CH674763A5 - Flexible pipe for transport of media - with specified permeation barrier - Google Patents

Abstract

A flexible pipe for the transport of media at a temp which differs from that of the environment has an inner pipe, made of thermoplastic material with a high thermal stability, covered by a permeation barrier. This barrier consists of a compressible padded material and a bare or coated metal foil which is surrounded by a tubular sheath. The inner pipe (18) e.g. for water (16) at 95 deg.C is pref. made of crosslinked polyethylene or un-crosslinked polybutane. The padded band (28) is wound with an overlap (30) and is a woven nylon band, coated unilaterally with an elastomer. A metal foil (10) is wrapped around it with an overlap (20) of 5mm for the edges. This area (20) is hermetically sealed or bonded. The sheath (32) is made of the same material as the inner pipe. The closed-cell PU foam (22) is protected by an aluminium foil (26) and a plastic shell (24)e.g. of low density polyethylene of PVC. USE/ADVANTAGE - This barrier is effective even for water molecules, independent of temp and loses nothing by repeated expansion and contraction. The pipe is easy to make with conventional materials and at low cost.

Description

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description

The invention relates to a flexible multi-purpose transport tube with a permeation barrier for liquids and / or gases which have a temperature difference from the environment, which tube has an inner tube made of a thermoplastic with high heat resistance, and the permeation barrier is protected from the outside.

Media transport tubes with an inner tube made of plastic have the disadvantage compared to metal tubes that they are permeable to gases with small molecules. The driving force of permeation is the difference in the partial pressure of the relevant components referred to as permeants between the inside and outside of the tube. If the molecules in question are sufficiently small, a temperature-dependent permeation takes place. The effects of permeation depend on the permeant, its quantity and location. In addition to neutral permeants, such as hydrogen, there are also those that show undesirable effects:

- In water-bearing, insulated pipes, water vapor diffuses through the inner pipe and reaches the insulation layer. Moist insulation materials lose their insulation value drastically. Analogously, oxygen molecules can penetrate from the outside into the diameter water and enrich it with oxygen. This promotes steel parts, e.g. a radiator in the same pipe system, the corrosion and also leads to premature aging of the plastic pipe.

- In the case of water-bearing, non-insulated pipes, the permeation of water from the inside to the outside does not play a significant role, but the diffusion of oxygen, in the manner mentioned above, has a disadvantageous effect.

These disadvantages have been attempted with various forms of training flexible media transport tubes.

By applying a plastic barrier that is less permeable than the thermoplastic pipe, permeants with larger molecules can be retained. However, plastic barriers are resistant to smaller molecules, such as Water, almost ineffective. It should also be noted that the permeability of each plastic to permeants increases with increasing temperature.

EP-A1 0 084 088 describes a flexible composite heat pipe with an inner pipe that conducts the medium and consists of two concentric plastic layers, between which a thin metal foil is arranged as a diffusion or permeation barrier. In contrast to a plastic barrier, a barrier made of a metal foil is absolutely impermeable to the molecules diffusing through the plastic. The outer plastic layer laminating the metal foil is additionally wrapped by a pressure bandage which acts as a reinforcement. Practice shows, however, that repeated expansion and contraction movements of the tube due to changes in temperature and pressure caused by operation pose a great risk of delamination and cracking of the metal foil. The problem arises because metal foil and plastic layers have different coefficients of expansion and moduli of elasticity. The pressure bandage, consisting of high-strength fibers, can only reduce the circumferential expansion of the tube, but not eliminate it.

In DE-A1 3 307120, which also relates to a heat conduction tube, it is proposed to use an inner tube made of a cross-linked plastic with a metallic layer applied on its inside and / or outside or within its conversion. Here the metal foil is even exposed to the full expansion force of the pipe because there is no pressure bandage.

The inventor has set himself the task of creating a flexible media transport tube for liquids and / or gases of the type mentioned at the outset, which has a permeation barrier which is also temperature-independent and effective and does not lose any of its functionality after repeated, operational expansion * and contraction movements of the inner tube , as well as simple and inexpensive to produce with commercially available materials.

The object is achieved according to the invention in that the permeation barrier consists of a compressible cushioning material lying on the thermoplastic inner tube and a bare metal foil coated on one or both sides, which is surrounded by a medium jacket tube.

The cushioning material largely absorbs the expansion movement of the inner tube.

The medium-carrying thermoplastic inner tube is preferably made of cross-linked polyethylene (VPE) or uncross-linked polybutane (PB).

The cushioning material, which is preferably in the form of an upholstery band, is applied to the outside of the thermoplastic inner tube in a manner known per se, longitudinally or spirally, in a snug manner, with the band edges overlapping.

The cushioning material applied to the thermoplastic inner tube can also consist of felt-like materials, such as nonwovens. All the materials used are known per se and are commercially available; they consist of woven, knitted or felt-shaped natural fibers or plastic fibers laminated with an elastomer.

The rough surface of the upholstery material has a relatively high frictional resistance compared to the outside of the thermoplastic inner tube, which makes it difficult or impossible to move the inner tube in the metal foil under mechanical action.

Furthermore, the cushioning material partially absorbs the temperature-related expansion of the thermoplastic inner tube in the radial direction. This leads to a reduced load on the less rapidly expanding, external metal foil.

The metal foil used as a moisture barrier of low mechanical strength is preferably made of aluminum or an aluminum alloy. The metal foil is preferably one or

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coated on both sides with a known thermoplastic. The expediently at most the same thickness as the metal foil itself, but preferably much thinner applied coatings are heat-sealable so that the overlapping band edges of the longitudinally or spirally applied metal foil can be hermetically sealed on the cushioning material.

The metal foil is preferably encased in a medium jacket tube made of plastic, for example made of cross-linked polyethylene or uncross-linked polybutene. In the case of non-insulated pipes, the medium jacket pipe is also the outer jacket.

In the case of insulating tubes, the metal foil or the medium jacket tube is covered in a manner known per se with a thermal insulation made of a foamed, preferably closed-pore plastic, for example polyurethane, crosslinked polyethylene or polyisocyanurate, optionally also mineral or glass wool, and with a protective outer jacket, for example made of low density polyethylene or polyvinyl chloride.

The flexible media transport tube according to the invention has the following possible uses, not exhaustively,:

1. Transport of liquid media in insulated pipes, with a temperature difference between the medium and the ambient temperature, with the smallest possible heat exchange, e.g. District heating pipes, drinking water pipes, process water pipes and cooling pipes.

2.Transport of liquid media in non-insulated pipes with a temperature difference from the medium to the environment, with the greatest possible heat exchange with the environment, e.g. Underfloor heating pipes and geothermal pipes.

The flexible media transport tube according to the invention for liquids and / or gases has significant advantages over known forms of training:

- If the inner tube expands due to temperature, the cushioning material absorbs part of the expansion. The risk of delamination or cracking is largely eliminated.

- The manufacturing process is simple.

- The permeation barrier is also effective against water permeation.

The flexible media transport tube according to the invention for liquids and / or gases is produced, for example, in a continuous process. The upholstery material is wound up in a spiral or folded in the longitudinal direction, the band edges of the upholstery material preferably applied in the form of a tape overlap. The coated or uncoated metal foil is then also spirally wound or folded over in the longitudinal direction, with sealed or glued, overlapping tape edges, if necessary. According to a preferred embodiment, the medium jacket tube is applied to the inner tube provided with the permeation barrier using known methods. Depending on the use of the media transport tube, an outer insulation layer and an outer tube are also applied using known methods.

The invention is explained in more detail with reference to the embodiment shown in the drawing. The single figure schematically shows a cut-away perspective view of an insulated flexible media transport tube.

The inner tube 18 filled with 95 ° C. hot water 16 is made of a thermoplastic material, for example of radiation-crosslinked polyethylene. On the outside of this plastic tube, a cushion tape 28 is drawn in a spiral shape, with overlapping tape edges 30, which consists of a woven nylon tape laminated with an elastomer. A metal foil 10 laminated on one side with a thermoplastic plastic is stretched longitudinally thereon, the band edges 20 of which form an approximately 5 mm wide overlap area in which the metal foil is hermetically sealed or glued. The thermoplastic inner tube 18 with the cushion band 28, the metal foil 10 and the medium jacket tube 32 form the flexible media transport tube according to the invention.

This media transport pipe can be used as a district heating pipe. It is surrounded by a thermal insulation 22, which consists of a closed-pore polyurethane foam.

The outer jacket 24 made of plastic with an inner aluminum foil 26 protects the district heating pipe.

In the case of a non-insulated media transport tube, the medium jacket tube 32 is also an outer tube.

Claims (1)

Claims 1.Flexible media transport tube with permeation barrier for liquids and / or gases which have a temperature difference from the environment, which tube has an inner tube made of a thermoplastic material with high heat resistance, and the permeation barrier is protected to the outside, characterized in that the permeation barrier consists of a on the thermoplastic Inner tube (18) lying on, compressible cushioning material (28) and a bare metal film (10) coated on one or both sides, which is surrounded by a medium jacket tube (32). 2. Media transport tube according to claim 1, characterized in that the medium jacket tube (32) consists of a temperature-resistant, flexible plastic. 3. Media transport tube according to claim 2, characterized in that the medium jacket tube (32) consists of cross-linked polyethylene or uncross-linked polybutene. 4. Media transport tube according to one of claims 1-3, characterized in that the medium jacket tube (32) is the outermost protective layer. 5. Media transport tube according to one of claims 1-4, characterized in that the thermo- 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 3rd 5 CH 674 763 A5 plastic inner tube (18) made of cross-linked polyethylene or uncross-linked polybutene. 6. Media transport tube according to one of claims 1-4, characterized in that the cushioning material as a cushioning band (28), preferably longitudinally or spirally, with overlapping band edges (30), on the outside of the thermoplastic inner tube (18). 7. Media transport tube according to one of claims 1-6, characterized in that the cushioning material (28) consists of felt-like materials, such as nonwovens, or of woven or knitted fibers. 8. Media transport tube according to one of claims 1-7, characterized in that the cushioning material (28) consists of natural or laminated with an elastomer plastic fibers. 9. Media transport tube according to one of claims 1-8, characterized in that the metal foil (10) consists of aluminum or an aluminum alloy and is preferably coated on one side with a thermoplastic, which metal foil (10) longitudinal or spiral, with overlapping band edges (20 ), on the cushion material (28). 10. Media transport tube according to one of claims 1-9, characterized in that the thermoplastic inner tube (18), the cushioning material (28), the metal foil (10) and the medium jacket tube (32) are coaxially encased by a thermal insulation layer (22), which extends up to the outer jacket (24) made of a plastic, the outer jacket preferably having an internal aluminum foil (26). 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 4th