FI127375B - Tube and method of making the tube - Google Patents

Abstract

The invention relates to an insulated ventilation pipe. The pipe comprises an insulating wall structure (10) arranged into pipe form, the wall structure comprising elongated cavities (16A-C) arranged into multiple layers in a radial direction of the pipe, whereby the wall structure is formed from thermoplastic polymer arranged as a unitary structure such that the wall structure forms a self-supporting bar. According to the invention the elongated cavities of the wall structure are entirely closed and adapted to run tangentially, perpendicular to the longitudinal direction of the pipe, around the longitudinal axis of the pipe. The insulated pipe according to the invention is simple to manufacture and install.

Description

Pipe and method for making the tube

Field of the Invention

The invention relates to pipes and their manufacture. In particular, the invention relates to polymer pipes which are provided with heat insulation.

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Background of the Invention

Insulated pipes are needed eg. construction. Typical applications for insulated pipes are ventilation ducts, sewer ducts and water lines. Depending on the application, insulation is needed, for example, to prevent heat loss and condensation on the outer surface of the pipes. Much of the pipe used by the construction industry is made of polymeric material.

The pipes can be insulated by a layer of insulating material arranged around the outer surface of the pipe. The insulating material may be, for example, wool, foam, cardboard or asbestos.

In addition, gas or vacuum insulated pipes are known.

For example, US 2003/0012918 discloses a pipe insulation jacket consisting of adjacent ducts filled with gas. After the ducts are filled, the sheath is arranged around the pipe, as with the other insulating materials mentioned above, for example by using straps, thereby increasing the heat insulating capacity of the pipe. GB 1283329, in turn, discloses a solution in which a metallic honeycomb structure is also provided between the two metal tubes to provide a tube of improved insulation value. Also known are solutions in which the wall of the tube comprises protrusions on which an additional layer is wrapped to form an insulating air gap on the surface of the tube. Such a structure is described in GB 762800 A.

In known solutions, the insulating material can be installed in the pipe before or after the pipe is installed in the application. In both cases, the isolation consists of a separate step. In the first case, pipe insulation makes it difficult to install the pipe itself, especially the joints, and the insulation typically has to be

20165472 prh 16 -03- 2018 to patch after installation. In the latter case, installing insulation is particularly laborious since the pipes typically comprise bends, branches and joints and are located in confined spaces. In both cases, securing the pipe insulation during final installation requires special precision to ensure that the insulation is sealed.

Poor quality or incorrect installation, on the other hand, can lead to condensation, freezing or excess heat loss, depending on the application.

In summary, traditional solutions are relatively cumbersome and time-consuming to install. The insulation material and its installation also significantly increase the price of the pipe product and / or pipe work.

Thus, there is a need for improved insulated pipes.

Summary of the Invention

The object of the invention is to solve the above problems. A particular object is to provide an insulated pipe which is simpler to install than known insulated pipes. It is also an object to provide an insulated tube that can be made from raw materials, even just one starting material.

It is a further object of the invention to provide a method of making such a tube.

The objects of the invention are achieved by the solutions according to the independent claims.

The insulated tube according to the invention comprises a tube arranged in the form of a tube having a plurality of layers of a cavity arranged radially in the tube. The cavities are formed of an integral structure of a thermoplastic polymer arranged. The cavities are arranged elongated and arranged to run in the tangential direction of the tube around the tube and the tube forms a self-supporting rigid rod.

In the process of the invention, the wall of the softened thermoplastic polymer is extruded into a tubular form, whereby the wall is formed by extruding elongated tube tangentially from the cavity into a plurality of layers in the radial direction of the tube.

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The invention provides significant advantages. At least two overlapping cavity layers, combined with the relatively low thermal conductivity of thermoplastic polymers, provide sufficient thermal insulation capability for many applications without the need for cumbersome pre- or post-installation dielectric materials. The integral construction with the cavities makes the tube rigid and allows the tube to be shortened as well as joints with tight joints between the inner tubes and the cavity structures. Thus, an intact, isolated fluid duct can be rapidly obtained.

It is possible to make the entire insulated pipe from just one starting material and without the need for a separate step of insulating the insulating material. These factors reduce the cost of manufacturing and installing the pipe. Due to the lack of separate insulating material, disassembly and recycling of the pipe from the installation site is also simpler and less costly at times.

On the other hand, many different starting materials can be used for the manufacture of the pipe, especially in comparison to the relatively narrow range of materials used for conventional pipe insulation.

The material may be fresh polymeric raw material or, on the other hand, recycled material, or a mixture thereof. Particularly preferably, at least some of the material is recycled material.

The present cavity structure improves not only the thermal but also the sound insulation of the pipe. Thus, it can also be used in applications where it is not necessary to prevent heat leakage, but where it is desired to reduce the passage of sound through the piping.

The dependent claims are directed to selected preferred embodiments.

According to one embodiment, the cavities are traced to at least three layers in the radial direction of the tube. Thus, when viewed in at least some, preferably all, radial directions, a straight cross-section of the tube cuts at least three different cavities. Such a pipe will provide a level of insulation comparable to typical wool and cellular insulation.

According to one embodiment, the cavities are stacked in layers relative to each other such that at least one cavity, preferably at least two cavities, is provided at each point of the tube when viewed in the radial direction of the tube. In other words, the partition walls of the cavities are disposed in different axial and / or tangential directions so that

20165472 prh 16 -03-2018 to form direct polymeric bridges, i.e. '' cold bridges '' between the inside and outside of the pipe. Although polymers have a relatively low thermal conductivity compared to, for example, metals, such a spacing wall structure has been found to be significantly superior to straight line partitions. According to one embodiment the cavities of the stacked layers is a half of the cavity length from offset position relative to each other, thereby minimizing the thermal conduction through the polymer.

According to one embodiment, the tube comprises a cavity which has all its sides, i. axially, radially and tangentially, air and water tight. Such fully enclosed cavities minimize heat transfer within the wall in the direction of the tube casing and further improve thermal insulation. Axially closed cavities are advantageous because the tube can then be cut without opening the cavities, which makes it easy to maintain the insulation level at, for example, the pipe joints and joints.

The cavities may be, for example, hexagonal or rectangular in cross-section.

In some embodiments, the wall and the cavities are made entirely of the same polymeric material. The polymeric material may be a blend of multiple polymers and comprise a fresh polymer, a recycled polymer, or both.

According to one embodiment, the polymer comprises recycled plastic, typically 30 to 100% by weight, preferably 50 to 100% by weight, of the total amount of polymer.

The tube, i.e. its wall with cavities, can be made by extruding one or more, preferably only one, thermoplastic polymer or polymer mixture into a tubular form. The extrusion process may comprise a coextrusion process in which at least an inner tube wall is extruded in a first step, extruded at least a portion of the cavity layers in one or more second steps, and the inner wall and cavity layers are joined to form an insulated tube.

Embodiments of the invention and their advantages will now be discussed in more detail with reference to the accompanying drawings.

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Brief Description of the Drawings

Figures 1A and 1B show perspective and plan view in cross-sectional view of a structure of the present tube in which the cavities are elongated and arranged to rotate the tube tangentially.

Figures 1C and ID are side and end views of parts of the present tube according to one embodiment.

Figures 1E-1G are perspective views of alternative cavity structures in which the cavities rotate the tube tangentially.

Fig. 2A is a schematic cross-sectional view of the structure of the present tube in a plane perpendicular to the longitudinal axis of the tube, with the cavities being elongated and arranged along the longitudinal axis of the tube.

Figures 2B and 2C are schematic cross-sections showing two alternative designs of the pipe of Figure 2A in a plane perpendicular to the transverse axis of the pipe.

Figures 2D and 2E are perspective views of alternative cavity structures in which the cavities 15 are arranged in the longitudinal direction of the tube.

Figures 3A and 3B schematically show a hexagonal cavity structure for tangential and axial cavities, respectively.

Figure 4 is a cross-sectional view of an example of a rectangular tube in a plane perpendicular to the longitudinal axis of the tube.

DETAILED DESCRIPTION OF EMBODIMENTS Herein, '' axial direction '' refers to the longitudinal direction of the tube and '' radial direction '' to the direction (s) passing through the center of symmetry and / or center of gravity. Tangential direction refers to a direction perpendicular to the axis of the tube which, in the case of a rotationally symmetrical (circular cross-sectional) tube, joins each tube.

20165472 prh 16 -03- 2018 at a point on the wall perpendicular to the tube axial and radial directions.

By "cavity" is meant a defined zone defined by a wall structure which is filled or can be filled with gas, such as air, or vacuumed. The individual cavity is bounded by walls made of polymer. The wall is thus made up of the cavities between the walls of the pipe interior and / or exterior of the tube. In this context, a "bounded" zone is considered to be bounded at least in the radial and tangential directions. The cavities, or at least some of the cavities, may also be limited in the axial direction, i.e. completely closed. Particularly at the ends of the tube, e.g. however, when viewed axially, the cavities may be open, although typically the cavities that may be open at the latest when the pipe is installed or joined are also closed at the ends of the pipe to improve insulation.

Generally, a "cavity" is defined as a cavity or channel formed inside a plastic material which, for at least one dimension, is larger than a closed or open cell formed in the plastic material expandable by foaming plastic.

As the wall comprises a plurality of radially superimposed cavity layers, it is understood that, when viewed in at least some radial directions, the pipe cross-sectional straight cuts at least two, preferably at least three, different cavities. In some embodiments, with the cavities suitably interlaced with one another, this condition is fulfilled in all radial directions at least at some axial points of the tube, preferably at most axial points. In some embodiments, this condition is fulfilled at all axial points of the pipe.

By "elongated" cavity is meant a cavity whose dimension in one direction of the cavity is at least three times, preferably 3.5-1000 times, relative to its dimensions in the perpendicular directions. According to the invention, the cavity is elongated in the tangential direction of the tube (annular or arcuate cavity.

In one embodiment, the cavities have an average diameter of about 0.5 to 100 mm, for example about 0.75 to 50 mm or 1 to 20 mm. The diameter of the cavities may vary according to the inner diameter of the tube, as further described below.

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Generally, one cavity will have a diameter of about 1% to about 25% of the inside diameter of the tube, and the cavity will have a cross-sectional area of about 0.1% to about 10% of the inside diameter of the tube.

Preferably, the cavities forming or surrounding the tube wall have a combined cross-sectional area of from about 10% to about 500%, for example from about 30% to about 200%, of the inner tube area5.

A "cohesive structure" of a wall or cavity refers to a structure in which at least the thermoplastic polymer forming the cavity walls is arranged in a continuous structure. Thus, adhesives between the various parts of the wall or other materials or means that hold the wall structure together are not used to form the cavities, but the wall is substantially free of such materials and means.

The unitary structure may have bands of different polymeric compositions, but in particular the unitary structure may comprise a substantially homogeneous polymeric material, incl. homopolymers, copolymers and substantially homogeneous polymer blends, a polymer structure.

The '' homogeneous structure '' does not exclude that, for example, the inner or outer surface of the tube is covered with a separate layer of material which does not consist of a thermoplastic polymer, but the term specifically refers to the integrity of the structure forming the cavities. For example, to increase fire safety, a metal layer such as aluminum foil or other coating may be provided around the outer surface of the pipe wall.

A uniform structure can be achieved by polymer extrusion. Thus, typically, the solution is formed by extrusion or a similar melt-working process in which the molten plastic mass is extruded through a die so that a cavity structure is formed in such a compression step.

In a particularly preferred embodiment, the formation of the structure is effected without foaming, whereby the cells of the structure do not contain the cells formed by the expansion of the plastic. Such an application therefore provides a mechanically resistant structure capable of forming at least a portion of the pipe wall, in particular of its pressure-resistant wall.

The drawings show embodiments of the present technology:

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Figures IA-IE show the construction of a tube according to one embodiment, wherein the cavities extend annularly, i.e. tangentially, around the inner tube. More specifically, the tube comprises a wall 10 which further comprises an inner wall 11, cylindrical, in the direction of the shell of the tube, an outer wall 14, and partitions 12, 13 arranged in the direction of the shell between them. In addition, wall 10 is provided with partitions 15A, 15B, 15C located in a plane perpendicular to the tube. The inner and outer walls 11, 14 and the dividing walls 12, 13, 15A, 15C, 15C together form the gaps 16A, 16B, 16C.

The cavities 16A, 16B, 16C in this example are arranged in three layers, each of which has a plurality of tubes tangentially rotating from the cavity adjacent. However, there may be, for example, 2 or 4 to 10 layers. Typically, there are 3 to 6 layers.

In this example, the cavities are rectangular in cross section, i.e., the inner, outer and partition walls are substantially flat and arranged at right angles to each other.

In order to obtain the best possible insulation, the cavities 16A, 16B of the successive layers; 16B, 16C are arranged such that the radial partitions are not aligned, but offset relative to each other, in this case the side of the cavity increment. This prevents the formation of direct cold bridges between the inner and outer surfaces of the pipe, which improves the thermal insulation capacity of the pipe.

In the exemplary embodiment of Figs. 1A-1D, additional tubular cavities 18 projecting from the outer wall 14 of the tube and rotating the tube are provided on the outer surface of the tube, which, however, do not form a full layer. This may be desirable for some applications. At the same time, the protruding cavities 18 further increase the insulation value of the pipe. Such protruding cavities 18 are not necessary. Thus, the outer wall of the tube may be defined by a full outer cavity layer, i.e. smooth.

Figure 1F shows a wall structure in which the tubular annular cavities 170A, 170B, 170C have a circular cross-section and the polymer fills the inter-cavity zones.

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Fig. 1G shows a wall structure in which the annular cavities 180B, 180C, 180D are hexagonal in cross-section (excluding the innermost, "" under "cavity layer 180A). Polymer partitions are flat. Also in these examples, the cavities 170A, 170B, 170C; 180A, 180B, 180C, 180D are sequenced in several layers interleaved to provide a greater total cavity volume and reduce cold bridges.

Figures 2A and 2B show an embodiment outside the present invention, wherein the tube wall 20 comprises longitudinal cavities 26A, 26B, 26C. In this example too, the cavities 26A, 26B, 26C are arranged in three layers in the radial direction of the tube.

The cavities 26A, 26B, 26C are defined by an inner wall 21, an outer wall 24 and two partitions 22, 23 parallel to the tube shell, and by the partitions 25A, 25B, 25C located in the radial-axial plane. Thus, cavity layers are formed, each having a plurality of adjacent tubes extending axially from the cavity.

In this solution too, the partitions 25A, 25B, 25C extending radially are arranged such that the partitions 25A, 25B of the adjacent layers; 25B, 25C are located at different locations, whereby the cavities overlap with each other so that no direct cold bridges are formed between the inner and outer surfaces of the pipe. Again, the overlap is preferably half the length of the cavity.

The solution of Fig. 2C further provides spacers 29A, 29B, 29C extending axially spaced from each other in a direction perpendicular to the axial direction, which also provides axially closed consecutive cavities 26A ', 26B', 26C 'instead of open cavities.

In the exemplary embodiment of Figures 2A-2C, the cavities are of a '' rectangular 'cross-sectional shape, but here too, the shape of the cavities can vary widely. As an example of alternative cavity designs, the tube of Figure 2D and 2E is shown in which the cavities are of circular cross-section. In the tube of Figure 2D, the cavities 270A, 270B, 270C are of uniform size, while the solution of Figure 2E has cavities 280A, 280B, 280C of different cross-sectional dimensions; 28IB;

281C. Thus, the cavities fill the wall efficiently, thereby increasing the cavity volume and the insulating capacity of the tube.

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In particular, as shown in Figure 2E, the wall may have uniformly sized large cavities 280A, 280B, 280C and smaller cavities 28B, 281C may be provided between the large cavities 280B, 280C in at least one layer having larger cavities 280B, 280C spaced apart. In particular, large cavities 280A,

280B, 280C may be the same number in each cavity layer and smaller from the cavity 280B, 280C are arranged in at least one of the outer layers of the tube wherein the larger cavities 280B, 280C have a greater distance than the innermost layer.

Figures 3A and 3B show variations of the above solutions in which the cavities 36A, 36B are hexagonal in cross-section. In the wall 30A of Fig. 3A, as in Figs. 1A-1D, the cavities are arranged tangentially, in this case to four layers. In the wall 30B of Fig. 3B, the cavities 36B are arranged axially, as in Figs. 2A-2C, in this case in three layers.

Above are shown tubes of substantially circular cross-section. However, the tube can be of any other cross-section, for example elliptical, rectangular or hexagonal. Figure 4 shows, by way of example, a tube of substantially rectangular cross-section, the wall 40 of which has two cavity layers. Again, the cavities 46 are elongated extending in the tangential direction of the tube.

The largest transverse inner dimension of the tube, i.e. the inner diameter is typically 30-500 mm, especially 50-250 mm. For example, the wall thickness of the tube may be 30 to 150 mm, typically 40 to 100 mm. For example, the radial dimension of a single cavity may be 130 mm, typically 3-20 mm.

The present pipe may be used, for example, as a building water pipe, such as a hot water or heating water pipe, typically having an internal diameter of 5 to 30 mm, or a drain pipe, typically having an internal diameter of 30 to 150 mm, or a ventilation pipe. In addition, the pipe of the invention is suitable for use in larger transmission lines, such as municipal sewerage or district heating lines.

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According to one embodiment, one or both ends of the tube comprise, as a unitary polymeric structure, a connecting part whose internal and / or external dimension differs from the corresponding basic dimension of the tube. For example, the coupling member may comprise a sleeve having an inside diameter equal to or greater than the basic diameter of the tube. The coupling member may be adapted to match a substantially identical or different pipe to provide a pipe joint or joint. The two pipes can also be connected to one another by means of a separate connecting part.

According to one embodiment, the coupling member is arranged to seal both the inner and outer walls of the two tubes, and possibly also the partitions, so that both the integrity of the fluid passage and the insulability of the wall are maintained at the joint. Such sealing can be achieved, for example, by means of a contraction and / or a sleeve and a separate sealing member such as a latch ring. Such a joint can be traced to be airtight, whereupon the tube may be steam cleaned if necessary.

As mentioned above, the tube comprises a self-supporting rigid rod. The length of the rod can be, for example, 1-10 m.

The tube can be made of any natural or synthetic thermoplastic polymeric material. Examples include polyvinyl chloride in its various forms (PVC, ETPVC, CPVC), polypropylene (PP), polycarbonate (PC), polyethylene (PE), preferably in cross-linked form (PEX), polystyrene (PS), polymethyl methacrylate (PMMA), acrylonitrile-butadiene (ABS), polybutylene (PB), polyvinylidene fluoride (PVDF), Nylon or other polyamide, or mixtures thereof and derivatives thereof. According to one embodiment, the tube comprises a recycled thermoplastic polymer material which may be one or more of the above-mentioned polymers.

Preferably, the tube is made of a hard, non-foamed plastic, as opposed to a foamed gas foam. In this case, the tube is made tight, hard and strong but still insulating due to the cavity structure.

As additives, the polymer may include additives typically used in the art, such as non-protecting agents, dyes, fillers or reinforcements.

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As noted above, the present tube may be completely fabricated in an extrusion process in one or more extrusion steps. Typically, the manufacturing process consists of coextrusion in which the output of two or more extruders is combined into one continuous tubular body. This facilitates the manufacture of the cavity structure. For example, with reference to Figs. For example, there may be 2-10 coextruders, typically 2-6.

According to one embodiment, the duct is a Ventilation duct. Such may be installed, for example, as part of an air conditioning system comprising at least one heat pump. In such rigid systems, there is a large difference between the indoor and outdoor temperatures of the pipeline, with a high risk of condensation without thermal insulation of the pipeline. Cooling systems with cooled air passing through the pipe are particularly at risk of condensation water damage outside the pipe. However, other types of ventilation systems also have the advantage of insulated pipe.

According to one embodiment, the pipe is a drain pipe. For example, non-insulated drains for sewer systems also carry a risk of condensation.

In ventilation and drainage pipelines, where the pressure is typically low, the pipe jointing technique may be, for example, a simple socket or rubber sealing joint, which primarily ensures the air / water tight connection of the actual fluid channels (inner pipes) of the pipes.

The pipe may also be a water pipe for a hot water or heating system. In such a system, the pressure in the piping is typically substantially higher than in a ventilation or drainage system. In this case, the pipe joining technique is preferably a press fit to ensure water tightness.

Claims (13)

An insulated pipe comprising a pipe-shaped wall (10, 20, 30A, 30B, 40) having a plurality of layers of cavities (16A-C, 26A-C, 26A'-C ', 36A) arranged radially in the pipe. 36B, 46, 170A-C, 180A-D, 270A-C, 280A-C, 281B-C) The cavities 5 are formed of a thermoplastic polymer arranged in an integral structure, characterized in that the tube comprises a self-supporting rigid rod, and the cavities are arranged elongated and arranged to run tangentially about the longitudinal axis of the tube. A pipe according to claim 1, characterized in that the cavities are arranged in at least 10 three layers. Pipe according to Claim 1 or 2, characterized in that the cavities are arranged in layers overlapping, such that at least one cavity, preferably at least two cavities, is provided at each point of the wall when viewed in radial directions of the tube. 4. The tube as claimed in claim 3, characterized in that the cavities in adjacent layers 15 is a half of the cavity length from offset position relative to each other. A pipe according to any one of the preceding claims, characterized in that at least some of the cavities are completely closed. A pipe according to any one of the preceding claims, characterized in that the cavities are arranged to run annularly around the longitudinal axis of the pipe. 20 A pipe according to any one of the preceding claims, characterized in that the cavities are arranged in hexagonal, rectangular or circular cross-section. A pipe according to any one of the preceding claims, characterized in that the wall is made entirely of the same polymeric material. 25 Tube according to any one of the preceding claims, characterized in that said thermoplastic polymer comprises recycled plastic, typically 30 to 100% by weight, preferably 50 to 100% by weight, of the total amount of polymer. 20165472 prh 16 -03- 2018 A tube according to any one of the preceding claims, characterized in that the wall is made by extruding a thermoplastic polymer into a tube. A process for the production of an insulated pipe comprising: - extruding the softened thermoplastic polymer wall (10, 20, 30A, 5 30B, 40) curing the wall to produce a tube, thereby: - extruded from the cavity (16A-C, 26A-C, 26A'-C ', 36A, 36B, 46, 170A-C, 180A-D, 270A-C, 280A-C, 281B-C) into the wall during extrusion 10 in the radial direction, characterized in that - the cavities are formed to run tangentially about the longitudinal axis of the tube. Process according to claim 11, characterized in that - extruding at least the inner wall of the tube in the first stage, - extruding at least a portion of the cavity layers in one or more other stages, - interconnecting the inner wall and the cavity layers in a softened state to form an insulated tube having a continuous wall structure. Method according to claim 11 or 12, characterized in that a pipe according to one of claims 1 to 10 is produced.