JP2003254479A - Connecting structure for double layer pipe, and joint structure for fire-prevention measures - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting structure for a double layer pipe in which a defect of mortar is eliminated, and efficiency in connecting work is effectively improved while reliability of fire-prevention measures at a joint part is also effectively improved. <P>SOLUTION: This connecting structure for the double layer pipe comprises a main pipe 1 made from the double layer pipe 2, a joint 2 connected to the main pipe 1, and a fire-prevention member 3a disposed between the main pipe 1 and the joint 2. The fire-prevention member 3a includes thermal expanding material, and thermally expands in a direction connecting at least the main pipe 1 and the joint 2. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting structure for a two-layer pipe in which a connecting portion between the two-layer pipe and the joint is fireproofed, and more specifically, between the main pipe made of the two-layer pipe and the joint. The present invention relates to a two-layer pipe connection structure in which a heat-expandable fire protection member is annularly arranged.

[0002]

2. Description of the Related Art When a pipe is to be inserted through a partition (penetration part of a fire compartment) of a partition such as a wall, floor, or ceiling that partitions a fire compartment, it is necessary to take fire protection measures. Such a pipe is formed by using, for example, a main pipe having a fire resistant two-layer structure including an inner pipe and a fire resistant outer pipe covering the inner pipe. Since the inner tube is usually formed of a material that is relatively inflammable such as synthetic resin, the outer peripheral surface of the inner tube is covered with a fire resistant outer tube to form a fire resistant two-layer tube. The outer tube is
For example, it is formed by hardening fiber-reinforced mortar.

When forming such a pipe, a main pipe in which a fluid is transported through the inside of the inner pipe is usually combined with a joint connecting one or more main pipes. Both the main pipe and the joint have a fireproof two-layer structure. The fitting is
A fire-resistant two-layer pipe (two-layer pipe) including an inner cylinder and a fire-resistant outer cylinder covering the outer peripheral surface of the inner cylinder. The main pipe is usually connected as follows.

As described above, the main pipe includes the inner pipe and the fire-resistant outer pipe that covers the outer peripheral surface of the inner pipe. To connect this to the joint, the outer peripheral surface of at least one end of the inner pipe is exposed. That is, a portion near one end of the outer pipe is cut off to expose the inner pipe. When connecting both ends of the main pipe to the joint, the other end side of the inner pipe is also exposed. The exposed portion of the inner pipe of the main pipe is inserted into the cavity in the inner cylinder from one end side of the inner cylinder of the joint. After that, joint treatment (joint treatment) is applied to the joint connecting these two for fire protection, and the exposed portion of the inner pipe of the main pipe is covered with a fire protection member to complete the connection of the main pipe. To complete.

As an example of the conventional fire protection construction method, there is a construction method in which the joint portion of the connection structure of the two-layer pipe is filled with a fire protection member made of an incombustible material. In this method, mortar is usually piled up as a non-combustible material and hardened so that no gap remains at the joint and the inner pipe is not exposed. However, the mortar filling work requires skill of the operator and the appearance of the connection structure is not good. In addition, since a relatively large external force may be applied to the building due to normal vibrations and earthquakes, mortar may crack or fall depending on the degree of hardening, making it difficult to take reliable fire protection measures. It was

Japanese Patent No. 2966391 discloses a construction method capable of eliminating the above-mentioned drawbacks of mortar. This publication discloses an elastic annular member (annular packing) as a fire protection member that can relatively easily carry out fire protection for joining a main pipe and a joint. This annular member is usually used as follows. First, the annular member is passed through the inner pipe exposed portion of the main pipe, and the inner pipe exposed portion is inserted into the joint inner cylinder. In this state, the non-insertion part of the inner pipe exposed part is set, the annular member is arranged so as to cover the entire circumference of the part, and the annular end surface of the inner pipe insertion end of the joint (that is, the inner cylinder and the outer part) The annular member is sandwiched between the main pipe and the joint so as to contact both the annular end face of the cylinder) and the annular end face of the outer pipe end of the main pipe (end on the side where the inner pipe is exposed). .
In this state, a gap remains at these joints and the inner pipe of the main pipe is exposed. Therefore, the main pipe and the joint are pressed in a state of being opposed to each other to compressively deform the annular member,
The annular end faces of both the main pipe and the joint and the annular end faces of both the front and back of the annular member (end faces orthogonal to the circumferential direction) are made to be in intimate contact with each other as much as possible. This completes the connection work and completes the connection structure. If such compressive deformation of the annular member can be reliably utilized, no gap remains at the joint portion, and reliable fire protection measures can be taken.

The above publication also discloses that a notch having a predetermined depth is annularly arranged in the elastic annular member in order to facilitate the compressive deformation of the portion held between the main pipe and the joint. .

[0008]

The construction method using the elastic annular member described above has advantages such as relatively simple work as compared with other construction methods. However, in the conventional construction method, in order to improve the reliability of the fire protection measures, it was necessary to prevent a gap from remaining at the joint portion of the two-layer pipe connection structure when the connection structure was completed (when there was no fire).

In particular, at the stage where the outer pipe of the main pipe is cut out by a predetermined length to expose the inner pipe, it is difficult to smooth the annular end surface of the cut end of the outer pipe. Therefore, in order to bring the annular member into close contact with each other so that no gap remains between the annular member and the end face of the outer tube cut end, it is necessary to reliably deform the annular member. That is, if the annular member is not reliably deformed, the reliability of the fire protection cannot be improved. Therefore, in order to increase the reliability of the fire protection measures, the operator has carefully and time-consumingly pressed the main pipe and the joint to deform the annular member as much as possible to fill the gap. Therefore, in the conventional two-layer pipe connection structure, if it is attempted to improve the reliability of the fire protection measures at the joint, it takes a long time for the connection work, and the work efficiency cannot be improved.

The present invention has been made in order to solve the above-mentioned problems, and can solve the drawbacks of mortar, while effectively increasing the reliability of fire protection measures at the joint portion, while also improving the efficiency of connection work. It is an object of the present invention to provide a double-layered pipe connection structure that can be improved in height.

[0011]

Means for Solving the Problems A connection structure for a double-layer pipe and a joint structure for fire protection measures of the present invention for solving the above problems are as follows. [1] A connection structure for a two-layer pipe, comprising a main pipe made of a two-layer pipe, a joint connected to the main pipe, and a fire protection member arranged between the main pipe and the joint, The main pipe has an inner pipe and a fire-resistant outer pipe covering the outer peripheral surface of the inner pipe, the outer peripheral surface of at least one end portion of the inner pipe is exposed, the joint, The main tube has an inner tube and a fireproof outer tube that covers the outer peripheral surface of the inner tube, and the inner tube of the main pipe has its outer peripheral surface exposed portion at one end in the central axial direction of the inner tube (inner tube insertion end). ) Side is inserted into the inner cylinder,
The fire protection member is arranged in an annular shape so as to cover the outer peripheral surface exposed portion of the inner pipe of the main pipe along the circumferential direction thereof, and the fire protection member comprises a heat-expandable material, A connection structure for a two-layer pipe, which is characterized by thermally expanding at least along a direction connecting the main pipe and the joint. [2] The two-layer pipe connection structure according to [1], wherein the fire protection member is made of an annular member containing a heat-expandable material, and thermally expands in a direction orthogonal to a radial direction of the annular member. [3] The thermally expandable material is expanded graphite, [1]
Alternatively, the two-layer pipe connection structure according to [2]. [4] A joint structure for fire protection used for forming the connection structure for a two-layer pipe according to [1], wherein the inner cylinder and the outer cylinder covering the outer peripheral surface of the inner cylinder, The inner pipe insertion end, into which the inner pipe of the main pipe to be connected is inserted, comprises the fire protection member including a thermally expansive material in close contact with the inner cylinder and the outer cylinder, and the inner pipe insertion end is provided. The main pipe has an opening through which the inner pipe can penetrate, and the fire protection member can be thermally expanded at least along a direction connecting the main pipe and the joint in a state where the inner pipe of the main pipe is connected. There is a joint structure for fire protection.

In the connection structure of the present invention, the fire protection member arranged annularly between the main pipe and the joint is along the direction connecting the main pipe and the joint, that is, the diameter of the fire protection member annular shape. Thermal expansion is performed so as to press the annular end surface of the outer pipe of the main pipe and the annular end surface of the joint along a direction orthogonal to the direction. As a result, even if the annular end surface of the outer pipe (cut end) is not smooth and a gap remains at the joint between the main pipe and the joint, the fire-prevention measure member thermally expands in the event of a fire,
It is possible to reliably close the gap in the joint portion. Further, even if there are variations in the number and size of the remaining gaps, the thermal expansion of the fire protection member can absorb the variations.

That is, according to the present invention, in the connecting work of the two-layer pipe, the pressing operation for largely deforming the fire protection member sandwiched between the main pipe made of the two-layer pipe and the joint is unnecessary. Therefore, it is possible to effectively enhance the efficiency of the connection work while surely increasing the reliability of the fire protection measures at the joint portion of the two-layer pipe connection structure.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. It should be understood that design changes, improvements, etc. can be appropriately made based on the knowledge of.

(Double Layer Pipe Connection Structure) FIG. 1 is a side view showing a main pipe 1 and a joint 2 which constitute an embodiment of a double layer pipe joint structure of the present invention. FIG. 2 shows an end portion (inner tube insertion end) of the joint 2, which constitutes one embodiment of the double-layered pipe connection structure of the present invention, that is, the inner tube 11 of the main tube 1 is inserted.
It is explanatory drawing which shows the opening part of the joint 2. FIG. 3 is a cross-sectional view in which a joint portion constituting one embodiment of the double-layer pipe connection structure of the present invention is enlarged and cut along a plane including a central axis of the double-layer pipe.

As shown in FIG. 1, the main pipe 1 includes an inner pipe 11
And a fire-resistant outer tube 12 that covers the outer peripheral surface of the inner tube 11. The outer peripheral surface of at least one end side of the inner pipe 11 is exposed. The exposed outer peripheral surface of the inner pipe 11 is a cavity (inner pipe) inside the joint 2 shown in FIG. 2 from one end (inner pipe insertion end) side of the inner cylinder 21 (see FIG. 3) in the central axis direction. Inner) 210. As shown in FIG. 3, the joint 2 also has a two-layer structure, and includes an inner cylinder 21 and an outer cylinder 22 that covers the outer peripheral surface thereof. The outer tube 12 and the outer tube 22 are made of fiber reinforced mortar, and the inner tube 11 and the inner tube 21 are made of vinyl chloride resin. Main pipe 1
Is a normal product of the type that has been used in the past, and a straight pipe that extends almost linearly or a bent product in the middle can be used. The joint 2 can also be a normal product of the type conventionally used.

Between the joint 2 and the outer pipe 12 of the main pipe 1, a fire protection member 3a made of a thermally expansive annular member 3 is sandwiched. As shown in FIG. 3, one annular end surface of the annular member 3 contacts the annular end surface 121 of the end portion of the outer tube 12 after the connection is completed. The inner diameter of the annular member 3 has such a size that the outer peripheral surface exposed portion of the inner pipe 11 can penetrate therethrough. Annular member 3
The inner diameter is approximately the same as the outer diameter of the outer peripheral surface exposed portion of the inner pipe 11, and covers the outer peripheral surface of the outer peripheral surface exposed portion of the inner pipe 11. On the other hand, the other annular end surface of the annular member 3 is in contact with the annular end surface 23 of the inner pipe insertion end of the joint 2. Further, from FIG. 3, the radial width of the annular member 3 is set to be substantially the same as the overall wall thickness of the joint 2, and the annular member 3 is at the inner pipe insertion end of the joint 2 and the entire annular end surface of the inner cylinder 21. In addition to the outer cylinder 22
By making contact with the entire annular end face of the, the reliability of fire prevention measures is enhanced more effectively.

In this way, the connection can be completed, and the connection structure of the double-layered pipe of the present embodiment can be completed. As shown in FIG. 3, inside the inner cylinder of the inner cylinder 21 (cavity 210)
An annular stopper 211 is provided inside. In such a case, normally, the tip of the inner pipe 11 is the annular stopper 211.
Since the inner pipe 11 having a length until coming into contact with the inner pipe 21 is inserted into the inner cylinder 21, the annular member 3 is in contact with the annular end surface 121 of the outer pipe 12 in that state, and the inner pipe insertion end of the joint 2 has an annular shape. End face 2
Make contact with 3.

The annular member 3 is an annular end surface 12 of the outer tube 12.
It does not have to be in close contact with 1. The annular member 3 thermally expands toward the annular end surface 121 of the outer pipe 12 of the main pipe 1 along a direction orthogonal to the radial direction thereof, and the annular member 3 thermally expanded at the time of a fire is connected to the joint portion of the connection structure. This is because the gap can be surely closed. Similarly, it is not necessary to be in close contact with the annular end surface 23 of the inner tube insertion end of the joint 2. However, as shown in FIG. 3, from the viewpoint of facilitating the connection work, the annular member 3 includes the annular end surface 23 of the inner pipe insertion end of the joint 2.
Is preferably in close contact with. From the same viewpoint, it is preferable that the annular member 3 be brought into close contact with the annular end surface 121 of the outer tube 12 in advance.

According to the present invention, even if a gap remains after disposing the heat-expandable annular member at the joint between the main pipe and the joint, the annular member thermally expands in the case of fire occurrence, and It is possible to reliably close the gap in the joint portion. However, even if there is no problem in terms of fire prevention, there are cases where the appearance is not preferable when such a gap is relatively large. For example, at the site where the connection structure is formed, it is necessary to cut the main pipe to adjust the length, and when the main pipe is cut manually, the annular end surface of the outer pipe is from the plane orthogonal to the length direction. It may shift and become slanted. In such a case, a relatively large gap remains after the thermally expandable annular member is arranged. When a relatively large gap remains after the annular member is arranged, for example, it is preferable that the gap be filled with foam to make the gap invisible.

When the foam is used as described above, it is preferable to use an annular laminate formed by laminating a heat-expandable annular member and an annular foam, and adhering them to each other as a fire protection member. For example, this annular laminated body is arranged so that the thermally expansive annular member is more closely attached to the annular end surface of the joint inner pipe, and foaming is provided between the annular end surface of the outer pipe of the main pipe and the thermally expansive annular member. If the body is packed, no gap is left between the outer tube and the annular member, and the appearance can be improved.
Since the foam deforms relatively easily, it is not necessary to strongly press the main pipe and the joint when the foam is packed in the gap. In addition, when the foam contains a relatively large number of pores, the performance of the foam itself as a fire protection member is not sufficient, but when a fire occurs, the thermally expanded annular member compresses and deforms the foam to prevent it from expanding. The holes are crushed and the annular member closes the gap at the joint portion of the connection structure.

The foam does not need to have high flame retardancy, but is preferably formed of a resin having relatively high flame retardance such as chloroprene and silicone.

(Joint Structure for Fire Prevention Measures) In order to form the connecting structure for the two-layer pipe of the above-described embodiment, it is preferable to use a joint structure for fire preventive measures as shown in FIG. That is, the inner cylinder 21 and the outer cylinder 22 that covers the outer peripheral surface of the inner cylinder 21.
And a fire protection member 3a containing a heat-expandable material that is in close contact with the inner cylinder 21 and the outer cylinder 22 at the inner tube insertion end, and the fire protection member 3a is capable of thermal expansion in a direction orthogonal to its radial direction. It is a joint structure for fire protection. The fire-prevention member 3a is usually an annular member as described above, and the inner diameter of the annular member is such that the exposed portion of the outer peripheral surface of the inner pipe 11 of the main pipe 1 can penetrate. The inner diameter of such an annular member is
Usually, it is almost the same as the outer diameter of the exposed portion of the outer peripheral surface of the inner pipe 11.

As the joint portion forming the joint structure for fire protection of the present invention, the joint portion used for ordinary pipe formation can be used as it is. For example, a double-sided tube having openings at both ends so that the inner tube of the main tube can be inserted from both ends, a substantially T-shaped three-way tube, a four-way tube with four openings, and one opening of both sides It is a single-ended tube closed with a stopper. As both tubes, a straight tube or an L tube having a substantially L shape can be used. Whichever joint is used, an annular member made of a heat-expandable material is preliminarily brought into close contact with the annular end surface around the opening corresponding to the inner tube insertion end. When there are two or more inner pipe insertion ends that require fire protection after connecting the main pipe, the annular member is closely attached to the annular end faces of all the inner pipe insertion ends. At this time, an annular member having a radial width that covers both the annular end surfaces of the inner cylinder and the outer cylinder is used so that the annular end surface of the inner cylinder of the joint is not exposed.

The inner diameter of the annular member may be substantially the same as the outer diameter of the exposed portion of the inner pipe of the main pipe inserted into the joint inner cylinder. By doing this, after the connection of the two-layer pipe is completed, the annular end faces of the annular member can almost completely cover both the annular end faces of the inner and outer pipes of the joint and the outer pipe of the main pipe, and in the event of a fire. The gap at the joint between the two-layer pipes can be effectively closed.

As the annular member, for example, a heat-expandable ring formed by molding a heat-expandable material can be used. An annular member made of such a heat-expandable ring is usually brought into close contact with the annular end surface of the joint using an adhesive. Examples of adhesives include acrylic adhesives, epoxy adhesives, rubber adhesives, cyanoacrylate adhesives, and silicone adhesives. Alternatively, a coating material containing a heat-expandable material and a binder may be applied to the annular end surface of the inner tube insertion end, and an annular member made of a solidified coating film may be adhered to the annular end surface. Examples of the solidification operation of the coating material include drying, curing, and natural cooling.

The heat-expandable ring used as the annular member is a molded body formed by using a composition containing a heat-expandable material and a binder. Usually, a ring-shaped sheet or tape containing a heat-expandable material and a binder is used. For example, it is formed by punching a heat-expandable sheet material into a ring shape. Alternatively, a heat-expandable tape having a predetermined length is wound in a circle so that the main surface (the widest surface) of the tape becomes an annular end surface,
The tape may be formed into a ring shape by adhering the vicinity of one end and the vicinity of the other end in the length direction.

The heat-expandable sheet or tape must be able to expand at least in the direction orthogonal to the major surface (ie, the thickness direction). Any material that can be thermally expanded in this direction may be used as long as it can be thermally expanded in this direction. However, it is preferably a sheet or tape having a unidirectional expansive property that is most thermally expanded in the thickness direction. The heat-expandable ring formed from the sheet or tape as described above can be arranged between the main pipe and the joint by aligning the thickness direction of the ring and the connecting direction of the main pipe and the joint. Therefore, after the connection is completed, only a very thin ring can be seen between the two-layer pipes, which is advantageous for improving the appearance of the completed connection structure. Moreover, in the event of a fire, the gap expands so that the gap between the joints between the two-layer pipes can be effectively closed, so the reliability of fire protection is not impaired.

The thickness of the heat-expandable sheet or tape is usually 0.3 to 7 mm, preferably 0.5 to 5 mm. When the ring is formed from the tape, the width of the tape is the radial width of the ring (annular member).

As in the embodiment shown in FIG. 3, the radial width of the annular member is preferably approximately the same as the wall thickness of the entire joint. If the annular end surfaces of the outer tube and outer cylinder are exposed, the annular end surfaces of the outer tube and outer tube are damaged by the flame in the event of a fire, creating a gap between the annular member and the annular member, and the expansion of the annular member is not in time. There are cases where the gap cannot be closed. If the radial width of the annular member is equal to or greater than the overall wall thickness of the joint, it is possible to effectively prevent the annular end surfaces of the outer tube and the outer cylinder as described above from being damaged by flame, and , Even if it is damaged, it can be delayed enough. On the other hand, when the radial width of the annular member exceeds the wall thickness of the entire joint, the appearance of the completed connection structure may be impaired.

The joint structure for fire protection measures of the present invention can perform fire protection measures on the connection structure between the main pipe and the joints only by using it in place of an ordinary joint, so that the connection work and the fire protection work work can be performed at the same time. And it can be done easily.

The heat-expandable ring forming the fire protection member used in the present invention is a ring-shaped molded body formed from a heat-expandable composition containing a heat-expandable material. Generally, it is formed from a sheet or tape containing a thermally expandable material and a binder, as described above. As a thermally expandable material,
Usually, vermiculite, water glass, expanded graphite, alkali metal silicate and the like are used. The binder is usually
A resin containing an organic polymer is formed alone or in combination of two or more. The resin may be a thermosetting resin or a thermoplastic resin. Examples of the resin include rubber-based resin and epoxy resin. In addition to the heat-expandable material and the binder, additives (ceramic fibers, glass fibers, pigments, lubricants, etc.) may be added to the heat-expandable composition.

A preferred thermally expandable material is expanded graphite. Expanded graphite is a tabular particle and expands most in the direction perpendicular to the wide surface of the plate. Further, when formed into a sheet or tape, it is easy to arrange flat plate surfaces having wide particles substantially parallel to the main surface of the sheet or tape. A sheet or tape containing such expanded graphite expands most in the thickness direction. Therefore, a relatively thin ring is used as the annular member, and the effect of improving the appearance of the connection structure is excellent without impairing the reliability of the fire protection measures.

The proportion of the heat-expandable material in the entire composition is appropriately determined so that the heat-expandable sheet or tape starts to expand at 100 ° C. or higher and exhibits a coefficient of expansion of 10% or higher in a free state. it can. Generally, the proportion of thermally expandable material is 5
Is about 50% by mass. The proportion of the binder in the entire composition is usually 30 to 95% by mass.

As the heat-expandable ring, one obtained by molding the heat-expandable composition into a ring shape which is continuous in the circumferential direction (endless ring) may be used, or the endless ring may be halved or a plurality of two or more. It is also possible to use a combination of divided pieces in the form of divided into. In short, when arranged between the main pipe and the joint, it is annularly arranged as a fire protection member made of a heat-expandable composition so as to cover the exposed portion of the inner pipe of the main pipe along its circumferential direction. I hope you can do it like this.

The heat-expandable ring forming the fire protection member used in the present invention can exhibit fire protection performance by expanding and closing the gap, so the ring itself does not need to be fire resistant. Therefore, it is not necessary to use a relatively large amount of a relatively expensive refractory material such as ceramics, so that the manufacturing cost can be reduced.

[0037]

EXAMPLES (Fire resistance test) Here, an example in which a fire resistance test was performed on the connection structure of the double-layer pipe of the present invention will be described. As shown in FIG. 4, first, the heating chamber 5 provided with one through hole 50 (diameter 200 mm) in the fire protection partition wall 51 was prepared. A main pipe 1a, 1b, 1c made of a fire-resistant double-layer pipe having a nominal diameter of 150 mm and joints 2a, 2b connectable to these main pipes are used to form a pipe for the fireproof partition wall 51, and a thermal expansion ring to be described later is formed. Was used for fire protection. Also,
A metal angle (a support base consisting only of a skeleton) was assembled, and the pipes were supported by the angle bars 6a, 6b, and 6c.
FIG. 4 is a side view showing a heating chamber provided with a pipe having a two-layer pipe connection structure, which is an embodiment of the present invention, and showing only the heating chamber 5 and the angle bars 6a, 6b, 6c in cross section. Is.

In each joint, a heat-expandable ring made of a heat-expandable tape was adhered to the annular end surface around the opening with an adhesive. The radial width of the heat-expandable ring was approximately the same as the wall thickness of the entire joint, and the ring inner diameter was approximately the same as the outer peripheral diameter of the inner pipe exposed portion of the main pipe connected to the joint. The heat-expandable ring was formed by winding the tape so that the main surface (the widest surface) of the tape was the annular end surface of the ring and bonding one end of the tape in the length direction and the other end thereof with an adhesive.
The heat-expandable tape used here was "trade name: Ultra GS" (manufactured by 3M Co.) and contained expandable graphite. The heat-expandable tape had a thickness of 3 mm.

The exposed inner pipe of the main pipe was passed through the joint with a heat-expandable ring thus prepared to form a pipe, and at the same time, fire protection measures for the joint portion were completed. In this example, the connection structure of the double-layer pipe could be completed easily and in a shorter time than the conventional method.

As shown in FIG. 4, in the connection structure of the two-layer pipe in the present embodiment, the non-heating side main pipes 1a, 1b were left with an opening left at the end opposite to the connection end with the joint. . The joint 2b arranged on the heating side is a joint composed of a single-ended pipe. The opening on the side opposite to the connection end of the joint 2b with the main pipe 1c was closed with a blind plug 4. Further, rock wool was filled in the gap left in the through hole 50 of the fireproof partition wall after passing through the pipe.

With respect to the connection structure of the two-layer pipe in this example produced in this way, the connection structure portion in the heating chamber 5 was heated with a flame under the conditions according to the ISO heating curve, and a 1-hour fire resistance test was conducted. I went. As a result, there was no spread of fire to the non-fire side, and no damage was found on the pipes on the non-fire side.

[0042]

As is apparent from the above, in the two-layer pipe connection structure of the present invention, the two-layer pipe can be easily connected by using the annular member that can eliminate the drawbacks of the mortar, and the fire-prevention measure at the joint portion can be obtained. It is possible to effectively improve the efficiency of connection work while effectively increasing the reliability of the.

[Brief description of drawings]

FIG. 1 is a side view showing a main pipe and a joint constituting one embodiment of a double-layer pipe joining structure of the present invention.

FIG. 2 is an explanatory view showing an end portion of a joint which constitutes one embodiment of the connecting structure for a double-layer pipe of the present invention.

FIG. 3 is a cross-sectional view in which a joint portion that constitutes one embodiment of a double-layer pipe connection structure of the present invention is enlarged and cut along a plane including a central axis of the double-layer pipe.

FIG. 4 is a side view showing a heating chamber provided with a pipe having a double-layer pipe connection structure, which is an embodiment of the present invention.

[Explanation of symbols]

1 ... Main pipe, 1a, 1b, 1c ... Main pipe, 2 ... Joint, 2a,
2b ... Joint, 3 ... annular member, 3a ... fire prevention member, 6
a, 6b, 6c ... Angle bar, 11 ... Inner tube, 12 ...
Outer tube, 21 ... Inner tube, 22 ... Outer tube, 23 ... Annular end surface, 50
... through hole, 51 ... fireproof partition wall, 121 ... annular end face, 21
0 ... cavity, 211 ... annular stopper.

Claims (4)

[Claims] 1. A two-layer pipe connection structure comprising: a main pipe made of a two-layer pipe; a joint connected to the main pipe; and a fire protection member arranged between the main pipe and the joint. The main pipe has an inner pipe and a fire-resistant outer pipe covering the outer peripheral surface of the inner pipe, and the outer peripheral surface of at least one end of the inner pipe is exposed, and the joint Has an inner cylinder and a fireproof outer cylinder that covers the outer peripheral surface of the inner cylinder, and the inner pipe of the main pipe has its outer peripheral surface exposed portion at one end portion (inner pipe in the central axis direction of the inner cylinder). It is inserted into the inner cylinder from the (insertion end) side, and the fire protection member is arranged annularly so as to cover the outer peripheral surface exposed portion of the inner pipe of the main pipe along its circumferential direction, The fire protection member comprises a heat-expandable material, and at least along a direction connecting the main pipe and the joint. Characterized by expansion, the connection structure of the two-layer tube. 2. The connection of the two-layer pipe according to claim 1, wherein the fire protection member is an annular member containing a heat-expandable material, and thermally expands in a direction orthogonal to a radial direction of the annular member. Construction. 3. The thermally expandable material is expanded graphite.
The double-layer pipe connection structure according to claim 1. 4. A joint structure for fire protection used for forming the connection structure for a two-layer pipe according to claim 1, wherein the outer cylinder covers the inner cylinder and an outer peripheral surface of the inner cylinder. When,
The inner pipe insertion end into which the inner pipe of the main pipe to be connected is provided with the fire protection member including a thermally expansive material in close contact with the inner cylinder and the outer cylinder, the inner pipe insertion end The main pipe has an opening through which the inner pipe can penetrate, and the fire protection member can be thermally expanded at least along a direction connecting the main pipe and the joint in a state where the inner pipe of the main pipe is connected. There is a joint structure for fire protection.