CH662402A5 - Pipe connection for pipelines which are provided with insulation - Google Patents

Abstract

In the case of such a connection, the pipeline parts, which consist of an inner pipe (1, 2), insulation (4, 5) and an outer pipe (6, 7), are initially connected to one another by welding the inner pipes (1, 2). An external pipe (8) which is fitted onto one of the outer pipes (6, 7) is then pushed over the ends of the outer pipes (6, 7), which ends are at a distance apart. The external pipe (8) has two pipe parts (9, 10) and an interposed intermediate pipe piece (11), the turns of a resistance heating wire (12) being laid in the pipe parts. Since the turns of the two pipe parts (9, 10) are connected to one another by means of a connecting wire (22) and in each case one electrical connection (23) is arranged on the pipe parts (9, 10), heat can be produced in the two pipe parts (9, 10) and the pipe parts (9, 10) can thus be welded to the ends of the outer pipes (6, 7). In addition, it is possible to determine in a simple manner whether the welding has been carried out without any defects, by means of at least one indicator (24) in the pipe parts (9, 10). In consequence, the connection of pipeline parts having insulation can be carried out quickly and reliably, especially in pipeline trenches. <IMAGE>

Description

       

  
 

** WARNING ** beginning of DESC field could overlap end of CLMS **.

 



   PATENT CLAIMS
1. Pipe connection for pipes, which consist of an inner tube (1,2>, an insulation (4, 5) and an outer tube covering the insulation (6, 7) made of plastic, and in which both the pipe joints of the inner tubes 2) firmly together and also the spaced ends of the outer tubes (6, 7) are connected by a push-over tube (8), the latter having two tube parts (9, 10) which are flexibly connected by an intermediate piece and have a resistance heating wire (12) laid in turns therein that the turns of the resistance heating wire (12) in the tube parts (9, 10) are parts of a single winding which is composed of these turns and a connecting wire (22).



   2. Pipe connection according to claim 1, characterized in that on the pipe parts (9, 10) each have an electrical connection (23), e.g. a plug contact is arranged.



   3. Pipe connection according to claim 1 or 2, characterized in that on the pipe parts (9, 10) at least one indicator (24) for indicating the connection of the pipe parts (9, 10) to the ends of the outer pipes (6, 7). is arranged.



   4. Method of connecting pipes to a pipe.



  Connection according to claim 1, characterized in that the two tube parts of the slide tube are simultaneously welded to the ends of the outer tubes by electrical heat generation in the turns of the resistance heating wire.



   The invention relates to a pipe connection according to the preamble of claim 1.



   If line parts of a pipeline provided with thermal insulation have to be connected to one another, the task arises of carrying out the connection of the inner pipe and the insulation in such a way that a reliably tight connection is achieved. Since the insulation is usually protected by a steel outer or jacket tube, a steel push-over tube is provided which is pushed over the ends of the outer tubes to be connected. First the ends of the abutting inner pipes are welded, after which the insulation is restored. Finally, the pushover tube is pushed over the connection point and onto it
Welded ends to the outer tube.



   It is also known to be the external or pipeline
Manufacture casing pipe from plastic. The ends that are spaced apart are connected by a plastic push-over tube. To make the pipe connection, the abutting ones
Ends of the inner tubes joined together, e.g.



  welded, whereupon the insulation is restored and the sliding tube is then pushed over the connection point. The ends of the pushover pipe are then connected to the ends of the outer pipes either by hot air welding or by shrink-wrap.



   Now it is known that with such pipe connections it is difficult to produce a perfect connection, especially in a pipe trench, which is why a relatively large amount of time is required for this. The leak test, e.g. by pressing, by
X-ray or ultrasound inspection, not or only with great difficulty, but on the other hand it is necessary that such a pipe connection must be absolutely tight in view of the operating requirements. Even slight traces of moisture in the space between the inner and outer pipe lead to high vapor pressures in the space in view of the mostly high temperatures of the medium flowing in the inner pipe, which damage the pipe connection, e.g.



  the shrink films can peel off.



  There is also a risk that the leakage protection devices installed in the intermediate space will respond as a result of the pressure increase, even though the inner pipe is not leaking. Various efforts have been made to facilitate the production of such pipe connections (EP-AI-0 029 632 and CH-A485 162).



  In both known cases, the slide tube is essentially made of two or more shell parts, which can be arranged more easily at the connection point, but here require a greater effort on the one hand when connecting the shell parts to one another and on the other hand when connecting to the outer tube ends.



   A significant advance over these known solutions is a pipe connection, in which the slide pipe is provided on its pipe parts with a winding made of a resistance heating wire. The welding of the pushover pipe to the pipe ends of the outer pipes is then achieved in that heat is generated in the winding by electrical energy supply, by means of which the pipe part of the pushover pipe is reliably welded to the pipe ends of the outer pipe.



   This is where the invention comes in, which is based on the object of designing a pipe connection of the type described at the outset in such a way that the welding of the pipe parts of the pushover pipe to the ends of the outer pipes can be further accelerated, but without thereby impairing the reliability of the connection.



   This object is achieved according to the invention in that the turns of the resistance heating wire in the tube parts are parts of a single winding which is composed of these turns and a connecting wire.



   A method is suitable for connecting pipes to the pipe connection according to the invention, in which the two pipe parts of the pushover pipe are simultaneously welded to the ends of the outer pipes by electrical heat generation in the turns of the resistance heating wire.



   The invention is shown in the drawing in one embodiment and described below. The figure shows a section through a pipe connection according to the invention, but only one half of the pipe and the pipe connection is shown.



   With the pipe connection shown in the figure, the ends of two pipe parts are connected, with the two ends of inner pipes 1, 2, e.g. made of metal or plastic, together, e.g. are connected by a weld 3. Between the inner tubes 1, 2 and outer tubes 6, 7 there is an insulation 4, 5 made of plastic. Before connecting the ends of the inner tubes 1, 2, a push-over tube 8 is pushed onto one of the two outer tubes 6, 7 and serves to close the ends of the outer tubes 6, 7 after the connection of the inner tubes 1, 2 has been completed and, if necessary, after the insulation has been renewed to connect the ends of the outer tubes 6, 7 to one another, as shown in the figure.



   The slide tube 8 has two tube parts 9, 10 which are connected to one another by an intermediate tube piece 11. In the simplest embodiment, the tube parts 9, 10 and the intermediate tube piece 11 are manufactured separately and then connected to one another, e.g. by mirror welding.



   The two pipe parts 9, 10 have near their inside



  wall a resistance heating wire 12 laid in turns, which can be connected to an electrical energy source, through which heat is generated in the resistance heating wire, which melts the inner wall of the tube parts 9, 10 and the ends of the outer tubes 6, 7 to the extent that a flawless tight connection is created. The reliability of the connection is increased in that, in the pushover tube 8, which is also made of plastic, the two tube parts 9, 10 are impressed with a shrinkage stress by expansion, which is released during the heat development in the resistance heating wire, as a result of which the two tube parts 9, 10 is reached on the ends of the outer tubes 6, 7.



   The welding of the pushover tube 8 to the ends of the outer tubes 6, 7, which concludes the production of the tube connection, is carried out in such a way that first one tube part and then the other tube part is welded to the corresponding tube end of the outer tubes 6, 7. The establishment of the connection can, however, be further accelerated if the two pipe parts 9, 10 are welded to one another. For this purpose, it is necessary to connect the turns of the resistance heating wire 12 in the two tube parts 9, 10 to one another by means of a connecting wire 22. The connecting wire 22 can either be embedded in the material of the intermediate tube piece 11 or extend along the inner wall of the intermediate tube piece 11.

   In the case of a monofilament wire winding, it is sufficient to have one electrical connection 23, e.g. to provide a plug contact to which the terminals of the electrical energy source are attached.



   So that the quality of the welding of the tube parts 9, 10 can be checked in a simple manner, it is expedient to provide at least one indicator 24 on the tube parts 9, 10 each. This can be a pin, for example, which is driven up by the welding pressure that arises during the welding and thus indicates the perfect welding.



   The interior between the inner and outer tubes can be dried and then foamed through an opening 20 in the slide tube 8. In this way, a fault-free, gas-tight and moisture-free pipe connection is obtained.


    

Claims (4)

 PATENT CLAIMS 1. Pipe connection for pipes, which consist of an inner tube (1,2>, an insulation (4, 5) and an outer tube covering the insulation (6, 7) made of plastic, and in which both the pipe joints of the inner tubes 2) firmly together and also the spaced ends of the outer tubes (6, 7) are connected by a push-over tube (8), the latter having two tube parts (9, 10) which are flexibly connected by an intermediate piece and have a resistance heating wire (12) laid in turns therein that the turns of the resistance heating wire (12) in the tube parts (9, 10) are parts of a single winding which is composed of these turns and a connecting wire (22).  2. Pipe connection according to claim 1, characterized in that on the pipe parts (9, 10) each have an electrical connection (23), e.g. a plug contact is arranged.  3. Pipe connection according to claim 1 or 2, characterized in that on the pipe parts (9, 10) at least one indicator (24) for indicating the connection of the pipe parts (9, 10) to the ends of the outer pipes (6, 7). is arranged.  4. Method of connecting pipes to a pipe. Connection according to claim 1, characterized in that the two tube parts of the slide tube are simultaneously welded to the ends of the outer tubes by electrical heat generation in the turns of the resistance heating wire.  The invention relates to a pipe connection according to the preamble of claim 1.  If line parts of a pipeline provided with thermal insulation have to be connected to one another, the task arises of carrying out the connection of the inner pipe and the insulation in such a way that a reliably tight connection is achieved. Since the insulation is usually protected by a steel outer or jacket tube, a steel push-over tube is provided which is pushed over the ends of the outer tubes to be connected. First the ends of the abutting inner pipes are welded, after which the insulation is restored. Finally, the pushover tube is pushed over the connection point and onto it Welded ends to the outer tube.  It is also known to be the external or pipeline Manufacture casing pipe from plastic. The ends that are spaced apart are connected by a plastic push-over tube. To make the pipe connection, the abutting ones Ends of the inner tubes joined together, e.g. welded, whereupon the insulation is restored and the sliding tube is then pushed over the connection point. The ends of the pushover pipe are then connected to the ends of the outer pipes either by hot air welding or by shrink-wrap.  Now it is known that with such pipe connections it is difficult to produce a perfect connection, especially in a pipe trench, which is why a relatively large amount of time is required for this. The leak test, e.g. by pressing, by X-ray or ultrasound inspection, not or only with great difficulty, but on the other hand it is necessary that such a pipe connection must be absolutely tight in view of the operating requirements. Even slight traces of moisture in the space between the inner and outer pipe lead to high vapor pressures in the space in view of the mostly high temperatures of the medium flowing in the inner pipe, which damage the pipe connection, e.g. the shrink films can peel off. There is also a risk that the leakage protection devices installed in the intermediate space will respond as a result of the pressure increase, even though the inner pipe is not leaking. Various efforts have been made to facilitate the production of such pipe connections (EP-AI-0 029 632 and CH-A485 162). In both known cases, the slide tube is essentially made of two or more shell parts, which can be arranged more easily at the connection point, but here require a greater effort on the one hand when connecting the shell parts to one another and on the other hand when connecting to the outer tube ends.  A significant advance over these known solutions is a pipe connection, in which the slide pipe is provided on its pipe parts with a winding made of a resistance heating wire. The welding of the pushover pipe to the pipe ends of the outer pipes is then achieved in that heat is generated in the winding by electrical energy supply, by means of which the pipe part of the pushover pipe is reliably welded to the pipe ends of the outer pipe.  This is where the invention comes in, which is based on the object of designing a pipe connection of the type described at the outset in such a way that the welding of the pipe parts of the pushover pipe to the ends of the outer pipes can be further accelerated, but without thereby impairing the reliability of the connection.  This object is achieved according to the invention in that the turns of the resistance heating wire in the tube parts are parts of a single winding which is composed of these turns and a connecting wire.  A method is suitable for connecting pipes to the pipe connection according to the invention, in which the two pipe parts of the pushover pipe are simultaneously welded to the ends of the outer pipes by electrical heat generation in the turns of the resistance heating wire.  The invention is shown in the drawing in one embodiment and described below. The figure shows a section through a pipe connection according to the invention, but only one half of the pipe and the pipe connection is shown.  With the pipe connection shown in the figure, the ends of two pipe parts are connected, with the two ends of inner pipes 1, 2, e.g. made of metal or plastic, together, e.g. are connected by a weld 3. Between the inner tubes 1, 2 and outer tubes 6, 7 there is an insulation 4, 5 made of plastic. Before connecting the ends of the inner tubes 1, 2, a push-over tube 8 is pushed onto one of the two outer tubes 6, 7 and serves to close the ends of the outer tubes 6, 7 after the connection of the inner tubes 1, 2 has been completed and, if necessary, after the insulation has been renewed to connect the ends of the outer tubes 6, 7 to one another, as shown in the figure.  The slide tube 8 has two tube parts 9, 10 which are connected to one another by an intermediate tube piece 11. In the simplest embodiment, the tube parts 9, 10 and the intermediate tube piece 11 are manufactured separately and then connected to one another, e.g. by mirror welding. ** WARNING ** End of CLMS field could overlap beginning of DESC **.