JP2011158158A - Branch pipe for flexible duct - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To positively prevent diameter expansion and diameter contraction following crushing deformation on a peripheral portion of an opening or internal pressure change of a main pipe in a simple structure. <P>SOLUTION: A support plate 3 and a flange part 2b of a branch pipe 2 are respectively disposed inside and outside the main pipe 1 while sandwiching an opening rim of an interior material 1a and a core material 1b therebetween, in the opening 1e of the main pipe 1. The support plate 3, the flange part 2b of the branch pipe 2, and the opening rim of the interior material 1a are connected. A plate member 4 is fixed to the outer side of the flange part 2b of the branch pipe 2 while sandwiching the opening rims of a heat insulating material 1c and an exterior material 1d therebetween. A through-hole 4a of the plate member 4 is adhered on the outer peripheral surface of a pipe body 2a of the branch pipe 2. Thereby, the branch pipe 2 is connected to the opening 1e of the main pipe 1 without cutting the core material 1b. Even if a pressure acts in a diameter expanding direction on the peripheral portion 1f of the opening 1e following internal pressure rising of the main pipe 1, the diameter expanding deformation of the opening rim of the exterior material 1d and the heat insulating material 1c is suppressed by the plate member 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a branch pipe for a flexible duct that is used when branching a flexible duct having excellent heat insulation performance in a branch structure of a pipe (duct) for an air conditioning facility disposed in a building or the like.

Conventionally, as a branch pipe for this type of flexible duct, it consists of a core body formed in a coil shape, a heat insulating layer, an interior skin and an exterior skin, and a flexible branching tool branched from the duct body, The flexible branching tool is composed of an air circulation body including an airtight layer and a heat insulating layer around a core formed in a coil shape, and a support plate fixed to one end of the air circulation body. By inserting the flexible branching tool into the opening formed on the side surface of the duct body from the inside to the outside of the duct body, the support plate protruding in a flange shape is locked around the opening, and the flexible branching tool It is connected so that it does not come out from the duct body, and then seals the boundary by wrapping adhesive tape from the outside to the boundary between the opening and the flexible branch, And ensuring connection and tightness between the transfected body and the flexible branch member, there is hermetically connected to the duct body (e.g., see Patent Document 1).
In addition, a flange that protrudes to the outer circumference is provided at the end of the connection fitting that is formed in a cylindrical shape. By inserting the metal fitting from the inside of the main pipe, the flange protrudes outside the main pipe so as to contact the inner peripheral surface around the opening, and between the flange and the fixing member arranged outside the main pipe. In some cases, the periphery of the opening is sandwiched and connected with screws, and the outer surface of the fixing member and the outer peripheral surface of the connection fitting are covered with a heat insulating material (for example, see Patent Document 2).

JP 2007-113803 A Design Registration No. 1352007

However, in such conventional branch pipes for flexible ducts, the branch pipes, which are flexible branching fixtures and connection fittings, are inserted from the inside of the main pipe into the openings of the main pipe, which is the duct body and the main pipe. Since the core material is cut at the peripheral portion of the opening portion, the peripheral portion of the opening portion of the main pipe is insufficient in strength, so that the shape retention performance is remarkably deteriorated and easily deformed.
As a result, when deployed in connection with another flexible duct, the peripheral portion of the opening of the main pipe may be crushed and deformed due to the tension balance with the other flexible duct, and the branch pipe protruding into the main pipe There was a risk that a part of the air would become an obstacle to the air flow and generate noise.
In addition, when the internal pressure of the main pipe rises during use, the peripheral part of the opening of the main pipe expands and expands, and accordingly the layer thickness of the heat insulating material is reduced and the heat insulating performance is reduced. There has been a problem that condensation tends to occur on the outer surface of the main pipe.
In particular, in the case of Patent Document 1, since the peripheral portion of the opening portion of the main pipe is thinly crushed and connected to the flange portion of the branch pipe, the heat insulation performance is reduced and dew condensation occurs on the outer surface of the main pipe. Since only the adhesive tape is wrapped around the boundary between the opening and the branch pipe from the outside and the boundary is sealed, the peripheral portion of the opening of the outer main pipe is also formed by the flange portion of the branch pipe. If the expansion and contraction of the diameter of the main pipe are repeated as the main pressure changes, pinholes and gaps are likely to occur at the boundary between the opening and the branch pipe. There was a risk that mold penetrated into the heat insulating material layer to generate mold and spread over the entire heat insulating material layer.
In the case of Patent Document 2, since the peripheral portion of the opening portion of the main pipe is thinly crushed and connected to the flange portion of the branch pipe, the heat insulating performance is lowered, and the outer surface of the fixing member is insulated from the heat insulating material. Condensation may occur even if it is covered, and the peripheral part of the opening of the main pipe arranged outside the flange part and the fixing member of these branch pipes expands and contracts in diameter as the main pressure changes. If diameter shrinkage is repeated, pinholes and gaps are likely to occur at the connection between the opening and the flange of the branch pipe, and moisture can penetrate into the insulation layer in the main pipe even in these pinholes and slight gaps. There was a possibility that mold was generated and spread over the entire heat insulating material layer.

  An object of the present invention is to cope with such a problem, and with a simple structure, the expansion and contraction of diameter expansion and contraction due to changes in the internal pressure of the main pipe and the deformation around the opening are reliably prevented. To prevent the expansion and expansion of the surrounding area of the opening for a long period of time, and to prevent the formation of dew condensation and mold inside by the penetration of condensed water while insulating the surrounding area of the opening and the branch pipe It is intended to prevent the occurrence of the trouble and facilitate the deployment of the main pipe and the branch pipe.

  In order to achieve such an object, the present invention provides a heat insulating material on the outer periphery of the interior material and the spiral core material, covers the outer peripheral side with an exterior material, and opens the interior material, the heat insulating material, and the exterior material. A flexible main pipe in which a portion is opened, and a branch pipe in which a flange portion is integrally formed along the outer peripheral surface of the interior material or the outer peripheral surface of the core material in the pipe main body that is inserted through the opening of the main pipe. A support plate provided along the inner surface of the opening edge of the interior material so as to surround the opening of the main pipe, and a through hole through which the pipe body of the branch pipe is inserted, and the opening of the main pipe A plate-like member provided along the outer surface of the exterior material in the peripheral portion of the main plate, and the support plate and the branch with the opening edge of the interior material and the core material sandwiched between the opening of the main pipe The flange part of the pipe is arranged inside and outside the main pipe, respectively The support plate, the flange portion of the branch pipe, and the opening edge of the interior material are connected, and the opening edge of the heat insulating material and the exterior material is sandwiched outside the flange portion of the branch pipe. The plate-like member is fixed, and the through hole of the plate-like member is closely attached to the outer peripheral surface of the pipe body of the branch pipe.

  In addition to the features described above, a cylindrical member is provided so as to face the outer surface of the plate-shaped member, and one end surface of the cylindrical member is brought into contact with the outer surface of the plate-shaped member, and the cylindrical member The inner peripheral surface is closely attached to the outer peripheral surface of the pipe body of the branch pipe.

  Further, in addition to the above-described features, the plate member and the tubular member are formed of a closed cell heat insulating material.

  Further, in addition to the above-described features, a belt is provided along the outer peripheral surface of the main pipe, and an end portion of the belt is fixed to the plate member.

In the present invention having the above-described features, the support plate and the flange portion of the branch pipe are respectively disposed inside and outside the main pipe with the opening edge of the interior material and the core material sandwiched between the opening of the main pipe, and the support plate and the branch pipe. The plate member and the opening edge of the interior material are connected to each other, and the plate member is fixed to the outside of the flange portion of the branch pipe with the opening edge of the heat insulating material and the exterior material interposed therebetween, and the through hole of the plate member is connected to the branch pipe By closely contacting the outer peripheral surface of the tube main body, the branch pipe is connected to the opening of the main pipe without cutting the core material, and as the internal pressure rises in the main pipe, Even if pressure is applied, the plate-like member suppresses the expansion deformation of the opening edge of the exterior material and the heat insulating material, so that the expansion of the diameter of the surrounding portion of the opening and the change in the internal pressure of the main pipe with a simple structure. Expansion and contraction can be reliably prevented.
As a result, flexible ducts at both ends and branch pipes of the main pipe are compared to the conventional one in which the core material is cut at the peripheral edge of the main pipe opening to allow the branch pipe to be inserted into the main pipe opening from the inside of the main pipe. When connecting and deploying, the peripheral part of the opening of the main pipe will not be crushed and deformed due to the tension balance with other flexible ducts, and obstacles will not protrude into the air flow in the main pipe. In addition to preventing the occurrence of pinholes and gaps due to repeated expansion and contraction due to changes in the internal pressure of the main pipe, it is possible to prevent moisture from entering the heat insulating material in the main pipe. Prevents mold from being generated.
Further, when an existing flanged branch pipe used for branching a round duct is used as the branch pipe, it is not necessary to design and manufacture a dedicated branch pipe, so that the manufacturing cost can be greatly reduced.

Furthermore, a cylindrical member is provided so as to face the outer surface of the plate-shaped member, and one end surface of the cylindrical member is brought into contact with the outer surface of the plate-shaped member, and the inner peripheral surface of the cylindrical member is When the branch pipe is brought into close contact with the outer peripheral surface of the pipe body, the plate-like member is positioned by the cylindrical member even if the pressure in the diameter expanding direction acts on the peripheral portion of the opening due to the increase in the internal pressure of the main pipe. Since it does not shift and the peripheral portion of the opening does not swell, diameter expansion of the peripheral portion of the opening can be reliably prevented over a long period of time.
As a result, pinholes and gaps do not occur due to repeated expansion and contraction due to changes in internal pressure of the main pipe over a long period of time, preventing moisture from entering the heat insulating material layer in the main pipe. The generation of mold due to mold can be prevented, and the construction of a further moisture-proof layer becomes unnecessary, and the repair work due to mold and branch pipe corrosion can be significantly reduced.

In addition, when the plate member and the cylindrical member are formed of closed cell heat insulating material, the condensed water does not soak into the plate member and the cylindrical member. It is possible to prevent the occurrence of internal condensation and mold caused by the penetration of condensed water while achieving heat insulation.
As a result, it is not necessary to install a further moisture-proof layer, and repair work due to mold and branch pipe corrosion can be significantly reduced.

Further, when a belt is provided along the outer peripheral surface of the main pipe and the end portion of the belt is fixed to the plate member, the belt is integrally attached to the main pipe and the branch pipe. Since the pipe can be suspended, the main pipe and the branch pipe can be easily arranged.
As a result, the time for deployment can be shortened.

It is a perspective view which shows the whole structure of the branch pipe for flexible ducts concerning embodiment of this invention. It is a vertical side view of FIG. FIG. 2 is an exploded perspective view of FIG. 1. It is a perspective view which shows the whole structure of the branch pipe for flexible ducts concerning other embodiment of this invention. It is a vertical side view of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1 to FIG. 5, the branch pipe A for flexible duct according to the embodiment of the present invention is provided with a heat insulating material 1 c on the outer periphery of the interior material 1 a and the spiral core material 1 b, and the outer peripheral side is exteriorized. A flexible main pipe 1 covered with a material 1d, a branch pipe 2 in which a flange portion 2b is integrally formed on the pipe body 2a along the outer peripheral surface of the interior material 1a or the outer peripheral surface of the core material 1b, and the interior material 1a. A support plate 3 provided along the inner peripheral surface and a plate-like member 4 provided along the outer surface of the exterior material 1d are provided.

The main pipe 1 is formed in a cylindrical shape like a flexible duct having a conventionally well-known structure.
The interior material 1a is formed of, for example, a non-woven fabric made of synthetic resin such as polyester resin or other materials, and is formed into a cylindrical shape by integrally winding a spiral core material 1b made of, for example, hard steel wire.
As an example of the manufacturing method, a core material 1b is fixed to one end of a strip-shaped interior material 1a, and the strip-shaped interior material 1a and the core material 1b are spirally wound so that one end of the interior material 1a overlaps. By adhering each other, the core material 1b is sandwiched between the inner and outer interior materials 1a so as not to be exposed.
The heat insulating material 1c is formed of, for example, a synthetic resin fiber such as glass wool or PET resin, or another material.
The exterior material 1d is formed of a film made of a synthetic resin such as a polyester resin or a film made of a noncombustible material such as aluminum.

Furthermore, at an appropriate position in the longitudinal direction of the main pipe 1, the interior material 1 a, the heat insulating material 1 c and the exterior material 1 d are cut in a circular shape so as not to cut the core material 1 b, so that it is approximately the same size as a branch pipe 2 described later. The opening 1e is opened, and its peripheral portion 1f is a plate-like member 4 described later.
Moreover, it is preferable to form the narrowing part 1g with the adhesive tape etc. in the longitudinal direction both ends of the main pipe 1 similarly to the flexible duct of a conventionally well-known structure.

The branch pipe 2 is formed of a rigid material such as metal, for example, and has a cylindrical pipe body 2a that is inserted through the opening 1e of the main pipe 1 and a flange portion 2b that is integrally formed at one end of the pipe body 2a. And the flange part 2b is curving so that the outer surface of the opening edge of the interior material 1a may be met.
Furthermore, it is preferable to open a plurality of through holes 2c through which a fastening member 5 described later is inserted in the flange portion 2b.
As the branch pipe 2, it is also possible to use an existing flanged branch pipe used for branching a round duct.

The support plate 3 is formed of a rigid material such as metal in an annular shape having the same size as the flange portion 2b of the branch pipe 2, and has a through hole 3a having the same size as the opening 1e of the main tube 1 at the center thereof. And it is curving so that the inner surface of the opening edge of the interior material 1a may be enclosed so that the opening part 1e of the main pipe 1 may be enclosed.
Furthermore, it is preferable that a plurality of through holes 3b through which fastening members 5 described later are inserted in the support plate 3 so as to coincide with the through holes 2c of the flange portion 2b.

  The plate-like member 4 is formed of a heat insulating material or a rigid material into a plate shape that is not easily elastically deformed along the outer peripheral surface of the main pipe 1, and has a through-hole 4a through which the pipe body 2a of the branch pipe 2 is inserted. The through hole 4a is in close contact with the outer peripheral surface of the pipe body 2a of the branch pipe 2.

The fastening member 5 is made of, for example, a rivet or a screw or a bolt.
In the illustrated example, a rivet is inserted and fastened as a fastening member 5 into the through hole 2c of the flange portion 2b and the through hole 3b of the support plate 3.
As another example, screws or bolts can be used instead of rivets.

And as a manufacturing method of branch pipe A for flexible ducts concerning the embodiment of the present invention, support plate 3 and branch pipe 2 are sandwiched between opening edge of interior material 1a and core material 1b in opening 1e of main pipe 1. These flange portions 2b are respectively disposed inside and outside the main pipe 1, and the support plate 3, the flange portion 2b of the branch pipe 2, and the opening edge of the interior material 1a are connected by a fastening member 5.
In the subsequent process, the plate member 4 is fixed in an airtight manner with an adhesive or the like so as to sandwich the opening edges of the heat insulating material 1c and the exterior material 1d on the outside of the flange portion 2b of the branch pipe 2. The plate-like member 4 is integrally attached to the main pipe 1 and the branch pipe 2 by fixing the through hole 4 a to the outer peripheral surface of the pipe body 2 a of the branch pipe 2 in an airtight manner, for example, with an adhesive.

According to such a flexible duct branch pipe A, the branch pipe 2 is connected to the opening 1e of the main pipe 1 without cutting the core 1b.
Furthermore, the portion where the opening 1e is opened in the main pipe 1 is because the interior material 1a, the heat insulating material 1c, and the exterior material 1d are cut into a circle, so that the strength of the peripheral portion 1f of the opening 1e is higher than that of other portions. If the internal pressure of the main pipe 1 rises during use, the surrounding portion 1f of the opening 1e may expand and deform.
However, the flexible duct branch pipe A according to the embodiment of the present invention is provided with the plate-like member 4 along the outer surface of the exterior material 1d in the peripheral portion 1f of the opening 1e, and therefore, the peripheral portion of the opening 1e. Even if pressure in the diameter increasing direction acts on If, the plate-like member 4 suppresses the opening edge of the exterior material 1d and the diameter expansion deformation of the heat insulating material 1c.
As a result, while having a simple structure with a small number of parts as a whole, it is possible to reliably prevent the expansion and contraction due to the crushing deformation and the change in the internal pressure of the main pipe 1 in the peripheral portion 1f of the opening 1e. .
Therefore, when a flexible duct (not shown) is connected to both ends of the main pipe 1 and the branch pipe 2, the peripheral portion 1f of the opening 1e of the main pipe 1 is crushed due to tension balance with other flexible ducts. Since there is no deformation and no obstacles protrude from the air flow in the main pipe 1, it is possible to prevent noise and the like, and to repeat the expansion and contraction due to the change in the internal pressure of the main pipe 1 Since pinholes and gaps do not occur, it is possible to prevent moisture from entering the heat insulating material 1c in the main pipe 1 and to prevent mold from occurring.
Further, if an existing flanged branch pipe used for branching a round duct is used as the branch pipe 2, it is not necessary to newly design and manufacture a dedicated branch pipe, so that the manufacturing cost can be greatly reduced.
Next, each embodiment of the present invention will be described with reference to the drawings.

  In the first embodiment, as shown in FIGS. 1 to 3, the tubular member 6 is provided so as to face the outer surface of the plate-like member 4, and one end surface 6 a of the tubular member 6 is provided on the plate-like member 4. The inner peripheral surface 6b is brought into close contact with the outer peripheral surface of the pipe body 2a of the branch pipe 2 while being brought into contact with the outer surface.

  The cylindrical member 6 is formed in a cylindrical shape that is difficult to elastically deform along the outer peripheral surface of the pipe body 2a of the branch pipe 2 with a heat insulating material or a rigid material, and one end face 6a of the plate-like member 4 is made of, for example, an adhesive. The inner peripheral surface 6b is fixed in an airtight manner to the outer peripheral surface of the tube main body 2a of the branch pipe 2 with, for example, an adhesive or the like.

Furthermore, in the example shown by FIGS. 1-3, the plate-shaped member 4 and the cylindrical member 6 are shape | molded with the heat insulating material of the closed cell.
As this heat insulating material, it is preferable to use a foamed heat insulating material having an independent foaming rate of 100% or close to it by foaming based on moisture-resistant NBR rubber or the like.

According to the branch pipe A for flexible ducts according to the first embodiment of the present invention, the tubular member 6 can be used even if the pressure in the diameter expanding direction acts on the peripheral portion 1f of the opening 1e due to the increase in the internal pressure of the main pipe 1. Thus, the plate-like member 4 is held without being displaced, so that the peripheral portion 1f of the opening 1e is not partially expanded and deformed.
Thereby, the expansion of the diameter of the peripheral portion 1f of the opening 1e can be reliably prevented over a long period of time.
Therefore, since pinholes and gaps do not occur due to repeated expansion and contraction due to changes in the internal pressure of the main pipe 1 over a long period of time, preventing moisture from entering the heat insulating material 1c in the main pipe 1, As a result, the occurrence of mold can be prevented, and further construction of the moisture-proof layer becomes unnecessary, and there is an advantage that the repair work due to the corrosion of the mold and the branch pipe 2 can be remarkably reduced.

  In particular, as shown in FIGS. 1 to 3, if the plate-like member 4 and the cylindrical member 6 are formed of a closed cell heat insulating material, the dew condensation water does not soak into the plate-like member 4 and the cylindrical member 6. Therefore, there is an advantage that it is possible to prevent the internal dew condensation and the generation of mold due to the penetration of dew condensation water while insulating the peripheral portion 1f of the opening 1e and the branch pipe 2.

  As shown in FIGS. 4 and 5, the second embodiment has a configuration in which a belt 7 is provided along the outer peripheral surface of the main pipe 1 and both end portions 7 a of the belt 7 are fixed to the plate-like member 4. Unlike the first embodiment shown in FIG. 3, the other configuration is the same as that of the first embodiment shown in FIGS.

The belt 7 is used when the main pipe 1 is suspended and supported. For example, it is preferable to provide a mounting hole 7b through which a suspension member (not shown) such as a screw suspended from the ceiling is inserted.
Furthermore, in order to attach the belt 7 to the main pipe 1 more firmly, it is preferable to fix both end portions 7 a of the belt 7 to the branch pipe 2.

In the example shown in FIG. 4 and FIG. 5, a perforated belt 7 c and a perforated belt 7 d in which a large number of mounting holes 7 b are perforated at predetermined intervals are arranged as the belt 7, and the perforated belt 7 c is arranged on the surface side. The both end portions 7a of the perforated belt 7c and the non-perforated belt 7d are connected to the pipe body 2a of the branch pipe 2 by fastening members 8 such as rivets, respectively, and The front surface and one end surface 6a of the cylindrical member 6 are fixed in an airtight manner with, for example, an adhesive.
As another example, both ends 7a of one belt 7 are connected to the pipe body 2a of the branch pipe 2 by a fastening member 8 such as a rivet, or the inner surface of the plate-like member 4 and the exterior material 1d It is also possible to adhere to the outer surface in an airtight manner, for example with an adhesive.

According to the flexible duct branch pipe A according to the second embodiment of the present invention, the belt 7 is integrally attached to the main pipe 1 and the branch pipe 2, and the suspension suspended from the ceiling with respect to the belt 7 is provided. By connecting the holding members, the main pipe 1 and the branch pipe 2 can be suspended and supported.
Thereby, there is an advantage that the main pipe 1 and the branch pipe 2 can be easily deployed, and the time for deployment can be shortened.

By the way, as a method of connecting the belt 7 and the suspension member, it is conceivable to insert a screw suspended from the ceiling into the mounting hole 7b of the belt 7 and sandwich the belt 7 with a double nut.
However, in this case, if the tip of the screw inserted through the attachment hole 7b or the corner of the nut contacts the exterior material 1d of the main pipe 1, the exterior material 1d may be damaged and the hole may be opened.
Therefore, as shown in FIGS. 4 and 5, if the belt 7 is arranged so as to overlap the holeless belt 7d so that the perforated belt 7c is arranged on the surface side, the tip of the screw inserted through the attachment hole 7b or There is an advantage that the corner portion of the nut does not come into contact with the exterior material 1d of the main pipe 1 and a hole can be prevented from being opened, and moisture can be prevented from entering the heat insulating material 1c in the main pipe 1.

In the previous embodiment, the tubular member 6 is provided so as to contact the outer surface of the plate-like member 4, but the present invention is not limited to this, and instead of the tubular member 6, the tube body 2 a of the branch pipe 2 is provided. A heat insulating material may be wound around the outer peripheral surface.
Further, the support plate 3, the flange portion 2 b of the branch pipe 2, and the opening edge of the interior material 1 a are connected by a fastening member 5 such as a rivet, for example. You may connect using.

DESCRIPTION OF SYMBOLS 1 Main pipe 1a Interior material 1b Core material 1c Heat insulating material 1d Exterior material 1e Opening part 1f Surrounding part 2 Branch pipe 2a Pipe body 2b Flange part 3 Support plate 4 Plate-like member 4a Through-hole 6 Cylindrical member 7 Belt 7a End part

Claims (4)

A heat insulating material is provided on the outer periphery of the interior material and the spiral core material, the outer peripheral side is covered with an exterior material, and a flexible main pipe in which an opening is opened in the interior material, the heat insulating material, and the exterior material;
A branch pipe in which a flange portion is integrally formed along an outer peripheral surface of an interior material or an outer peripheral surface of the core member, in a pipe main body that is inserted through the opening of the main pipe;
A support plate provided along the inner surface of the opening edge of the interior material so as to surround the opening of the main pipe;
A plate-shaped member having a through-hole through which the pipe main body of the branch pipe is inserted and provided along an outer surface of the exterior material in a peripheral portion of the opening of the main pipe;
The support plate and the flange portion of the branch pipe are respectively arranged inside and outside of the main pipe with the opening edge of the interior material and the core material sandwiched between the opening of the main pipe, and the support plate and the branch. The plate-like member is fixed to the outside of the flange portion of the branch pipe with the opening edge of the heat insulating material and the exterior material sandwiched between the flange portion of the pipe and the opening edge of the interior material, A branch pipe for a flexible duct, wherein the through hole of the plate-like member is brought into close contact with the outer peripheral surface of the pipe body of the branch pipe.   A cylindrical member is provided so as to face the outer surface of the plate-like member, and one end surface of the cylindrical member is brought into contact with the outer surface of the plate-like member, and the inner peripheral surface of the cylindrical member is set to the branch. The branch pipe for flexible ducts according to claim 1, wherein the branch pipe is closely attached to an outer peripheral surface of the pipe body of the pipe.   The branch pipe for a flexible duct according to claim 1 or 2, wherein the plate-like member and the cylindrical member are formed of a closed cell heat insulating material.   4. The flexible duct branch pipe according to claim 1, wherein a belt is provided along an outer peripheral surface of the main pipe, and an end of the belt is fixed to the plate member.

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