JPS6330548B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for conducting wires in pipes mainly buried underground, such as gas pipes and water pipes, and particularly relates to pipes of small diameter and with many bends. This invention relates to a wiring method suitable for application to conduits.

In city gas piping, the supply gas conduit for supplying city gas to each household from a branch pipe buried in a public road or the like is a complicated pipe as shown in FIG. That is, a service pipe 2a is connected to the branch pipe 1, and a pipe branched from the service pipe 2a forms a horizontal part 4a through a bend part 3a, and further reaches a T-shaped pipe part 5 through a bend part 3b. A pipe branching upward from the T-shaped pipe portion 5 is connected to the service channel 2b via a rising portion 6a, and a pipe branching downward is connected to a water tank 7. The pipe branched from the service channel 2b passes through a bend portion 3c, a horizontal portion 4b, bend portions 3d and 3e, is exposed above the ground at a rising portion 6b, and is connected to a meter (not shown). Furthermore, if there is an obstacle in the middle of the piping, the horizontal parts 4a and 4b are bent using the elbows 8 to avoid the obstruction, as shown by the chain lines in FIG. This results in complicated piping.

By the way, the supply gas conduit is generally used to convey city gas for use in a single household, so it is generally of a small diameter and usually has a nominal diameter of about 1 inch. The inner diameter a of this conduit is approximately 27 mm at the straight pipe section, and the inner diameter hardly changes at the bend section as shown in Figure 2. In this case, as shown in FIGS. 3 to 5, the inner diameter c is enlarged to about 35 mm.

BACKGROUND TECHNOLOGY Now, conventionally, as a general method for threading a string-like object into a pipe, a running body called a pig is inserted into the pipe, and the tip of the string-like object is connected to the rear part of the running body.
There is a known method in which a fluid (usually air) pressure is applied to the rear part of the pig, the fluid pressure causes the pig to travel inside the pipe, and the pig draws a string-like object into the pipe and inserts it. Widely used.

Problems to be Solved by the Invention However, it is extremely difficult to apply this method to small-diameter pipes with many bends, such as the above-mentioned supply gas conduit. In other words, the force that makes the pig run is generated by the pressure of the fluid, so if the pipe diameter is small, the pressure receiving area where the pig receives pressure is small, so even if the fluid pressure is high, the force that makes the pig run is large enough. Therefore, the force with which the pig pulls the string-like object is small. Moreover, if there are many bends, the frictional resistance between the string-like object and the inner surface of the tube is large, and a large force is required for insertion.

In addition, in the above method, fluid pressure is applied to the rear part of the pig and the pig is moved by the fluid pressure, so if fluid leaks forward from between the inner surface of the pipe and the pig, the efficiency will be greatly reduced. , the pig cannot run. Therefore, the pig must be made of an elastic material, and its outer surface must be in pressure contact with the inner surface of the tube at all times.

However, the fluctuation rate of the supply gas conduit is large in relation to the pipe diameter, and the pig cannot follow the fluctuation. Even if a pipe with an inner diameter of 100 mm had a maximum diameter variation of 12 mm, the ratio would be only 12%, and the elasticity of the pig could sufficiently follow the diameter variation. Maximum of 8 in just 27mm tube
If the diameter fluctuates by millimeters, the ratio would be as high as 30%, making it impossible for the pig shape to follow.
Therefore, if the pig is large, it will not be able to pass through a bend with a small diameter, but if the pig is small enough to pass through a bend, the pig will not be able to pass through a bend with a large diameter, such as an elbow, service tee, or T-shaped pipe. A large amount of air leaks between the holes, making it impossible to pump the pig.

Furthermore, according to the conventional method, air pressure is applied to the rear part of the pig to push it forward, so it
In bends and the like, there is no problem because the direction in which the pig should move is fixed, but in cases where the pig has a T-shaped tube portion 5 or a service tee 2, it is difficult to move the pig in the correct direction. For example, if a pig is pushed into the T-tube section 5 shown in FIG. 1 from above, it is easy to imagine that the pig will try to move straight downward through the T-tube section 5. It is extremely difficult to bend this at the T-shaped tube portion 5 and direct it toward the service tee 2a. In addition, in Service Team 2b, although a forward force is applied to the pig that entered from the side, a force to bend it downward is not applied, so in order to direct the pig downward, pressurization must be temporarily stopped. However, it is necessary to remove the cap of the service tool 2b, manually turn it around, insert it into the lower tube, and then close the cap and apply pressure again.

The present invention has been made in view of the above circumstances, and includes the steps of: generating rapid airflow intermittently within the pipe; and causing the traveling body to travel within the pipe by being swept away by the airflow;
To correctly run a running body and insert a string-like object into a pipe without considering fluid leakage between the inner surface of the pipe and the running body, even for small-diameter pipes that have branch parts and service channels. The purpose is to provide a method that allows for

Means for Solving the Problems According to the present invention, a running body to which the tip of a string-like object is later connected is inserted into a pipe, and the running body is caused to run inside the pipe by gas pressure to move the string-like object into the pipe. In this method, the end of the tube on the side where the moving body reaches is closed, gas is inserted into the tube from the end of the tube on the side from which the moving body starts, and the inside of the tube is pressurized. A rapid airflow is generated within the tube by rapidly opening the end on the body arrival side, and the airflow pushes the traveling body through the tube from the starting side toward the arrival side.

Embodiment FIG. 6 shows a state in which a string-like elongated object 10 is to be inserted into the supply gas conduit 9 by the method of the present invention. The meter mounting portion of the rising portion 6b of the conduit 9 is removed, and that portion is used as the end on the starting side of the traveling body. A starting fitting 11 is attached to the starting tube end, and an air feed pipe 12 and a pressure gauge 13 are attached to the starting fitting 11. 14
is a running body, and the tip of a string-like object 10 is connected to the rear side thereof, and is inserted into the conduit 9 from the starting fitting 11.

The traveling body 14 has a head 15 which is smaller than the diameter of the smallest part of the pipe, and a skirt 16 made of an extremely flexible material is provided on the rear side of the head 15 and widens towards the end. The diameter of the tip of the skirt 16 is approximately equal to the diameter of the largest diameter portion of the conduit 9.

The upper end of the starting fitting 11 is closed with a gasket 17, a washer 18, and a cap 19, and the gasket 1
7 and the hole 20 of the washer 18 are filled with the string-like material 1.
0 is inserted. Note that the starting metal fitting 11 may be a closed container, and the string-like material 10 may be wound and stored in the container.

On the other hand, the upper cap of the service ch 2a is removed and the bottom is closed with a stopper 21.
The leakage of city gas from the branch pipe 1 and the inflow of air into the branch pipe 1 are prevented. A transparent tube 24 is connected to the upper part of the service tee 2a via a reducer 22 and a joint fitting 23, and a joint fitting 25
A valve 26 is attached via. Further, a pressure gauge 27 is attached to the lower part of the valve 26.

Now, when compressed air is inserted from the air supply pipe 12, air pressure acts on the rear part of the traveling body 14, and this pressure causes the traveling body 14 to be forced into the conduit 9 toward the end on the destination side. . At the beginning of the pumping, the frictional resistance between the string-like material 10 and the inner surface of the conduit 9 is small, and the traveling body 14 can travel within the conduit 9 by the air pressure while pulling the string-like material 10. . At this stage, there is no difference from the conventional method.

However, when the traveling body 14 advances to a certain extent, the resistance of the string-like object 10 becomes large, and it becomes impossible to advance using only air pressure. Furthermore, even if the air pressure is increased, air leaks between the traveling body 14 and the inner wall of the conduit 9, and the pressure difference between the front and rear of the traveling body 14 cannot be made sufficiently large, making it impossible for the traveling body 14 to travel. . Furthermore, as described above, it is difficult to bring the outer surface of the traveling body 14 into close contact with the inner surface of the tube to prevent air leakage.

Here, in the present invention, the valve 26 is closed and compressed air is injected from the air supply pipe 12, and the conduit 9
Pressurize the entire inside. This air passes between the inner surface of the conduit 9 and the traveling body 14 and spreads throughout the conduit 9,
The entire interior of the conduit 9 is pressurized.

When the valve 26 is then suddenly opened, the compressed air in the conduit 9 is suddenly released from the valve 26, and a rapid airflow is generated in the conduit 9 from the starting side to the destination side. The traveling body 14 is carried away by this air current and travels toward the end of the conduit 9 on the reaching side. When the traveling body 14 stops again, the valve 26 is closed again to pressurize the inside of the conduit 9, and the valve 26 is opened again to push the traveling body 14 away by the airflow, which is repeated until the traveling body 14 reaches the reaching end. It will make you reach it. Whether or not the running body 14 has reached the reaching side is determined by the string-like object 10 inside the transparent tube 24.
You can check by visually observing whether or not it is passing through.

Effect In the present invention, the tube is once closed, compressed air is inserted to pressurize the entire inside of the tube, and then the end on the destination side is opened to release the air, so the tube is directed from the starting side to the destination side. A sudden airflow occurs. The airflow then wraps around the vehicle, carrying the vehicle with it and pushing it away, causing the vehicle to travel toward the destination along with the airflow.

Effects of the Invention According to the present invention, the traveling body 14 is not pushed by air pressure to make it travel, but the traveling body 14 is placed on the airflow generated in the conduit 9 and is pushed away by the airflow to make the traveling body 14 travel. 9. There is no need for it to be strongly pressed against the inner surface. Therefore, there is no need to take into account the variation in the diameter of the inner surface of the conduit 9, and since the frictional resistance is small, the traveling body 14 can be easily run even at a relatively low air pressure. Furthermore, since the traveling body 14 is not strongly rubbed in the conduit 9 or caught at bent portions, it is particularly suitable as a method for inserting the string-like object 10 into the supply gas conduit 9 which has a small diameter and has many bends. There is.

Furthermore, according to the present invention, the airflow in the conduit 9 not only sweeps away the running body 14 but also wraps around and sweeps away the string-like object 10 extending behind the running object 14, so that the string-like object 10 and the inner surface of the conduit 9 The frictional resistance between the strings 10 and 10 is reduced, and the burden of the running body 14 pulling the string-like object 10 is also reduced, making it possible for the running body 14 to travel easily.

Furthermore, according to the present invention, the airflow flows unilaterally from the starting side to the destination side of the conduit 9, and even if there is a branch, the airflow only occurs in the correct direction within the branch. Further, in the service tee 2 as well, a bent air flow is formed along a desired path. Therefore, since the traveling body 14 travels along with the airflow, it will not proceed in the wrong direction at the branching point, and can also bend and pass the service station 2 without any problem.

In addition, even in the conventional method, if compressed air is supplied by a compressor with a large discharge amount, the traveling body 1
It is also possible to put 4 on the airflow and push it away,
In many cases, it is not possible to use such a large capacity compressor. In the present invention, airflow is generated by intermittently pressurizing compressed air into the pipe and then rapidly releasing it, so that a small compressor with a small capacity can sufficiently achieve the purpose.

It should be noted that the traveling body 14 used in the present invention preferably has a shape that can easily ride the airflow as shown in the examples, but it is not particularly limited to this shape, and any structure may be used. It's okay. For example, a light ball such as a fishing float with a diameter of about 20 mm can be used, and a sufficient effect can be achieved. Further, although a conventionally commonly used pig can be used as it is as the traveling body 14 of the present invention, in the present invention, the traveling body 1
It is not necessary to prevent air from leaking from the outer periphery of the pipe, but rather it is necessary to ride the flow of air that occurs within the pipe, so use a pipe that is one or two times smaller than the one used in the conventional method. It is preferable to use

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a supply gas conduit that supplies city gas to each household. Figures 2 to 5 are
FIG. 2 is an enlarged central vertical cross-sectional view of a bend portion, an elbow, a service tee, and a T-tube portion of the supply gas conduit shown in FIG. 1; FIG. 6 is a central vertical sectional view showing a state in which the present invention is to be implemented. 9... Conduit, 10... String-like object, 14... Running body.

Claims (1)

[Claims] 1. A method in which a running body to which the tip of a string-like object is later joined is inserted into a pipe, and the running body is caused to travel inside the pipe by gas pressure, so that the string-like object is inserted over the entire length of the pipe. Close the end on the side where the traveling body reaches,
Gas is inserted into the tube from the end of the tube on the side where the traveling body starts, pressurizing the inside of the tube, and then the end of the tube on the side where the traveling body reaches is suddenly opened to create a rapid airflow inside the tube. A method for inserting a string-like object into a pipe, the method comprising: pushing a running body through the pipe from a starting side to a destination side.