DOUBLE PIPE SYSTEM

Description

[0001] The invention relates to a double pipe system and its method for installation with a medium-carrying primary pipeline and a secondary pipeline arranged around the primary pipeline for protection, comprising pipes and fittings of the primary pipeline, wherein the pipes and fittings of the primary pipeline are connected to one another, pipes and fittings of the surrounding secondary pipeline, wherein the pipes are designed as one-piece plastic pipes and the fittings as half-shells.

[0002] Double-containment piping systems are either required by law or installed by end users to prevent the unexpected release of hazardous chemicals into the environment or to prevent personal injury. Double-containment piping systems are also used to protect particularly expensive equipment (machinery, IT infrastructure). The secondary piping consists of a protective pipe that encloses the inner or primary fluid-carrying pipe. Secondary containment systems can be either buried or above ground, pressurized or as a drainage system, and usually have some type of leak detection system. Today's systems are connected using simultaneous or cascade welding. The joining technology varies greatly from continent to continent. However, in Europe in particular, the connections are increasingly realized using heat welding (for polyolefins).

[0003] It is known from the prior art that prefabricated fittings are manufactured with an inner and outer fitting, which are then connected to an inner and outer pipe. Due to the many different diameters of the inner and outer pipes and the various fittings such as tees, elbows, etc. that must be prefabricated, a high inventory is required, which is no longer desirable today. Similarly, secondary containment pipes are manufactured by inserting a smaller inner / main pipe into a larger outer / containment pipe and fitting it with a centering piece. Connecting the pipes to the fittings is then the most difficult task. Existing systems require a considerable number of simultaneous connections for an installation.Typical bonded joints are created by first applying a primer to both mating surfaces; then applying cementite to both surfaces. Then, quickly joining the mating pieces with a quarter turn, and then holding the pieces in place for 30 seconds to a minute until the cementite sets. Understandably, this process is even more difficult when attempting to make an internal and external joint simultaneously. There are twice as many surfaces to prepare, and the inner pipe must be secured to the protective pipe to ensure complete seating of the socket. Furthermore, when performing a simultaneous joint, the internal joint is made "blind."Other disadvantages of existing systems include the inability to inspect the internal connection during pressure testing and the difficulty of locating and repairing a defective connection if a leak occurs.

[0004] US 5 087 308 discloses a method for connecting double pipe systems, which is only suitable for straight pipes without branches.

[0005] The object of the invention is to propose a double pipe system and an associated method for its assembly, which enables a high degree of flexibility in the assembly of a double pipe system without having to carry a large number of different parts and ensures good accessibility of the inner pipe as well as a reliable connection technology.

[0006] This object is achieved according to the invention by the double pipe system of claim 1.

[0007] The inventive double pipe system with a medium-carrying primary pipeline and a secondary pipeline arranged around the primary pipeline for protection includes pipes and fittings of the primary pipeline, wherein the pipes and fittings of the primary pipeline are connected to one another, preferably by welding or gluing. The pipes and fittings of the primary pipeline are preferably made of plastic, but primary pipelines made of metal surrounded by a secondary pipeline made of plastic are also conceivable. In addition, the inventive double pipe system has pipes and fittings of the surrounding secondary pipeline, wherein the pipes are designed as one-piece plastic pipes and the fittings as half-shells. The half-shells of the fitting and the adjoining pipes of the secondary pipeline are connected to one another by means of electrofusion sockets.Fittings connected to the fitting are also connected to each other using electrofusion sockets.

[0008] It has proven advantageous if the electrofusion sleeves are designed as one-piece, hollow-cylindrical sleeves. This allows the use of standard electrofusion sleeves, which are temporarily pushed onto the pipe of the secondary pipeline during assembly. Before welding, they are preferably pushed halfway onto the fitting and then welded to the pipe and fitting. The electrofusion sleeves preferably have two heating elements, preferably heating wire coils, arranged on both sides of the sleeve and each welded to the fitting and the pipe of the secondary pipeline.

[0009] Preferably, the half-shells are formed by a parting plane running centrally through the fitting along the axis. This means that the two half-shells are preferably symmetrical.

[0010] It is advantageous if the fittings of the secondary pipeline do not have heating elements, i.e. the half shells do not have heating elements.

[0011] A further advantageous embodiment has been shown for at least one half-shell of a fitting in the secondary pipeline to have a seal running along the parting plane, wherein the seal forms a materially bonded connection with the half-shells of the fitting in the area of ​​the electrofusion socket or at the connecting piece after the electrofusion socket has been firmly installed and welded to the secondary pipeline. The seal runs along the edge or wall of the half-shell in the parting plane. The parting plane runs along the axis of the fitting and divides it into two symmetrical half-shells. The seal preferably runs in the middle of the edge. It has been shown to be advantageous for the seal to be arranged on the outer edge of the edge in the area of ​​the connecting pieces of the half-shells, so that the seal is in direct contact with the electrofusion socket and forms a materially bonded connection with it when heated.

[0012] It is advantageous if the pipes and fittings of the primary pipeline are connected by electric welding. This allows the same welding process to be used for both the primary and secondary pipelines. Other joining methods, such as adhesive bonding or butt welding, are also conceivable for the primary pipeline.

[0013] Preferably, the fittings of the primary piping system are designed as electrofusion fittings.

[0014] The fittings are preferably designed as tees, branch pieces, and / or bends. This means that the tee, branch piece, and / or bend of the secondary pipeline are designed as half-shells and are welded together during assembly using an electrofusion socket.

[0015] It is advantageous if the half-shells of the fitting each have a connection nozzle on the connection side, whereby the outer diameter of the connection nozzle preferably corresponds to the outer diameter of the pipe. The connection nozzles of the fitting have a smaller outer diameter than the middle section of the fitting. This gives the fitting or the half-shells a step against which the electrofusion sleeve rests during assembly, thus specifying the exact position of the electrofusion sleeve and allowing the installer to see how far the electrofusion sleeve needs to be pushed over the fitting for it to be installed correctly. If two fittings are welded together, it is advantageous if the fittings have markings on their connection nozzles, which show the installer whether the electrofusion sleeve is in the correct position.

[0016] It has proven advantageous to incorporate spacers in the fittings, ensuring the concentric arrangement of the primary and secondary pipelines. The spacers ensure that the primary and secondary pipelines are concentrically spaced from each other. The spacers also serve to axially position the fitting relative to the primary pipeline.

[0017] Preferably, spacer elements are also provided in the pipes, although these do not have to be identical to those of the fitting.

[0018] As a preferred embodiment, the fitting of the secondary pipeline has at least one clip, which serves to temporarily fix the half-shells to the primary pipeline. This makes it easier to slide the electrofusion sleeve onto the fitting of the secondary pipeline. The clip can be subsequently attached to the half-shell as a separate component or can be incorporated into the half-shell during injection molding.

[0019] Another preferred possibility is that the spacer element already has the property of providing a certain degree of self-locking on the primary pipeline, which also has the effect of temporarily fixing the fitting to the primary pipeline so that the installer can slide on the electrofusion sleeve more easily because he does not need to hold it in place.

[0020] The inventive method for installing the double piping system includes the following steps: welding a section of the primary pipeline to at least one fitting and pipe, preferably using electric welding for welding the fittings and pipes of the primary pipeline. The welding is performed in sections to, on the one hand, test the welding and, on the other hand, attach or thread the pipes of the secondary pipeline in sections. The welding of the sections of the primary pipeline is divided in such a way that a pipe of the secondary pipeline can be pushed onto at least one side of the primary pipeline.

[0021] In addition, the electrofusion joints are temporarily positioned on the outer diameter of a secondary pipeline pipe that is to be pushed onto the primary pipeline. The secondary pipeline pipe, on which the electrofusion joint(s) are temporarily positioned, is then pushed onto the primary pipeline pipe, which has already been partially welded to a fitting.

[0022] After the primary pipelines or a section of them have been installed, they can be tested under pressure and possible leaks can be detected.

[0023] A secondary pipeline fitting is then preferably attached around a primary pipeline fitting by joining two half-shells. Of course, it is also possible to attach a secondary pipeline fitting consisting of two half-shells around a primary pipeline pipe. This is usually done at support points where the pipeline is fixed.

[0024] To weld the secondary pipeline, the electrofusion socket, temporarily positioned on the outer diameter of the secondary pipeline pipe, is partially pushed over the secondary pipeline fitting, consisting of the two half-shells, and welded. The electrofusion socket is positioned approximately halfway on the pipe's outer diameter and the other half on the fitting.

[0025] Preferably, the electrofusion sleeve is pushed over the connecting piece of the fitting of the secondary pipeline or the two half-shells until it reaches a stop. The stop is preferably formed by the larger cross-section in the middle area of ​​the fitting.

[0026] An embodiment of the invention is described with reference to the figures, whereby the invention is not limited to the embodiment. They show: Fig. 1 shows a section of a double pipe system according to the invention with only one half-shell, Fig. 2 shows a half-shell of the double pipe system according to the invention, Fig. 2a shows a half-shell of the double pipe system according to the invention in which the seal is arranged externally in the area of ​​the connecting pieces, Fig. 3 shows a section of a double pipe system according to the invention, Figs. 4 - 6 show the inventive method for installing the double pipe system step by step, Fig. 7 shows a section of a double pipe system according to the invention with only one half-shell with visible clips and Fig. 8 shows two fittings connected to one another with an electrofusion sleeve.

[0027] The Fig. 1 The drawing shows a three-dimensional view of a partially welded fitting 7 of the secondary pipeline 3, with the upper half-shell hidden. The electrofusion sleeve 9 shown on the right is already correctly positioned and welded to the fitting 7. Whereas the left and lower electrofusion sleeves 9 still have to be pushed onto the connecting piece 13 of the fitting 7. The double pipe system 1 according to the invention has a primary pipeline 2 through which the medium circulates. The primary pipeline 2 has pipes 4 and fittings 5 ​​that are welded to one another, preferably by means of electrofusion sleeves 16, although other types of connection are also conceivable, such as gluing or butt welding. The primary pipeline 2 is preferably made of plastic, although a metallic pipeline as the primary pipeline is also conceivable.

[0028] Furthermore, the double pipe system 1 according to the invention includes a secondary pipe 3 which is arranged around the primary pipe system 2.

[0029] The secondary pipeline 3 serves to protect the environment or personal injury from escaping media in the event of leaking primary pipeline systems 2. The secondary pipeline 3 contains pipes 6 and fittings 7, with the fittings 7 being designed as half-shells 8. The pipes 6 are designed as one-piece plastic pipes and are generally manufactured by extrusion. The pipes 6 are pushed over the pipe 4 of the primary pipeline 2, whereby only a partial section of the primary pipeline 2 is installed at a time, in order to then install the secondary pipeline 3. The two half-shells 8 of the fitting 7 of the secondary pipeline 3 are attached around the corresponding point on the primary pipeline 2. In most cases, the point is also a fitting 5 of the primary pipeline 2, as in the Fig. 1 The half shells 8 of the fittings 7 can also be attached at other locations, for example by serving as a bearing point 18 to which the double pipe system 1 is attached, which Fig. 3 can be seen. For a concentric arrangement of the two pipelines 2, 3, the half-shells 8 have spacer elements 17 which concentrically space the fittings 5, 7 from each other. They also serve for the axial positioning of the half-shells 8. In Fig. 1 The course of the seal 10 is clearly visible, extending along the edge or wall 12 of the half-shell 8. When welding using the electrofusion sleeves 9 arranged on the fittings 7 of the secondary pipeline 3, the seal 10 is firmly bonded to the half-shells 8 in the area of ​​the electrofusion sleeves 9. Fig. 2 shows a half-shell 8 of a fitting 7 of a secondary pipeline 3. The connecting pieces 13 are clearly visible, onto which the electrofusion sleeve 9 is pushed for welding the half-shells 8 or the fitting 7. The shoulder 15, which is formed due to the smaller diameter of the connecting piece 13 compared to the central area 14 of the half-shell 8 or the fitting 7, creates a stop for the electrofusion sleeve 9, whereby the sleeve is correctly positioned. In addition, Fig. 2 Again, the course of the seal 10 along the edge 12 of the half-shell 8 is clearly visible. The seal 10 runs in the parting plane 11 of two half-shells 8, which form a fitting 7. In Fig. 2 An embodiment is shown in which the seal 10 runs centrally over the entire edge of the half-shell 8. In the Fig. 2a An embodiment is shown in which the seal 10 is arranged in the area of ​​the connecting pieces 13 on the outside, on their outer diameter, in order to connect directly to the electric welding sleeve 9 during welding. Fig. 3 shows different fittings 7 designed as half-shells 8. As an example, a T-piece such as a 90° angle is shown, although other fittings such as branch pieces, bends, or half-shells for attachment points designed as bearing points 18 are also conceivable.

[0030] Fig. 4 - 6 show the inventive method for installing the double pipe system 1 step by step. Fig. 4 shows the section of the primary pipeline 2 that is already installed, preferably by welding the pipes 4 and fittings 5, so that the pipe 6 of the secondary pipeline 3 can be pushed over it. However, the section of the primary pipeline 2 is only welded to such an extent that at least one side of the primary pipeline 2 remains accessible for the secondary pipeline 3 to be pushed over it. In addition, Fig. 4 the preparation of the pipe 6 of the secondary pipeline 3 by temporarily arranging an electrofusion sleeve 9 on the outer diameter of the pipe 6 and then pushing the pipe 6 as well as the electrofusion sleeves 9 arranged on both sides of the pipe onto the section of the primary pipeline 2. Fig. 5 shows how the pipe 6 with the electrofusion sockets 9 arranged on it is pushed onto the primary pipeline 2. Fig. 6 shows the pipe 6 of the secondary pipeline 2 pushed up to the fitting 7. Subsequently, the electrofusion sleeves 9 are pushed onto the connecting piece 13 of the fitting 7 up to the shoulder 15. The electrofusion sleeves 9 are then welded. This leads to a double pipe system 1 as in Fig. 3 shown. Fig. 7 shows an open fitting 7 of the secondary pipeline 3 or a half-shell 8 with the primary pipeline 2 running therein. The clips 18 attached therein are clearly visible, which easily fasten the half-shells 8 to the primary pipeline 3 for assembly. This offers the advantage of an easy temporary arrangement of the half-shells 8 on the primary pipeline 2, which makes it easier for the installer to attach the second half-shell and slide on the electrofusion sleeve 9.

[0031] In Fig. 8is shown when two fittings 7 of the secondary pipeline 3 are welded directly together, without a pipe section in between. The electrofusion sleeve 9 is then arranged in the center of the two connecting pieces 13 of the fittings, with the axial positioning of the electrofusion sleeve 9 preferably being specified by indicators on the fittings.

Claims

1. Double pipe system (1) with a primary pipeline (2) conducting a medium and a secondary pipeline (3) which is arranged around the primary pipeline (2) for protection, containing pipes (4) and fittings (5) of the primary pipeline (2), wherein the pipes (4) and fittings (5) of the primary pipeline (2) are connected together, and pipes (6) and fittings (7) of the surrounding secondary pipeline (3), wherein the pipes (6) of the secondary pipeline (3) are configured as one-piece plastics pipes and the fittings (7) of the secondary pipeline (3) have an axis and are configured as half-shells (8), wherein the half-shells (8) of the fittings (7) and the adjoining pipes (6) of the secondary pipeline (3) are connected together by means of electric welding sleeves (9), or the half-shells (8) of the fittings (7) of the secondary pipeline (3) and the adjoining fittings (7) consisting of half-shells (8) are connected together by means of electric welding sleeves (9), characterized in that at least one half-shell (8) of a fitting (7) has a seal (10) running along a parting plane (11) running parallel to the axis, wherein the seal (10) in the region of the electric welding sleeve (9) creates a material connection with the half-shells (8) of the fitting (7) or the half-shells (7) and the electric welding sleeve (9) .

2. Double pipe system (1) according to Claim 1, characterized in that the electric welding sleeves (9) are configured as one-piece hollow cylindrical sleeves.

3. Double pipe system (1) according to Claim 1, characterized in that the half-shells (7) are formed by a parting plane running centrally through the fitting (7) along the axis.

4. Double pipe system (1) according to one of Claims 1 to 3, characterized in that the pipes (4) and fittings (5) of the primary pipeline (2) are connected together by electric welding.

5. Double pipe system (1) according to one of Claims 1 to 3, characterized in that the fittings (5) of the primary pipeline are configured as an electric welding sleeve (16).

6. Double pipe system (1) according to one of Claims 1 to 5, characterized in that the fittings (5, 7) are configured as a T-piece, branching piece and / or as a curved piece.

7. Double pipe system (1) according to one of Claims 1 to 6, characterized in that the half-shells (8) of the fitting in each case have a connecting piece (13) on the connection side, wherein the outer diameter of the connecting pieces (13) preferably corresponds to the outer diameter of the pipe (6).

8. Double pipe system (1) according to one of Claims 1 to 7, characterized in that spacer elements (17) are arranged in the fittings (7), wherein the spacer elements (17) ensure the concentric arrangement of the primary pipeline and secondary pipeline to one another.

9. Double pipe system (1) according to one of Claims 1 to 8, characterized in that at least one clip (18) is arranged in the fittings (7) in order to fix the half-shells (8) temporarily to the primary pipeline (2).

10. Method for installing the double pipe system according to one of Claims 1 to 9, containing the following steps: welding a sub-portion of the primary pipeline (2) to at least one fitting (5) and at least one pipe (4), temporarily arranging an electric welding sleeve (9) on the outer diameter of a pipe (6) of the secondary pipeline (3) which is to be pushed onto the primary pipeline (2), pushing the pipe (6), with the electric welding sleeve (9) of a secondary pipeline (3) temporarily arranged thereon, onto the pipeline portion of the sub-portion of the primary pipeline (2) welded to a fitting (5), attaching a fitting (7) of the secondary pipeline (3), preferably around a fitting (5) of the primary pipeline (2), by combining two half-shells (8), characterized in that the electric welding fitting (9) which is temporarily arranged on the outer diameter of the pipe (6) of the secondary pipeline (3) is pushed over the connecting piece of the fitting (7), consisting of the two half-shells (8), and welded.