METHOD FOR PRODUCING A HEATING CABLE AND HEATING CABLE PRODUCED ACCORDING TO THIS METHOD

PROCEDE DE FABRICATION D'UN CABLE CHAUFFANT ET CABLE CHAUFFANT REALISE SELON CE PROCEDE

English Abstract

The invention concerns an electric heating cable intended for pipelines. Sections (11a, 12a and 13a) of three phase conductors (11, 12 are 13) are stripped respectively. These sections are intended to be installed and both secured in place and electrically connected to each other inside a box (14) having, for example, a central cavity (15) having a rectangular cross-section, the depth of which is at least equal to the length of the stripped sections (11a, 12a and 13a) and the length of which is preferably greater than the transverse cross-section of these stripped sections of the phase conductors. They are secured in the central cavity (15) with a conductive binder (16), for example a tin solder, in order to ensure they are secured in place and electrically connected to each other.

French Abstract

L'invention concerne un câble électrique chauffant destiné à des pipelines. Trois conducteurs de phases (11, 12 et 13) sont dénudés respectivement sur des tronçons (11a, 12a et 13a). Ces tronçons sont destinés à être mis en place et fixés d'une part et électriquement raccordés entre eux d'autre part à l'intérieur d'une boîte (14), ayant par exemple une cavité centrale (15) de section rectangulaire, dont la profondeur est au minimum égale à la longueur des tronçons dénudés (11a, 12a et 13a) et dont la longueur est de préférence supérieure à la section transversale de ces tronçons de conducteurs de phase dénudés. Ils sont fixés dans la cavité centrale (15) avec un liant (16) conducteur, par exemple une soudure à l'étain pour assurer la fixation et le raccordement électrique entre eux.

Claims

¨ 8 ¨
What is claimed is,
1. A method for producing an electric heating cable, the heating cable
comprising
three phase conductors individually insulated relative to one another by an
insulation,
the method comprising:
stripping the insulation from ends of the three phase conductors to provide
three stripped ends;
introducing the three stripped ends of the three phase conductors into at
least
one cavity of a box, comprised of a metallic material or a ceramic, from an
open end
of the box, arranging in the at least one cavity the three stripped ends so as
to be
spaced apart from each other across an entire length of the three stripped
ends in a
direction perpendicular to a longitudinal direction of the three phase
conductors, and
introducing a thermofusible conductive binding agent into the at least one
cavity, the
box comprising a closed bottom and further comprising a sidewall connected to
the
bottom, wherein the closed bottom extends perpendicular to the longitudinal
direction
of the three phase conductors, and wherein the sidewall, viewed in a
longitudinal
section view, extends in the longitudinal direction, wherein the closed bottom
and the
sidewall delimit the at least one cavity and wherein the open end of the box
is
positioned opposite the closed bottom and spaced apart from the closed bottom
in the
longitudinal direction, wherein the at least one cavity of the box comprises a
plurality
of cavities, wherein each one of the three stripped ends has one of the
cavities
associated therewith;
individually soldering the three stripped ends of the three phase conductors,
inserted into the box so as to terminate inside the box, to an inside of the
at least one
cavity of the box by the solid thermofusible conductive binding agent in the
associated
cavities, respectively, to produce a mechanical and electrical connection
between the
three stripped ends of the three phase conductors, and electrically connecting
the
three stripped ends by the thermofusible conductive binding agent in a star
connection end, wherein the three phase conductors are projecting from the
solid
thermofusible conductive binding agent at the open end of the box and the box
with
the closed bottom is the end of the electric heating cable where the electric
heating
cable ends viewed in the longitudinal direction, wherein the at least one
cavity has
a depth that is at least equal to a length of the three stripped ends of the
three
phase conductors.

-- 9 --
2. The method according to claim 1, wherein the thermofusible conductive
binding
agent is introduced into the at least one cavity prior to introducing the
three stripped
ends and is present as a cold solid mass in the at least one cavity, the
method further
comprising heating the thermofusible conductive binding agent contained in the
at least
one cavity to make the thermofusible conductive binding agent fluid,
subsequently
introducing the three stripped ends into the fluid thermofusible conductive
binding
agent contained in the at least one cavity, and cooling the thermofusible
conductive
binding agent together with the introduced three stripped ends to produce the
mechanical and electrical connection.
3. The method according to claim 1, wherein the three stripped ends are
introduced into the at least one cavity prior to introducing the thermofusible
conductive
binding agent, the method further comprising heating a predetermined mass of
the
thermofusible conductive binding agent to make the thermofusible conductive
binding
agent liquid and pouring the liquid thermofusible conductive binding agent
into the at
least one cavity containing the three stripped ends.
4. The method according to claim 1, further comprising selecting the
thermofusible
conductive binding agent from a tin-based alloy for soldering.
5. The method according to claim 1, further comprising selecting the
thermofusible
conductive binding agent from a nickel-based alloy for soldering.
6. The method according to claim 1, further comprising selecting the box
from a
box made of an electrically conductive metallic material.
7. The method according to claim 1, further comprising selecting the box
from a
box made of an electrically non-conductive material.
8. An electric heating cable comprising:
three phase conductors individually insulated relative to one another by an
insulation and each comprising a stripped end from which the insulation has
been stripped;
a box, comprised of a metallic material or a ceramic, the box comprising a
closed bottom and a sidewall connected to the closed bottom, wherein the
closed
bottom extends perpendicular to a longitudinal direction of the three phase
conductors, and wherein the sidewall, viewed in a longitudinal section view,
extends
in the longitudinal direction, wherein the closed bottom and the sidewall
delimit at
least one cavity and wherein the box has an open end positioned opposite the

¨ 10 ¨
closed bottom and spaced apart from the closed bottom in the longitudinal
direction;
the three stripped ends introduced from the open end of the box into the at
least one cavity, wherein the three stripped ends arranged in the at least one
cavity
are spaced apart from each other across an entire length of the three stripped
ends
in a direction perpendicular to the longitudinal direction of the three phase
conductors;
a solid thermofusible conductive binding agent that is disposed in the at
least
one cavity and provides a mechanical and electrical connection between the
three
stripped ends of the three phase conductors inside the at least one cavity and
the
three stripped ends are electrically connected by the thermofusible conductive

binding agent in a star connection end, wherein the three phase conductors
terminate inside the box and project from the solid thermofusible conductive
binding
agent at the open end of the box, and wherein the box with the closed bottom
together with the solid thermofusible conductive binding agent is the end of
the
electric heating cable where the electric heating cable ends viewed in the
longitudinal
direction, wherein the at least one cavity has a depth that is at least equal
to a length
of the three stripped ends of the three phase conductors;
wherein the at least one cavity of the box comprises a plurality of cavities,
wherein each one of the three stripped ends has one of the cavities associated

therewith, and wherein the three stripped ends are individually soldered by
the solid
thermofusible conductive binding agent in the associated cavities,
respectively.
9. The cable according to claim 8,wherein the thermofusible conductive
binding
agent comprises a tin-based soldering alloy.
10. The cable according to claim 8, wherein the thermofusible conductive
binding
agent comprises a nickel-based soldering alloy.
11. The electric heating cable according to claim 8, wherein the three
stripped ends are
introduced into the thermofusible conductive binding agent disposed in the at
least one
cavity when the thermofusible conductive binding agent is made fluid by
heating and the
three stripped ends are fixed in the thermofusible conductive binding agent
when the
thermofusible conductive binding agent solidifies upon cooling.
12. The electric heating cable according to claim 8, wherein the three
stripped ends are
parallel to each other.
Date recue / Date received 2021-12-21

¨ 11 ¨
13. An electric heating cable comprising:
three phase conductors individually insulated relative to one another by an
insulation and each comprising a stripped end from which the insulation has
been
stripped;
a box comprising a closed bottom and a sidewall connected to the closed
bottom, wherein the closed bottom extends perpendicular to a longitudinal
direction
of the three phase conductors, and wherein the sidewall, viewed in a
longitudinal
section view, extends in the longitudinal direction, wherein the closed bottom
and the
sidewall delimit at least one cavity and wherein the box has an open end
positioned
opposite the closed bottom and spaced apart from the closed bottom in the
longitudinal direction, wherein the box consists of an electrically conductive
metal;
the three stripped ends introduced from the open end of the box into the at
least one cavity, wherein the three stripped ends arranged in the at least one
cavity
are spaced apart from each other across an entire length of the three stripped
ends
in a direction perpendicular to the longitudinal direction of the three phase
conductors;
a solid thermofusible conductive binding agent that is disposed in the at
least
one cavity and provides a mechanical and electrical connection between the
three
stripped ends of the three phase conductors inside the at least one cavity and
the
three stripped ends are electrically connected by the thermofusible conductive

binding agent in a star connection end, wherein the three phase conductors
terminate inside the box and project from the solid thermofusible conductive
binding
agent at the open end of the box, and wherein the box with the closed bottom
together with the solid thermofusible conductive binding agent is the end of
the
electric heating cable where the electric heating cable ends viewed in the
longitudinal
direction, wherein the at least one cavity has a depth that is at least equal
to a length
of the three stripped ends of the three phase conductors.
14. The electric heating cable according to claim 13, wherein the three
stripped
ends are introduced into the thermofusible conductive binding agent disposed
in the
at least one cavity when the thermofusible conductive binding agent is made
fluid by
heating and the three stripped ends are fixed in the thermofusible conductive
binding agent when the thermofusible conductive binding agent solidifies upon
cooling.


¨ 12 ¨
15. The electric heating cable according to claim 13, wherein the three
stripped
ends are parallel to each other.
16. An electric heating cable comprising:
three phase conductors individually insulated relative to one another
by an insulation and each comprising a stripped end from which the insulation
has
been stripped;
a box, comprised of a metallic material or a ceramic, the box comprising a
closed bottom and a sidewall connected to the closed bottom, wherein the
closed
bottom extends perpendicular to a longitudinal direction of the three phase
conductors, and wherein the sidewall, viewed in a longitudinal section view,
extends
in the longitudinal direction, wherein the closed bottom and the sidewall
delimit at
least one cavity and wherein the box has an open end positioned opposite the
closed bottom and spaced apart from the closed bottom in the longitudinal
direction;
the three stripped ends introduced from the open end of the box into the at
least one cavity, wherein the three stripped ends arranged in the at least one
cavity
are spaced apart from each other across an entire length of the three stripped
ends
in a direction perpendicular to the longitudinal direction of the three phase
conductors;
a solid thermofusible conductive binding agent that is disposed in the at
least
one cavity and provides a mechanical and electrical connection between the
three
stripped ends of the three phase conductors inside the at least one cavity and
the
three stripped ends are electrically connected by the thermofusible conductive

binding agent in a star connection end, wherein the three phase conductors
terminate inside the box and project from the solid thermofusible conductive
binding
agent at the open end of the box, and wherein the box with the closed bottom
together with the solid thermofusible conductive binding agent is the end of
the
electric heating cable where the electric heating cable ends viewed in the
longitudinal
direction, wherein the at least one cavity has a depth that is at least equal
to a length
of the three stripped ends of the three phase conductors;
wherein the box comprises an insulating sleeve arranged around an outer wall
of the box.
17. The cable according to claim 16, wherein the at least one cavity is a
common
central hollow for all of the three stripped ends.
Date recue / Date received 2021-12-21

¨ 13 ¨
18. The electric heating cable according to claim 16, wherein the three
stripped
ends are introduced into the thermofusible conductive binding agent disposed
in the
at least one cavity when the thermofusible conductive binding agent is made
fluid by
heating and the three stripped ends are fixed in the thermofusible conductive
binding
agent when the thermofusible conductive binding agent solidifies upon cooling.
19. The electric heating cable according to claim 16, wherein the three
stripped
ends are parallel to each other.
Date recue / Date received 2021-12-21

Description

CA 02910942 2015-10-29
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Translation of European Patent No. 14726314.9
BACAB S.A.
METHOD FOR PRODUCING A HEATING CABLE AND
HEATING CABLE PRODUCED ACCORDING TO THIS METHOD
Technical field
The present invention concerns a method for producing an electric heating
cable, in particular for an underwater pipeline-type conduit, this cable
comprising a group of phase conductors individually insulated with respect to
one another and a star-shaped connection end where the ends of said phase
conductors are connected to one another, said cable being covered by an
insulating sleeve and coiled in a spiral around said conduit.
The present invention also concerns an electric heating cable, in particular
for
a pipeline-type underwater conduit, produced according to the above method,
this cable comprising a group of phase conductors individually insulated with
respect to one another and a star-shaped connection end where the ends of
said phase conductors are connected to one another, said cable being
covered by an insulating sleeve and coiled in a spiral around said conduit.
Prior art
Cables of this type are already known in which said connection end of the
phase conductors comprises on the one hand phase conductor loops folded
back on themselves, and on the other hand a conductive metallic crimping
part intended both for pressing the phase conductor loops against another
and for electrically connecting the phase conductors to one another.
This embodiment, shown by Figure 1 that illustrates the closest prior art,
creates a substantial additional thickness on the connection end of the phase
conductors that must be insulated in this zone, generally by means of a
thermo-retractable sleeve. This sleeve is on the one hand difficult to
position,
and on the other hand, its positioning takes a lot of time.

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Furthermore, the security of the joint is not totally guaranteed due to the
fact
that the positioning of the cable by coiling it in a spiral around the conduit

creates substantial stresses which risk detaching the crimping part, and this
can lead to poor mechanical strength as well as to a poor electrical
connection.
Finally, the slightest imperfection, either as regards the mechanical strength
of
the crimping part or as regards the electrical connection, may have serious
consequences, it being known that the lifespan of conduits surrounded with
heating cables must be around twenty years and that these conduits are
positioned at a great depth on ocean floors, meaning that it is absolutely
impossible to reach them in order to carry out repairs if there is a problem.
The current solutions are therefore associated with both technical and
economical disadvantages such that a method that is more reliable as regards
mechanical strength and electrical safety, offering furthermore the advantage
of simplified and fast positioning of the connection end, makes them of great
benefit to the users. The economic benefit of saving time when preparing the
connection end is considerable due to the fact that this operation is carried
on
a specialist ship adapted for the laying of pipelines and the hourly cost for
use
of which is extremely high.
Various types of heating cable have been produced and are described in prior
publications. The international application published under No. WO
2010/032017 Al describes a self-regulating heating cable made up of a first,
a second and a third electrical supply conductor. The first conductor is
connected electrically to the second conductor by means of a first
electrically
conductive heating element that has a first resistance coefficient. The second

conductor is connected electrically to the third conductor by means of a
second electrically conductive heating element that has a second resistance
coefficient. During use the three electrical supply conductors are not
interconnected.

CA 02910942 2015-10-29
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French Patent No. 1,407,180 describes a heating cable intended for
agriculture, comprising two resistance wires that have different ohm values
for
different applications and different voltages applied to the wires that are
connected to a power source at one end and are connected to one another at
their other end. The insulated wires are placed directly in the ground to be
heated for growing.
Presentation of the invention
The present invention proposes overcoming all of the disadvantages
mentioned above by producing an economical, effective and reliable heating
cable, production of which is very much simplified in comparison to the
techniques currently being used.
This aim is achieved by the method according to the invention as defined in
the preamble and characterised in that a section with a stripped end of each
of said phase conductors as well as a conductive binding agent that is
thermofusible and hardens when cold are introduced into at least one central
cavity of a box that is open at one end, and in that said sections with
stripped
ends of said phase conductors are soldered to the inside of said central
cavity
of said box by means of said binder in order to provide a mechanical and
electrical connection between said phase conductors.
According to a first embodiment a box that has a closed bottom and of which
said at least one central cavity contains a mass of said cold, hardened binder

is used, said box and/or the binder that it contains is/are heated in order to

make it/them fluid, said sections with stripped ends of said phase conductors
are introduced into the inside of said at least one central cavity and the
whole
thing is cooled.
According to a second embodiment, a box that has a closed bottom and at
least one central cavity is used, said sections with stripped ends of said
phase
conductors are introduced into the inside of said at least one central cavity,

and a predetermined mass of said cold binder that has previously been

CA 02910942 2015-10-29
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heated in order to make it liquid is poured into said at least one central
cavity
containing said sections with stripped ends of said phase conductors.
For this purpose one can advantageously use a binder made from an alloy for
soldering to tin or a binder made of an alloy for soldering to nickel.
Preferably, a box made of an electrically conductive metallic material is
used.
According to one advantageous embodiment, a box made of an electrically
non-conductive material is used.
This aim is also achieved by the cable according to the invention as defined
in
the preamble and characterised in that said connection end of said phase
conductors comprises an open box on at least one end, and comprising at last
one central cavity, this box being arranged to receive a section with a
stripped
end of each of said phase conductors as well as a conductive binder agent
that is thermofusible and can harden when cold in order to provide a
mechanical and electrical connection between said sections with stripped
ends of said phase conductors inside said cavity of said box.
Particularly advantageously, said binder agent comprises an alloy for
soldering to tin or an alloy for soldering to nickel.
Said box is preferably made of a metallic material that has a high
conductivity
coefficient.
According to a first embodiment, said box comprises a common central hollow
for the stripped conductor sections.
According to a variant, said box comprises a number of cavities respectively
dedicated to said stripped conductor sections, soldered individually in the
respective cavities.

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Brief description of the drawings
The present invention and its main advantages will become clearer from the
description of different embodiments, with reference to the attached drawings
in which:
Figure 1 shows a diagrammatic view of an embodiment known according to
the prior art and which is currently used within the framework of an
application
as a heating cable for pipelines,
Figure 2 is a longitudinal sectional view of a preferred embodiment of the
joint
zone of the phase conductors of the cable according to the invention, and
Figure 3 is a cross-sectional view of the preferred embodiment of the joint
zone of the phase conductors of the cable according to the invention.
Best ways of realising the invention
Currently, the pipelines are equipped with a heating cable that is coiled in a

spiral on the outside of the conduit, fixed at regular intervals to this
conduit by
straps, the whole thing being covered with an insulating envelope. The
heating cable normally comprises three phase conductors that are each
stripped on an end section and which are connected in a star shape. In
practice, the end sections are individually stripped over a certain length,
are
folded back on themselves and crimped by means of a crimping strap. Given
the diameter of the phase conductors, the creation of a loop by folding back a

conductor section, the connection of three similar loops creates a substantial

additional thickness that the operator must insulate before incorporating it
into
the peripheral wall of the conduit. The installation is weakened due to the
very existence of this additional thickness that also weakens the insulating
envelope that will be positioned around the pipeline. Figure 1 shows
diagrammatically a phase conductor 2 loop 1 folded back and crimped by
means of a crimping strap 3.
The solution provided by the invention makes it possible to eliminate said
weakening and to make the connection far more efficient and quick. The

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longitudinal sectional view of Figure 2 and the cross-sectional view of Figure
3
show an embodiment of the connection of the phase conductors according to
the invention. In the example shown, three phase conductors 11, 12 and 13
are respectively stripped on sections 11a, 12a and 13a. These sections are
intended to be positioned and fixed mechanically on the one hand, and
connected electrically to one another on the other hand, inside a box 14 that
has, for example, a hollow with a rectangular section, forming at least one
central cavity 15 the depth of which is as a minimum equal to the length of
the
stripped sections 11a, 12a and 13a, and the length of which is preferably
greater than the cross-section of these stripped phase conductor sections.
There can be just one central cavity or it can be sub-divided into several sub-

cavities by partitions. However, it is essential that the phase conductors are

coupled electrically to one another, either directly by a conductive binder or
by
the conductive binder and the walls of the box, provided that the material
from
which the box is made is also conductive.
The box 14 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
similar. The cavity 15 is intended to contain a conductive connecting material

16, for example a tin-based soldering alloy or a nickel-based soldering alloy,

or similar for example. Two specific cases can be shown: either the binder is
initially contained in the cavity or the sub-cavities, and it has to be heated
in
order to melt it so as to bring its cold solid state to its hot liquid state,
or it will
be poured, hot, into the cavity, or the sub-cavities, in which the stripped
phase
conductor sections will have been placed beforehand. In the first case, upon
positioning the stripped conductor sections 11a, 12a and 13a, the box 14 is
heated until the conductive connecting material 16 melts, and this makes it
possible to securely connect said sections to the box 14 and to provide the
electrical coupling between the phase conductors. In the second case, the
stripped conductor sections 11a, 12a and 13a are introduced into the hollow
15 which is empty, and the conductive connecting material 16 is poured in the
liquid state, after preliminary heating, into the box in order to fix said
phase
conductors and to connect them electrically to one another. The three
conductors are juxtaposed and the only additional thickness is that of the
wall

CA 02910942 2015-10-29
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of the box 14 which can be reduced to the minimum. The electrical
connection is perfect and the stability of the connection is guaranteed.
The view of Figure 3 shows, furthermore, an insulating sleeve 17 that is
located around the outer wall of the box 14 in order to provide the electrical

insulation of the connection of the three phase conductors 11, 12 and 13.
In the example illustrated, the box comprises a common central hollow for the
three stripped conductor sections 11a, 12a and 13a. According to one
version, the hollow 16 can be sub-divided into three cavities dedicated
respectively to the three stripped conductor sections 11a, 12a and 13a,
soldered individually in the respective cavities. Since the box is made of a
conductive material such as, for example, a copper alloy, the quality of the
electrical connection of the three phase conductors is guaranteed.
The present invention is not limited to the embodiments described, but can be
subject to different modifications or variations. In particular, the practical

implementations may be adapted to the intended applications, the materials
used then being able to be varied according to these applications.

Representative Drawing