Method for manufacturing a heating cable and heating cable manufactured according to this method

Abstract

A method for manufacturing an electric heating cable that can be wound spirally around a submarine pipeline, wherein this cable comprises a group of phase conductors (11, 12, 13) that are individually insulated from one another, wherein the cable is covered with an insulating sheath (17), characterized in that a section with an exposed end (11a, 12a, 13a) of each of the phase conductors (11, 12, 13) and a conductive binder (16) that is hot-melt and cold-curable is inserted into at least one central cavity (15) of a housing (14), and that the exposed end sections (11a, 12a, 13a) of the phase conductors (11, 12, 13) are soldered together within the central cavity (15) of the housing (14) using the binder (16) to create a mechanical and electrical connection between the phase conductors (11, 12, 13). 12, 13) and thus create a star-shaped connection end.

Description

Technical field

[0001] The present invention relates to a method for manufacturing an electric heating cable, in particular for an underwater pipeline, wherein this cable has a group of phase conductors that are individually insulated from each other and a star-shaped terminal end where the ends of the phase conductors are connected to each other, wherein the cable is covered with an insulating sheath and wound spirally around the corresponding line.

[0002] The present invention also relates to an electric heating cable, in particular for an underwater pipeline, which is manufactured according to the above-mentioned method, wherein this cable has a group of phase conductors which are individually insulated from each other and a star-shaped terminal end where the ends of the phase conductors are connected to each other, wherein the cable is covered with an insulating sheath and wound spirally around the corresponding line. State of the art

[0003] Cables of this type are already known in which the terminal end of the phase conductors has, on the one hand, loops of phase conductors folded on themselves, and on the other hand, a conductive metal part for crimping, which is designed to simultaneously crimp the loops of phase conductors together and to electrically connect the phase conductors together.

[0004] These in Fig. The embodiment shown in Figure 1, which represents the closest prior art, creates a significant additional thickening at the terminal end of the phase conductors, which in this area generally need to be insulated by means of a heat-shrinkable sheath. This sheath is difficult to apply and its application is time-consuming.

[0005] Furthermore, the security of the connection is not absolutely guaranteed, as attaching the cable by spirally wrapping it around the conductor creates significant stresses that can loosen the crimping part, which can lead to both poor mechanical strength and a poor electrical connection.

[0006] Finally, the slightest imperfection, both in terms of the mechanical strength of the part to be crimped and the electrical connection, can have serious consequences, taking into account that the service life of the lines surrounded by heating cables must be around twenty years and that these lines are located at great depths on the seabed, making them completely inaccessible for any repair should any problems arise.

[0007] The existing solutions therefore exhibit both technical and economic disadvantages, making a method that is more reliable in terms of mechanical strength and electrical safety, and which also offers the advantage of a simplified and rapid connection end setup, highly attractive to users. The economic significance of saving time in preparing the connection end is considerable, as this process is carried out on a specialized pipeline-laying vessel, whose hourly rate is extremely high.

[0008] Various types of heating cables are known and described in prior publications. The international application published under number WO 2010 / 032017 A1 describes a self-regulating heating cable consisting of a first, a second, and a third power supply conductor. The first conductor is electrically connected to the second conductor by means of a first electrically conductive heating element having a first resistance coefficient. The second conductor is electrically connected to the third conductor by means of a second electrically conductive heating element having a second resistance coefficient. During use, the three power supply conductors are not connected to each other.

[0009] French patent no. 1,407,180 describes a cable intended for agricultural use, comprising two resistance wires with different resistance values ​​for various applications and with different voltages applied to the wires. The cables are connected at one end to a power source and at the other end to each other. The insulated wires are laid directly in the soil of the crops to be heated. Description of the invention

[0010] The present invention aims to eliminate all the aforementioned disadvantages by creating an inexpensive, effective and reliable heating cable, the manufacture of which is greatly simplified compared to currently known techniques.

[0011] This problem is solved in the method according to the invention, as specified in the preamble, by introducing a section with an exposed end of each of the phase conductors and a conductive binder that is hot-meltable and cold-curable into at least one central cavity of a housing, and by soldering the exposed end sections of the phase conductors within the central cavity of the housing using the binder to ensure a mechanical and electrical connection between the phase conductors.

[0012] According to a first embodiment, a housing is used which has a closed bottom and whose at least one central cavity contains a mass of the cold-cured binder, wherein the housing and / or the binder it contains is heated to make it liquid, wherein the exposed end sections of the phase conductors are inserted into the interior of the at least one central cavity and the arrangement is cooled.

[0013] According to a second embodiment, a housing is used which has a closed bottom and at least one cavity, wherein the exposed end sections of the phase conductors are inserted into the interior of the at least one central cavity and wherein a predetermined mass of cold binder, which has been previously heated to make it liquid, is poured into at least one central cavity containing the exposed end sections of the phase conductors.

[0014] For this purpose, it is advantageous to use a binder formed from an alloy for soldering with tin or from an alloy for soldering with nickel.

[0015] Advantageously, a housing made of an electrically conductive metallic material is used.

[0016] According to an advantageous embodiment, a housing is used that is made of an electrically non-conductive material.

[0017] This problem is also solved according to the invention in the case of the cable as described in the preamble by the fact that the terminal end of the phase conductors has a housing which is open at at least one end and which has at least one central cavity, and that the housing is provided to receive an exposed end section of each phase conductor and a mass of hot-melt and cold-curable conductive binder in order to ensure a mechanical and electrical connection between the exposed end sections of the phase conductors inside the cavity of the housing.

[0018] According to a particularly advantageous embodiment, the binder mass comprises an alloy for soldering with tin or an alloy for soldering with nickel.

[0019] The housing is advantageously made of a metallic material with a high conductivity coefficient.

[0020] According to a first embodiment, the housing has a common central recess for the exposed conductor sections.

[0021] According to another embodiment, the housing has several recesses, each corresponding to the exposed conductor sections, which are individually soldered in the respective recesses. Summary description of the drawings

[0022] The present invention and its main advantages will become clearer in the description of the various embodiments with reference to the accompanying drawings. These show:

[0023] Fig. 1 a schematic representation of an embodiment known from the prior art, which is frequently used in an application as a heating cable for pipelines,

[0024] Fig. 2 in longitudinal section a preferred embodiment of the connection area of ​​the phase conductors of the cable according to the invention and

[0025] Fig. 3 in cross-section a preferred embodiment of the connection area of ​​the phase conductors of the cable according to the invention. Best embodiments of the invention

[0026] Currently, pipelines are fitted with a heating cable that is spirally wound around the outside of the pipe and regularly attached to it with flanges, all covered by an insulating sheath. The heating cable typically has three phase conductors, each exposed at one end and connected in a star configuration. In practice, the end sections are individually exposed over a certain length, folded back on themselves, and crimped using a crimp strip. Due to the diameter of the phase conductors, the formation of a loop by folding back one conductor section and connecting three similar loops creates a significant thickening, which the operator must insulate before attaching it to the outer wall of the pipe. The installation is weakened simply by the presence of this thickening, which also weakens the insulating sheath applied around the pipeline. Fig. Figure 1 schematically shows a loop. 1 of the phase conductor 2 , which is folded and crimped using a crimp strip 3 is crimped.

[0027] The solution according to the invention makes it possible to avoid weakening and to produce the connection much more efficiently and quickly. The longitudinal section according to Fig. 2 and the cross-section according to Fig. Figure 3 shows an embodiment of the connection of the phase conductors according to the invention. In the illustrated embodiment, three phase conductors are shown. 11 , 12 and 13 each in sections 1a , 12a and 13a exposed. These sections are designed to be, on the one hand, installed and mechanically fastened, and on the other hand, electrically connected within a housing. 14 to be connected to each other, which, for example, has a recess with a rectangular cross-section that has at least one central cavity 15forms a depth at least equal to the length of the exposed sections 11a , 12a and 13a The cavity corresponds to the cross-section of these exposed sections of the phase conductors and its length is preferably greater than the cross-section of these exposed sections. A single central cavity may be provided, or it may be subdivided into several sub-cavities by partitions. However, it is essential that the phase conductors are electrically coupled to each other, either directly by a conductive binder or by the conductive binder and the walls of the housing, provided that the material from which the housing is made is also conductive.

[0028] The case 14 It can be made of a conductive material, for example a copper alloy. It can also be made of a non-conductive material, for example ceramic or the like. The cavity 15It serves to hold a conductive connecting material. 16 , for example, a tin-based or nickel-based solder alloy, or the like. Two cases can occur: Either the binder is initially contained in the cavity or sub-cavities and must be heated to melt it from its solid, cold state to its liquid, hot state, or it is poured hot into the cavity or sub-cavities where the exposed sections of the phase conductors have previously been arranged. In the first case, the housing 14 when arranging the exposed sections of the phase conductors 1a , 12a and 13a until the conductive connecting material melts 16 heated, causing the sections to become firmly attached to the casing 14They can be connected and the electrical connection between the phase conductors can be ensured. In the second case, the exposed sections of the phase conductors 11a , 12a and 13a into the empty recess 15 introduced and the conductive connecting material 16 The liquid, after prior heating, is poured into the housing to secure the phase conductors and connect them electrically. The three conductors are arranged side by side, and the only thickening is that of the housing wall. 14 , which can be reduced to a minimum. The electrical connection is perfect and the stability of the connection is guaranteed.

[0029] Fig. Figure 3 also shows an insulating cover 17 , which surround the outer wall of the housing 14 is arranged to provide electrical insulation for the connection of the three phase conductors 11 , 12 and 13to ensure.

[0030] In the example shown, the housing has a common central cavity for the three exposed conductor sections. 11a , 12a , 13a open. According to one variant, the cavity 16 be divided into three cavities, each corresponding to the three exposed conductor sections 11a , 12a and 13a The three phase conductors are individually soldered into their respective cavities. Since the housing is made of a conductive material, such as a copper alloy, the quality of the electrical connection of the three phase conductors is ensured.

[0031] The present invention is not limited to the described embodiments, but may be subject to various modifications or variations. In particular, the practical implementations can be adapted to intended applications, and the materials used can then be selected according to these applications.

Claims

[1] Method for manufacturing an electric heating cable, in particular for a submarine pipeline type, wherein this cable has a group of phase conductors which are individually insulated from each other and a star-shaped terminal end where the ends of the phase conductors are connected to each other, wherein the cable is covered with an insulating sheath and is wound spirally around the conductor, characterized by that a section with an exposed end ( 11a , 12a , 13a ) each of the phase conductors ( 11 , 12 , 13 ) and a conductive binder ( 16 ), which is hot-meltable and cold-curable, in at least one central cavity ( 15 ) of a housing ( 14 ) is introduced, and that the exposed end sections ( 11a , 12a , 13a ) the phase conductor ( 11 , 12 , 13 ) within the central cavity ( 15 ) of the housing (14 ) with the help of the binder ( 16 ) are soldered to create a mechanical and electrical connection between the phase conductors ( 11 , 12 , 13 to ensure. [2] Method according to claim 1, characterized by that a case ( 14 ) is used, which has a closed bottom and at least one central cavity ( 15 ) a mass of the cold-cured binder ( 16 ) contains, wherein the housing ( 14 ) and / or the binder ( 16 ), which it contains, is heated to liquefy it, with the exposed end sections ( 11a , 12a , 13a ) the phase conductor ( 11 , 12 , 13 ) into the interior of at least one central cavity ( 15 ) are introduced and the arrangement is cooled. [3] Method according to claim 1, characterized by that a case ( 14) is used, which has a closed bottom and at least one central cavity ( 15 ) exhibits, with the exposed end sections ( 11a , 12a , 13a ) the phase conductor ( 11 , 12 , 13 ) into the interior of at least one central cavity ( 16 ) are introduced and wherein a predetermined mass of cold binder ( 16 ), which has been previously heated to make it liquid, into at least one central cavity ( 15 ) is cast, which contains the exposed end sections of the phase conductors. [4] Method according to claim 2, characterized by that a binder ( 16 ) is used, which is formed from an alloy for soldering with tin. [5] Method according to claim 2, characterized by that a binder ( 16 ) is used, which is formed from an alloy for soldering with nickel. [6] Method according to any one of claims 1 to 5, characterized by that a case ( 14 ) is used, which is made from an electrically conductive metallic material. [7] Method according to any one of claims 1 to 5, characterized by that a case ( 14 ) is used, which is made from an electrically non-conductive material. [8] Electric heating cable, in particular for a submarine pipeline type, wherein this cable has a group of phase conductors which are individually insulated from each other and a star-shaped terminal end where the ends of the phase conductors are connected to each other, wherein the cable is covered with an insulating sheath and wound spirally around the line, characterized by that the connection end of the phase conductors ( 11 , 12 , 13 ) a housing ( 14 ) has which is open at at least one end and has at least one central cavity ( 15) exhibits that the housing is designed to accommodate an exposed end section ( 11a , 12a , 13a ) of each phase conductor ( 11 , 12 , 13 ) and a mass of hot-melting and cold-curing, conductive binder ( 16 ) is intended to provide a mechanical and electrical connection between the exposed end sections ( 1a , 12a , 13a ) the phase conductor ( 11 , 12 , 13 ) inside the cavity ( 15 ) of the housing ( 14 to ensure. [9] Cable according to claim 8, characterized by that the mass of binder ( 16 ) includes a tin-based soldering alloy. [10] Cable according to claim 8, characterized by that the mass of binder ( 16 ) includes a nickel-based alloy for soldering. [11] Cable according to claim 8, characterized by that the case ( 14) consists of an electrically conductive metallic material. [12] Cable according to claim 8, characterized by that the casing is made of an electrically non-conductive material. [13] Cable according to one of claims 11 or 12, characterized by that the case ( 14 ) a common central cavity ( 15 ) for the exposed conductor sections ( 11a , 12a and 13a ) exhibits. [14] Cable according to claim 11, characterized by that the case ( 14 ) several cavities ( 15 ) for the respective exposed conductor sections ( 11a , 12a , 13a ) exhibits components that are individually soldered into the respective recesses.