JP2010065768A - Fire resistant two-layer pipe joint and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fire resistant two-layer pipe joint wherein a clearance is formed between the outer periphery of an inner pipe of a socket portion of the fire resistant two-layer pipe joint and a mortar, the separation and fall-off of mortar fragments due to the breakage of the mortar of an outer pipe are further prevented even when the inner pipe is swollen and deformed by pressing or striking a straight pipe therein during manufacturing the fire resistant two-layer pipe and constructing a pipe, and troublesome manufacturing processes including manually fixing sheets or paper are also improved, and to provide a manufacturing method thereof. <P>SOLUTION: After the outer periphery of the socket portion of a synthetic resin inner pipe joint is covered with a nonwoven cloth including a thermoplastic material, the synthetic resin inner pipe joint is set in a split-type mold. After pouring uncured fire resistive hydraulic material thereinto from a mold filling port, it is removed from the mold and cured. Thus, the fire resistant two-layer pipe joint 1 is manufactured which has a nonwoven cloth layer 12 between the outer periphery of the socket portion 14 of the synthetic resin inner pipe joint and the fire resistive hydraulic material 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fireproof two-layer pipe joint in which the surface of an inner pipe joint made of a synthetic resin base material is coated with a hydraulic material having fire resistance (hereinafter also referred to as “mortar”) and a method for manufacturing the same.

  Conventionally, in order to impart heat resistance to a material having no heat resistance, a fire-resistant double-layer tube is known as an example of covering the surface with a material having fire resistance. A general fireproof double-layer pipe is obtained by coating the outer periphery of a synthetic resin pipe such as a polyvinyl chloride pipe with mortar mixed with short fibers or the like.

Synthetic resin pipes such as polyvinyl chloride pipes are lighter than metal pipes and are excellent in chemical resistance, impact resistance, etc., and are therefore used for drain pipes, ventilation pipes, etc. .
However, the synthetic resin pipe is inferior in fire resistance, and there is a risk that the fire spreads at the time of a fire and burns out and further spreads through a fireproof wall or the like perforated for a water pipe or the like.
For this reason, a fireproof double-layer pipe in which the outer periphery of a polyvinyl chloride pipe is covered with a fiber-containing mortar is generally used as a building material.

  In this type of refractory double-layer tube, cracking of mortar becomes a problem. This crack includes a crack based on the difference in thermal expansion coefficient between the polyvinyl chloride pipe and the mortar and a crack during construction. In particular, in piping work, there is a problem with cracks and breakage of the joint receiving part for inserting and connecting the inner pipe (the part where the inner diameter is large so that other inner pipes can be inserted when connecting the inner pipe of synthetic resin) It becomes.

The inner diameter portion of the joint is provided with a taper that slightly narrows in the depth direction from the inlet, and the inner diameter of the narrow portion is slightly smaller than the outer diameter of the straight pipe inserted therein.
For this reason, when a straight pipe is inserted into the joint and connected, it is necessary to push in strongly so as to expand the joint inner diameter. At that time, the polyvinyl chloride pipe does not crack because of its elasticity, but the brittle outer pipe (mortar) may crack.
Further, in order to push the straight pipe strongly, for example, when connecting the straight pipe to the branch pipe portion of the joint, an impact such as hitting the opposite side of the branch pipe portion of the joint may be applied. Mortar) may crack.

Conventionally, in order to prevent cracks, a buffer material layer such as paper or styrene foam is usually provided on the outer periphery of the polyvinyl chloride tube and covered with mortar, or alternatively, the outer surface of the polyvinyl chloride tube Means such as providing a gap between the mortars is employed.
However, although these methods are effective in preventing cracks due to thermal expansion and cracks due to the difference between the inner diameter of the joint and the outer diameter of the straight pipe, they are not effective for cracks due to impact as described above. .
For this reason, various proposals have been made to provide a gap between the inner tube and the outer tube.

  Polyvinyl chloride tubes have a thermal expansion coefficient that is almost an order of magnitude higher than that of mortar. Therefore, when curing the mortar, the mortar expands as the polyvinyl chloride tube thermally expands while the mortar is uncured by heat curing, but the polyvinyl chloride tube contracts during cooling after curing. However, the mortar does not shrink, and a gap is formed between the mortar of the outer tube and the inner tube, or alternatively, the outer surface of the inner tube is coated with a sheet whose end is bonded to the inner tube in advance. There is a proposal to create a gap between the inner tube and the sheet (see Patent Document 1).

Japanese Patent Publication No. 60-23010

  However, even if the method as described in the above-mentioned patent document 1 can provide a gap between the inner tube and the outer tube, the sheet is bonded or the paper is bonded with cellophane tape for the manufacture. Such a troublesome means as described above is used. Moreover, these means do not contribute at all to the reinforcement of the mortar of the outer pipe, and the risk of breakage or dropout of the mortar is inevitable when an impact such as striking the straight pipe is applied.

  The present invention has been made in order to solve the above technical problem, and forms a gap between the outer periphery of the inner tube of the receiving portion of the fireproof two-layer pipe joint and the mortar, and manufacture of the fireproof two-layer tube. Even when the inner pipe bulges and deforms due to impact such as press-fitting or hammering of the straight pipe at the time of pipe construction, improvement of the prevention of detachment of mortar fragments due to damage of the mortar of the outer pipe, prevention of dropping, and An object of the present invention is to provide a fireproof two-layer pipe joint and a method for manufacturing the same, in which complicated manufacturing processes such as manual sheet and paper fixing are improved.

The present invention
[1] A fireproof two-layer pipe joint in which the outer periphery of a synthetic resin inner pipe joint is covered with a fireproof hydraulic material, and a nonwoven fabric layer is provided between the outer periphery of the receiving portion of the synthetic resin inner pipe joint and the fireproof hydraulic material. Refractory double-layer pipe fittings, characterized in that
[2] The fireproof two-layer pipe joint according to [1], wherein the nonwoven fabric layer is bonded to the fireproof hydraulic material so that a surface portion thereof is integrated with the fireproof hydraulic material. ,

[3] The fireproof bilayer according to [1] or [2], wherein the nonwoven fabric is felt or spunbond containing a thermoplastic material and has heat sealability or heatset property. Pipe fittings,
[4] The nonwoven fabric layer according to any one of [1] to [3], wherein the nonwoven fabric layer is provided on an outer periphery of the receiving portion of the synthetic resin inner pipe joint, or on an outer periphery and a stepped portion. Fireproof double layer pipe fittings,
[5] The fireproof two-layer pipe joint according to any one of [1] to [4], wherein the nonwoven fabric layer has a thickness of 0.1 to 5 mm,
[6] The synthetic resin inner pipe joint has a linear shape having two receptacles, and the nonwoven fabric layer is heat-sealed, heat-set, or a plurality of spot welds on the outer peripheral surface of the synthetic resin inner pipe joint The fire-resistant two-layer pipe joint according to any one of [1] to [5],

[7] After covering the outer periphery of the receiving portion of the synthetic resin inner pipe joint with a nonwoven fabric containing a thermoplastic material, the synthetic resin inner pipe joint is set in a split mold, and is not inserted from the mold inlet. After injecting a cured fire-resistant hydraulic material, demolding and curing, a method for producing a fire-resistant two-layer pipe joint,
[8] The nonwoven fabric has heat sealability, and when the uncured fire resistant hydraulic material is injected, the nonwoven fabric surface is impregnated with the fire resistant hydraulic material so that the surface of the nonwoven fabric layer and the fire resistant material The method for producing a fire-resistant two-layer pipe joint according to [7], wherein the hydraulic material is integrated.
[9] The above [7] or [8], wherein the nonwoven fabric is formed into a cylindrical shape in advance, and the outer periphery of the receiving port portion is covered by covering the nonwoven fabric with the receiving port portion of the synthetic resin inner pipe joint. The manufacturing method of the fireproof two-layer pipe joint according to the description,
[10] The non-woven fabric is in the form of a tape or a sheet, and the non-woven fabric is wound around the outer periphery of the receiving port portion of the synthetic resin inner pipe joint, and heat-sealed, heat-set, or a plurality of spot welding is performed. The method for producing a fireproof two-layer pipe joint according to any one of the above [7] to [9], wherein the outer periphery is covered; and

[11] The above-mentioned problems have been solved by developing a fire-resistant piping that is constructed using the fire-resistant double-layer pipe joint according to any one of [1] to [6].

According to the present invention, in a fireproof two-layer pipe joint in which the outer periphery of a synthetic resin inner pipe joint is coated with a fireproof hydraulic material, a thermoplastic resin is used instead of a sheet or paper layer between the inner pipe and the outer pipe (mortar). By providing the heat-sealable non-woven fabric layer containing the material, the non-woven fabric layer can be easily fixed by heat-sealing or the like, the production is greatly simplified, and the outer tube (mortar) is broken or broken. Peeling and dropping off can be prevented.
Further, according to the fireproof two-layer pipe joint according to the present invention, it is possible to reinforce the outer pipe (mortar) of the receiving port, which has been a problem of the fireproof two-layer pipe, and further, the entire inner pipe is covered with the nonwoven fabric layer. In this case, the vibration of the synthetic resin inner pipe is prevented from being transmitted to the outer pipe, which can contribute to the soundproofing effect.

Hereinafter, the present invention will be described in more detail.
A fireproof two-layer pipe joint according to the present invention is a fireproof two-layer pipe joint in which the outer periphery of a synthetic resin inner pipe joint is covered with a fireproof hydraulic material, and the outer periphery of the receiving part of the synthetic resin inner pipe joint and the fireproof hydraulic A nonwoven fabric layer is provided between the materials. And as for the said nonwoven fabric layer, Preferably, the surface part is integrated with the said fire-resistant hydraulic material, and also contains a thermoplastic material and has heat-sealability.
In addition, the method for producing a fireproof two-layer pipe joint according to the present invention greatly improves the productivity of the fireproof two-layer pipe joint, and further impregnates the surface of the non-woven fabric and reinforces the mortar with the non-woven fabric layer. The present invention also provides a production method capable of preventing delamination and dropping even when the mortar is damaged.

The fire-resistant two-layer pipe joint according to the present invention is for connecting a fire-resistant two-layer pipe as well as conventionally known, and is a drain pipe, a vent pipe, and the like constructed through a fire-resistant wall. It can be used for other piping.
A polyvinyl chloride pipe is mainly used as the inner pipe of the fireproof two-layer pipe, and its surface is made of a fireproof hydraulic material such as a mortar to impart fire resistance and heat resistance. Covered by a tube. At this time, the refractory double-layer pipe and its joint are usually required to have a slight gap between the inner pipe and the outer pipe for processing during connection construction.

Synthetic resin inner pipe joints have been heretofore known and are mainly made of polyvinyl chloride, and have two connection ports (receiving ports) such as DS sockets (straight) and L-shapes. There are three-way pipe joints with three connection ports, such as pipe joints, Y-shaped and T-shaped, four-way pipe joints with four connection ports, such as crosses and X-shaped.
The present invention is applicable regardless of whether the diameters of the receiving portions are the same or different.

As the fire-resistant hydraulic material in the present invention, a hydraulic material that is fire-resistant and does not lose its strength even at high temperatures that are flame-retardant or non-flammable, such as cement, gypsum, clay, diatomaceous earth, and the like is used. Preferably, a mortar mainly composed of cement, which is used for a fireproof double-layer pipe, or a fiber mortar mixed with a short fiber is used because of its excellent practicality.
The thickness of the outer tube formed of the fire resistant hydraulic material varies depending on the inner tube diameter, and is appropriately set so as to have necessary strength and fire resistance.

The nonwoven fabric used in the present invention preferably has no springback because the pressure is released upon demolding after mortar injection during the production of the fireproof two-layer pipe joint. For this purpose, the thickness of the nonwoven fabric is preferably 5 mm or less.
The thickness of the nonwoven fabric is preferably from 0.1 to 5 mm, more preferably from the viewpoint of obtaining the effects of the present invention such as the formation of a sufficient gap between the outer periphery of the inner tube and the mortar. 2 to 3 mm.

The raw material of the nonwoven fabric preferably contains a thermoplastic material. A blend with a non-thermoplastic material may be used, but in order to enable heat setting, heat sealing or spot welding (including adhesion by means other than heating such as ultrasonic bonding and high frequency bonding), for example, thermoplasticity Felt, spunbond and the like including the material are preferable.
Thus, if the nonwoven fabric contains a thermoplastic material and has heat sealability or heat setting properties, the inner tube of a synthetic resin such as a polyvinyl chloride tube is directly used using a trowel or a high frequency wave, It can be heat set, heat sealed or spot welded.

The non-woven fabric has raised fibers on the surface and has undulations, which is effective for integration with the mortar, and has heat resistance equivalent to that of polyvinyl chloride. preferable.
As the thermoplastic material contained in the nonwoven fabric, polyester, polyamide, polyolefins such as polyethylene and polypropylene, and fibers such as polyvinyl chloride are preferably used.

As the shape of the nonwoven fabric, a tape shape, a sheet shape, or a cylindrical shape is preferably used.
If it is tape-like or sheet-like, it is wrapped around a synthetic resin inner pipe joint or covered by wrapping, etc., and then heat-set the non-woven fabrics or heat seal or spot weld the synthetic resin inner pipe joint Can be fixed.
Specifically, the immobilization is performed by spot welding, line welding, or the like using a welding roller sealing machine, a heat sealing machine, a high frequency welding machine, or the like.

Further, the nonwoven fabric may be formed into a tubular shape in advance by heat sealing or the like, and fitted into the inner pipe joint so as to be fixed. The immobilization may be performed by heat sealing or the like, and when the non-woven fabric includes a heat-shrinkable thermoplastic material, the cylindrical non-woven fabric can be shrunk and fixed.
In addition, heat sealing, heat setting, spot welding, and fixing by shrinking, in order to prevent the nonwoven fabric from turning over when the mortar is pressed in later, the inner part of the inner pipe joint (opposite the opening) It is preferable to select an appropriate location.

  The nonwoven fabric layer in the present invention is preferably formed on the outer periphery of the receiving portion of the synthetic resin inner pipe joint, or on the step portion in addition thereto. In some cases, it may be formed so as to cover the entire outer periphery of the inner tube. Moreover, you may make it coat | cover the receptacle part or a receptacle part, and the whole step part. In particular, it is preferable to cover both the receiving port portion and the stepped portion because the nonwoven fabric can be prevented from being turned over at the time of mortar injection.

In the production method according to the present invention, after covering the outer periphery of the synthetic resin inner pipe joint with a nonwoven fabric as described above, this is set in a mold, and the mortar is placed between the nonwoven fabric and the mold from the center. Press fit.
Thereby, a mortar enters into the raising | fluff or uneven | corrugated | grooved part of the surface of a nonwoven fabric, and a nonwoven fabric and a mortar are integrated.
At this time, although the mortar is impregnated on the surface of the nonwoven fabric, it is preferable not to penetrate the outer peripheral surface of the inner pipe joint by adjusting the density and thickness of the nonwoven fabric and the pressure of the mortar press-fitting.

And after forming the nonwoven fabric layer which the mortar adhere | attached on the outer periphery of the synthetic resin inner pipe joint, this is taken out from a metal mold | die, heat-cured, and hardens uncured mortar.
When the temperature of heat curing is high, the curing is completed in a short time. However, when the synthetic resin inner pipe joint is made of polyvinyl chloride, the maximum temperature of heat curing is about 60 ° C. which is the upper limit of the usable temperature. Curing of the mortar (cement mortar) is completed in about 3 hours.
In this heat curing, a gap is formed between the mortar of the inner tube and the outer tube (actually, the inner surface of the nonwoven fabric layer to which the mortar is bonded) due to the difference in thermal expansion coefficient between the synthetic resin inner tube joint and the mortar.

In the fireproof two-layer pipe joint obtained as described above, the mortar (outer pipe) bonded and integrated with the surface portion of the nonwoven fabric layer is efficiently reinforced by the nonwoven fabric layer formed by impregnating the mortar. ing.
For this reason, the impact resistance has been remarkably improved compared to the case where the outer tube is formed of mortar alone without the non-woven fabric layer interposed. No dropout will occur.
On the other hand, when a paper layer is interposed, the paper itself does not have heat sealability and heat setability, so that the construction for fixing and the like becomes more complicated, and the paper surface is smoother than the nonwoven fabric. Therefore, the integration with the mortar is not sufficiently achieved, and the strength of the paper itself is low, so that the reinforcing effect of the mortar is inferior.

When connecting a straight fireproof double-layer pipe, a DS socket is used, but the straight pipe is cut in advance for length adjustment. In this cutting, the inner tube was slid to one side by the length twice as long as the length to be inserted into the joint to be connected (the inner tube was pulled out from the outer tube), and the slid outer tube was cut. Thereafter, the inner tube is slid and returned to its original state. For this reason, the outer tube and the inner tube need to be relatively movable and are not fixed.
When inserting the straight pipe into the DS socket joint, the inner pipe is inserted while holding the outer pipe of the straight pipe.

For this reason, the outer tube and inner tube of the DS socket need to be fixed. Conventionally, after the DS socket is inserted after cutting a separately manufactured outer tube for the DS socket to an appropriate length. However, it has been manufactured by complicated processes such as inserting an adhesive insertion tube between the two and injecting the adhesive to fix it.
On the other hand, in the present invention, the inner pipe joint is inserted into a non-woven tubular body suitable for the length of the DS socket and fixed to the DS socket by heat sealing or the like, depending on the required strength, or The inner pipe joint is covered with a sheet of the width of the length and heat-sealed. After fixing by heat-sealing or the like at the center or a place where the connection is not hindered, the mortar of the necessary thickness on the surface part Therefore, the manufacturing process becomes extremely easy.

Hereinafter, the present invention will be specifically described with reference to the drawings. The drawings are for explaining the technical idea of the present invention, and can be changed without losing the idea.
FIG. 1 is a cross-sectional view of a fireproof double-layer pipe joint 1 and an insertion part 2 of a fireproof double-layer pipe straight pipe, and shows a state before connection.
FIG. 2 is a cross-sectional view showing a state in which the fireproof two-layer pipe joint 1 and the fireproof two-layer pipe straight pipe 2 of FIG. 1 are connected.
The fireproof two-layer pipe joint 1 has a diameter larger than that of the other part so that the receiving part can insert the inner pipe of the two-layer pipe straight pipe 2. The receiving portion of the joint 1 is composed of four layers of a mortar outer tube 11, a nonwoven fabric layer 12, a gap 13, and a synthetic resin inner tube 14 in order from the surface.
In addition, in FIG. 1, the nonwoven fabric layer 12 is also formed in the receptacle part (expanded diameter part) and level | step-difference part of the coupling 1. FIG. The nonwoven fabric layer 12 is not formed on the other part of the outer periphery of the inner tube 14, but the effect of the present invention can be obtained regardless of whether it is formed or not.
On the other hand, although the nonwoven fabric layer is not formed in the fireproof two-layer pipe straight pipe 2, since the present invention relates to the fireproof two-layer pipe joint 1, this does not affect the effect of the present invention. Absent.

FIG. 3 is a cross-sectional view of the refractory double-layer pipe DS socket 3 and shows a state in which the nonwoven fabric layer 12 is heat-sealed to the synthetic resin inner pipe 14. The DS socket 3 is composed of four layers of an outer tube 11, a nonwoven fabric layer 12, a gap 13, and an inner tube 14 in the same manner as a normal joint, and flexible fire resistance is provided on both end surfaces of the outer tube 11 and the nonwoven fabric layer 12. It is preferable to fit the joint ring 16.
The DS socket 3 holds the outer tube 11 and fixes the nonwoven fabric layer 12 and the inner tube 14 so that the positional relationship between the outer tube 11 and the inner tube 14 does not change even when pressure is applied to the inner tube 14. It is preferable to keep it.

  FIG. 4 is a cross-sectional view of a Y-shaped three-way joint, and the overall shape is different, but the configuration of the receiving portion is the same as in FIGS. In this case, since the outer tube 11 and the inner tube 14 have irregularities, they may be fixed, but it is not necessary to fix the nonwoven fabric layer 12 and the inner tube 14.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not restrict | limited by the following Example.
[Example 1]
Nominal diameter 100 mm DS socket (tube inner diameter: 99.8 mm, tube outer diameter: 113.6 mm, D ₁ = 140 mm), inner diameter 115 mm, width 95 mm, cylindrical spunbond (spunbond nonwoven fabric “ELTAS”) "Ester E01050; manufactured by Asahi Kasei Fibers Co., Ltd.) was applied and welded to the DS socket uniformly at a rate of 3 in the horizontal direction every 90 ° in the vertical direction using a roller sealer at 220 ° C.
This is set in a mold, mortar is injected and molded at a slurry pressure of 50 kg / cm ² , steam-cured at 60 ° C. for 3 hours, dried at 50 ° C. for 2 hours, and fire-resistant double-layer tube DS socket (outside the socket) (Tube outer diameter: 150 mm).
Then, after the elapse of one week, the following evaluations and tests were performed on 10 points. These results are shown in Table 1.
(1) Diameter expansion gap: 0.35 mm or more is good (2) Polyvinyl chloride pipe connection on both sides, insertion pressure of 45 to 46 kg (mortar damage evaluation)
(3) After connecting polyvinyl chloride pipes on both sides, hold at 40 ° C for 2 hours (mortal damage evaluation)
(4) After connecting polyvinyl chloride pipes on both sides, hold for 2 hours at 60 ° C
(5) Three drop tests from 50cm height (exfoliation evaluation of mortar fragments)

[Comparative Example 1]
A refractory double-layer tube socket was manufactured in the same manner as in Example 1 except that a mortar was directly injected and molded at a slurry pressure of 50 kg / cm ² into a DS socket having a nominal diameter of 100 mm without coating.
The fireproof double-layer tube socket was evaluated and tested in the same manner as in Example 1. These results are also shown in Table 1.

[Comparative Example 2]
In Example 1, a fireproof double-layer tube socket was manufactured in the same manner as in Example 1 except that cardboard (0.5 mm thickness, width 45 mm) was wound around the center of the DS socket instead of the spunbond.
The fireproof double-layer tube socket was evaluated and tested in the same manner as in Example 1. These results are also shown in Table 1.

[Example 2]
In the same manner as in Example 1, a DS socket was manufactured, and after one week after curing, only the spunbond-mortar coating part was placed on an iron table having a hole with a diameter of 113.6 mm, and only the DS socket part was placed. The pushing piece was put on, and only the polyvinyl chloride pipe was pushed down, and the pressure at the time when the piece started to shift was measured to evaluate the welding strength. The measurement was performed 5 times. The measurement results are shown in Table 2.

[Comparative Example 3]
A refractory double-layer tube DS socket was manufactured by performing mortar injection molding and curing in the same manner as in Example 1 except that a span bond having a width of 95 mm was wrapped around the same DS socket as in Example 1 and stopped with cellophane tape. . Thereafter, after one week, the welding strength was evaluated in the same manner as in Example 2. The results are also shown in Table 2.

The present invention relates to a fireproof two-layer pipe joint in which the outer periphery of a synthetic resin inner pipe joint is covered with a fireproof hydraulic material, instead of providing a sheet or paper between the inner pipe and the outer pipe (mortar), a thermoplastic material Is provided with a non-woven fabric layer having heat sealability.
For this reason, since a nonwoven fabric can be fixed by heat sealing, heat setting, or the like, the manufacturing process is greatly simplified. Furthermore, the manufactured refractory double-layer pipe joint is capable of damaging the outer pipe (mortar) even when the inner pipe bulges and deforms due to impacts such as straight pipe press-in or hammering during pipe construction. It is improved in terms of preventing mortar debris from peeling off and falling off.
Therefore, it is useful as a joint for a fireproof double-layer pipe that penetrates the fireproof compartment.

It is sectional drawing which shows the state before the connection of the fireproof two-layer pipe joint and fireproof two-layer pipe straight pipe of this invention. It is sectional drawing which shows the state which connected the fireproof two-layer pipe joint and fireproof two-layer pipe straight pipe of FIG. It is sectional drawing which shows the state by which the nonwoven fabric layer of the fireproof two-layer pipe DS socket was heat-sealed by the synthetic resin inner pipe. It is an example of sectional drawing of a Y-shaped fireproof two-layer pipe joint.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fireproof two-layer pipe joint 2 Fireproof two-layer pipe straight pipe 3 DS socket 11 Mortar outer pipe 12 Nonwoven fabric layer 13 Crevice 14 Synthetic resin inner pipe 15 Step part 16 Fireproof joint ring

Claims (11)

  A fireproof two-layer pipe joint in which the outer periphery of a synthetic resin inner pipe joint is coated with a fireproof hydraulic material, and a non-woven fabric layer is provided between the outer periphery of the receiving portion of the synthetic resin inner pipe joint and the fireproof hydraulic material. A fireproof two-layer pipe joint characterized by having   The fireproof two-layer pipe joint according to claim 1, wherein the nonwoven fabric layer is bonded to the fireproof hydraulic material so that a surface portion thereof is integrated with the fireproof hydraulic material.   The fireproof two-layer pipe joint according to claim 1 or 2, wherein the nonwoven fabric is felt or spunbond containing a thermoplastic material and has heat sealability or heatset property.   The fireproof two-layer pipe joint according to any one of claims 1 to 3, wherein the nonwoven fabric layer is provided on an outer periphery of the receiving portion of the synthetic resin inner pipe joint or on an outer periphery and a stepped portion.   The fireproof two-layer pipe joint according to any one of claims 1 to 4, wherein the nonwoven fabric layer has a thickness of 0.1 to 5 mm.   The synthetic resin inner pipe joint has a linear shape having two receiving portions, and the nonwoven fabric layer is bonded and fixed to the outer peripheral surface of the synthetic resin inner pipe fitting receiving portion by heat sealing, heat setting or a plurality of spot weldings. The fireproof two-layer pipe joint according to any one of claims 1 to 5, wherein the fireproof two-layer pipe joint is provided.   After coating the outer periphery of the synthetic resin inner pipe joint with a non-woven fabric containing a thermoplastic material, the synthetic resin inner pipe joint is set in a split mold, and uncured fireproof from the mold inlet. A method for producing a fire-resistant two-layer pipe joint, wherein a hydraulic material is injected, then demolded and cured.   The nonwoven fabric has heat sealability, and when the uncured fire-resistant hydraulic material is injected, the surface of the nonwoven fabric is impregnated with the fire-resistant hydraulic material, and the surface of the nonwoven fabric layer and the fire-resistant hydraulic material The method for manufacturing a fireproof two-layer pipe joint according to claim 7, wherein:   The fireproof two-layer pipe joint according to claim 7 or 8, wherein the non-woven fabric is formed into a cylindrical shape in advance, and the outer periphery of the receiving port portion is covered by covering the non-woven fabric with the receiving port portion of the synthetic resin inner pipe joint. Manufacturing method.   The non-woven fabric is in the form of a tape or a sheet, and the non-woven fabric is wrapped around the outer periphery of the receiving port portion of the synthetic resin inner pipe joint, and the outer periphery of the receiving port portion is formed by heat sealing, heat setting, or plural spot welding. It coat | covers, The manufacturing method of the fireproof two-layer pipe joint in any one of Claims 7-9 characterized by the above-mentioned.   A fireproof pipe constructed using the fireproof two-layer pipe joint according to any one of claims 1 to 6.

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