JPS59131423A - Coating method of inside of pipe - Google Patents

Abstract

PURPOSE:To prevent fluid completely from leaking through a large corroded hole or a joint portion and to make possible easy perforation at a branch pipe portion by using a composite tube. CONSTITUTION:A tube 1 of thermoplastic resin having a low strength near 100 deg.C and a tube 2 of thermoplastic resin or rubber that is in contact with the inside of the low strength tube 1, can be peeled near 100 deg.C and shows high strength near 100 deg.C are extruded under a state where they can be released from each other and combined to make a composite tube 4. If this tube 4 is inserted into a tube 6 in operation to supply compressed steam, the low strength tube 1 and the high strength tube 2 are stuck closely to the inner wall of the pipe and bonded by bond 3 with the inside of the pipe. The high strength tube 2 is drawn out and air is extracted through the ends of branches 7, 7' to perforate the low strength tube 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for coating the inner surface of water pipes, gas pipes, etc., particularly for repairing and rehabilitating existing pipes thereof.

[Background of the invention]

Traditionally, when existing pipes such as water pipes and gas pipes became obsolete, the road was dug up and replaced with new pipes. However, in cases where roads cannot be dug up due to recent road conditions, there is an increasing need to repair and rehabilitate buried pipes.

As a method of rehabilitating pipes that are buried tens to hundreds of meters long, after cleaning the insides of aging cast iron pipes, ductile pipes, steel pipes, etc., you can paint them with epoxy resin or use cold-curing epoxy. The method used was to apply resin to the outer surface of the nylon tube, draw the nylon tube into the tube, expand the tube under pressure, and bring it into close contact with the tube wall.

However, with the method of applying epoxy resin, the coating thickness is uneven, making it difficult to completely seal holes penetrating the pipe wall and gaps between connections, and it is difficult to completely seal gaps between holes and connections when mechanical vibrations are applied after repair. Cracks and the like may occur, causing problems with airtightness. On the other hand, the method of coating nylon tubes uses room-temperature curing epoxy resin, which has poor workability (
There are restrictions on its use (hardening quickly in the summer and very difficult to harden in the winter, etc.), and furthermore, because nylon tubes without branch pipes are used, branch pipes to homes and offices are buried. This method could not be applied in the areas where

Therefore, in place of the conventional method described above, there has been a demand for a pipe rehabilitation method for water, gas, etc., which can completely seal and repair even through holes and gaps between connections, and which can be applied to existing pipes with branch pipes.

[Summary of the invention]

The present invention provides a construction method that is an alternative to the conventional construction method described above, and its gist is that a thermoplastic resin tube (1) that has low strength at around 100°C and a thermoplastic resin tube (1) that has low strength at around 100°C and a (1) After providing a tube (2) made of thermoplastic resin or rubber that is in contact with the inner surface and can be peeled off near the loo'c and has high strength near 100°C, inside the high strength tube (2) The low-strength tube (1) is bonded to the inner surface of the tube with an adhesive by introducing pressurized steam into the tube, and then the high-strength tube (2) is recovered and the low-strength tube (2) is bonded to the inner surface of the tube using an adhesive. By creating a pressure difference between the inner and outer surfaces of the strong tube (1), the low strength tube (1) is created.
A method for coating the inner surface of a tube, characterized in that the wall is burst-opened at a tube branch.

[Detailed description of the invention]

The "strength" of a tube as defined in the present invention refers to the strength when a tube that is tightly attached to the inner surface of a tube having a branch pipe is destroyed by the internal pressure ν of the tube at the branch pipe and opens a hole. It is expressed by the internal pressure, or internal pressure resistance.

Moreover, the "low" strength in the tube (1) means a relatively low strength compared to the "high" strength in the tube (2).

Further, "near rxoooc" means a range where the temperature difference from 100°C is within about 10°C.

The thermoplastic resin tube (1) having low strength near 100'C in the present invention includes polyethylene resin, ethylene vinyl acetate resin, ethylene ethyl acrylate resin, ethylene glycidyl methacrylate resin, ionomer resin,
Saponified ethylene vinyl acetate resin, ethylene propylene resin, polybutene-1 resin, polyolefin resin)) One or more types of multi-component copolymers obtained by graft polymerization of maleic anhydride, methacrylic acid, vinyltrimethoxysilane, etc. are kneaded. Preferably, a thermoplastic resin is formed into a tube shape and then crosslinked by irradiation with X-rays, γ-rays, electron beams, etc., or by other appropriate means (for example, adding a crosslinking agent). The resin tube has an internal pressure resistance of 0.15 Kf/cm or less at around 100°C.

In addition, the tube (2) made of thermoplastic resin or rubber that has high strength at around 100°C is made of polyp d and ren resin, polymethylpentene resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyvinylidene chloride resin, nylon 6, Nylon 66, nylon 11.
Vulcanized rubbers such as nylon 12 resin, polyurethane resin, silicone resin, fluororesin, and copolymer resins thereof, natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, nitrile rubber, acrylic rubber, silicone rubber, and fluorine rubber are used. I can do it. It may be a single-layer tube made of a composition made by kneading one or more of these resins or vulcanized rubbers, or it may be a tube composed of multiple layers when used in combination with any other resin. It's okay. In short,
It is important that the finished tube as a whole exhibits high strength at 100°C. High strength tube (
2) indicates that the strength near 100°C is 0 on the internal pressure resistance display.
．． It is preferable that the pipe be designed to have a pressure of 97 am” or more in order to easily control the water vapor pressure inside the pipe.

The solubility constant (hereinafter abbreviated as SP value) of the thermoplastic resin or rubber used for the high-strength tube (2) is the SP value of the thermoplastic resin used for the low-strength tube (1).
It is preferable that the distance is 1.0 or more from the value, since the high-strength tube (2) can be easily recovered. As an example of a combination of a low-strength tube (1) and a high-strength tube (2), the SP value of polyolefin resin is approximately 8.0, while polyethylene terephthalate resin is 10.8, polyvinylidene chloride resin is 12.2, and nylon is 12. Resin 145 or the like can be used.

In the present invention, a low-strength tube (1) is first inserted into the tube, and then the high-strength tube (2) is inserted into the inner surface of the low-strength tube (1). Alternatively, the high-strength tube (2) may be provided on the inner surface of the low-strength tube (1) so as to be able to be peeled off from each other near io o 'c. A composite tube consisting of a tube may be inserted into the canal. Furthermore, the present invention may use a composite tube in which the low-strength tube (1) is provided on the inner surface of the high-strength tube (2), and when this composite tube is used,
A method is adopted in which the composite tube is inserted into the tube while being inverted.

Any composite tube has low strength (1
) and a high-strength tube (2) are preferably laminated to have an elongation rate of 10096 or more at around 100°C. The reason for this is that the composite tube can be easily deformed when inserted into a pipe with its outer diameter reduced or inserted into a bent pipe, making the insertion process easier.

Composite tubes are produced by separately manufacturing a low-strength tube (1) and a high-strength tube (2).
It was manufactured by inserting a high-strength tube (2) into 1), and conversely, a low-strength tube (2) was inserted into a high-strength tube (2).
Although it is possible to manufacture the composite structure by inserting 1), it is more efficient to extrude it simultaneously using two extruders to form a composite structure. Furthermore, it is more preferable to insert a flat belt into the composite tube in advance, since this makes it easier to recover the high-strength tube (2) by pulling it into the tube.

The construction method of the present invention will be explained below with reference to the drawings.

Figure 1 is a cross-sectional view of an example of a composite tube used in the construction method of the present invention, in which a high-strength tube (2) is extruded and coated on the inner surface of a low-strength tube (1) in a peelable state. It has a composite structure.

Applying silicone oil or the like as a lubricant between the layers of these tubes (1) and (2) is particularly effective when inserting into a curved pipe or recovering a high-strength tube (2).

The outer circumference tζ of the low-strength tube (1) can be adjusted by providing an additional adhesive layer (3), or by providing an adhesive layer (3) on the inner surface of the tube in advance and then pulling the composite tube from the tube end. It's okay to be crowded. The adhesive may be a hot melt adhesive or a thermosetting adhesive such as an epoxy resin or a urethane resin.

Figure 2 shows the composite tube (4) in Figure 1 flattened to make it easier to insert it into the tube using binding wire or tape.
5) shows the state when the diameter is reduced. The diameter reduction method may have any shape such as a U-shape, a cross-shape, or a star-shape in cross section.

Figure 3 shows composite tubes (4) bound with adhesive bind tape (5) and branch pipes (7) (7)'
The figure shows a state in which a pulling rope (8) and a pulling machine (9) are inserted from one end into the interior of an existing pipe (6) having a bent pipe.

When inserting the tube, it is best to avoid friction between the tube and the conduit. As shown in Figure 1 (If hot melt adhesive (3) cannot be applied to the outer circumference of the tube in advance, it is also possible to apply epoxy adhesive etc. to the tube surface while pulling in the 41 tube (4) in Figure 3). It is possible.

FIG. 4 shows a state in which the composite tube is drawn into the tube and then a pressurized liquid or gas is introduced from one end to coat the inner surface of the tube. After sealing both ends of the drawn tube, liquid or gas is introduced into the tube to break up the binding tape and create a circular tube shape inside the tube, resulting in a low-strength tube (1) and a high-strength tube (1). 2) is in close contact with the inner wall of the tube and is adhered to the inner surface of the tube with adhesive (3). The pressure inside the tube is controlled by a pressure gauge μs.

To uniformly heat a long existing pipe of 50 to 100 looms in a short period of time, blow hot air into the pipe, run a steam hose through the entire length, or install a heater (heating vig) that partially heats the pipe inside the pipe. Although a method of passing the pipe over its entire length is conceivable, a method of sending pressurized steam from one end of the pipe is simple and preferable.

It is more preferable to set the pressure inside the pipe to 0.15Ky/(1)2 or more.The reason for this is that the existing pipe has a difference in height of at least 1m, so condensed water (drainage) accumulates in the lower part, and it is difficult to drain it. This is because a pressure of 0.15 Ky/crrtQ or more is required. The composite tube needs to be strong enough to withstand that pressure without breaking. During steam heating, the high-strength tube (2) serves to protect the low-strength tube (1). That is, it is necessary for the low-strength tube (1) to fit completely against the inner wall of the tube, and for the tube to be evenly adhered to curved pipe portions such as 45° and 90° elbows by water vapor pressure. Therefore, the composite tube is heated to at least 100°C
It is desirable that the elongation rate is 100% or more in the vicinity;
If it is less than %, the curved pipe portion becomes flat and the amount of gas or liquid in the liquid medium decreases.

On the other hand, since the low-strength tube (1) needs to be bonded to the inner wall of the tube by steam heating after being attached to the inner wall of the tube, it is also desirable that the tube (1) be crosslinked in order to prevent the tube (1) from flowing. Further, there is an adhesive between the low-strength tube (1) and the inner surface of the tube, but it is desirable that this adhesive hardens as quickly as possible after heating is started.

FIG. 5 is a vertical cross-sectional view showing a situation in which a low-strength f (f use) is opened at a branch part after recovering a high-strength tube located on the inner surface of a composite tube. High-strength tube (2) After collecting the tube, vacuum is drawn from the tip of the branch pipe (7) (7)' to open the low-strength tube (1), but while collecting the high-strength tube (2), vacuum is applied. At this time, the degree of vacuum is such that the pressure difference between the inside of the tube is 100 MHg or more, that is, 14 Kp/cm2 or more, and the hole can be easily opened. (90°C ~
It is necessary to maintain the temperature at around 110°C.

As the temperature decreases significantly, the strength of the tube increases and Q
, 14 K97cm2 pressure difference will not destroy the tube, and if the temperature rises too much, the low-strength tube (1) may be damaged while the high-strength tube is being recovered.

In addition, if the hole cannot be opened by vacuuming V), the hole can be opened by applying internal pressure to the inner surface of the tube, but the pressure at this time must be at a pressure that does not damage the low-strength tube (1) in the corroded hole. There must be.

As described above, the pipe inner surface coating method of the present invention can completely cover large corrosion holes and leakage from connecting parts by using the above composite tube, and can also uniformly coat curved pipes. A hole can be easily opened in the branch pipe portion.

The present invention will be explained below based on examples.

Examples Low-strength thermoplastic resin tubes A1B and C (inner diameter 102 mm,
The tubes D1E and F (inner diameter 100 mm, wall thickness 0.2 mm) made of three different materials are each molded as high-strength thermoplastic resin tubes, and coated into 100 A steel pipes. We conducted an experiment. Tubes A, B and C were further irradiated with 12 Mrad of electron beam.

The physical properties of each tube are shown in Table 1, and the gel fraction was determined from xylene insoluble at 120°C.
The tensile strength, elongation rate, and internal pressure fracture strength are the values at 100°C.

Tubes D, E, and F were inserted inside tubes A, B, and C, respectively, to obtain three types of composite tubes, ADlBE and CF.

The outside of the composite tubes (i.e. tubes A, B and C)
After applying epoxy adhesive to the outside of the
The composite tube was inserted into a 00A steel pipe (inner diameter 105 m, length 50 m) while being pulled in from one end. After insertion, after sealing both ends of the tube, 0.1 to 2. OKy/α pressurized air was introduced into the tube to break up the bind tape, and pressurized steam was then introduced from one end to bring the low-strength tube into close contact with the inner wall of the tube and harden the epoxy adhesive.

At this time, the water vapor pressure inside the pipe was controlled to 50.20 Kg/c1rLs so that it could adhere sufficiently to the curved pipe section. When the temperature reaches approximately 100°C over the entire length of the tube and the adhesive has hardened, immediately stop the water vapor and install a high-strength tube recovery device, then turn the high-strength tube inward and recover the stuck part. While recovering the tube by pulling it out to the side of the device, the branch pipe section was evacuated and a hole was opened.

As a result of the above example, the following points were confirmed.

In other words, the high-strength tube was collected very smoothly, the holes were opened only at the designated branching points, and when the tube was cut after cooling, the steel tube and the low-strength tube were firmly bonded to each other. It was confirmed that the tube was stretched along the curvature at the time of cutting, that there were no wrinkles or air pockets in the tube, and that the corrosion hole and flange joint were completely sealed by the tube.

Comparative Example As a comparative example, tubes A, B and (4-
A lining experiment was conducted by inserting it into a 10OA steel pipe. As a result of the experiment, it was found that at a water vapor pressure of 0.05 KP/(7)2 after the tube was inserted, the tube did not adhere sufficiently to the inner wall of the tube, leaving many air pockets and increasing the flow resistance inside the tube. When the water vapor pressure was further increased to 0.20 Ky/cm", it was found that the tube burst at branch pipe sections, corrosion holes, and flange joints, indicating that the tube was not functioning as a coating for the inner surface of the tube. Ta.

From the above results, it has been demonstrated that the present invention is extremely effective for providing good coating on the inner surface of the existing pipe and at the same time opening only the branch pipe portion, and shows the superiority of the present invention. .

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the tube for coating the inner surface of a pipe used in the present invention, Fig. 2 is a cross-sectional view of the tube used in the present invention when it is flattened, and Fig. 3 is a state in which the tube is inserted into an existing pipe. Figure 4 is a vertical cross-sectional view showing the state in which the inner surface of the tube is coated by supplying pressurized fluid from one end after the tube has been drawn into the tube, and Figure 5 is a vertical cross-sectional view showing the state in which the inner surface of the tube is coated by supplying pressurized fluid from one end after the tube has been drawn into the tube.
FIG. 2) is a longitudinal cross-sectional view showing the state of openings at the branch portion of the low-strength tube (1) after collecting the tube (1). (1)...A thermoplastic resin tube that has low strength near 100℃, (2)...A tube made of thermoplastic resin or rubber that has high strength near 100℃, (3).
・・Book≠Φ− Instantaneous adhesive, (4)・・・Composite tube, (5)・・・Binding tape, (6)・・・・
・Existing pipe, (7X7) '...branch pipe, (9)...
...Retraction machine.

Claims (1)

[Claims] (1) Inside the pipe, there is a thermoplastic resin tube (1) that has low strength at around 100°C, and a thermoplastic resin tube (1) that is in contact with the inner surface of the low-strength tube (1) and that is peelable at around 100°C and has high strength at around 100°C. Tube (2) made of thermoplastic or rubber
After providing a
) are bonded together with an adhesive, and then the high-strength tube (2) is collected, and a pressure difference is created between the inner and outer surfaces of the low-strength tube (1) at the pipe branching part, thereby reducing the low-strength tube (1). A method for coating the inner surface of a tube, characterized in that the wall of the tube (1) is ruptured and opened at a tube branching portion.