KR20060020076A - Two-pack polyurethane lining method and steel pipe and fitting applied by such method - Google Patents

Abstract

The present invention relates to steel pipes used for pipes such as water and sewage, general water, and other fluid transport, and the inner surface of the steel pipe is coated with a solvent-free, quick-drying two-component polyurethane resin, which is a polymer plastic resin, and the outer surface thereof is a conventional method or the same type of polyurethane. It is to be able to protect steel pipe from various corrosive environments by coating with resin.

In consideration of the demanding working conditions and characteristics of general polymeric plastic resin coating materials, the two-component polyurethane resin coating materials used in the present invention are used with an inert gas from the time of storage in a container so as not to be affected by moisture in the air. The built-in heating and stirring device maintains a low viscosity until the paint material reaches the injector, allowing the two paint materials to mix well and spray paint at a relatively low pressure, resulting in a stable coating and small diameter. By using a centrifugal rotary nozzle, a small diameter steel pipe, which is difficult to spray spraying, can be coated inside. According to the present invention, the required coating film thickness can be obtained by only one coating without the use of a separate primer, and the coating material does not contain a solvent, it is quick-drying, and the curing of the coating proceeds rapidly even at low temperature in winter, thereby improving the quality of the coating film as well as improving productivity. It is possible. The present invention is applied to the installation method and the work method and the coating method for the release pipe required when the inner and outer surfaces of the steel pipe (straight pipe) in the factory mechanized coating using a two-component polyurethane resin.

According to the present invention, it is possible to improve the water quality of the tap water and to prolong the service life of the pipe, and also, according to the excellent physicochemical performance of the coating film, replacement demand for various piping materials is expected.

Solvent-free quick-drying two-component polyurethane resin, coating, steel pipe, anticorrosive, spray

Description

Two-pack polyurethane lining method and steel pipe and fitting applied by such method}

1 is a cross-sectional view of a steel pipe coated with a two-component polyurethane resin on the inner and outer surfaces of the steel pipe

2 is a cross-sectional view of the steel pipe coated with two-component polyurethane resin on the inner surface of the steel pipe and coated with asphalt, coal tar enamel or polyethylene.

3 is a schematic diagram of a series of coating machine systems for two-component polyurethane resin coating materials from each storage vessel to the final injection device.

Figure 4 is an illustration of a method of painting the inner surface of the steel pipe with a two-component polyurethane resin by a mechanical method

5 is an exemplary view showing a cross-sectional structure and an operating structure of a centrifugal rotary nozzle dedicated to coating a small diameter inner two-component polyurethane resin.

6 is an illustration of a method of painting the outer surface of the steel pipe with a two-component polyurethane resin by a mechanical method

The present invention relates to steel pipes used for pipes such as water and sewage, gas and petrochemical piping, industrial water and other fluid transport, the inner surface of the steel pipe is coated with a solvent-free, quick-drying two-component polyurethane resin, the outer surface of the same type of poly The urethane resin or coal tar enamel or asphalt coating or polyethylene coating is used to protect the steel pipe from various corrosive environments.

The inner and outer surfaces of the steel pipe need to be constructed in a manner suitable for the characteristics of the transport fluid and the installation environment so that the transport fluid is protected from contamination and the steel pipe itself is protected from corrosion. The most commonly applied method is the coating and lining method, which directly affects the safety and life of steel pipes. Therefore, the quality of the coating material used directly for painting and the coating technology for coating the coating material on the steel pipe are very important. Do. In particular, in the case of water pipes, the water quality of tap water flowing inside the steel pipe has a direct impact on the public's health. In Korea, the national standard (KS D3565) for the water supply coating steel pipe, which accounts for most of the water supply steel pipe, specifies only a single item of 'liquid epoxy' as the inner coating material. Although there are cases of peeling and using solvents containing components such as benzene and toluene, it is still used for water supply because no suitable coating material and technology have been developed despite the possibility of dissolution.

The present invention is coated with a two-component polyurethane resin of a quick-drying solventless type of high-molecular plastic resin on the inner surface of the steel pipe, the outer surface of the steel pipe is applied to the conventional anticorrosive technology (coal tar enamel coating, asphalt coating, polyethylene coating, etc.) or As with the inner surface, the present invention relates to a method of coating a polyurethane resin coating material and a product manufactured by such a method. In general, a polyurethane resin is obtained by chemically combining isocyanates and polyols, and a polyurea resin is obtained by combining isocyanates and amines. These polymer plastic resins have various physical properties depending on the blending ratio of the raw materials used and the difference in the synthesis and reaction methods. Will stand out. In general, polyurethane resins are sensitive to moisture, so they are not used for corrosion protection of steel materials such as steel pipes, but for inspection or industrial materials such as foam insulation materials, whereas polyurea resins do not react well with moisture. It is usually used for anticorrosive construction. However, since polyurea resin coating material has high viscosity, high pressure spraying (usually more than 2,500 psi) should be applied when painting steel pipe, and paint should be heated and insulated to very high temperature (typically 70 ℃ or more). The injection distance of the liver should be maintained at 70cm or more. Therefore, when the diameter of the steel pipe is small (for example, 700 mm or less in diameter), there is a limitation that the painting work is impossible, and since the adhesive strength is low, a primer must be applied to compensate for the adhesive strength before painting. In case of bonding, in order to prevent damage to the coating film due to the heat effect of welding, there is a problem such as not leaving about 70 cm at the end of the steel pipe as unpainted part.

The present invention centers on the technology of determining the requirements for materials used to apply a solvent-free, solvent-free, quick-drying two-component polyurethane resin-based coating material to a steel pipe, and applying such coating material to the inner or outer surface of the steel pipe. It is done. To this end, there must be a coating material that satisfies the quality conditions above a certain level, and a technique for painting the coating material on the inner or outer surface of the steel pipe is also required. In Korea, there is no quality standard or standard for applying polyurethane resin-based paint to piping steel pipes, especially drinking water steel pipes. Developed separately, the present invention relates to a technique for producing a product by applying a method of applying the developed polyurethane resin to steel pipes.

That is, the coating film thickness (usually 0.5mm ~ 3.0mm) needed to be obtained can be obtained by only one coating without using primer, and the inner surface of steel pipe with small diameter (for example less than 700mm) is minimized by minimizing the spray coating distance. It should be possible and the performance of other coatings should be able to meet the required quality level.

The present invention consists of equipment, apparatus and process technology necessary for obtaining a product coated with a solvent-free quick-drying two-component polyurethane resin on the inner surface or the outer surface of a steel pipe for the purpose of anticorrosion.

First, the structure of the product is coated with a two-component polyurethane resin on both the inner and outer surfaces of the steel pipe 1, as illustrated in Figures 1 and 2, or the inner surface of the steel pipe is coated with a two-component polyurethane resin, but the outer surface is asphalt It is coated with a conventional method such as coal tar enamel or polyethylene. In Fig. 1, (2) shows an inner coating film coated with a two-component polyurethane resin, and (3a) shows an outer coating film coated with a two-component polyurethane resin, and the thickness of the coating film depends on the use of the product and the environment of use. There is a difference, but inside is 0.5mm ~ 1.0mm and outside is 0.6 ~ 3.0mm. In FIG. 2, the outer coating film 3b is coated with conventional asphalt, coal tar enamel, polyethylene, etc. according to the order of the customer, and the thickness of each coating film is specified by the orderer or specified by the national standard. The inner and outer coatings of these steel pipes are applied not only to straight pipes but also to release pipes, and also to field joints of steel pipes.

Equipment and equipment for coating two-component polyurethane resins include blasting equipment for removing mill scale and rust and other foreign matter from the inner and outer surfaces of the surface to be coated before painting the steel pipe, Heating device to remove moisture and maintain the temperature required for painting, a series of coating systems (storage vessels, pressure pumps, pressure hoses, spray guns, etc.) from storage to final spraying of two-component polyurethane resins, The main facility is a pipe rotating facility for painting while rotating the steel pipe.

The two-component polyurethane resin is composed of agent A, which contains MDI (diphenylmethane diisocyanate) as a main component, and agent B, which is a polyol containing various additives, and the like. Store in each container before starting. Referring to the treatment process of the paint (A agent, B agent) for the coating operation by spraying, first, as shown in Figure 3 to prevent the electric heating device and deposits on the agent A container 5 and the agent B container (6) In order to prevent the paint material (A and B) from reacting with the moisture in the air, each container is a vacuum pump (4) immediately after filling or refilling the material. And discharged with N) and then connected with nitrogen gas container (7), and the agent A and B heated to a constant temperature (range of 30 ℃ ~ 50 ℃) in each vessel through the two-component pressure pump (8) After being pressurized and heated in the middle, it is connected to the spray device (spray gun 10) through a high pressure hose 9 equipped with an electric heating device. When the switch of the injector is operated to start the painting operation, the agent A and the agent B are pressurized into the mixer 11 from each of the high pressure hoses, and then mixed instantly and sprayed onto the steel pipe through the spray tip 12. After finishing the painting work, the mixed paint material remaining in the injector is connected with a hose from the solvent pump 13 to the spray gun 10 so as to clean the solvent. By using the above series of coating systems, the fluidity is improved by keeping the viscosity of the coating material low, so it is easy to maintain the proper mixing ratio, and spray coating is possible even at a relatively low pressure (2,000psi or less), and the influence of moisture is blocked. As a result, anticorrosive coating by a two-component polyurethane resin is possible on the inner and outer surfaces of the steel pipe.

First, the equipment as shown in Figure 4 is used to coat the two-component polyurethane resin on the inner surface of the steel pipe. Pipe rotating device (14) for rotating steel pipe (1), internal painting controller (15) with opening and closing control of painting material supply line and reciprocating operation and height adjusting device for painting material, high pressure hose (9) And a dedicated inner surface manipulator (16) which has built-in necessary pipes and wirings and attaches the final injection device 17 so as to reciprocate the inner surface over the entire length of the steel pipe and perform painting work. The inner injector 17 uses a commercially available two-component spray gun when the diameter of the steel pipe is large (400 mm or more in the technique of the present invention), but when the diameter is smaller, the centrifugal spray nozzle shown in FIG. 5 is used. The use of spray nozzles can be more than 400 mm, which does not limit the method of coating depending on the steel pipe diameter. Small diameter steel pipes, which are difficult to paint the inner surface with a spray device, use a device as shown in FIG. That is, the rotating nozzle 19 for injecting the mixing material of which mixing is completed is made to rotate at high speed by the drive motor 22, and the coating material supplied by the mixing apparatus 18 through the high pressure hose 9 (made by A). (B agent) is a device having a structure that is pressurized into the internal space of the nozzle cup 20 in a mixed state, and then injected by centrifugal force through the nozzle hole 21 circumferentially drilled at the end of the rotating nozzle.

With the above equipment and equipment, the two-component polyurethane resin coating material (A and B) is completely mixed at low viscosity, and spray coating is possible at a relatively low pressure. It is possible to paint the inner surface of the diameter (80mm ~ 3,000mm).

In case of bituminous coating such as asphalt or coal tar enamel among existing methods of coating method, the inner surface is first coated with two-component polyurethane resin before the coating. If the tube needs to be heated to a temperature of 150 ° C. or higher, the outer coating is applied first, and then the inner surface is coated with a two-component polyurethane resin. In the latter case, since cooling water is used inside or outside the steel pipe to cool the heated steel pipe and the outer surface coating, the temperature of the inner surface of the steel pipe is 80 to prevent moisture from absorbing the inner surface of the steel pipe. In order to promote the removal of moisture by latent heat when the temperature is about ℃ ~ 90 ℃, completely drain the moisture from the inner surface of the steel pipe using dried compressed air and then coat the inner surface.

When painting the outer surface of the steel pipe with a two-component polyurethane resin, as shown in Fig. 6, the steel pipe 1 is placed on the rotating device 23, and the bogie 24 having the structure 25 provided with the injection device is mounted on the steel pipe. Spray coating while conveying in the longitudinal direction of the contrary, on the contrary, by fixing the structure (25) in which the injector is installed and by mounting the tube rotating device on the mobile trolley, the steel pipe can be rotated and longitudinally conveyed and sprayed from the outer surface.

The two-component polyurethane coating on the inner and outer surfaces of the release tube, not the straight tube, is spray coated using the basic coating machine system of FIG. The centrifugal nozzle of Fig. 5 is used for the small diameter that the injection device for spray coating cannot enter. In addition, where the spray does not reach or the part that needs to be repaired as the corner of the release pipe, the coating material is in a separate container or cup. Immediately after mixing (form A and B), the mixed solution is poured into the site or coated with a brush or roller before the curing reaction begins. This method can be applied to small diameter straight or short pipes as well as to shaped tubes.

According to the present invention, it is possible not only to use a solvent on the inner surface of the water pipe, but also to improve the performance of the coating film, and to produce a coated steel pipe product, thereby improving the water quality of the tap water and prolonging the service life of the pipe. It can be integrated with the same material and construction quality as the unit, and can shorten the air from the start of construction to water supply. In addition, due to the excellent physical and chemical performance of the coating film, it can be used for sewage, general water, and petrochemical piping other than water supply, which is expected to replace expensive piping materials, which is advantageous for the domestic and overseas market development.

Claims (6)

Two-component polyurethane resin coating material (A and B) Agitator to prevent sedimentation and electric heating device for heating and warming the coating material are installed inside each container, and a temperature control device is installed to vacuum the air inside. A container for a coating material having a structure that can be discharged out by using a pump, a device for supplying an inert gas to each coating material container, a two-component high pressure pump for spray coating a two-component paint, and an electric heating type Sprayer system with high pressure hose, spray gun, mixer, spray tip and solvent pump to flush out paint material remaining inside the sprayer when the paint stops, and using such a system for the inside or outside of the steel pipe. How to paint two-component polyurethane resin In coating two-component polyurethane resin on the inner surface of the steel pipe, a bogie equipped with a manipulator equipped with an injector is sprayed in the longitudinal direction of the steel pipe so that the steel pipe can be sprayed on the rotating device while being placed on the rotary device. Apparatus and method for painting The apparatus and method for coating a two-component polyurethane resin using a rotating nozzle using a centrifugal force on an inner surface of a steel pipe. In coating two-component polyurethane resin on the outer surface of the steel pipe, a bogie equipped with a structure equipped with an injector is sprayed in the longitudinal direction of the steel pipe to spray-paint the outer surface of the steel pipe while the steel pipe is placed on the rotary device and rotated. Apparatus and method for painting the outer surface of steel pipe while fixing the structure on which the spraying device is attached or transporting the bogie equipped with the steel pipe rotating device in the longitudinal direction of the steel pipe In coating the inner or outer surface of the release tube with two-component polyurethane resin, prepare each coating material (A and B agent) in a separate cup or container, mix them in one cup or container, and pour them into the area to be coated. How to paint with a brush or roller Products coated with two-component polyurethane resin on both the inner and outer surfaces of the steel pipe and coated with two-component polyurethane on the inner surface of the steel pipe and coated with asphalt, coal tar enamel or polyethylene.

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