JPS5845176A - Manufacture of refractory pipe joint - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention covers the outer peripheral surface of a synthetic resin pipe suitable for water supply and drainage pipes, such as a hard vinyl chloride pipe, with a fire-resistant inorganic material to prevent ignition in the event of a fire. The present invention relates to a method for manufacturing a fire-resistant pipe joint suitable for connecting composite pipes, which prevents fire from traveling inside the pipe and spreading to an adjacent room when used in a pipe.

The most technically important thing about this type of composite pipe and its fittings is that the synthetic resin pipes and fittings, which have a significantly high coefficient of thermal expansion, are coated with an inorganic material that has a relatively small coefficient of thermal expansion. The objective is to prevent harmful cracks from occurring in the outer layer of the tube, which is the coating layer, due to thermal stress caused by expansion of the synthetic resin tube, for example, when hot water flows down.

The simplest method for this is to provide a certain gap between the inner tube and the outer tube, but one way to create and maintain this gap is to manufacture each tube individually with a precise diameter. When combining an outer layer tube and an inner tube using an insertion method, or when covering an inner tube with a semi-cylindrical outer layer tube, 2.
A method has been adopted in which composite material is formed through three synthetic resin bands or a cushioning synthetic resin foam. Another method is to wrap the synthetic resin foam sheet around the outer periphery of the inner tube and then apply and form the outer layer.

However, among the inner pipes, pipe joints in particular originally have extremely diverse shapes and come in a variety of sizes, so creating a matched structure with gaps as described above requires a complicated manufacturing process. In addition, as mentioned above, the method of applying Cussimin material in advance and then applying it afterwards makes it difficult to fix the Cussimin material in a uniform and flat layer due to the unique elasticity of the Cussimin material, resulting in defects in the outer coating layer. Since it tends to cause uniformity, there are many problems as an industrial manufacturing method.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fire-resistant pipe joint that eliminates the above-mentioned drawbacks and is free from the risk of cracking due to thermal stress. As a result of extensive research in accordance with these objectives, the present inventors have developed a thin layer of paper, film, cloth, etc., to which a material that changes volume during water absorption and desorption is adhered or contained, to the socket of a synthetic resin pipe joint. Wrap it around the outer peripheral surface, and then cover and mold the wrapped part and the remaining outer peripheral surface with a mixed material whose main components are a hydraulic inorganic material and water, so that the material attached to or contained in paper, film, or cloth swells. If it is cured in a gelled state and then dried,
The present invention was completed based on the discovery that it can withstand thermal stress caused by thermal expansion when hot water flows down.

In the present invention, it is difficult at this stage to theoretically explain the unexpected result that the treatment using a material whose volume changes during water absorption and desorption is performed only on the outer peripheral surface of the socket. Considering this together with the observation that cracks in the outer layer pipe due to thermal stress when reinforcement is not used always start from the end of the socket, and then grow toward the center and become wider, the I think it's understandable.

Examples of materials that change in volume during water absorption and desorption in this study include the following.

Asbestos, diatomaceous earth, fly ash, various clay minerals,
engineering) IJ syngite material, starch and starch derivatives,
Water-soluble gelatin such as CMC, MC, HEC, HPC, proteins such as casein, cellulose derivatives, tannin, lignin, alginic acid, gum arabic, polyvinyl alcohol, polyethylene oxide, polypropylene oxide, polyacrylic acid, polymethacrylic acid ,
Water-soluble polyester, polyepoxy compound, ketone formaldehyde resin, polyvinylpyrrolidone, polyamine polyelectrolyte, urea formaldehyde resin, melamine formaldehyde resin, 7'enol formaldehyde resin, etc., but in the present invention, of course, two or more of the above materials are used in combination. It's okay.

Furthermore, it will be clear from the following description that the structure of the present invention is not limited to these exemplified materials in any way.

Various known methods can be used to attach or incorporate the above-mentioned materials into a thin layer such as paper, film or cloth. To give some examples, a method of immersing the thin layer body in a liquid in which these materials are dissolved and drying it;
In addition to methods such as attaching powders of these materials using a binding agent such as adhesive, methods of adding and filling these materials to the raw material of the thin layer body and forming them into a film or fiber, or simply forming a fibrous structure. There is a method of simply attaching it physically between spaces, etc.

Hydraulic inorganic materials used in the present invention include, for example, Portland cement, silica cement, blast furnace cement, fly ash cement, alumina cement, various ettringite cements, magnesium carbonate, and various gypsums, and if necessary, these can be used for reinforcement and fire resistance. Asbestos, rock wool, glass fiber,
It is also effective to add wood wool, synthetic fibers, natural fibers, steel fibers, copper wire, mica, perlite, vermiculite, calcined vermiculite, volcanic rock, silica sand, aluminum hydroxide, calcium carbonate, calcium silicate, etc. .

In the present invention, the effect of the thin layer body such as paper, film, or cloth to which a material that changes volume when absorbing or desorbing water is attached or contains a material that changes in volume when water is absorbed or desorbed is that water is Until the hydraulic inorganic material hardens and forms a structure, it retains a larger space in a gel state between the outer tube, which is the broken layer, and the synthetic resin inner tube than after dehydration. There is a particular thing. After the hydraulic inorganic material hardens, the above-mentioned gel releases water and contracts during the drying process of the multilayer tube, and a certain gap is formed between the outer layer tube and the inner tube. Therefore, the amount of the various materials to be attached to or contained in the thin layer such as filter paper, film, or cloth used in the present invention should be selected in consideration of the degree of shrinkage during drying and the required thickness of the gap. good.

As a method of wrapping the thin layer body as described above around the outer peripheral surface of a synthetic resin pipe joint and adhering or fixing it, the outer periphery of the thin layer body is coated with a mixture of a hydraulic inorganic material and water, for example. The pipe joint, which is wrapped around the outer peripheral surface of the socket, is set in a mold that can be divided into upper and lower parts and has a desired inner shape, and the slurry of the hydraulic inorganic material is cast between the mold and the pipe joint. There are ways to include it.

The curing method for the hydraulic inorganic material may be either room temperature curing or heating curing, and it is preferable to hold it in a humid air condition during this time. This multilayer tube is then dried.

Even when the pipe joint manufactured according to the present invention is used in piping, not only does it not cause any adverse effects on the coating layer due to thermal stress caused by thermal expansion when high-temperature fluid passes through it, but also does not cause any adverse effects on the outer peripheral surface of the socket during manufacture. It has the advantage that only simple processing is required.

Hereinafter, the present invention will be explained in more detail according to examples.

Example 1 Hard vinyl chloride pipe joint with openings on three sides (nominal Hi
A piece of tissue paper was dipped into a 9-inch aqueous solution of CMC, wrapped around the outer circumferential surface of each socket of (oo) in one layer, and fixed with adhesive tape. Next, this pipe joint can be divided into two parts, upper and lower, and each end is fixed using a holder in a chloroprene rubber formwork with an inner shape that is 15 mm larger than the diameter of the hard vinyl chloride pipe joint. After filling the mixture by press-fitting it with the following composition through the injection hole provided at the bottom of the mold, the mold was placed in a curing chamber, heated to 50° C., and held for 5 hours.

Composition (parts by weight) Ordinary Portland cement 45 Alkali-resistant glass fiber chicory spudded strands 1.4 Chrysotile asbestos 3.5 Silica powder 10 Light aggregate (perlite) 7 Thickener (methyl cellulose) 01 Water 33 Demolding after cooling naturally After 3 weeks of air-drying, the pipe was connected to a hard PVC pipe, and hot water at a temperature of 85°C was flowed down for 20 minutes at a speed of 301!/mm.During and after this test, the fire resistance of the present invention was maintained. No cracks due to thermal stress were observed in the coating layer of the pipe joint, and no abnormality was observed in the inner pipe.

Comparative Example 1 A pipe joint was manufactured using exactly the same operations and procedures as in Example 1, except that the tissue paper was used as it was without any treatment.

After 3 weeks of air-drying, this product was subjected to the same hot water flow test as in Example 1. As a result, although no abnormality was observed in the inner tube, a crack approximately one gate in width was formed in the coating layer, connecting each socket in a bellows shape.

Claims (1)

[Claims] A method for manufacturing a fire-resistant pipe joint in which the outer peripheral surface of the synthetic resin pipe joint is coated with a fire-resistant inorganic material, the method comprising attaching a material that changes in volume during water absorption and desorption to the outer peripheral surface of the socket of the synthetic resin pipe joint. Alternatively, a thin layer of paper, film, cloth, etc. containing the same is wrapped, and the wrapped portion and the remaining outer peripheral surface are coated with a kneaded material mainly composed of a hydraulic inorganic material and water, and cured and dried. A method for manufacturing a fire-resistant pipe joint.