JPH0140668B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for coating the inner surface of existing gas pipes or water pipes, which is mainly used when repairing the inner surface of existing gas pipes or water pipes that are buried underground. It is something.

[Prior Art] In recent years, various methods have been proposed for repairing existing pipes, such as gas pipes and water pipes, buried underground from the inside so as to regenerate the pipes from corrosion while remaining buried. When performing such repairs, first clean the inside of the pipe, polish the inside of the pipe by sandblasting, etc., remove rust and deposits, and then coat the inside of the pipe with a hardening resin such as epoxy resin. are giving.

[Problems to be solved by the invention] In this case, there is a limit to the thickness of the resin layer that can be formed in one coating, and even with high viscosity resin (for example, 10,000 to 30,000 cps/18°C), the required thickness It is difficult to make it into a resin layer. This is because if you try to form a considerable amount of resin layer in one coating, the resin will sag during the hardening process and accumulate at the bottom of the pipe, making the lining layer thickness uneven. This is because you will not be able to maintain your sexuality. Therefore,
It is possible to obtain the required resin layer by repeating coating many times, but the previous resin layer must be cured before the next coating is applied, resulting in a large loss of time, and the repeating of coating does not improve workability. . As a result, costs will increase.

[Means for Solving the Problems] The present invention has been made based on the above circumstances, and involves coating the raised surface with a resin to a considerable thickness, and then promoting hardening of the resin, preventing drooping, and coating the lower side of the pipe. The purpose of the present invention is to provide a coating method for the inner surface of a tube that can prevent resin from accumulating in the tube.

For this purpose, the present invention provides resin lining treatment on the inner surface of the tube in a required manner, and then introduces a pig connected with a wire into the tube and blows air into the tube to reduce the air flow rate around the pig. The pig is moved within the pipe in this state.

Further, the present invention provides a method in which the inner surface of the tube is treated with resin lining in a required manner, and then pigs connected by wires are introduced into the tube, and the pigs are freely connected to the wires to provide a turbulent flow element. The present invention is characterized in that air is blown into the pipe to increase the air flow velocity around the pig, and at the same time, the pig and the turbulence element are moved within the pipe.

[Example] Hereinafter, an example of the present invention will be specifically described with reference to the drawings. In the figure, reference numeral 1 indicates an existing pipe such as a gas pipe buried underground.When repairing the inside of the pipe, the pipe is divided into units of length suitable for repair, and the pipe is cut at the pit 2. Open both ends. In this state, pressurized air or the like is sent into the existing pipe 1 from one end to remove dust inside, and then sandblasting is performed to polish the inner surface of the existing pipe 1 to remove rust and deposits. Let's do it. The above is conventionally known pretreatment.

Next, as shown in FIG. 2, the hose 4 is connected to one end of the existing pipe 1, and the hose 4 is led out to the ground, and the hose 4 is connected to the swirl flow generator 6 connected to the compressor 5. do. This swirl flow generator 6 gives a swirl to the compressed air from the compressor 5, and a nozzle 9 is connected to the resin tank 8 by the air pressure regulated from the compressor 5 via the pressure regulating valve 7. Liquid resin is injected through the tube.

A hose 10 is connected to the other end of the existing pipe 1, and this hose 10 is communicated with a vacuum pump 12 via a filter 11. Below the filter 11, a tank 13 for storing resin is connected. It is provided.

After such preparation, in the first stage, a relatively low viscosity epoxy resin (400 cps to 600 cps) is injected from the nozzle 9, and positive pressure is applied by the compressor 5 and vacuum pump 12. It is pumped inside the existing pipe 1 under negative pressure. At this time, the liquid resin dispersed in the airflow in the form of a mist by the action of the swirl flow generator 6 adheres to the inner surface of the tube, and also penetrates into and blocks corrosion holes that have occurred due to corrosion. In this way, coating layer A is formed.

In addition, in order to avoid that the resin layer of the first stage formed in this manner becomes non-uniform in the longitudinal direction within the existing pipe 1, resin coating may be performed from the opposite side. After the coating layer is cured, in the second step, a relatively high viscosity epoxy resin (10,000 to 30,000 cps/18°C) is injected from the nozzle 9, and as before, it is sprayed into the existing pipe 1 as shown in Figure 3. A coating layer B is formed as follows. In this case, a sufficient resin layer is provided so that the layer thickness of the coating is substantial.

Therefore, after coating, the coating layer B sag, and the sagging resin tends to accumulate at the bottom of the tube, as shown in FIG.

Next, the spherical pigs 14 connected by wires are passed through the existing pipe 1 as shown in FIG. In this case, both ends of the existing pipe 1 are closed with flanges 16, 16 which have openings through which the traction rope 15 is passed, compressed air is supplied from the compressor 5, and suction is performed by the vacuum pump 12 on the opposite side. The pig 14 is preferably made of a light elastic material and has a diameter slightly smaller than the inner diameter of the tube when the desired coating layer thickness is formed.

When the wire connecting pig 14 moves inside the existing pipe 1, the airflow flowing inside the existing pipe 1
4, the velocity of the flow increases, blowing off the drippings of resin, pushing up the resin that has accumulated at the bottom of the existing pipe 1, and causing the compressor to combine the compressed air with the rising temperature. Contact with the resin accelerates the curing of the resin. By this,
Even if the thickness of one coating layer is increased, a uniform coating state can be obtained.

What can be seen in FIG. 6 is an embodiment in which a light ball-shaped turbulence generating element 19 is attached in the middle of a wire 17 connecting the pigs 14 via a short wire 18. Here, the wire 18 is fixed to the wire 17 via a universal joint 20.

In this example, when the pig moves, the resin accumulated on the lower side of the tube is splashed up by the turbulence generating element 19 which floats in the air flow. Therefore, uniformity of the coating layer can be achieved more effectively than when only the pig 14 is passed through.

FIG. 7 shows an example in which the turbulence generating element 19 has a cylindrical shape, and here, a bead-shaped protection element 21 is inserted through the wire 17.

In this embodiment, the pneumatic method was used as the resin coating method, but it goes without saying that other conventionally known means may be used.

[Effects of the Invention] As detailed above, the present invention prevents dripping of resin by passing pigs connected by wires into a coated pipe and simultaneously passing airflow to increase the flow velocity on the surface of the coating layer. This has the effect of correcting any sagging, maintaining a uniform layer thickness, and promoting hardening. Furthermore, by having a turbulent flow element, the resin that has dripped down the inside of the tube is thrown up, preventing the resin layer from shifting to the lower side, making it possible to achieve a more uniform layer thickness. Therefore, excellent effects such as the number of times of coating can be significantly reduced, working time can be shortened, and costs can be reduced can be obtained.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view showing the initial situation for inner surface treatment of an existing pipe, FIG. 2 is a longitudinal cross-sectional view showing the coating situation in the first stage, and FIG. The figure is a vertical cross-sectional view showing the coating situation in the second stage, Figure 4 is a cross-sectional view of the existing pipe, and Figure 5 is a cross-sectional view of the existing pipe.
The figure is a longitudinal sectional view showing a post-coating process, and FIG. 6 is a longitudinal sectional view showing another post-coating process. 1...Existing pipe, 2...Pit, 3...Joint part,
4... Hose, 5... Compressor, 6... Swirling flow generator, 7... Pressure regulating valve, 8... Resin tank, 9
... Nozzle, 10 ... Hose, 11 ... Filter, 12 ... Vacuum pump, 13 ... Tank,
14... Pig, 15... Traction rope, 16... Flange, 17, 18... Wire, 19... Turbulence generating element, 20... Universal joint, 21... Protection element.

Claims (1)

[Claims] 1. Lining the inner surface of the pipe with a resin in a required manner, then introducing a pig connected with a wire into the pipe, blowing air into the pipe to increase the air flow rate around the pig, A method for coating the inner surface of a pipe, characterized in that the pig is moved within the pipe in that state. 2. Lining the inner surface of the tube with a resin in a required manner, then introducing pigs connected by wires into the tube, and providing a turbulence element freely connected to the wire between the pigs, By blowing air,
A method for coating the inner surface of a tube, characterized in that the air flow velocity around the pig is increased and the pig and turbulence element are moved within the tube.