layers 5 of the two pipes 1 above the heating layer junction 4j.

The junctions of tube 2j, of insulation layers 3j,

5j and of heating layer 4j form a junction 6 between the two tubes 1 which reproduces the stacking of the layers of each of the pipes 1 to form a mechanical and electrical continuity (conduction and insulation) between the pipes 1.

In addition, between each of the preceding steps or in the last step, a step of heating the junction 6 between the first and second pipes 1 is optionally carried out in order to crosslink or solidify the matrices 11b.

Each junction of insulation layer 3j, 5j and heating 4j can be made with appropriate strips

----- rnd-épend-ant-e-sv — C -'- e-st — à — dire — a — strip — cempesTte — rs-oTarrte - for each junction of insulation layer 3j, 5j, and a composite strip 10 of the type of figure 2 or figure 4 for the heating layer junction 4j.

Optionally, a single composite strip 10 of the type of FIG. 5, comprising two secondary portions 19 can be used to form in a single winding the three layers of the junction 6.

In the case as shown in the figures, in which the junction 6 has a conical shape, a composite strip 10 having a trapezoidal shape can advantageously be used. In this way, at each turn of the winding of the strip in the junction 6, as shown in FIG. 13, the end edges 13a, 13b naturally shift, which allows better contacting of the junction layer. 17 with 4 heating layers of each pipe 1. This also allows ............. to have ........ a ....... diffusion of. .... material ......... of ........ the ........ layer ...... of 10 junction 17 over the entire contact surface with each heating layer 4. This improves the conductivity of this heating layer junction 4j (reduction of the electrical contact resistance).

The trapezoidal shape of the composite strip 10 is advantageously adapted to the shapes of the ends of the pipes 1, such that when the composite strip 10 is wound up, the latter forms a junction 6 of complementary shape to said ends of the pipes. In particular, the pipe diameters, the thickness of the composite strip 10, and the shape of the ends of the pipes must be taken into account to establish the trapezoidal shape of the composite strip 10.

Another method for forming a junction between two pipes 1 of the type of FIG. 1 will now be explained.

This process plus implements a main band 11

----- préeédeïwent — de-er-tte -; - L ---------------------------------- --------- a junction layer 17 is produced directly on the pipes 1 prior to the winding of the main strip 11 around the pipes 1.

In particular, the method comprises an electrical junction process in which at least the following steps are carried out:

- Applying a junction layer 17 on each heating layer 4 or around a layer previously arranged on said heating layers (4), each junction layer 17 being composed of an electrically conductive junction material, and the junction layers 17 are brought into contact with the heating layer 4 of the first pipe and with the heating layer 4 of the second pipe, and

- Applying the main strip 11 on said junction layer 17 by winding around the tubes.

......................... This process .......... only requires ........ one .. ............ 10 main strip 11 and the material of the tie layer. It is therefore not necessary to have a composite strip 10 prepared in advance and incorporating a junction layer 17. However, this process takes longer to implement in the field.

Finally, it is possible with one or more composite bands 10 and / or main bands 11, as presented in the present description, to form junctions between substantially identical pipes and having several heating layers in the thickness of the pipes.

In particular, a composite strip 10 having an alternation of insulating portions (such as the secondary portion 19) and of conductive portions (such as the main portion 18) can be produced. The junction of all the layers, and in particular all the heating layers 4, is thus produced by a single winding of said specific composite strip 10.

Claims (17)

1. composite strip (10) extending in a main direction (P) between first and second ends (10a, 10b), said composite strip comprising a main strip (11) comprising first fibers (11a) embedded in a matrix (11b), said first fibers being of carbon, electrically conductive material, and said matrix being composed of at least one polymer, TO lâclTEê composite tape being characterized ëïï cë that it further comprises a junction layer (17) formed of an electrically conductive junction material, said junction layer being disposed on the main strip, only at the first and second ends (10a, 10b) of the composite strip. 2. A composite strip according to claim 1, in which the joining layer (17) has the form of strips extending along the first and second ends (10a, 20 10b), each of said having bands a width in the main direction greater than 1 cm, and preferably greater than 5 cm. 3. Composite tape according to one of claims 1 25 to 2, in which the layer of junction (17) to a thickness between 0.05 mm and 1 mm. ----- 4 -.------- Ban.cLe — comp-o.sù-te — se-l- & n —— d - @ - s— £ @ ^ & ndiGa-ti- © -ns - 1 to 3, in which the joining material is chosen from a list comprising a polymer loaded with electrically conductive particles, a polymer loaded with metallic particles, a polymer loaded with silver particles, a polymer loaded with metallized carbon fibers, a polymer loaded with copper fibers, a polymer loaded with woven copper fibers. 5. Composite strip according to one of claims 1 to 4, wherein the first fibers (11) extend substantially in the main direction. 5 6. Composite strip according to one of claims 1 to 5, in which the first fibers (11) extend in a fiber direction (F) forming a fiber angle (β) with the main direction, said fiber angle being between 0 degrees and 45 degrees, and preferably between 0 degrees and 10 degrees. 7. Composite strip according to one of claims 1 to 6, in which the composite strip (10) has a trapezoid shape having two lateral edges (14a, 14b) which extend 15 in directions parallel to each other and two end edges (13a, 13b) which belong to the ends of the composite strip and which extend in directions converging towards each other, the joint layer (17) extending parallel to each edge 20 end. 8. A composite strip according to claim 7, in which the end edges (13a, 13b) form an angleί of convergence (χ) between 0.1 degree and 20 degrees, and Preferably between 0.1 degree and 5 degrees. j ---- 9 ~ .------ Band — uumpuslLe — according to — a — cteB — claims 11 ------ at — 8 -, - ee-mp-re-nant — en— © -la-t-ne — une — pe-rt-i-en — 1-a-t-é-raie— (-1-9 -) - in — uner direction secondary (S) i substantially perpendicular to the 30 direction main ( P), said side portion born including not said raw fibers and including of second fibers (20) drowned in the matrix, said second fibers being formed of a second material no driver electricity - 35 10. The composite strip of claim 9, wherein the second material is glass. 11. Method for forming a junction between a first pipe and a second pipe in which each 5 pipe (1) comprises an internal hollow tube (2) and a heating layer (4) located in the thickness of said pipe, said heating layer (4) comprising fibers formed of a conductive material, and in which : - providing a composite strip (10) extending 10 in a main direction (P) between first and second ends (10a, 10b), said composite strip comprising a main strip (11) comprising first fibers (11a) embedded in a matrix (11b), said first fibers being in carbon material 15 electrically conductive, said matrix being composed of at least one polymer, and said composite strip further comprising a junction layer (17) formed of an electrically conductive junction material, said junction layer being arranged on the main band, 20 - an electrical junction is made between the first and second conduits by performing the following step: - the composite strip (10) is applied to each heating layer (4) or to a layer arranged 25 previously on said heating layers by winding around the tubes (2), and in which the layer ----------- de — j-onc-tion - (- L7 -) - de — la — Bande — composi-te — est — mise — en — GQn-ba-ct ---- with the heating layer (T) of the first pipe and with the heating layer (4) of the second pipe. 12. The method of claim 11, wherein the junction layer (17) is disposed only at the ends (10a, 10b) of the composite strip, and wherein the junction layer (17) of the first end (10a) 35 is brought into contact with the heating layer (4) of the first pipe and the junction layer of the second end (10b) is brought into contact with the heating layer (4) of the second pipe. 13. The method of claim 11 or the 5 claim 12, wherein each pipe (1) has an end of substantially conical shape at least in the thickness of the heating layer, and in which one chooses a composite strip (10) having a trapezoid shape having a suitable geometry to the shapes of the ends of the TO pipes so that, during the electrical connection stage, the composite strip (10) forms a junction having a shape substantially complementary to the conical ends of the heating layers of the pipes by the winding of the composite strip trapezoidal around the tubes. 14. Method according to one of claims 11 to 13, wherein the first and second ends (la, lb) of the pipes (1) are first machined to release a cylindrical portion of each tube and to form a shape 20 conical in at least the heating layer (4) of each tube (2). 15. Method according to one of claims 11 to 14, wherein, before the electrical junction step, one performs 25 a step of welding the tube (2) of the first pipe with the tube (2) of the second pipe. ----- 16 ------- Process — s-el-on — 1-a — re-we-n-dica-tion—! 15 -, - dans — laque-l — o-neffectue a junction step of insulation after the welding step and before the electrical junction step, in which an insulating strip is applied comprising second fibers embedded in a matrix, said second fibers being formed of a second material which is not electrically conductive, said second material being for example glass. 17, Method according to one of claims 11 to 16, wherein after the step of applying a composite strip, a heating step is carried out during which the said composite strip applied between the first and 5 second lines (1) for crosslinking the matrix (11b) of the composite strip. 18. A method of forming a junction between a first pipe and a second pipe, and in which each Pipe (1) comprises an inner hollow tube (2) and a heating layer (4) located in the thickness of said pipe, said heating layer (4) comprising fibers formed of a conductive material, and in which : - a main strip (11) is provided comprising First fibers (11a) embedded in a matrix (11b), said first fibers being of carbon, an electrically conductive material, and said matrix being composed of at least one polymer, and - an electrical junction is made between the 20 first and second lines by performing the following steps: - a junction layer (17) is applied to each heating layer (4) or around a layer previously placed on said heating layers (4), each junction layer (17) being made of a material of electrically conductive junction, and the 3L sununction layers (17) put in uunLacL avow your cuuulie ------ eha-uf-fa-ge - (- 4 -) - de — La — p-rem-i-è-re — e © -Rdui-be — et — av-es — 1-a —Eo-uehe — overheating (4) of the second pipe, and 30 - the main strip (11) is applied to said junction layer (17) by winding around the tubes.