DE9308621U1 - Plastic fitting - Google Patents

Description

Plastic fitting

The invention relates to a plastic fitting for connection to a plastic pipe , in particular a plastic gas pipe, for example a tapping saddle for welding to the plastic pipe, wherein a closure element, for example a pipe insert, closes a fitting nozzle to the outside by means of a detachable sealing element, for example an O-ring seal.

Such plastic fittings have already become known in various designs. Reference is made, for example, to DE-PS 34 11 079, EP-A2 86 359 and EP-A2 396 273. In addition, reference should be made to French patent 73.04257 for a drilling fitting.

Plastic fittings of the type in question are often used in pipes whose media have a certain risk potential. For example, in gas pipes. In this context, it is essential that it can be practically ruled out that such media can escape through leaks or the like.

In view of the above-described prior art, one aim of the invention is to provide a plastic fitting that is easy to handle when installed, but also has the highest possible safety potential with regard to the unintentional escape of a medium.

This aim is achieved in the subject matter of claim 1, whereby the sealing element, which is located in a fitting nozzle, is covered by a cap and that the cap is permanently connected to the fitting nozzle, in particular

VGN: 233 633 21 095 Mü./Gau 07.06.1993

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is welded to the fitting nozzle. The inventive concept therefore includes a double seal, on the one hand, a seal is created in the conventional manner between an insert in the fitting nozzle and the fitting nozzle by means of a detachable, insertable sealing element such as in particular an O-ring. On the other hand, this first sealing element is covered by a further cap, which in turn is firmly connected to the fitting nozzle in the overlap with the sealing element, namely preferably welded. With regard to the weldability of the cap to the fitting nozzle, it is provided that the cap has a welding module, for example in the manner already known in the prior art for directly welding the fitting to a plastic pipe. In addition, it is preferably provided that the cap also has a screw thread for screwing the connection to the fitting nozzle. Such a cap, which on the one hand can be welded to the fitting nozzle, but on the other hand can also be - merely - screwed on, is particularly advantageous during the installation stage. As an alternative to screwing, it can also be provided that the cap - or two-part design as explained in more detail below - can initially only be secured in a form-fitting manner by overlapping it, before a permanent securing by welding is carried out. As long as the installed plastic pipe is not yet filled with medium and the fitting on the fitting nozzle may have to be opened again - or the drilling is only carried out later - such a cap makes it possible to close the fitting nozzle so that no contamination etc. can penetrate from the outside, but also to open it again as long as a hermetic seal is not yet desired. In this case, it is also recommended to use the screw thread.

VGN: 233 633 21 095 Mü./Gau 07.06.1993

de should be arranged geometrically in such a way that an axis of the screw thread runs approximately at right angles to an extension plane of the welding module. While the thread extends approximately in the axial direction of the fitting nozzle, the welding module can interact with an end face of the fitting nozzle, essentially in an initial extension at right angles to the axis of the thread. In this case, the welding can be carried out between an end face of the fitting nozzle that runs approximately perpendicular to an extension direction of the fitting nozzle and a cap base of the cap. In a further embodiment, the cap can also consist of a dome part and a sleeve, whereby the sleeve can be arranged both in overlap with the dome part and in overlap with the fitting nozzle and can be welded to both the dome part and the fitting nozzle. In this case, the cap is therefore constructed in two parts. A certain advantage can be seen in the fact that the known sleeve welding technology can also be used here with regard to a cap that closes a fitting nozzle. With regard to the design of such a sleeve in detail, reference is made to the German patent application 42 42 214, which was not previously published, the disclosure content of which is hereby fully included in the disclosure of the present application. In detail, it is provided that an edge of the cap part facing the fitting nozzle sits on the closure element approximately in the area of the detachable seal. This is possible if the detachable seal is in turn covered by a back part or an integrated back of the closure part, on which - in axial extension of the fitting nozzle - the cap then sits. In both of the described embodiments, the cap has an air space above the detachable seal.

VGN: 233 633 21 095 Mü./Gau 07.06.1993

The air space is hermetically sealed to the outside by the welding on the one hand, and on the other hand by the removable seal to the inside of the fitting and ultimately to the plastic pipe on which the fitting sits. Conversely, double protection is achieved with regard to the medium carried in the plastic pipe.

The invention is explained further below with reference to the accompanying drawing, which, however, only represents exemplary embodiments. Here:

Fig. 1 shows a cross section through a drilling fitting with a welded cap, a first embodiment;

Fig. 2 shows a cross section according to Fig. 1 with a cap of a second embodiment;

Fig. 3 shows a cross section according to Fig. 1 or Fig. 2, with a cap of a third embodiment.

Shown and described - initially with reference to Fig. 1 - is a tapping fitting 1 with a cutting element 3 located in a fitting nozzle 2. The tapping fitting 1 can be welded to a plastic pipe in a known manner using a welding module 4, whereby the plastic pipe is not shown in detail. A connection can be made, for example, to a house supply via a branch 5.

The cutting element 3 is sealed against the fitting nozzle 2 by means of a radially acting O-ring seal 22 in the embodiment according to Fig. 1. In addition, a cap 6 is provided, which is connected to the

VGN: 233 633 21 095 Mü./Gau 07.06.1993

Fitting nozzle 2 is welded by means of a welding module 7. In detail, the welding module 7 is arranged in a cap base 8 and interacts with an end face 10 of the fitting nozzle 2 that extends transversely to a longitudinal axis 9 of the fitting nozzle 2. In addition, an external thread 11 is formed radially on the outside in the upper end area of the fitting nozzle 2 , which interacts with a corresponding internal thread of the cap 6. The thread is formed concentrically to the longitudinal axis of the fitting nozzle 2 and thus extends essentially at right angles to an extension plane of the welding module 7.

An electrical connection to the welding module 7 can be established in a manner known per se via plug formations 12 in the cap 6 in order to generate the necessary welding voltage or welding current. The plug connections 7 are formed on an outer upper surface of the cap 6. Axes 13 of the plug connections 12 are arranged in a V-shape relative to one another.

The embodiment according to Fig. 2 differs from the embodiment according to Fig. 1 _in that the O-ring seal 22 also interacts with an end face 14 of the fitting nozzle 2, in the same way as the welding module 7 welds the cap 6 to the end face 10 of the fitting nozzle 2. For this purpose, the fitting nozzle 2 is designed in its upper region in cross-section as can be seen to be stepped, with larger steps than in the embodiment according to Fig. 1.

In the embodiment according to Fig. 3, the cap is composed of a dome part 15 and a sleeve part 16. Comparable to the embodiment according to Fig.

VGN: 233 633 21 095 Mü./Gau 07.06.1993

2 , the cutting element 3 or the O-ring seal 22 located therein interacts with an end face 10 of the fitting connector 2. The sleeve 16 is welded to both the dome part 15 and the fitting connector 2 - at 17 or 18 - via a suitable inner-wall welding module. This welding module can consist in detail, as in the exemplary embodiment, of an embedded or back-injected resistance heating wire. In this respect, there is no actual separable module. In this context, reference is also made to the German patent application P 42 42 214.0. The relevant content is also fully included in the present application. As can be seen in detail, the sleeve 16 also has a radially inward-pointing projection 19 located approximately halfway along its length, by means of which the sleeve 16 rests on a surface of the cutting element 3 (which can also be made of a metallic material such as aluminum). On the other hand, an end face 20 of the dome part 15 rests on this projection 19. Furthermore, the projection 19 also ensures that the dome part 15 in conjunction with the sleeve 16 can initially only be plugged together and thus held in a form-fitting manner.

It is clear that in all three designs an air volume 21 is enclosed above the removable O-ring seal, which is sealed to the outside by the weld between the cap or sleeve and the fitting nozzle and to the inside by the O-ring seal. Accordingly, there is a very high level of security against the escape of medium from a line to the outside via this route.

VGN: 233 633 21 095 Mü./Gau 07.06.1993

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The features of the invention disclosed in the above description, the drawing and the claims can be important for the realization of the invention both individually and in any combination. All features disclosed are essential to the invention. The disclosure of the application hereby also fully includes the disclosure content of the associated/attached priority documents {copy of the prior application).

VGN: 233 633 21 095 Mü./Gau 07.06.1993

Claims (8)

Expectations 1. Plastic fitting for connection to a plastic pipe, in particular a plastic gas pipe, e.g. tapping saddle for welding to the plastic pipe, whereby a closure element, e.g. a tapping insert (3), closes a fitting nozzle (2) to the outside by means of a detachable sealing element, e.g. an O-ring seal, characterized in that the sealing element is covered by a cap (6., 15, 16) and that the cap (6) is non-detachably, in particular welded to the fitting nozzle (2). 2. Plastic fitting according to claim 1 or in particular according thereto, characterized in that the cap (6) has a resistance heating wire (7). 3. Plastic fitting according to one or more of the preceding claims or in particular according thereto, characterized in that the cap (6) further has a screw thread (11) for screw connection to the fitting socket (2). 4. Plastic fitting according to one or more of the preceding claims or in particular according thereto, characterized in that an axis (9) of the screw thread (11) runs approximately at right angles to an extension plane of the welding module (7). 5. Plastic fitting according to one or more of the preceding claims or in particular according thereto , characterized in that the welding between an end face (10) of the VGN: 233 633 21 095 Mü./Gau 07.06.1993 fitting nozzle (2) and a cap base (8) of the cap (6). 6. Plastic fitting according to one or more of the preceding claims or in particular according thereto, characterized in that the cap (6) consists of a dome part (15) and a sleeve (16), wherein the sleeve (16) is arranged both in overlap with the dome part (15) and in overlap with the fitting nozzle (2) and is welded both to the dome part (15) and to the fitting nozzle (2). 7. Plastic fitting according to one or more of the preceding claims or in particular according thereto, characterized in that an edge (20) of the dome part (15) facing the fitting socket (2) sits on the closure element (3) approximately in the area of the detachable seal. 8. Plastic fitting according to one or more of the preceding claims or in particular according thereto, characterized in that the cap (6) encloses an air space (21) above the detachable seal. VGN: 233 633 21 095 Mü./Gau 07.06.1993