Weldable half-shells

Abstract

To propose a fitting for a secondary pipeline of a double pipe system which can be produced in a simple and low-cost manner and in which it is possible to check the connecting points of the primary and secondary pipelines during assembly.SOLUTION: A fitting includes: two half-shells 2 composed of plastic, wherein each of the half-shells has an integrated heating wire, wherein each heating wire is arranged in the region of a connecting piece 4 and the heating wire has a plurality of meandering windings, wherein each heating wire is arranged in a groove provided for the heating wire in the half-shell; and connecting elements 7 which connect the two half-shells. The fitting has spacer elements arranged on the inner circumference of the half-shells for concentric arrangement of the fitting with respect to a primary pipeline.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The invention relates to a coupling for the connection of a secondary plastic line of a double-pipe system, comprising two half shells made of plastic, each half shell having an integrated heating wire, the heating wire being arranged in the region of a respective connecting pipe piece, the heating wire having a number of meandering windings, the heating wire being arranged in a groove provided in the half shell for the heating wire, and a connecting element connecting the two half shells. [Background technology]

[0002] Double pipe systems are legally required or installed by the end user to prevent unexpected releases of dangerous chemicals into the environment or to prevent personal damage. Furthermore, double pipe systems are used to protect particularly expensive installations (machines, IT infrastructure). The secondary pipeline consists of a protective pipe that surrounds the inner or primary pipe that guides the fluid. The secondary retention system may be laid in the ground or above ground, under pressure or configured as a drainage system and usually has a kind of detection system to detect leaks. Today's systems are connected to each other by simultaneous welding or cascade welding. The joining techniques vary greatly from continent to continent. However, especially in Europe, the joining is increasingly realized by high-temperature welding (with polyolefins).

[0003] From the prior art it is known that already prefabricated joints with inner and outer joints are produced, which are then connected to the inner and outer pipes, respectively. Due to the very different diameters of the inner and outer pipes and the large number of joints, such as T-joints, elbow joints, etc., which have to be prefabricated, a very large stock is required, which is undesirable today. In a similar manner, the secondary containment pipe is produced by inserting a smaller inner / main pipe into a larger outer / containment pipe and providing a centering member. In this case, the connection of the pipe to the shaped member is the most difficult task. Existing systems require a significant number of simultaneous connections for installation. A typical adhesive connection is made by first applying a primer to both surfaces to be assembled, then applying a cementite coating to both surfaces, quickly joining the parts to be assembled by a quarter turn, and then holding the parts for 30 seconds to 1 minute until the cementite bonds. It can be seen that this method is more difficult to carry out if it is intended to simultaneously produce the inner and outer connections. The surface that must be prepared is doubled, and the inner pipe must be attached to the protective pipe to ensure a perfect fit of the sleeve. Moreover, when carrying out the simultaneous connection, the inner connection is performed "invisibly". Yet another disadvantage of the existing system is that the inner connection cannot be inspected during the pressure test, and in case of leakage, it is difficult to locate and repair the defective connection. Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the invention is to provide a coupling for a secondary line of a double-pipe system which is simple and inexpensive to manufacture and which allows inspection of the connection between the primary line and the secondary line during installation. [Means for solving the problem]

[0005] This object is achieved according to the invention in that the coupling comprises spacer elements arranged on the inner periphery of the half-shells for concentrically positioning the coupling relative to the primary line.

[0006] The coupling according to the invention for the connection of secondary plastic lines of a double-pipe system comprises two half shells made of plastic. The half shells each have an integrated heating wire, which is arranged in the region of the connecting pipe piece. The heating wire has a number of meander-shaped windings in the region of the connecting pipe piece, i.e. the heating wire runs along or in a groove provided on the inner diameter of the half shells, where the heating wires are connected to each other via radii or preferably run in lines extending parallel to each other. The heating wire is arranged in the half shells in a groove provided for it, which is preferably attached in the half shells by embedding. Furthermore, the coupling comprises fastening elements for joining the two half shells. The two half shells are fastened to each other by the fastening elements, which are arranged on the outer diameter along the parting plane, preferably at regular intervals, in order to form a good weld. The coupling comprises spacer elements arranged on the inner circumference of the half shells for concentrically arranging the coupling with respect to the primary pipe. The design of the secondary pipeline joint according to the invention allows the two half shells to be fitted around the already assembled primary pipeline, so that the welds or connections of the primary pipeline can be inspected first and then the secondary pipeline can be fitted around it.

[0007] It is shown that the spacer element is preferably formed as a circular segment-shaped plate that rests against the outer diameter of the primary line. The spacer element is arranged concentrically in the half shells, preferably integrally formed therewith or attached thereto by injection molding. It is preferred that the spacer element is arranged in the central region of the half shells between the regions of the connecting pipe pieces.

[0008] Preferably, the heating wire extends along the flanges of the half-shells, the half-shells being defined by a split plane extending along and through the central or longitudinal axis of the joint, thereby forming the open flanges of the half-shells.

[0009] Preferably, the heating wire windings arranged in the region of the connecting piece are connected to one another via a heating wire running along the flange, so that uniform heating is obtained.

[0010] It is advantageous if the half shells have weld indicators, by means of which it is possible to detect whether welding has already been carried out. The weld indicators are preferably arranged along the flanges of the half shells. The two half shells joined to form a joint are preferably designed symmetrically with respect to a point, so that the joint has two weld indicators, which are respectively arranged at the beginning and the end of a central region. The central regions are each followed by a connecting tube piece.

[0011] It is indicated as a preferred embodiment if the connecting element is formed as a separate or integrally arranged snap connection. It is advantageous if the connecting element is arranged along the separation of the two half shells which are assembled to form a joint. For this purpose, the half shells preferably have opposing through holes in which the connecting element or snap connection is arranged or the connecting element is directly attached to the half shells by injection molding.

[0012] It has been shown to be advantageous if the snap connection is formed from a fastening element which can be attached to the half-shell or which is integrally molded or attached by injection molding to the half-shell, and a clip which can be attached to the half-shell or which is integrally molded or attached by injection molding to the half-shell. Preferably, the fastening element is arranged on one side of the half-shell and the clip is arranged on the other side of the half-shell, with corresponding reversed arrangements on the opposing half-shell, by which the half-shells can be joined to one another.

[0013] It proves to be advantageous if the joint is designed as a T-joint, an elbow joint or a bent joint.

[0014] Preferably, the half shells are symmetrical or point-symmetrical, which optimizes the economical manufacture of such joints. The invention will now be described with reference to the drawings, with the aid of which the invention is not limited to the specific embodiments. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 shows a three-dimensional view of a joint according to the invention for a secondary plastic pipeline. [Diagram 2] FIG. 2 shows a three-dimensional view of a half shell of a joint according to the invention fitted with a connecting element; [Diagram 3] FIG. 2 is a three-dimensional view of a half shell of a joint according to the invention; [Figure 4] FIG. 2 is a three-dimensional view showing a connecting element. [Diagram 5] FIG. 2 is a three-dimensional view showing a half shell with a primary conduit inserted therein; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The diagram shown in FIG. 1 shows a three-dimensional view of a coupling 1 according to the invention. The coupling 1 is used for the connection of a secondary line 11 of a double-pipe system and surrounds a coupling 20 of a primary line 10 and a pipe or pipe section of the primary line, as shown in FIG. 5, where one half-shell 2 of the coupling 1 has been omitted for clarity. In the drawing, exclusively elbow couplings are shown as couplings 1, which of course also include T-shaped and bent couplings for connecting secondary lines 11. The coupling 1 comprises two half-shells 2 made of plastic, preferably symmetrical or point-symmetrical. The two half-shells 2 are abutted against each other at a parting plane 19 extending along the central or longitudinal axis 12, so that the flanges 17 of the half-shells come into contact with each other and form a closed coupling 1. The half-shells 2 have an integrated heating wire 3, which is arranged in the region of the respective connecting pieces 4 and runs as a meander-shaped winding 5. The winding 5 runs on the inner diameter 8 of the half-shells 2 in the region of the connecting pieces 4. In this region, the coupling 1 is welded to the tube of the secondary line 11. The heating wire 3 runs in a groove 6 provided for this purpose, in which the heating wire 3 is preferably embedded. The two half-shells 2 are connected to one another via a connecting element 7, which, as shown in FIG. 4, is formed as a separate part. In this case, an embodiment in which a snap connection is attached by injection molding is also conceivable. It is advantageous if the connecting element 7 is formed as a snap connection which is inserted into a through hole 13 arranged on the edge of the flange 17 of the half-shells 2. Preferably, as shown in Figure 2, the clip 14 is disposed on one side of the half-shell 2 and the fastening member 15 is disposed on the other side of the half-shell 2, and correspondingly disposed in the opposite half-shell 2. As best shown in Figures 2 and 3, the half-shell 2 has a spacer element 9 on its inner diameter 8 in its central region 18, which is adapted to abut against the fitting of the primary line 10.This allows the half-shells 2 to have an inner diameter that is adapted to the secondary pipe in the region of the connecting piece 4, and in the central region 18 the fitting of the primary pipe 10 to be arranged in a form-locking manner centrally in the fitting 1. The inner diameter 8 in the region of the connecting piece 4 is welded directly to the pipe of the secondary pipe, and the fitting of the primary pipe 10 is surrounded in a form-locking manner by the two half-shells 2 of the fitting 1 according to the invention. The spacer element 9 is preferably configured as a plate with the shape of a circular segment and is arranged integrally on the inner diameter of the half-shells 2. In this way, the half-shells 2 rest in the assembled state against the fitting of the primary pipe and are welded to the pipe of the secondary pipe 11 with the connecting piece.

[0017] 2 and 3 it can be seen even better that the heating wire 3 runs along the flange 17 and connects the windings 5 ​​in the connecting piece 4 to one another. Furthermore, it is advantageous if a weld indicator 16 is arranged on the half-shell 2 in order to detect whether the weld has already been carried out. FIG. 5 shows a section of a double-pipe system, with one of the half-shells 2 omitted, in order to show how the primary pipe 10 or the joint is arranged inside. It can be seen even better that the half-shell 2 according to the invention is not only welded to the other half-shell (omitted in this figure), but also to the pipe of the primary pipe, and that the joint of the secondary pipe 11 is centrally arranged in a form-locking manner in the joint 1 according to the invention. [Explanation of symbols]

[0018] 1. Joint 2 Half shells 3 Heating Wires 4 Connection pipe piece 5 Heating Wire Winding 6 grooves 7 Connecting elements / snap connections 8 Inner surface of half shell 9 Spacer Element 10 Primary pipeline 11 Secondary pipe line 12 central axis, longitudinal axis 13 Through hole 14 clips 15 Fixing member 16 Welding display section 17 Flange 18 Central area 19 Splitting plane 20 Primary Pipe Joints

Claims

1. A joint (1) for connecting secondary plastic conduits in a double-tube system, comprising two plastic split shells (2), each split shell (2) having an incorporated heating wire (3), each heating wire (3) positioned in the region of a connecting tube piece (4), the heating wire (3) having a plurality of meander-shaped windings (5), and each heating wire (3) positioned in a groove (6) provided in the split shell (2) for the heating wire, the joint (1) having split shells (2) and a connecting element (7) connecting the two split shells (2), The joint (1) is characterized in that it has a spacer element (9) arranged on the inner circumferential surface (8) of the split shell (2) for positioning the joint (1) concentrically with respect to the primary pipeline (10).

2. The joint (1) according to claim 1, wherein the spacer element (9) is formed as a circular segment-shaped plate that abuts against the outer diameter of the primary conduit (10).

3. The joint (1) according to claim 1 or 2, wherein the heating wire extends along the flange of the split shell.

4. The joint (1) according to claim 3, wherein the heating wire windings (5) arranged in the region of the connecting pipe piece (4) are connected to each other via the heating wire (3) extending along the flange (17).

5. The joint (1) according to claim 1, wherein the split shell has a welded marking portion.

6. The coupling (1) according to claim 1, wherein the coupling element (7) is formed as a separate or integrally arranged snap coupling portion with the coupling.

7. The snap joint (1) according to claim 6, wherein the snap joint portion is formed of a fixing member (15) that can be installed inside the split shell (2) or is integrally disposed on the split shell, and a clip (14) that can be installed inside the split shell (2) or is integrally disposed on the split shell.

8. The joint (1) according to claim 1, wherein the joint (1) is formed as a T-shaped joint, an elbow joint, or a curved joint.

9. The joint (1) according to claim 1, wherein the split shell (2) is formed symmetrically or point-symmetrically.

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