EP0099805A1 - Assembly for an electrical connection through a conduit made up of several elements - Google Patents

Abstract

Assembly allowing at least one electrical connection to be made through a pipe formed of elements fixed to each other, each element having a first end and a second end adapted to mechanically cooperate with the complementary ends of the adjacent pipe elements. This assembly comprises per pipe element: - a sheath (5) having two ends, placed inside said element and in which is housed at least one conductor, a first connector (12) fixed to one end of said sheath and which is held in the first end (10) of said pipe element, - a second connector (14) fixed to the other end of said sheath and which is held in the second end of said pipe element, - a double connector (13) having a first end comprising at least one contact and a second end comprising at least one contact electrically connected to the previous one, the first end of said double connector cooperating electrically with the first connector (12) of a neighboring pipe element, the second end of the double connector (13) cooperating electrically with said second connector (14), and - means for positioning and fixing the connectors (21, 22, 23, 27, 51). The invention is particularly applicable to the production of electrical connections through a drill string.

Description

The present invention relates to an assembly making it possible to produce at least one electrical connection between two points through a pipe, such an electrical connection being able to be used, inter alia, for supplying certain devices from an electrical source, or transmission of coded information in the form of electrical signals.

This assembly can be used, for example, in a drill string. It can then transmit certain information, electrically coded, from the bottom of the well, such as, for example, the direction of the well, the mechanical stresses exerted on certain parts, the temperature, the pressure, etc.

The devices used according to the prior art which can be illustrated by the US patents 2,096,359, 3,518,609, 3,696,332 and 3,879,097, the German patents or patent applications 1,236,439 and 1,465,924, and the application British Patent 1,026,512, generally have at least one of the four main drawbacks mentioned below.

The first drawback is the consequence of the arrangement of the electrical contact surface along a plane at the base of the rod or of the pipe element. Under these conditions, in fact, during the vertical storage of the elements constituting the pipe, the electrical contact surface becomes dirty, scratched and deteriorates rapidly in contact with the ground.

The second drawback stems from the fact that the wire or cable used for the electrical connection is placed inside the pipe and that the actual residual passage section is no longer similar to the initial passage section, thus, in the in the case of an initially circular passage section pipe, the installation of a conductive cable makes the actual passage section different from a circle.

This can hinder certain operations such as the passage and centering of the tool in the pipe, all the more so since the angular position of the cable relative to the pipe is not constant.

The third drawback stems from the fact that, according to the prior art, there is no simple and effective device for cleaning the electrical contacts.

Finally, the fourth drawback is due to the wear of the various parts participating in the connection due to the numerous assemblies and disassemblies.

These drawbacks are eliminated, or at least very substantially reduced, by the use of the device according to the invention.

• - une gaine ayant deux extrémités, placée à l'intérieur dudit élément et dans laquelle est logé au moins un conducteur,
• - un premier connecteur fixé à une extrémité de ladite gaine qui est maintenu dans la première extrémité dudit élément de conduite,et qui coopère électriquement avec ledit conducteur,
• - un deuxième connecteur fixé à l'autre extrémité de ladite gaine qui est maintenu dans la deuxième extrémité dudit élément de conduite, et qui coopère électriquement avec ledit conducteur,
• - un connecteur double possédant une première extrémité comprenant au moins un contact,et une deuxième extrémité comportant au moins un contact relié électriquement au précédent, la première extrémité dudit connecteur double coopérant électriquement avec le premier connecteur d'un élément de conduite voisin, la deuxième extrémité du connecteur double coopérant électriquement avec ledit deuxième connecteur, et
• - des moyens de positionnement et de fixation des connecteurs.

This device consists of an assembly making it possible to produce at least one electrical connection through a pipe formed of elements fixed to each other, each element having a first end and a second end adapted to mechanically cooperate with the complementary ends of the pipe elements. adjacent. This set includes, per driving element:

• - a sheath having two ends, placed inside said element and in which is housed at least one conductor,
• a first connector fixed to one end of said sheath which is held in the first end of said pipe element, and which cooperates electrically with said conductor,
• a second connector fixed to the other end of said sheath which is held in the second end of said pipe element, and which cooperates electrically with said conductor,
• a double connector having a first end comprising at least one contact, and a second end comprising at least one contact electrically connected to the previous one, the first end of said double connector cooperating electrically with the first connector of a neighboring pipe element, the second end of the double connector cooperating electrically with said second connector, and
• - means for positioning and fixing the connectors.

According to an embodiment according to the invention, the double connector is a wearing part, produced with softer materials than those of the parts with which it cooperates. This double connector is easily removable.

In addition, devices are provided for automatic cleaning and isolation of the various electrical contacts when assembling two adjacent pipe elements.

According to the invention, the fact of placing the conductor in the sheath, makes it possible to be master of the actual passage section of the pipe. It is thus possible, in particular, to overcome the drawbacks indicated above, of the devices according to the prior art, by having a circular passage section for the fluid.

• - la figure 1 représente un puits de forage,
• - la figure 2 montre deux éléments d'une conduite, équipés de l'ensemble de connexion et réunis entre eux,
• - la figure 3 représente le connecteur double amovible,
• - la figure 4 illustre un détail de fixation du deuxième connecteur à l'aide d'un boulon spécial servant au centrage du connecteur double, et
• - la figure 5 montre une variante de réalisation des moyens de positionnement et de fixation.

An exemplary embodiment according to the invention, more particularly applied to drill pipes, is described below with reference to the accompanying drawings in which:

• FIG. 1 represents a wellbore,
• FIG. 2 shows two elements of a pipe, equipped with the connection assembly and joined together,
• FIG. 3 represents the removable double connector,
• FIG. 4 illustrates a detail of fixing the second connector using a special bolt used for centering the double connector, and
• - Figure 5 shows an alternative embodiment of the positioning and fixing means.

In order to facilitate understanding of the following example, the type of the various connectors has been fixed. Thus, the first connector will be a connector of the male type, the second connector, a female connector, the double connector will be said to be an intermediate connector, its first end will be female and the second male. Likewise, the first end of the pipe will be a male end and the second end of this pipe, a female end. It is obvious that the preceding details are in no way limiting and that it is possible to have mixed connectors, that is to say that, for example in the case of a double electrical connection, the connectors include a female type contact and male type contact.

FIG. 1 represents an embodiment according to the invention, applied to a drill string 1. The well is designated by the reference 2. The reference 3 designates a drilling tool which can be replaced by any tool or by a probe of measurement. The junction between the various elements making up the drill string was not shown.

An example of this junction is shown in Figure 2.

It is of course possible in certain cases to use the drill stand, or even earth or mud, as an electrically conductive medium. This allows an electrical circuit to be produced by using only a single insulated electrical conductor in the sheath. This is also the case of a single conductor which will be described in detail below, but the invention is also applicable to the case of several conductors.

In the case of Figure 1, the electrical conductor 4 is embedded in the mass of a sheath 5 internal to the pipe. The electrical conductor 4 can be equipped with its own insulation, especially if the sheath 5 is not sufficiently electrically insulating.

In the case illustrated in FIG. 1, the conductor 4 connects an apparatus 6 to a surface installation 7, these two assemblies cooperate electrically with one another. It is possible to use the assembly allowing an electrical connection according to the invention, even when the drill pipe is rotating. To do this, it is necessary to have at least one rotating contact. This can be constituted, for example, by a ring 8 cooperating electrically with a contact 9; such devices being known from the prior art, will not be detailed in the present description.

FIG. 2 represents the junction between two adjacent elements of a pipe, each of these elements being equipped with different parts allowing the electrical connection. In this figure, the two elements of the pipe are screwed together. The invention is applicable to any type of connection by screwing or otherwise, from the moment when the operation of connecting the different elements together calls for at least one axial displacement.

The male side 10 of a pipe element is screwed to the female side 11 of the neighboring pipe element. The references 5a and 5b respectively designate the sheath containing the electrical conductor on the male side of a pipe element, and on the female side of the neighboring element.

The connection assembly comprises, in addition to the sheath, a male connector 12, an intermediate connector 13, a female connector 14, as well as fixing means.

The mechanical connection between the male connector 12 and the sheath 5a or between the female connector 14 and the sheath 5b can be carried out, depending on the nature of the materials used, by molding, for example by vulcanization, or by casting thermosetting resins, or else by welding, or by any other means. This connection, designated respectively by 15a and 15b, is made after the electrical connection of the ends of the conductive wire 4 housed in the sheath 5 has been made with the conductors of the connectors 12 and 14 respectively.

The male connector 12 comprises a body 16 provided with a passage for an electrical conductor, with a clearance for housing a contact 17, which in the case of FIG. 2 is embedded, at least partially, in a layer of thermosetting resin 18 , a groove 19 intended to receive a seal 20 used to wring the contact 42 and possibly to seal the compartment containing the contacts 17 and 42, as well as positioning and fixing means. The latter may include a ball 21 which is partially housed in a housing arranged inside the male side 10 of the pipe element, a part 22 holding the ball 21 in its housing, this part 22 is itself subject to the body of the male connector 16 by a bolt 23. Once in place, the part 22 abuts against the ball 21 and thus realizes the axial and rotational positioning of the male connector. In order to facilitate disassembly of the male connector, it is possible to produce a bore, threaded over at least a certain length, in the part 22. This bore, parallel to the axis of the pipe and passing right through the part 22 , is positioned to face a rigid solid part of the male connector, so that a force is exerted tending to separate the part 22 from the male connector, by screwing a bolt having a sufficient length in said bore.

According to another embodiment (Figure 5) the positioning and fixing means may include a lug 60 cooperating with a housing 61 formed inside the pipe element on the male side 10 and with a bore 62 formed in the first connector 12. The lug 60 may comprise a circular groove cooperating with a retaining member 63, such as an elastic stop ring (commonly called a "circlip") or a pin. Other devices for immobilizing the lug can be used, these devices, being known to those skilled in the art, will not be described in more detail.

The female connector 14 comprises a body 24 provided with a passage for an electrical conductor, a clearance for housing a contact 25, which in the case of FIG. 2, is at least partially embedded, in a layer of thermosetting resin 26, means positioning constituted for example by shims 27 as well as fixing means such as conical pins 28. The body 24 of the female connector may have grooves on its outer surface, these connecting the compartment 29 with the interior sheath via the orifices 30. It will not depart from the scope of the present invention by providing grooves and orifices on the first connector 12. These orifices may advantageously lead to one or more cavities 31 adapted, by their shape, to minimize the pressure drops while protecting the edges of the orifices 30 which would otherwise tend to wear out quickly. Finally, the body 24 of the connector has a flare cooperating with the inner shoulder on the female side of the pipe element.

The intermediate connector 13 comprises a body 32 provided with a passage 33 for the conductor connecting the contact 42 on the female side 34 (see FIG. 3) of this same connector. The male side 35 of the intermediate connector has a clearance on its outer wall to accommodate a contact 36 which, in the case of FIGS. 2 and 3, is at least partially embedded in a layer of elastomer 37, as well as a groove 38 intended to receive a seal 39, possibly wringing. The body 32 of the intermediate connector ends on the female side 34 by strips 40 which support a part advantageously made of elastomer 41 in which is housed the contact 42. The elastomer part 41 comprises two lips, one called the upper 43, the other lower 44, intended to perform the wiping and sealing functions. The lamellae 40 act as a stiffener and prevent the creep of the elastomer constituting the part 41. Likewise, reinforcing elements 47 and 48 provide the lips with permanent elasticity. These reinforcing elements may consist, for example, of springs, split rings, etc.

In certain cases, it is necessary to arrange clearances 45 and 46 behind the lips, so as to allow the deformation of the elastomer during the introduction of the male connector, without creating significant mechanical stress.

The body 32 of the intermediate connector has a shoulder 49 which cooperates with the top of the female connector 14, and a groove 50 intended to contain a seal 57, is arranged on the shoulder 49.

The intermediate connector 13 can be kept in abutment on the female connector by bolts 51 which pass through the female connector and are screwed onto the female element 11 of the pipe.

The axial positioning of the intermediate connector is achieved by the shoulder 49 which cooperates with the top of the female connector 14. The angular positioning can be achieved by centering pins which cooperate with housings produced in the female connector 14 and in the connector respectively intermediate 13. Another possible solution for angularly positioning the intermediate connector is shown in FIG. 4. According to this embodiment, a pin 28 is used having a conical part 52, surmounted by a cylindrical part 53 serving as a pin. centering with bores made on the intermediate connector 13. The conical part 52 of the pin 28 rests on a tapered bore 54 formed in the female connector 14, as well as in the female side 11 of the pipe element, so as to hold the latter in place. The pin 28 holds the connector 14 in place when the intermediate connector 13 has to be dismantled.

The number of electrical connections to be made which was one in the previous example can be increased. Thus, Figure 4 shows the case of a female connector allowing a double electrical connection.

In the case where the relative angular position of the pipe elements with respect to each other is defined, it is possible to make several contacts on a single and same circumference, axial lips, for example, electrically insulating the various contacts.

According to the invention, in the case where several electrical connections are made, it is possible to have a distribution of the contacts of the female connector different from that of the contacts of the male connector. For example, if you wish to establish two electrical connections, you could have two annular contacts placed on separate planes on the male connector and two contacts, each having an arc shape, placed in the same plane but electrically isolated from each other, on the female connector.

According to the invention, it is possible to coat, at least certain parts of the connectors exposed to the flow, with anti-wear material.

Finally, the number of conductors used per electrical connection can be greater than one, which reduces the risk of breakdown.

Examples of a method of fitting the assembly according to the invention

The following two examples are by no means limiting.

First example:

This example relates to the case where the different manufacturing tolerances on the various constituent elements are identical to allow all of them to be fitted with sheaths with conductors 5a, 5b of the same lengths.

It is therefore advantageous to have already assembled the female connector, the sheath and the male connector together. Then simply thread the male connector into the conduit element to be fitted and pull until the flare of the female connector abuts against the shoulder made on the female side of this conduit element, put the pins 28 in place, lock the male connector on the conduit element with the ball 21, the locking piece 22 and the nut 23, and put the intermediate connector in place by fixing it to the using screw 51.

Second example:

Case where the manufacturing tolerances of the various elements constituting the pipe are not identical to allow them to be fitted all with sheaths 5a, 5b of the same length.

• - on mesure la longueur entre l'épaulement 55 et l'épaulement 56 en forme de tronc de cône. Cette cote détermine l'épaisseur de la cale 27 à utiliser de sorte que la distance séparant les contacts 25 de l'épaulement 55 de l'élément de conduite côté femelle 11, soit identique pour tous les éléments de conduite.
• - On introduit la gaine 5b équipée du connecteur femelle 14, par le côté femelle 11 de l'élément de conduite et l'on tire sur cette gaine jusqu'à ce que le connecteur femelle se mette en place, il est alors possible de connaître la cote réelle que devra avoir la gaine conductrice 5b, de sorte que la distance séparant le contact 17 de l'épaulement 55a de l'élément de conduite côté mâle 10, soit identique pour tous les éléments de la conduite.
• - On retire cet ensemble de l'élément de conduite et l'on découpe à la cote déterminée précédemment,
• - on procède à la liaison électrique entre le connecteur mâle et l'extrémité libre de la gaine conductrice, puis on réalise un raccordement approprié entre ces deux pièces,
• - il suffit alors de poursuivre les opérations comme indiqué dans le premier exemple, mais sans oublier la cale 27.

It is therefore advantageous to have female connectors already fitted with sheaths comprising the conductors whose length is greater than or equal to that necessary to equip the largest pipe element. However, we proceed as follows:

• - The length between the shoulder 55 and the shoulder 56 in the form of a truncated cone is measured. This dimension determines the thickness of the shim 27 to be used so that the distance separating the contacts 25 from the shoulder 55 of the female side pipe element 11 is identical for all the pipe elements.
• - Introducing the sheath 5b equipped with the female connector 14, by the female side 11 of the pipe element and pulling on this sheath until the female connector is put in place, it is then possible to know the actual dimension that the conductive sheath 5b should have, so that the distance separating the contact 17 from the shoulder 55a from the male side pipe element 10, is identical for all the pipe elements.
• - This assembly is removed from the pipe element and cut to the dimension determined previously,
• - an electrical connection is made between the male connector and the free end of the conductive sheath, then an appropriate connection is made between these two parts,
• - it then suffices to continue the operations as indicated in the first example, but without forgetting the shim 27.

During the fitting of the intermediate connector 13 on the connector 14, the seal 39 can spin or wipe the contacts 25. However, the essential role of this seal 39 as well as that of the seal 57 is to seal the contacts 25 and 36. Indeed, these parts being disassembled only for the replacement of the intermediate connector, it suffices to ensure the cleanliness of the contacts before this operation which, after all, is infrequent.

During the fitting of the male connector 12 and the intermediate connector 13, the seal 20 performs the wringing and cleaning of the contact 42, while the upper lip 43 performs the wringing and cleaning of the contact 17 of the male connector. At the end of the operation, the upper lip 43 as well as the lower lip 44 seal the contact between the male connector and the intermediate connector, this seal being able to be reinforced by using reinforcing elements 47 and 48.

The relative movements of the male connector with respect to the intermediate connector have little influence on the wiping of the contacts, from the moment when there is generally a translational movement from one part with respect to the other. It does not matter whether this is combined with a continuous or alternating rotational movement.

It should be said that the position of the male contact 12 relative to the shoulder 55a is calculated as a function of the tolerance allowed on the distance separating this shoulder 55a from the top 58 of the pipe element considered, so that when this distance is at the minimum dimension, the lower part 59 of the male connector does not exceed the top 58 of the pipe element considered. Thus, during the vertical storage of the pipe elements, the face 58 resting on the ground, the male connectors are not damaged. It is the same on the female side of the pipe element, the dimensions of the intermediate connector being calculated so that it does not protrude from the pipe element.

To replace the intermediate connector 13, simply unscrew the screws 51 to release it. The female connector remaining in position thanks to the pins 28 and the balls 21.

The sheath 5 can be made of a material such as the material sold under the brand "Rilsàn" (well known to those skilled in the art) which has excellent mechanical qualities. The electrical conductor can be placed in a groove made along the sheath. In order to facilitate the connection between the sheath and the connectors 12 and 14, it is possible, in certain cases, to fix metal sleeves at the ends of the sheath by an appropriate method. If the connectors have a metal part, then it becomes possible to solder the connectors to the sleeves.

Of course, in the case where it is necessary to adjust the length of the sheath to that of the pipe element, it is possible to act either on the length of the sheath itself, or on that of at least one of the sleeves, or , when the sheath is already equipped with at least one sleeve of fixed length, by adding an additional length-adjusting sleeve.

The latter solution allows the use of elements whose length is standardized, such as sheaths or sheaths equipped with sleeves, which is particularly advantageous from an economic point of view.

Claims (23)

1. - Assembly making it possible to produce at least one electrical connection through a pipe (1) formed of elements fixed to each other, each element having a first end and a second end, adapted to cooperate mechanically with the complementary ends of the elements neighbors, characterized in that it comprises, by driving element: - a sheath (5) placed inside said element and in which is housed at least one conductor (4), - A first connector (12) fixed to one end of said sheath which is held in the first. end (10) of said pipe element and which cooperates electrically with said conductor (4), - a second connector (14) fixed to the other end of said sheath which is held in the second end of said pipe element and which cooperates electrically with said conductor (4), - a double connector (13) having a first end (34) which comprises at least one contact (42) and a second end (35) comprising at least one contact electrically connected to the previous one, the first end (34) of said double connector ( 13) cooperating electrically with the first connector (12) of a neighboring pipe element, the second end (35) of the double connector (13) cooperating electrically with said second connector (14), and - means for positioning and fixing the connectors (21, 22, 23, 27, 28, 51). 2. - An assembly according to claim 1, characterized in that said second connector (14) is positioned and held in place by at least one pin (28) having over a certain length a conical part (52) cooperating with a conical bore ( 54) produced on said second connector (14) and with the adjacent pipe element (11.). 3. - An assembly according to claim 2, characterized in that said pin (28) is surmounted by a cylindrical part (53) allowing the positioning of the double connector (13). 4. - An assembly according to claim 1, characterized in that at least the second connector (14) or the first connector (12) is provided with at least one outer groove connected to at least one bore (30) allowing the equipping the space (29) defined by the two complementary ends of neighboring elements and by the various parts making it possible to make the electrical connection with the interior of the pipe. 5. - An assembly according to claim 4, characterized in that said bore (30) opens into a cavity (31) having a shape adapted to limit the wear of the edges of said bore (30). 6. - assembly according to claim 5, characterized in that several bores (30) are made on the same diameter and in that they open into a cylindrical groove (31) having a flat bottom and the side swept by the discharge gently sloping. 7. - An assembly according to claim 1, characterized in that the second connector (14) is made of a rigid material to which is attached at least one conductive ring (25) held in place by a thermosetting resin or by an elastomer (26) . 8. - An assembly according to claim 1, characterized in that the second connector (14) has, on its upper part, a diameter greater than the smallest internal diameter of the pipe. 9. - An assembly according to claim l, characterized in that the outside diameter of the first connector (12) is at most equal to the smallest inside diameter of the pipe (1). 10. - assembly according to claim 1, characterized in that the means for positioning and fixing the first connector (12) comprise at least one ball (21) partially accommodating in a cavity produced inside the first end (10 ) of the conduit element, at least one part (22) holding said ball (21) in its housing, said part (22) being itself held on the first connector (12) by a bolt (23). 11. - assembly according to claim 10, characterized in that said part (22) holding said ball (21) has a bore which passes through said part (22) right through, this bore being threaded on at least a certain portion of its length and being positioned so as to face a rigid solid part of the first connector (12), so that a force is exerted tending to separate said piece (22) from the first connector (12) by screwing it 'a bolt of sufficient length in said bore. 12. - assembly according to claim 1, characterized in that said double connector (13) is held in abutment on said second connector (14) by means of at least one screw (51) screwed onto the second end of the pipe (11). 13. - Assembly according to claim 1, characterized in that said double connector (13) comprises housings (38, 50) receiving seals making it possible to ensure the sealing function and possibly dewatering of the electrical contact between said connector double (13) and the second connector (14). 14. - The assembly of claim 1, characterized in that the first end (34) of the double conenctor (13) is made of an elastomer (41) having reinforcing elements (40). 15. - An assembly according to claim 1, characterized in that the first end (34) of the double connector (13) comprises lips (43, 44) making it possible to perform the wiping and sealing functions of the electrical contacts ( 17, 42) between the double connector (13) and the first connector (12). 16. - An assembly according to claim 15, characterized in that the first end (34) of the double connector (13) has clearances (45, 46) in the vicinity of the lips (43, 44), said clearances (45, 46) allowing the volume of material displaced by the recoil of the lips (43, 44) to be received when the first connector (12) is introduced. 17. - An assembly according to claim 1, characterized in that the positioning of the second connector (14) is ensured by shims (27) placed between the element of the pipe and said second connector (14). 18. - Assembly according to claim 1, characterized in that the first connector (12) comprises at least one housing (19) intended to receive a seal (20) making it possible to perform the functions of spinning and / or sealing of the electrical contact (42). 19. - Assembly according to claim 1, characterized in that at least some parts of the connectors (12, 13, 14) exposed to the flow are covered with anti-wear material. 20. - assembly according to claim 1, applied in the case where the passage section at the connection is less than the passage section at the sheath (5), characterized in that the evolution of the intermediate sections takes place gradually from the narrowest section at the connection, to the sheath following the direction of the fluid. 21. - assembly according to claim 1, characterized in that the means for positioning and fixing the first connector (12) comprise at least one lug (60) cooperating with a housing (61) formed inside the element conduit and with a bore in the first connector and a retaining member. 22. - Method of setting up an assembly making it possible to produce at least one electrical connection through a pipe (1) formed of elements fixed to each other, each element having a first end and a second end, adapted to mechanically cooperate with the complementary ends of the neighboring elements, comprising, per pipe element: - a sheath (5) placed inside said element and in which is housed at least one conductor (4), a first connector (12) fixed to one end of said sheath which is held in the first end (10) of said pipe element and which cooperates electrically with said conductor (4), - a second connector (14) fixed to the other end of said sheath which is held in the second end of said pipe element and which cooperates electrically with said conductor (4), - a double connector (13) having a first end (34) which comprises at least one contact (42) and a second end (35) comprising at least one contact electrically connected to the previous one, the first end (34) of said double connector (13) cooperating electrically with the first connector (12) of a neighboring pipe element, the second end (35) of the double connector (13) cooperating electrically with said second connector (14), and - means for positioning and fixing the connectors (21, 22, 23, 27, 28, 51),
characterized in that the second connector (14) being already fixed to the sheath (5), the latter having a length greater than that necessary to equip the pipe element, is cut to the length suitable for said pipe element, then is fixed to the first connector (12) by vulcanization or by equivalent means, once the electrical connection has been made. 23. - Method of setting up an assembly making it possible to produce at least one electrical connection through a pipe (1) formed of elements fixed to each other, each element having a first end and a second end, adapted to cooperate mechanically with the complementary ends of the neighboring elements, comprising per pipe element: - a sheath (5) placed inside said element and in which is housed at least one conductor (4), a first connector (12) fixed to one end of said sheath which is held in the first end (10) of said pipe element and which cooperates electrically with said conductor (4), - a second connector (14) fixed to the other end of said sheath which is held in the second end of said pipe element and which cooperates electrically with said conductor (4), - a double connector (13) having a first end (34) which comprises at least one contact (42) and a second end (35) comprising at least one contact electrically connected to the previous one, the first end (34) of said double connector ( 13) cooperating electrically with the first connector (12) of a neighboring pipe element, the second end (35) of the double connector (13) cooperating electrically with said second connector (14), and means for positioning and fixing the connectors (21, 22, 23, 27, 28, 51),
applied in the case where a sheath optionally comprising at least one sleeve is used, the length of the assembly thus formed being less than that of the pipe element to be fitted, characterized in that the length of the 'assembly thus formed by the addition of a length take-up sleeve.

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