JPH0433506B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention ensures sealing performance and preventive maintenance from the inner surface of the pipe while it is buried, for existing pipes such as gas pipes mainly installed underground. This invention relates to a method for repairing the inner surface of an existing pipe by forming a resin lining film on the inner surface of the pipe.

[Conventional technology]

In existing pipes, corrosion occurs due to long-term installation, which can cause leaks.Recently, for the purpose of leak repair or preventive maintenance, a resin lining film is formed on the inner surface of the pipe while the existing pipe is buried. Repairs are being made.

One type of this lining repair method is, for example, as seen in the prior art described in Japanese Patent Publication No. 58-50779, in which resin is introduced into the existing pipe by being pushed by a pig, and is pulled by the pig. A repair method has been proposed in which a coating is formed on the inner surface of the pipe by the resin flowing backward from the circumferential surface of the pig as the resin is being moved.

[Problem to be solved by the invention]

A problem with this repair method is when it is necessary to leave some areas on the inner surface of the pipe that are not lined. In conventional construction methods, the outer diameter of the pig is determined in advance according to the diameter of the existing pipe in order to form the desired gap between the inner wall of the pipe and the outer circumference of the pig. Unless some resin is completely consumed, the resin flows out through the gap between the inner wall of the pipe and the outer circumference of the pig and forms a lining for the inner surface of the pipe.

Another problem with this construction method is that when the pig pushes the resin, the resin pressure generated by contact with the inner wall of the pipe increases or decreases depending on the amount of resin. When the resin pressure is high, the pig contracts in the radial direction and the gap width between the inner wall surface of the pipe and the outer periphery of the pig expands. Conversely, when the resin pressure decreases, this gap width narrows, which causes the resin to shrink in the longitudinal direction of the pipe. The problem is that the lining film thickness is not constant.

The present invention was proposed in view of the above-mentioned problems, and can prevent the formation of a coating on the inner surface of a tube in areas where lining is not required, and can reduce the thickness of the coating without being affected by the amount of resin. The present invention aims to provide a method for repairing the inner surface of an existing pipe, which can be uniformly formed by regulating the thickness to a desired thickness.

[Means to solve the problem]

In order to achieve this object, the present invention introduces liquid resin and a pig that moves by pushing this resin into the pipe of an existing pipe, and when the resin is moved inside the pipe by pulling the pig, the circumferential surface of the pig and the inner wall of the pipe are In a repair method in which a coating is formed on the inner surface of the pipe with resin flowing out from between the pipe and the pipe, the pig has a stretchable membrane-like body on the outer periphery inside the pig body made of an elastic material that can be expanded and contracted, A cylindrical pressure chamber whose front and rear walls are made of highly rigid plate-like bodies is provided concentrically with the pig body, and during the movement of the pig, the required fluid pressure is applied to the pressure chamber to bulge the circumference of the pig, thereby increasing the outer circumference of the pig. It is characterized by construction in such a way that the gap between the pipe and the inner wall of the pipe is opened/closed or controlled to a required interval.

[Effect]

In this type of repair method, the outer diameter of the pig is adjusted and controlled as necessary, and the gap between the inner wall of the pipe and the outer circumference of the pig is opened and closed, allowing the selection of areas to be lined or areas not to be lined. becomes possible.

In addition, by controlling the gap between the inner wall of the pipe and the outer circumference of the pig to the required interval, the thickness of the coating formed can be regulated as desired.Also, by adjusting the above interval according to the amount of resin, changes in resin pressure can be controlled. It becomes possible to form a film with a uniform thickness in the tube length direction without being affected by the above.

〔Example〕

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings.

In the figure, reference numeral 1 is a pig made of an elastic material such as sponge, and support end plates 2 and 3 are provided at the front and rear ends of the pig.
They are connected by a rod 4 that is inserted through the. Rings 5 and 6 are attached to the front and rear ends of the rod 4, and tow ropes 7 and 8, which also serve as length measuring wires, are attached to these rings facing forward and backward.

Also, located at the rear of the pig 1, there is a pressure chamber 9 inside which can expand in the radial direction in response to fluid pressure.
is formed. The pressure chamber 9 has front and rear walls made up of highly rigid plate-like bodies 10 and 11, and an outer periphery made of a surrounding wall made of an elastic and stretchable film-like body 12. A conduit 13 for introducing fluid is communicated within the pressure chamber 9.

In the figure, reference numeral 14 is a guide protrusion provided on the outer circumferential portion of the pig 1 (excluding the portion where it expands in the radial direction) for making the lining resin film uniform.

When the pig 1 configured as described above is introduced into the existing pipe A with the required amount of lining resin B placed on the front side of the pig 1 and moved inside the pipe by being pulled by the towing rope 7, the pig The resin B in front of the pig 1 flows out from the gap C between the outer circumference of the rear part of the pig 1 and the inner wall surface of the pipe, and the lining is applied so as to form a coating on the inner surface of the pipe after advancing.

In this case, when there is no need to perform lining at a required location, fluid pressure, such as hydraulic pressure, water pressure, or air pressure, is supplied to the pressure chamber 9 via the conduit 13. As a result, the rear outer periphery of the pig 1 expands in the radial direction by an amount proportional to the fluid pressure, the gap C is closed, and the rear outer periphery of the pig 1 is brought into close contact with the inner wall surface of the pipe. Therefore, resin B is removed from the rear outer circumference of pig 1.
outflow is prevented, and the construction of the lining is substantially prevented.

Furthermore, at the required locations for lining, when the fluid pressure supplied into the pressure chamber 9 through the pipe line 13 is released, the diameter of the rear outer circumference of the pig 1 is reduced and a gap C is created between the pipe and the inner wall surface. A lining film having a required thickness is formed on the inner wall of the tube in accordance with the clearance of the gap C.

In addition, resin pressure is generated in the resin B that is pushed by the pig 1 and moves inside the pipe due to frictional contact with the inner wall surface of the pipe, and this resin pressure changes as the amount of resin decreases. The amount of resin B that flows out changes, and the thickness of the film changes.

Therefore, in the early stages of movement when the amount of resin is large, appropriately regulated high fluid pressure is introduced into the pressure chamber 9 via the pipe 13 to prevent the gap C from being unexpectedly enlarged by the resin pressure. When the amount of resin decreases as the resin progresses and the resin pressure decreases, the fluid pressure introduced into the pressure chamber 9 is controlled to gradually decrease. As a result, the amount of resin B flowing out from the gap C becomes constant without being affected by fluctuations in resin pressure due to a decrease in the amount of resin, and the thickness of the lining film can be made uniform over the entire length of the pipe. It becomes like this.

〔Effect of the invention〕

As described in detail above, the present invention can adjust and control the outer diameter of the pig as necessary to open and close the gap between the inner wall of the pipe and the outer periphery of the pig, so it is possible to select areas to be lined or areas not to be lined. The effect of partially applying lining can be obtained by doing this.

In addition, the amount of expansion of the circumferential surface of the pig due to fluid pressure is determined by the balance between the fluid pressure and the elasticity of the elastic material that forms the pig, so the gap between the inner wall of the pipe and the outer circumference of the pig is controlled to the required distance by fluid pressure. Therefore, the thickness of the lining film to be formed can be adjusted as desired. At this time, since the front and rear walls of the cylindrical pressure chamber are composed of highly rigid plate-like bodies, the amount of bulge of the membrane-like body at the outer periphery depends only on the displacement of the membrane-like body and is highly accurate. It becomes a perfect circle. In addition, by adjusting and controlling the above-mentioned spacing depending on the amount of resin, the thickness of the lining film can be made constant and uniform over the entire length of the pipe without being affected by changes in resin pressure. .

[Brief explanation of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of the present invention;
FIG. 2 is an enlarged longitudinal sectional side view of the main part. 1... Pig, 2, 3... Support end plate, 4... Rod,
5, 6... Ring, 7, 8... Traction rope, 9... Pressure chamber,
DESCRIPTION OF SYMBOLS 10, 11...Plate-like body, 12...Membrane-like body, 13...Pipeline, 14...Support guide protrusion, A...Existing piping, B...
resin.

Claims (1)

[Scope of Claims] 1. Introducing liquid resin and a pig that moves by pushing the resin into the pipe of an existing pipe, and when moving the resin inside the pipe by pulling the pig, from between the circumferential surface of the pig and the inner wall of the pipe. In the repair method that forms a coating on the inner surface of the pipe with flowing resin, the above pig has an elastic membrane-like body on the outer periphery inside the pig body made of an elastic material that can be expanded and contracted, and the front and rear walls are rigid. A cylindrical pressure chamber made of a plate-like material with high pressure is provided concentrically with the pig body, and during the movement of the pig, the required fluid pressure is applied to the pressure chamber to bulge the circumference of the pig, and the outer circumference of the pig and the inner wall of the pipe are connected. A method for repairing the inner surface of existing pipes, which is characterized by opening and closing gaps or controlling them to the required intervals.