JP3285668B2 - Removal method of plastic pipe lined in pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended for repairing or reinforcing pipes mainly buried underground, such as gas pipes, water pipes, sewage pipes, communication and power line laying pipes. If a plastic pipe is inserted inside and lined, the plastic pipe becomes obsolete,
When the plastic pipe is crushed for some reason and its function as a pipe is impaired, it relates to a method for removing the old plastic pipe from the pipe when relining the pipe. is there.

[0002]

2. Description of the Related Art Conventionally, when a plastic pipe in a pipeline is removed as described above, the plastic pipe is cut and removed little by little, or the plastic pipe is heated and softened, and forcibly pulled from the pipeline. Unplug was done.

[0003]

However, in the method of cutting and removing a plastic pipe, it is not easy to cut a lining material in a long pipe, it takes a long time, and the pipe itself is removed. Also often hurt.

Further, in the method of drawing out a plastic pipe, even if the plastic pipe is heated and softened, it is not easy to pull out a bulge along the inner surface of the pipe, and it is extremely large. It takes power. Further, if the pulling force is excessive, the plastic pipe may be broken, and it is more difficult to remove the plastic pipe remaining in the pipe.

The present invention has been made in view of the above circumstances, and has as its object to provide a method for easily pulling out a plastic pipe lined with a small force from the inside of the pipe. .

[0006]

Means for Solving the Problems According to a first aspect of the present invention, both ends of a plastic pipe lined in a pipe are hermetically sealed, and the inside of the plastic pipe is depressurized to connect the plastic pipe to the pipe. It is characterized in that the plastic pipe is peeled from the inner surface, the sectional shape is reduced and deformed, and then the plastic pipe is pulled out from the inside of the pipeline.

[0007] The second invention is the first invention, wherein:
The plastic pipe lined in the pipe is heated over its entire length, and the inside of the plastic pipe is decompressed while the plastic pipe is softened.

In a third aspect of the present invention, a plastic pipe lined with a pipe is filled with pressurized steam and heated.
Next, both ends of the plastic pipe are hermetically sealed, the inside of the plastic pipe is depressurized by the condensation of the pressurized steam, and the plastic pipe is separated from the inner surface of the pipe, and the cross-sectional shape is reduced and deformed. It is characterized in that a plastic pipe is pulled out of the pipe.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a step of reducing the cross-sectional shape of a plastic pipe in a pipe lined by the first invention. FIG. 1A shows a lined pipe, 1 is a pipe, and 2 is a plastic pipe inserted along the inner surface of the pipe 1. FIG. 3 is an enlarged cross-sectional view of the lined pipe.

[0010] Both ends 3 of the plastic pipe 2 are peeled off from the inner surface of the pipe 1, and the ends 3 are crushed and fused together to be hermetically sealed.
The tip of the hose 4 connected to the decompression pump is connected. This state is shown in FIG.

When the pressure inside the plastic pipe 2 is reduced by the pressure reducing pump via the hose 4, the plastic pipe 2 is crushed by the external pressure as shown in FIGS. 1 (c) and 4, and its sectional shape is reduced. In this state, by pulling the plastic pipe 2 from one side, the plastic pipe 2 can be easily pulled out from the pipeline 1.

The plastic pipe 2 is usually made of a hard thermoplastic resin such as polyethylene or polyvinyl chloride, and has a considerable rigidity. In such a case, the second invention is applied and the plastic pipe 2
It is preferable that the heating is performed by feeding a heating fluid into the inside of the inside, or by sending a heating fluid between the plastic pipe 2 and the pipe 1 while reducing the pressure, thereby softening the plastic pipe 2.

FIG. 2 shows a state in which the third invention is carried out. In FIG. 2 (a), a pressurized steam is fed from a hose 5 into a plastic pipe 2 lined in a pipeline 1, and the plastic The pipe 2 is heated and softened, and the plastic pipe 2 is filled with pressurized steam.

The plastic pipe 2 is sufficiently heated,
When the pressurized water vapor is sufficiently filled in the plastic pipe 2, both ends 3 of the plastic pipe 2 are peeled off from the pipe line 1 as shown in FIG.

Then, the sealed plastic pipe 2
Inside, the pressurized steam condenses as it cools,
As shown in FIG. 4C and FIG. 4, it is crushed by the atmospheric pressure to reduce the cross-sectional shape. By pulling the plastic pipe 2 from one side in this state, the plastic pipe 2 can be easily pulled out from the pipeline 1.

The following experiment was conducted to confirm the effects of the present invention.

A polyethylene pipe having an inner diameter of about 150 mm and a thickness of 5 mm is inserted through a steel pipe having an inner diameter of 150 mm and a length of 30 m containing four 45 ° bends, and is heated and pressurized to expand the pipe. It was then lined and cooled to room temperature.

Next, the polyethylene pipe was heated by blowing live steam into the polyethylene pipe, and was pulled by connecting a winch to one end of the polyethylene pipe to pull out the polyethylene pipe from the steel pipe. Could not.

Next, both ends of the polyethylene tube are sealed,
When the inside of the polyethylene pipe was depressurized with a vacuum pump from one end, the polyethylene pipe was crushed into a substantially U-shaped cross section in the steel pipe, and when it was pulled out, it could be pulled out with a force of about 240 kg.

When the same polyethylene pipe is lined with the same steel pipe, live steam is blown into the polyethylene pipe and heated, and after the live steam is released from the end of the polyethylene pipe, both ends of the polyethylene pipe are sealed. ,
In about 10 minutes, the polyethylene pipe collapsed in the steel pipe in a substantially concave cross section. When this polyethylene pipe was pulled out of the steel pipe, it could be pulled out with a force of about 350 kg.

[0021]

According to the present invention, according to the present invention, the plastic pipe 2 lined along the inner surface of the pipe 1 is crushed when the pressure is reduced, and the sectional shape is reduced.
The frictional resistance between the plastic pipe 2 and the pipeline 1 is greatly reduced.

Therefore, even in the case where the plastic pipe 2 cannot be pulled out by heating and softening, it can be easily pulled out with a smaller force by reducing the cross-sectional shape of the plastic pipe 2. It can be pulled out even if it has a bent portion such as a bend.

Further, according to the present invention, the plastic pipe 2 can be pulled out at one time over its entire length.
The plastic pipe 2 can be removed in a short time, there is no need to cut the plastic pipe 2 into small pieces, and there is no risk of damaging the pipeline 1.

Further, according to the third invention, it suffices to provide a pressurized steam supply facility and does not require a decompression pump as in the first invention, so that the plastic pipe 2 can be pulled out by a simpler operation. it can.

[Brief description of the drawings]

FIG. 1 is a central longitudinal sectional view showing a step of removing a plastic pipe 2 from a pipeline 1 according to the first invention.

FIG. 2 is a central longitudinal sectional view showing a step of removing a plastic pipe 2 from a pipeline 1 according to a second invention.

FIG. 3 Pipeline 1 lined with plastic pipe 2
Cross section of

FIG. 4 is a cross-sectional view showing a state in which a cross-sectional shape of a plastic pipe 2 is reduced in a pipe 1;

[Explanation of symbols]

 1 pipeline 2 plastic pipe

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takuji Sokawa 3-7-1, Ichiriyama, Otsu-shi, Shiga Prefecture (72) Inventor Hitoshi Saito 1--24, E-604, Kamishinta, Toyonaka-shi, Osaka (56) References JP-A-2-8016 (JP, A) JP-A-60-165214 (JP, A) JP-A-62-121034 (JP, A) JP-A-53-32968 (JP, A) (58) Survey Field (Int. Cl. ⁷ , DB name) B29B 17/00 B29C 63/00 B09B 3/00

Claims (3)

(57) [Claims] 1. Both ends of a plastic pipe (2) lined in a pipe (1) are hermetically sealed, and the inside of the plastic pipe (2) is depressurized to connect the plastic pipe (2) to the pipe (1). ) A method for removing a plastic pipe lined in a pipeline, wherein the plastic pipe (2) is pulled out from the inside of the pipeline (1) while being peeled off from the inner surface and reduced in cross-sectional shape. 2. A plastic pipe (2) lined in a pipe (1) is heated over its entire length, and the inside of the plastic pipe (2) is decompressed while the plastic pipe (2) is softened. The method for removing a plastic pipe lined in a pipeline according to claim 1, characterized in that: 3. A plastic pipe (2) lined with a pipe (1) is filled with pressurized steam and heated, and then both ends of the plastic pipe (2) are hermetically sealed, and the plastic pipe (2) is closed. The pressure inside the plastic pipe (2) is reduced by condensation to peel off the plastic pipe (2) from the inner surface of the pipe (1), and at the same time, reduce the cross-sectional shape and deform the plastic pipe (2). ), A method of removing a plastic pipe lined in a pipeline