JPS63309425A - Lining method for inside of pipe - Google Patents

Abstract

PURPOSE:To perform easily lining of the inside of a pipe by economical facilities, by a method wherein a conductive and expandable hollow body is pierced through within a thermal recovery tube and the thermal recovery tube is recovered through heating by heating the conductive and expandable hollow body through electrification so that an external circumferential part of the thermal recovery tube abuts against the inside of a pipe. CONSTITUTION:A conductive and expandable hollow body is pressurized and expanded by injecting, for example, air through a pressure control instrument 7 and pressure supply device connected with the pressure control instrument 7, and the conductive and expandable hollow body 4 is electrified and heated through an electrification terminal 5 and electric power source connected with electrification terminal 5. When the conductive and expandable hollow body 4 is pressurized and expanded, it becomes that an adhesive layer 3 of an external circumferential part of a thermal recovery tube 2 is caused to adhere to the inside of a pipe 1. The thermal recovery tube 2 is thermally recovered through electrification and heating of the conductive and expandable hollow body 4. In this instance, pressure and a temperature of the conductive and expandable hollow body 4 are set up appropriately and held for a necessary period of time so that the thermal recovery tube 2 adheres strongly to the inside of the pipe 1 with uniform force, the inside of the pipe 1 is lined with the thermal recovery tube 2.

Description

DETAILED DESCRIPTION OF THE INVENTION r Industrial Field of Application 1 The present invention relates to a method for coating the inner surface of a tube (same as a cylinder).

r Conventional technology 1 As is well known, in fluid transport pipes such as water pipes, gas pipes, and chemical industry pipes, rust occurs on the inner surface of the pipes due to aging, and other contaminants adhere and accumulate. , eventually the entire pipe becomes obsolete.

If such a situation is left untreated, fluid leakage is likely to occur, which could lead to a major accident. Therefore, appropriate measures should be taken in advance, such as repairing and rehabilitating the pipe or replacing it with a new pipe. There is.

The above-mentioned pipe construction is generally expensive, and in particular, when constructing underground pipes under roads, there are restrictions due to traffic conditions. Efforts are being made to simplify, reduce construction costs, and shorten the construction period.

An example of this is a resin coating type anticorrosive coating method, in which a hardening resin such as an epoxy resin is applied to the inner surface of the pipe after cleaning.

On the other side, the tube-expanding anticorrosive coating method involves expanding a plastic tube or a thermo-expandable tube and bringing it into close contact with the inner surface of the tube, in which case the tube is heated from inside. , and means for pressurizing and holding the expanded shape.

Problems to be Solved by the Invention j The above-mentioned resin coating type anti-corrosion coating method is difficult to coat the inner surface of the tube with a sufficiently large and uniform resin coating, so it is difficult to apply a high-strength anti-corrosion coating layer. Moreover, since it takes time for the resin to harden, the construction period cannot be shortened as much as expected.

The tube expansion anticorrosive coating method described above requires continuous supply of heat and pressure into the tube in order to maintain the heating and pressurizing conditions necessary for tube expansion, and special equipment is required for this purpose. In addition to being necessary, in order to efficiently apply the generated heat and pressure, the ends of the tubes to be coated must be strictly treated, which poses problems in terms of economic efficiency and ease of handling of the equipment.

In view of the above-mentioned problems, the present invention aims to provide a method for coating the inner surface of a tube that can be easily carried out using simple and economical equipment. In order to achieve the desired object, the present invention provides a method for heating and recovering a heat-recoverable tube disposed in a pipe and covering the inner surface of the tube with the heat-recoverable tube. The conductive expandable hollow body is inserted through the conductive expandable hollow body, and the conductive expandable hollow body is heated with electricity so that the conductive expandable hollow body is pressurized and expanded so that the outer peripheral portion of the heat recovery tube comes into contact with the inner surface of the tube. It is characterized by heating and recovering the heat-recoverable tube.

1 Effect 1 In the method of the present invention, when covering the inner surface of a tube with a heat-recoverable tube, it is only necessary to pressurize and expand the conductive expanding hollow body inserted into the heat-recoverable tube and heat it with electricity. The inner surface of the tube can be easily covered with the heat-recoverable tube that has been heated and recovered through the expandable hollow body.

"Example" Figures 1 to 3 show an example of the method of the present invention in the order of its steps.

First, each member and each device shown in FIGS. 1 to 3 will be explained.

The tube l whose inner surface is to be coated mainly has a circular cross section,
Depending on the case, it may have a polygonal cross section.

The material of the tube 1 is metal, ceramic, synthetic resin, a composite thereof, or the like.

A specific example of the tube 1 is a fluid transport tube having a circular cross section.

The heat-recoverable tube 2 has a characteristic of recovering to a predetermined shape by heating.

For example, when the heat-recoverable tube 2 is made of synthetic resin, it is preferably crosslinked to exhibit heat resistance.

As a specific example, the heat-recoverable tube 2 is a tube made of polyolefin such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, or a mixture of any of these polyolefins and rubber, which is cross-linked by electron beam irradiation. A cross-linked tube is formed by silane cross-linking, etc., and the cross-linked tube is heated and deformed to reduce its diameter, and then cooled and solidified to impart shape memory properties. It is obtained by stretching the length, then cooling and solidifying it in that state to impart thermal expandability.

An adhesive layer 3 as illustrated may be provided on the outer circumferential surface of the heat-recoverable tube 2, and the adhesion between the heat-recoverable tube 2 and the pipe 1 can be improved through the adhesive layer 3.

The adhesive layer 3 is made of a hot melt adhesive made of a modified polyolefin resin such as a polyamide resin, an ethylene vinyl acetate resin, or an ethylene acrylic resin, or a thermosetting adhesive such as an epoxy resin.

The conductive expandable hollow body 4 is sealed at one end.

The other end is open.

The electrically conductive expanding hollow body 4 has electrical conductivity and heat resistance that can be heated with electricity, and expands and contracts by pressurizing and depressurizing the inside thereof.

More specifically, the conductive expandable hollow body 4 is composed of a cylindrical member made of conductive fiber fabric (woven fabric or knitted fabric) and a heat-resistant resin laminated on the cylindrical member.

The conductive fibers mentioned above are made of, for example, carbon fibers, graphite fibers, etc., and the heat-resistant resins are made of, for example, fluororesin, polyimide resin, polyamide-imide resin, etc.

Electrical terminals 5 are connected to both ends of the conductive edge ILI fabric in the conductive expansion hollow body 4, and a pressure regulator 7 equipped with a valve B is connected to the open end of the conductive expansion hollow body 4. It is attached removably.

Note that a power supply (not shown) is connected to the energizing terminal 5, and a pressure supply device (not shown) is connected to the pressure regulator 7.

Next, one embodiment of the method of the present invention will be explained in order of its steps.

In the process shown in FIG. 1, a heat-recoverable tube 2 having an adhesive layer 3 is placed inside a tube 1 whose inner surface has been cleaned, and a conductive expandable hollow body 4 is inserted into the heat-recoverable tube 2. Ru.

In the process shown in FIG. 2, the conductive expanding hollow body 4 is pressurized and expanded by an obvious means such as injecting air through the pressure regulator 7 and the pressure supply device connected thereto, and the conductive expanding hollow body 4 is expanded under pressure. The electrically conductive expanding hollow body 4 is heated by electricity through the terminal 5 and a power source connected thereto.

In the above, when the conductive expandable hollow body 4 is pressurized and expanded, the heat recovery tube 2 also expands, and the adhesive layer 3 on the outer periphery of the tube 2 is brought into close contact with the inner surface of the tube 1. By heating the expandable hollow body 4 with electricity, the heat recovery tube 2 recovers heat.

At this time, the pressure and temperature of the conductive expanding hollow body 4 are appropriately set so that the heat recovery tube 2 strongly adheres to the inner surface of the tube 1 with uniform force, and the appropriate state is maintained for the necessary time. Then, the inner surface of the tube 1 is covered with a heat-recoverable tube 2.

FIG. 3 shows a state in which the conductive expanding hollow body 4 and its appendages have been removed from the inside of the tube 1 whose inner surface is coated with the heat-recoverable tube 2, thus completing the predetermined process.

rSpecific Example J When carrying out a specific example of the method of the present invention, the specifications of each part were set as follows.

In the case of main pipe 1, a steel pipe with an inner diameter of 53 mm and a length of 2 mm was used, and its inner surface was cleaned by washing in a conventional manner.

In the case of the inherently recoverable tube 2, a low-density polyethylene tube with a wall thickness of 1.5 m and an outer diameter of 55 mm is used, and an adhesive layer 3 made of dimer acid-based polyamide resin with a softening point of 140° C. is coated around the outer circumference with a thickness of 0.5 m. 5m
After forming the adhesive layer, the tube with the adhesive layer is axially
．． The tube was stretched three times to obtain a heat-recoverable tube 2 having an outer diameter of 49 mm and a length of 2.3 m.

In the case of this conductive expandable hollow body 4, it is made of a plain weave conductive fiber fabric made of carbon fiber with a volume resistivity of 1×10-2Ω-C■ (volume resistivity) and has a thickness of 0.4
After forming a cylindrical body with m layers and an outer diameter of 50 mm, a 0.1 m thick polytetrafluoroethylene resin layer is laminated on the inner and outer peripheral surfaces of the cylindrical body to form a conductive expanding hollow. One end of the hollow body 4 was sealed to have a length of approximately 2.5 m.

The above-mentioned current supply terminal 5 is attached to the conductive expansion hollow body 4, and the above-mentioned pressure regulator 7 is attached to the open end.
were connected.

In the above-mentioned specifications, when carrying out each process described in FIGS. 1 to 3, the conductive expanding hollow body 4 maintains its internal pressure (air pressure) at 0.1 kg/cm2 and starts energizing. Due to the current supply, the surface temperature of the conductive expanding hollow body 4 increases to 140
-150°C.

When the heat-recoverable tube 2 is thermally recovered by such electrical heating and the adhesive layer 3 on its outer periphery is brought into close contact with the inner surface of the tube 1, the internal pressure of the conductive expansion hollow body 4 is maintained at 0.1 kg/cm2. , After that, the above-mentioned electricity supply is stopped and these adhesive layers 3,
The conductive expanding hollow body 4 was naturally cooled to room temperature.

Below is a tube 1 whose inner surface is coated with a heat-recoverable tube 2.
The conductive expanding hollow body 4 and its attachments were removed from the inside, and the mechanical properties and adhesion of the tube inner surface coating were physically measured, and it was confirmed that the tube was sufficiently durable for practical use.

"Effects of the Invention" As explained above, according to the method of the present invention, when heating and recovering a heat-recoverable tube to coat the inner surface of the tube, an electrically conductive expanding hollow body is inserted into the heat-recoverable tube, Since the conductive expanding hollow body is simply expanded under pressure and heated with electricity, the inner surface of the tube can be coated with excellent mechanical properties and coating adhesion using simple and economical equipment.・It is possible to simplify K, reduce construction costs, and shorten construction period.

[Brief explanation of the drawing]

FIGS. 1 to 3 are explanatory diagrams showing one embodiment of the method of the present invention in the order of its steps. l...Tube to be coated on the inside 2...Heat-recoverable tube 3...Adhesive layer 4...Electroconductive expansion Hollow body 5... Terminal for energizing 6... Pressure regulator valve 7...
・・Pressure regulator

Claims (2)

[Claims] (1) In a method of heating and recovering a heat-recoverable tube placed in a pipe and covering the inner surface of the tube with the heat-recoverable tube, an electrically conductive expanding hollow body is inserted into the heat-recoverable tube, and the conductive The heat-recoverable tube is expanded under pressure so that the outer peripheral portion of the heat-recoverable tube comes into contact with the inner surface of the tube.
A method for coating the inner surface of a tube, characterized in that the conductive expanding hollow body is electrically heated to recover the heat recoverable tube. (2) The method for coating the inner surface of a tube according to claim 1, wherein the conductive expanding hollow body is composed of a cylindrical material made of carbon fiber and a heat-resistant resin laminated on the cylindrical material.