JPS58984B2 - Manufacturing method of fireproof double layer pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves directly wrapping a hydraulic water-containing mat made of a non-combustible material and a binder around the outer peripheral surface of a synthetic resin pipe, and then shrinking the mat mainly made of non-combustible material by drying and reducing the shrinkage of the synthetic resin. The present invention relates to a method for manufacturing a fire-resistant double-layer pipe that is obtained by reducing stress caused by thermal expansion of the pipe.

In general, synthetic resin pipes such as PVC have superior chemical resistance, inner smoothness, and ease of construction due to their light weight compared to metal pipes, so they are suitable materials for drainage pipes and ventilation pipes, but on the other hand, Since it has poor fire resistance, it has a major drawback in that, for example, it easily burns down in the event of a fire and generates toxic gas.

On the other hand, a fireproof double-layered pipe in which the outer circumferential surface of a synthetic resin pipe is coated with a noncombustible material, such as an asbestos-vinyl double-layered pipe that combines a PVC pipe and an asbestos cement pipe, is said to be a useful pipe that fully covers the drawbacks of the synthetic resin pipe. be able to.

However, in conventional asbestos-vinyl double-layer pipes, if asbestos cement is wrapped directly around the outer circumferential surface of the PVC pipe, cracks will occur in the asbestos cement covering material due to expansion and contraction. When they are combined, a suitable gap is provided between the two to absorb expansion and contraction and prevent the occurrence of cracks (see Japanese Patent Publication No. 7770/1983).

However, it has been found that the asbestos vinyl double-layer pipe according to the above-mentioned patent publication has the following drawbacks.

(1) Because there is a gap between the asbestos cement pipe and the PVC pipe, the asbestos cement pipe is likely to crack due to external forces during transportation or construction handling.

(2) Inserting a PVC pipe into an asbestos-cement pipe is not easy and often damages the asbestos-cement pipe or causes harmful cracks.

Next, FIGS. 1 and 2 show conventional two-layer pipes, where 1 is an asbestos cement pipe, 2 is a PVC pipe, and 3 is a pipe for forming a gap between the asbestos cement pipe 1 and the PVC pipe 2. These are intermediate forming members, and when forming the two-layer pipe, asbestos cement pipe 1 is made by wrapping asbestos cement around the outer peripheral surface of the metal pipe using a paper making machine or other method, and hardening it to the extent that asbestos cement forms. After that, the asbestos cement pipe 1 is manufactured by drawing out the metal pipe, and the metal pipe is generally a commercially available product such as a gas pipe. Therefore, the inner diameter of the asbestos cement pipe 1 is determined by the outer diameter of the metal pipe.

Standards such as JIS usually specify the outer diameter dimensions of pipes, and for example, regarding a 100 mmφ pipe, the outer diameter of both gas pipes and PVC pipes is 114.3 mm and 0.8 mm.

Theoretically, it is impossible to insert all the PVC pipes 2 of the same diameter into the asbestos cement pipe 1 made separately in this way. This method is only possible in combination with No. 2, which has a smaller outer diameter, resulting in poor work efficiency and yield, and is extremely disadvantageous in terms of cost.

In addition, this difficult work may cause extremely small scratches on the asbestos cement pipe 1 that are not visible to the naked eye, and these small scratches on the asbestos cement pipe 1 may be caused by drying shrinkage, vibrations and external forces during transportation, and external forces during various handling. It grows and expands due to thermal expansion of the PVC pipe 2, causing cracks or breakage, and significantly reducing fire resistance.

In order to improve this difficult work even a little, the asbestos cement pipe 1 may be made a little larger, an intermediate forming member 3 may be provided to form a gap between the asbestos cement pipe 1 and the PVC pipe 2, or the PVC pipe Various methods can be used, such as adding protrusions (not shown) to the PVC pipe or changing the shape of the PVC pipe, but none of them are perfect, and problems in terms of cost and quality control remain. I can't deny it.

In contrast, the present invention seeks to propose a method for producing a fire-resistant double-layer pipe that can eliminate the above-mentioned drawbacks more economically. A two-layered pipe is formed by covering the surface side that contacts the synthetic resin pipe with a hydraulic water-containing mat made of a noncombustible material mainly made of inorganic or mineral fibers coated with fine aluminum powder and a binder, and the outer layer of the two-layered pipe is During curing, hydrogen gas is generated by the reaction between the fine aluminum powder and the alkaline solution in the binder or the alkaline solution added separately, and a foam layer is formed on the outer pipe portion in contact with the synthetic resin pipe. Thus, according to the invention, it has become possible to adopt an advantageous manufacturing method of directly wrapping asbestos cement on PVC pipes, which was previously impossible, and it is possible to obtain refractory asbestos vinyl double-layer pipes extremely economically. Not only that, but also damage caused by forcibly combining different materials with different diameters that are manufactured separately, such as conventional double-layer pipes, adverse effects on quality, and intermediate formation of limited protrusions or areas. It is possible to obtain an extremely stable fireproof two-layer pipe without locally concentrated stress caused by members.

Next, the present invention will be explained in more detail with respect to the fireproof double-layer pipe and its joint obtained by the method of the present invention shown in FIGS. 3 to 8.

First, in FIGS. 3 and 4, 11 is an asbestos cement pipe, 12 is a PVC pipe, and 13 is a porous intermediate layer. The mixed aluminum fine powder is foamed by the cement alkali or a separately added alkali, or the aluminum fine powder is reacted with the water-soluble adhesive previously applied to the surface of the synthetic resin pipe with the alkali. FIG. 5 shows a joint of the refractory double-layer pipe treated in the same manner as before.

2 Furthermore, FIGS. 6 to 8 show an example of an apparatus for carrying out the method of the present invention, in which slurry-like asbestos cement raw material liquid 22 having a concentration of approximately 15 to 30% is pumped as appropriate by a pump or gutter (not shown). The feed is supplied to a vat 36, which is provided with feed rolls 2/1, 2/2 and an agitator 37 whose gaps can be adjusted, and these feed rolls rotate in the direction of the arrow to feed the raw material liquid 22 in the vat 36. It is extruded from the gap between the two feed rolls.

In addition, the feed roll 2/2 is supported at both ends by air cylinders (not shown) and is configured to be able to move up and down, so that there is no need to push out the raw material liquid 22 in the vat 36 to the outside. When the feed roll 2/2 is lowered, the gap between the feed rolls 2/1 and 2/2 becomes zero, and at this time, the rotation of the feed rolls 2/1 and 2/2 is stopped.

That is, at the same time as the feed rolls 2/1 and 2/2 rotate, the feed roll 2/2 is lifted to a pre-adjusted gap, and the raw material liquid 22 is supplied onto the running endless felt (hereinafter simply referred to as felt) 23. Ru.

On the other hand, the felt drive roll 24 is rotated by a drive device (not shown) to rotate the felt 23 in the direction of the arrow, and the raw material liquid 22 pushed out from the gap between the feed rolls 2/1 and 2/2 is deposited on the felt 23. Sheet film 3
8, and excess moisture is absorbed when passing through the suction box 30, resulting in a required moisture content of 100 to 30%.
It is wrapped around the PVC pipe 27.

In this case, the PVC pipe 27 is mostly wrapped in the felt 23 and compressed by the drive roll 24 and the tightening roll 25, and once the raw material film 38 is wrapped around the PVC pipe 27 to a predetermined thickness, The seaming roll is moved to the position 25' shown by the dotted line, whereby the felt 23 is in the state shown by the dotted line, and the salt and PVC pipe 27 enclosed therein is pushed out to the position 27' shown by the dotted line. The tube rotates due to gravity and is transferred to a curing process (not shown).

Further, the seaming roll 25 is attached to a seaming arm 26, and an air cylinder (not shown) is attached to the seaming arm to determine the direction in which the PVC pipe 27 is wound and pushed out (indicated by the dotted line). The next empty PVC pipe 28 is supplied from the PVC pipe supply device 29, and the Shimizu Java 3
5 and the whipper 31 wash the felt 23, and the roll 3
3 and 34 dehydrate the felt 23, and a roll 32 is a tensioning device for the felt 23, which is adjusted when changing the size of the PVC pipe 27.

When replacing the finished PVC pipe 27 with the next empty PVC pipe 28, stop the running of the felt 23, and stop the rotation of the feed rolls 2/1 and 2/2. falls, the gap between the feed rolls 2/1 and 2/2 becomes zero, and the raw material liquid 22 is no longer supplied onto the felt 23.

The thickness of the raw material film 38 is adjusted using feed roll 2/1.
, 2/2, and of course the thickness of the raw material film 38 can also be adjusted by changing the gap between the feed rolls 2/1° and 2/2.

From the above, according to the present invention, before wrapping the asbestos cement raw material 22 around the outer peripheral surface of the PVC pipe 27 in the fireproof double-layered pipe to be formed as described above, fine aluminum powder and water are mixed together. After spraying an appropriate amount of fine aluminum powder liquid supplied from a mixing device (not shown) using a pump or the like onto the raw material film 38 from the Java pipe 39 while controlling it appropriately using an automatic valve or the like, the raw material film is then coated with PVC. The aluminum fine powder may be wrapped around the outer peripheral surface of the pipe 27, or the fine aluminum powder may be sprinkled on the raw material film by an appropriate method without mixing with water, or the outer peripheral surface of the PVC pipe 27 may be coated with fine aluminum powder in advance. A mixture with a water-soluble adhesive may also be applied.

In this case, the fine aluminum powder reacts with the alkali contained in the asbestos cement raw material liquid or with the alkali that should be added separately to generate hydrogen gas and foam, and the hydrogen gas is wrapped around the outer peripheral surface of the PVC pipe 27. The hydrogen gas mixes into the asbestos cement raw material film 38 to be treated, making it porous, and the hydrogen gas also creates partial voids on the surface of the PVC pipe.

This porosity and partial void formation have the effect of reducing stress caused by drying shrinkage after hardening of asbestos cement and thermal expansion of the PVC pipe, and also effectively make the asbestos cement porous and partially form voids. For this purpose, additives such as alkali and asbestos cement hardening accelerator may be used.

Furthermore, in the process in which the fine aluminum powder in the outer peripheral surface layer of the PVC pipe reacts with alkali to generate hydrogen gas, partial voids and asbestos are generated on the outer peripheral surface of the PVC pipe by transferring the PVC layer pipe. It is also possible to deform the porous part of the cement to create a total void, and the amount of fine aluminum powder used for this foaming is approximately 0.00% of the asbestos cement wrapped around the outer circumference of the PVC pipe. Approximately 0.01 to 1% of the raw material is used, which corresponds to a layer with a thickness of 5 mm, and the synthetic resin pipe is usually 40 to 200 mmφ x 2 m, and the thickness varies depending on the diameter, but is about 2 to 10 mm, and the fireproof coating is The thickness also varies depending on the diameter, but is about 6 to 12 mm.

In addition, the noncombustible materials used for the slanted fireproof double-layer pipe are asbestos,
Inorganic or mineral fibers such as glass fiber and rock wool are used, and cement, gypsum, water glass, etc. are used as the binding material.

Furthermore, synthetic resin pipes are not limited to PVC pipes, but can be applied to all synthetic resin pipes, and the method of directly forming a layer of noncombustible material on synthetic resin pipes is limited to the method shown in Figure 6. Needless to say, the present invention is applicable to all paper making methods, injection methods, etc.

[Brief explanation of drawings]

Figures 1 and 2 show an example of a fire-resistant double-layer pipe produced by the conventional manufacturing method, and Figures 3 to 5 show an example of a fire-resistant double-layer pipe produced by the method of the present invention and its joint. show,
FIG. 6 is a schematic side view showing an apparatus for carrying out the method of the present invention, and FIGS. 2 and 8 are explanatory views showing the main parts of the apparatus shown in FIG. 6. The correspondence relationship between the main parts shown and the symbols is as follows. 11... Asbestos cement pipe, 12... PVC pipe, 13... Porous intermediate layer, 2/1゜2/2... Feed roll, 22
... Slurry uniform asbestos cement raw material liquid, 23 ... Endless felt, 27 ... PVC pipe, 28 ... Empty PVC pipe, 3
6... Butt, 38... Sheet-like raw material film.

Claims (1)

[Scope of Claims] 1 A synthetic resin pipe is coated with a hydraulic water-containing mat made of a non-combustible material and binder mainly made of inorganic or mineral fibers and coated with fine aluminum powder on the surface side in contact with the synthetic resin pipe. During the curing of the outer layer of the double-layered pipe, hydrogen gas is generated by the reaction between the fine aluminum powder and the alkaline solution in the binder or the alkaline solution added separately, and synthetic side fat is formed. A method for producing a fire-resistant double-layer pipe, characterized by forming a foamed portion in the outer layer pipe portion in contact with the pipe. 2. Production of a fire-resistant double-layer pipe according to the production method according to claim 1, characterized in that the fine aluminum powder is applied to the side of the hydraulic water-containing mat that is in contact with the synthetic resin pipe. Method. 3. Production of a fire-resistant double-layer pipe according to the production method according to claim 1, characterized in that the application of the aluminum fine powder is the application of the aluminum-containing water-soluble adhesive onto the synthetic resin pipe. Method. 4. A method for manufacturing a fire-resistant two-layer pipe according to any one of claims 1 to 3, characterized in that the two-layer pipe is rolled during the foaming process.