FI121332B - Pre-insulated pipe and method for forming it - Google Patents

Description

Pre-insulated pipe and method for forming it

Background of the Invention

The invention relates to a tube comprising a base layer and an insulating layer arranged on the outside thereof and an outer layer 5 arranged on the outside of the insulating layer.

A further object of the invention is a method of forming a pipe, the method comprising forming a pipe core layer, fitting an insulating layer outside the frame layer, compressing the insulating layer and fitting an outer layer on the insulating layer.

10 Pipes are made of different materials and for different applications. Pipes are typically used to conduct liquid or gas. Thus, the pipes are used, for example, as plumbing pipes, sewers, ventilation ducts, etc. Most typically, for example, ducts are made of metal such as aluminum or plastic, for example polyethylene or polypropylene. In some applications, the pipes are insulated from the outside. For example, an insulating layer is applied to the ventilation duct when the duct is adapted to a condition where the air temperature is lower than the temperature of the air flowing inside the duct, i.e. the duct requires a thermal insulation. On the other hand, the dielectric layer is sometimes required as a condensation dielectric, i.e. in a situation where, for example, the temperature of the air flowing inside the ventilation duct is lower than the temperature of the air outside the duct.

Some pipes, such as sewer pipes and ventilation ducts, typically have a fairly large external cross-section. Large diameter pipes are quite difficult to handle. Further, the cost of transporting such tubes easily increases quite high. In addition, care must be taken to protect and keep the pipes intact before installation, for example during transport.

BRIEF DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a novel type and improved insulated pipe.

The tube of the invention is characterized in that the insulating layer is compressed during storage and transport and that the outer layer is large enough to remain protected from the insulating layer upon expansion of its normal size.

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Further, the method according to the invention is characterized in that the outer layer is so large that it protects the dielectric layer when the dielectric layer expands to its normal size.

The idea of the invention is that the tube has a base layer and an insulating layer fitted on the outside thereof. An outer layer is provided on the outside of the insulating layer and the insulating layer is compressed prior to installation. The idea of one embodiment is that the outer layer compresses the insulation layer prior to installation. When the dielectric layer is compressed before installation, the outer cross-section of the pipe is reasonably small. It follows from this that the tube is reasonably easy to handle. Further savings will also be made in transport and storage costs. The outer layer may be arranged to protect the insulation layer prior to installation. Thus, during handling, storage and transport, the pipe is protected from weather, knocks and the like.

According to one embodiment, the outer layer is arranged such that prior to pipe installation it is loosened from squeezing the insulating layer and the outer layer is large enough to remain protected by the insulating layer even though the insulating layer has expanded to its normal size.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be explained in more detail in the accompanying drawings, in which Figure 1 schematically shows an end view of the pipe and cross-sectioned prior to pipe installation, Figure 2 shows an end view of the pipe, cross sectional and in place, Fig. 4 is a cross-sectional view prior to installation and FIG. 4 shows the end of the tube of FIG. 3, sectioned and installed.

In the figures, the invention is illustrated in simplified form.

30 In the figures, like parts are denoted by like reference numerals.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Figure 1 shows a tube having a base layer 1. The base layer 1 can be, for example, a metal such as aluminum or plastic. The plastic backing layer 1 may be, for example, polyethylene PE, crosslinked polyethylene PEX or polypropylene PP or other suitable plastic. An insulating layer 2 is provided on the outside of the body 3 layer 1. The insulating layer 2 may be, for example, a closed cell polyethylene foam, a polyester fiber, a polyurethane foam, or any other suitable insulating material. An outer layer 3 is arranged on the outside of the insulating layer 2.

The insulating layer 2 is compressed to a thickness of, for example, 1 to 2 cm. The insulating layer 2 can be compressed, for example, by wrapping shrink plastic around it. The shrink plastic may be, for example, a strip of polyethylene PE having a thickness of 0.02 to 0.5 mm. The shrink plastic is thus wrapped very tightly so that the insulating layer 2 is compressed. 10 The shrink wrap can be wrapped with tape so that there is a gap between the tapes of different turns if the insulating layer 2 is nevertheless compressed. The shrink wrap can also be wrapped in such a way that the strips of different turns are placed side by side or partially overlapping, whereby the outer layer 3 also protects the insulating layer 2 in its entirety against weather conditions, for example.

The uniform outer layer 3 can also be arranged over the compressed insulating layer 2, for example, by mechanically compressing the insulating layer 2 while pulling the tubular outer layer 3 over the insulating layer 2. Further, the insulating layer 2 can also be compressed by means of vacuum. The tubular outer layer 3 may be formed of, for example, polyethylene PE having a thickness of 0.02 to 0.5 mm. The waterproof outer layer acts as a moisture barrier, ie the outer layer protects the dielectric layer from moisture.

Figure 2 shows the tube in place. Prior to installation, the insulating layer 2 has been compressed by the outer layer 3 to remain compressed to 25. At the construction site, the outer layer 3 is cut open, for example, with a knife. The insulation layer 2 can then expand to its normal volume. If the insulating layer 2 has been compressed, for example 1 to 2 cm thick, it may, for example, be 5 to 6 cm thick in the normal volume.

When the pipe is installed, the outer layer 3 can be completely removed from the insulating layer 2. If desired, the outer layer 3 may, for example, be left above the dielectric layer 2 as shown in Figure 2.

Figure 3 shows a tube in which the insulating layer 2 is compressed, for example mechanically. Before the insulating layer 2 is compressed, an outer foil 3 is arranged around the tube as an outer layer 3. The thickness of the aluminum foil 35 may be, for example, 0.02 to 0.5 mm. The insulating layer 2 is compressed, for example, by means of a tube wrapping device. At the same time, a sheet is formed on the aluminum film formed by the outer layer 3. The end of this plaster is taped to hold in place with the longitudinal tape 4 of the tube.

Figure 4 shows the pipe 5 of Figure 3 installed. Before or during pipe installation, the tape 4 has been removed to allow the pleat formed on the aluminum film to straighten. In this case, the insulating layer 2 can also be expanded. However, the aluminum foil forming the outer layer 3 remains outside the insulating layer 2. In this case, the outer layer 3 also protects the insulating layer 2 during use of the pipe. The aluminum foil 10 on the insulating layer 2 is useful, for example, when the insulating layer 2 acts as a condensation insulation and the insulating material is a breathable material such as polyester fiber.

The outer layer 3 can be arranged to remain outside the insulating layer 2 during use of the tube also by pulling a tubular plastic film, i.e. a bag, on the insulating layer 15 of the tube. Thereafter, air is drawn from inside the plastic film so that a negative pressure is formed inside the plastic film. This vacuum and the plastic film together compress the insulating layer 2. At the installation site, for example, a hole can be made in the plastic film at its end, whereby the vacuum is removed from the inside of the plastic film and the insulation layer can expand to its normal dimensions. Thus, even if desired, the plastic film can be left as an outer layer 3 on top of the insulating layer 2. Thus, the outer layer 3 protects the insulating layer 2 from moisture both before and after installation.

In some cases, the features set forth in this application may be used as such, despite other features. On the other hand, the features disclosed in this application can be combined, if necessary, to form different combinations.

The drawings and the description related thereto are intended only to illustrate the idea of the invention. The details of the invention may vary within the scope of the claims. Particularly advantageously, the disclosed solution is suitable for use with ventilation ducts. Thus, the insulated pipe is then a ventilation duct. Ventilation ducts are typically quite large in diameter, and external insulation further complicates storage, handling and transportation. The tube may have a circular cross-sectional shape as shown in the figures, or else the cross-sectional shape may be angular, such as a rectangle, or other. Preferably, the outer layer 3 is fitted to extend to the ends of the tube, whereby the outer layer 3 protects the ends of the tube prior to installation, and no separate end caps 5 are required.

Claims (14)

A pipe comprising a base layer (1), an insulating layer (2) mounted on the outside thereof and an outer layer (3) arranged on the outside of the insulating layer, characterized in that the insulating layer (2) is compressed during storage and transport and so large that it remains protected by the insulating layer (2) after the insulating layer (2) has expanded to its normal size. A pipe according to claim 1, characterized in that the outer layer (3) compresses the insulating layer during storage and transport 10. Pipe according to claim 1 or 2, characterized in that the outer layer (3) is a continuous layer on the insulating layer (2). Pipe according to claim 3, characterized in that the outer layer (3) acts as a moisture barrier to the insulating layer (2). Pipe according to one of the preceding claims, characterized in that, when the insulating layer is compressed, a pleat is formed in the outer layer (3), the end of which is taped to remain in place by means of tape (4). Pipe according to one of the preceding claims, characterized in that the outer layer (3) is arranged to protect the ends of the pipe. A pipe according to any one of the preceding claims, characterized in that the pipe is a ventilation duct. A method for forming a pipe, comprising forming a pipe body layer (1), fitting an insulating layer (2) on the outside of the body layer (1), compressing the insulating layer (2) and applying an outer layer (3) on the insulating layer (2). (3) is so large that it protects the dielectric layer (2) when the dielectric layer (2) expands to its normal size. Method according to claim 8, characterized in that the insulating layer (2) is mechanically compressed. Method according to Claim 8 or 9, characterized in that the insulating layer (2) is compressed by wrapping on its outside the tape forming the outer layer (3). Method according to one of Claims 8 to 10, characterized in that an outer layer (3) is fitted on the outside of the insulating layer (2) and only thereafter the insulating layer (2) is compressed such that a pleat is formed on the outer layer (3). 4). Method according to one of Claims 8 to 10, characterized in that a bag is fitted on the outside of the insulating layer (2) and the insulating layer (2) is compressed by suctioning air from the inside of the bag so that the insulating layer (2) is compressed together. Method according to one of Claims 8 to 12, characterized in that an outer layer is also provided to protect the ends of the tube. Method according to one of Claims 8 to 13, characterized in that the duct is a ventilation duct.