SE462762B - FLEXIBLE WIRING PIPE FOR WATER AND GAS MEDIUM AND WAY FOR PREPARATION OF THE PIPE - Google Patents

Description

The object of the invention is to provide such a pipe which is completely corrosion-resistant to media which are inert to plastic.

The flexibility of the pipe must not be significantly reduced. Furthermore, the pipe must be monitorable with regard to tightness. Finally, diffusion through the walls of the inner and outer tubes should be avoided. The object is achieved according to the invention with a conduit which has the feature according to claim 1.

The metal foils present in the construction both on the plastic inner tube and on the plastic outer tube ensure that the annulus is gas-diffusion-tightly shielded, ie prevents migration of gas molecules through the plastic tubes.

This is particularly advantageous when the annular space between the inner and outer tubes is vacuum monitored.

Between the inner tube and the outer tube there is preferably a helical spacer, preferably of thermoplastic. The spacer is suitably mounted with bias, so that the inner tube can be pressurized more strongly. Alternatively, the outer tube can be kept at a distance from the inner tube by applying a helical running profile to the outer upper surface of the inner tube. In many cases, it can also be advantageous to use a longitudinally slit corrugated plastic pipe as a spacer.

Such corrugated plastic pipes are available on the market.

The invention further relates to a method for manufacturing a conduit according to the invention, which method has the feature that one first extrudes a thermoplastic tube, that a metal foil coated on both sides with copolymer is applied to the extruded tube. preferably of aluminum, which application is carried out with longitudinally overlapping strip edges, that an additional thermoplastic tube is extruded on the metal foil, that a plastic strand is wound on the shaped tube so helically and with prestress that on the plastic strand and with 10 In addition to a distance of the composite tube, a thermoplastic tube is further extruded, that this tube is encapsulated by means of a metal strip coated on both sides with copolymer, which enveloping is carried out with band edges overlapping in the longitudinal direction and that the metal strip extrudes another thermoplastic tube.

It is convenient to first produce the inner composite tube continuously, test it with respect to tightness and at the same time take care of the crosslinking, as described above, and finally, also in one working step, apply the spacer and the outer tube.

The invention will now be described in more detail with reference to the accompanying, schematic drawing of an exemplary embodiment.

Denoted by 1 is a plastic pipe, which preferably consists of crosslinked polyethylene. This inner plastic tube 1 has a casing of an aluminum foil 2, which has a longitudinally extending overlapping seam 3. The aluminum foil 3 is surrounded by a second plastic tube 4, which suitably also consists of crosslinked polyethylene. The aluminum foil 2 has on its upper surface an unspecified copolymer coating, which ensures an intimate gluing of the aluminum foil 2 both with the inner tube 1 and with the outer tube 4. The inner tube 1, the aluminum foil 2 and the outer tube 4 thus form a composite tube 5. Concentrically at a distance from this tube 5 is an outer tube 6, which is preferably constructed in the same way as the inner, composite tube 5, i.e. of an inner plastic tube 7, an aluminum foil 8 with overlapping strip edges 9 and an outer plastic tube Also at the outer composite tube 6, the tubes 7 and 10 are intimately glued together with the aluminum foil 8.

On the composite tube 5 there is a helically arranged plastic string 11, which provides a uniform distance and an annular gap 12 between the composite tube 5 and the composite tube 6, which 462 762 10 15 20 25 30 35 4 serves a density monitoring purpose. Suitably for this purpose such a pressure is maintained in the annulus 12 during the operation of the conduit, which is above the pressure of the medium transported in the inner composite tube 5. In the event of a leak either at the composite pipe 5 or at the composite pipe 6, the pressure in the annulus 12 drops, and the leakage is indicated by means of a pressure monitoring device (not shown).

Because the composite pipes 5 and 6 have been made diffusion-tight by means of the aluminum foil 2 and 8, respectively, the annulus 12 can advantageously also be actuated with vacuum.

The conduit according to the invention can be manufactured in very large lengths, wound on conventional cable drums and laid like electrical cables. Thus, for example, it is possible to wind a pipe with an outer diameter of 100 mm in one piece with a length of about 300 m on a cable drum. When extending this pipe, you can then avoid costly and system safety jeopardizing splicing points.

In the production of the conduit shown, it is conveniently done to first extrude and cool the inner tube 1. On the inner tube 1, the aluminum foil 2 is continuously applied longitudinally and with overlapping strip edges and the tube 4 is extruded on the aluminum foil 2. Thanks to the extrusion heat the copolymer layers applied to both sides of the aluminum foil 2 both with the tube 1 and with the tube 4. At the same time the strip edges 3 are glued together.

In particular, the tube 1 is made of a polyethylene in which silane molecules are grafted in a manner known per se and which, when access to moisture, causes a crosslinking of the material. If, for example, the composite pipe 5 is exposed to a humid, warm atmosphere, crosslinking of the pipe 1 will take place.

The composite tube 5 is wound in a subsequent working step with the plastic string 11, which serves as a spacer for the outer composite tube 6. 462 762 5 Preferably, the spacer 11 is applied to the composite tube 5 with a bias. Then the plastic tube 7 is extruded with such a diameter that the tube 7 lies on the spacer 11. Then, as described in connection with the composite tube 5, the application of the aluminum foil 8 and the extrusion of the outer tube 10 takes place.

Claims (4)

462 762 10 15 20 25 30 PATENT REQUIREMENTS Flexible conduit for transporting liquid or gaseous media, consisting of two mutually concentrically arranged plastic tubes, the inner tube (5) and the outer tube (6) being kept at a distance from each other by means of suitable spacers (II) so that there is an annular space (12) between the tubes (5, 6), which is constantly controllable by means of a monitoring device, characterized in that the annular space (12) is gas-diffusion-tight closed both outwards and inwards by means of the inner tube (5) and the outer tube ( 6) glued together metal foils (2, 8) and that the annular space (12) is affected by a pressure deviating from the normal pressure. Pipe pipe according to Claim 1, characterized in that a helical spacer (11) is arranged between the inner pipe (5) and the outer pipe (6), preferably of thermoplastic, which is applied with prestressing. Pipe pipe according to Claim 1, characterized in that the inner pipe (5) has a helical running profile on its surface facing the annular space. 4. A method of manufacturing a conduit according to claims 1 and 2, characterized in that a thermoplastic tube is first extruded, in that a metal foil coated on both sides with copolymer, preferably of aluminum, is applied to the extruded tube, which application is made with longitudinally overlapping strip edges, that an additional thermoplastic tube is extruded onto the metal foil, that a plastic strand is wound on the plastic tube so formed helically and with prestress, on the plastic strand and at a distance from the composite tube an further f »462 762 7 tubes of thermoplastic, this tube encloses with a metal strip coated on both sides with copolymer, which enveloping is performed with longitudinally overlapping strip edges and that an additional thermoplastic tube is extruded on the metal strip.