JPS5922653B2 - How to line the inner surface of the tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for uniformly lining the inner surface of a tube with a thermoplastic resin.

Conventionally, the lining method involves inserting a thermally expandable thermoplastic resin tube into a tube to form a double tube, and heating the tube sequentially from one end to the other to heat the thermally expandable thermoplastic resin tube. A method has been adopted in which the diameter is expanded and the tube body is closely lined.

However, in the above method, it is necessary to heat the double pipe sequentially and uniformly from one end to the other, and this process is not only very time-consuming and troublesome, but also
It is difficult to heat uniformly, and there are variations in heating, which causes variations in the expansion diameter, causing deflection, and in extreme cases, abnormal expansion and cracking of the resin tube.

The object of the present invention is to provide a lining method which does not have the drawbacks mentioned above.
That is, the object of the present invention is to provide a method that can uniformly and easily line a tube body with a thermoplastic resin tube without causing deflection.

That is, the gist of the present invention is to pressurize a heated fluid into a thermoplastic resin tube having an outer diameter smaller than the inner diameter of the tube inserted into the tube, and at the same time to pressurize the heated fluid between the tube and the resin tube. The method of lining the inner surface of a tube body is characterized in that the pressure is increased to approximately the same pressure as the inside of the resin tube, the resin tube is heated in this state, and then the pressure between the tube body and the resin tube is gradually reduced.

Examples of the pipe used in the present invention include pipes used in water supply and drainage pipes, sewage pipes, etc., such as steel pipes, asbestos pipes, hume pipes, and ceramic pipes, with steel pipes being particularly preferred.

The thermoplastic resin pipe used in the present invention is a pipe, tube, etc. obtained by molding a thermoplastic resin, and in the present invention, it is heated with a heating fluid such as steam or hot water, so the temperature is 90 to 150°C. Preferably, thermoplastic resin pipes are softened by thermoplastic resins such as polyethylene, polyvinyl chloride, polypropylene, ABS, etc.
Examples include tubes.

Since the thermoplastic resin tube is inserted into the tube body, the outer diameter of the resin tube is smaller than the inner diameter of the tube body.

Also, thermally expandable tubes may be used. In the present invention, the thermoplastic resin tube is inserted into the tube body.

Next, a heating fluid such as steam or hot water is injected into the thermoplastic resin tube to pressurize the inside of the resin tube, and at the same time, the space between the resin tube and the tube body is also pressurized with a fluid such as air. At this time, the pressure within the resin tube and between the resin tube and the tube body must be kept approximately the same so that the resin tube does not deform. Moreover, the pressure at this time is not limited at all, but is preferably 1.0 to 7.0 k.
g/d, particularly preferably 1.5 to 5.0 kg/C
It is d. Further, the heating temperature of the resin tube may be any temperature suitable for deforming the resin tube, and it is generally preferable to heat the resin tube to a temperature of 90 to 150°C. Further, the pressurization and heating time may be any time sufficient to uniformly heat the resin tube, and is generally preferably set to 3 to 60 minutes. In the present invention, after the resin tube is heated as described above, the pressure between the resin tube and the tube body is gradually reduced.

The resin tube is softened by heating and the inside of the resin tube is pressurized, so when the pressure between the resin tube and the tube body is reduced, the resin tube expands in diameter and is lined with the tube body. After the above-mentioned heating expansion is completed, cooling is performed, but the cooling method is not limited in any way. For example, the injection of steam or hot water is stopped, and while the steam or hot water is extracted, compressed air at room temperature is cooled. A method may be adopted in which the water is cooled by feeding the water.

Since the method for lining the inner surface of a tube body according to the present invention has the above-described configuration, the resin tube is heated uniformly, and the pressure difference between the inside and outside of the resin tube is always almost constant when the diameter is expanded, so the thickness is uniform without unevenness. It can be used as a backing. Furthermore, since the method of the present invention does not heat the pipe body from the side, but heats it from within the resin pipe using a heating fluid, it is also suitable for repairing old pipes buried underground or for lining pipe runs including bent pipes. It is possible. Next, an example of the lining method of the present invention will be described.

Polyethylene pipe with an exception diameter of 601n and a wall thickness of 5.51mm (
Polyethylene density 0.94rr3, melt index 0.2) was made into a 1m long steel pipe with flanges at both ends (SGP8
OA, inner diameter 80.6! l) Insert a compressed air injection device into the steel pipe by inserting the polyethylene vibe into the steel pipe and sealing the gap between the pipe and the steel pipe at both ends, and inject main steam and compressed air into one end of the polyethylene pipe. A condensed water outlet was provided at the other end of the device and the pipe.

Steam and air were injected from the pipe injection device and the steel pipe injection device, respectively, at a gauge pressure of 3 kg/Cd.
After 30 minutes, blowing from the steel pipe injection device was stopped, the pressure was gradually reduced, and 10 minutes after the blowing stopped, the pressure was released to atmospheric pressure.

Claims (1)

[Scope of Claims] 1. Pressurizing a heated fluid by pressurizing it into a thermoplastic resin tube having an outer diameter smaller than the inner diameter of the tube inserted into the tube, and at the same time A method for lining the inner surface of a tube body, which comprises pressurizing the resin tube to approximately the same pressure as the inside of the tube, heating the resin tube in this state, and then gradually reducing the pressure between the tube body and the resin tube. 2. The method for lining the inner surface of a pipe according to claim 1, wherein the pipe is a steel pipe. 3. The method for lining the inner surface of a tube according to claim 1, wherein the thermoplastic resin tube is a polyethylene tube. 4. The method for lining the inner surface of a pipe according to claim 1, wherein the heating fluid is steam.