JPS5930470B2 - External lining method for metal pipes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of applying a resin lining to the outer surface of a metal tube.

BACKGROUND ART Conventionally, as a method of applying resin lining to the outer surface of irregularly shaped pipes such as elbow pipes and T pipes, and relatively short straight pipes, there is a method using a fluidized dipping method.

In this method, the pipe to be lined is heated and immersed in a fluidized tank in which resin powder flows, and then the flow of the resin powder is stopped to weld the resin powder to the outer surface of the pipe. Although some results can be achieved, a large amount of air is sent into the fluidization tank to fluidize the resin powder, so after putting the pipe to be lined into the fluidization tank and immersing it, stop the air supply to fluidize the resin powder. Even when the fluidization tank is stopped, air remains in the fluidized tank, which creates a path for air to pass through the lining film, causing unevenness and wrinkles in the film, or when the resin powder is welded to the lined pipe. There was a problem that a film containing air could be formed.
This is due to a decrease in the bulk density of the resin powder due to residual air in the fluidization tank.To solve this problem, after the fluidization of the resin powder has stopped, the resin powder is pressurized from above. Although some methods have been used to increase the bulk density of the resin powder, this method does not allow sufficient removal of air between the resin powders, making it difficult to increase the bulk density of the resin powder. It was not possible to form a satisfactory lining film. The present invention was made with the aim of solving the problems of the conventional fluidized immersion lining method as described above. After pouring the fluidized resin powder into the fluidized tank and immersing it,
The method for lining the outer surface of a metal tube in which the flow of resin powder is stopped and the resin powder is welded to the outer surface of the pipe is characterized in that after the flow of the resin powder is stopped, air in the fluidized tank is sucked. It is something.

Next, an example of implementation of the present invention will be explained with reference to the drawings.

1 is a fluidized tank; 2 is a resin powder as a lining material put therein; 3 is a pipe for supplying and discharging air to the fluidized tank 1; and 3a is a pipe 3 with many branches located in the fluidized tank 1. 4 is a blower; 5 is an air suction pipe connected to the blower 4; 6 is an opening/closing door provided on the pipe 5;
7 is a pipe connecting the pipe 3 and the suction pipe 5, 8 is an opening/closing damper provided on the pipe T, 9 is a switching damper, 10 is a pipe connecting the blower 4 and the switching damper 9, 11 is a switching damper 9 and the pipe 1
12 is an exhaust pipe connected to the switching damper 9, and the switching damper 9 is connected to the pipe 11 or the exhaust pipe 12 by switching the damper 9.

When constructing the lining, first, the opening/closing damper 6 is opened, the opening/closing damper 8 is closed, and the switching damper 9 is communicated with the pipe 11, and the blower 4 is driven to blow air into the suction pipe 5. Suction from blower 4, piping 10,
Nozzle 3a via switching damper 9, piping 11, 7 and 3
The pipe P to be lined heated above the melting temperature of the resin powder 2 is thrown into the fluidized tank 1, and the pipe P to be lined heated to a temperature higher than the melting temperature of the resin powder 2 is poured into the fluidized tank 1 and immersed therein. 6 is closed, the opening/closing damper 8 is opened, and the switching damper 9 is communicated with the exhaust pipe 12 to suck the air in the fluidization tank 1 through the nozzle 3a, and the air is transferred to the pipe 3.
, 7, the suction pipe 5, the blower 4, the piping 10, the switching damper 9, and then the exhaust pipe 12.

By doing this, after the resin powder 2 stops flowing, the air between the resin powders is discharged from the fluidized tank 1, and the bulk density of the resin powder 2 in the tank 1 increases. It adheres well to the outer surface, producing a high-quality lining film with no irregularities, wrinkles, or pinholes.

In fact, using a blower with a suction force of 1400 mAg,
When the B-bend pipe was lined with polyethylene by the above method, an extremely high-quality lining film was formed on the surface of the bend pipe.

The present invention is as described above, and in a method of lining the outer surface of a metal tube by a fluidized dipping method, conventionally, a heated pipe to be lined is immersed in a tank in which resin powder, which is a lining material, flows, and then the resin powder is flowed. In order to stop the process and increase the bulk density of the resin powder to obtain a high-quality lining film, methods such as applying pressure to the resin powder from above have been adopted. In contrast, the present invention has solved the problem where it was not possible to obtain a high-quality lining film because the height could not be increased sufficiently, and foreign matter often got mixed into the resin powder, causing unevenness, wrinkles, pinholes, etc. to be formed in the lining film. This method increases the bulk density of the resin powder by sucking the air in the tank after the flow of the resin powder has stopped, so the work is safe and there is no risk of foreign matter getting mixed into the resin powder, and the bulk density of the resin powder can be increased. Since it can be made sufficiently high, an extremely high quality lining film can be obtained. It goes without saying that the method of the present invention is not limited to lining the outer surface of vent pipes, but can also be applied to lining irregularly shaped pipes such as T pipes and straight pipes.

In addition, when implementing the method of the present invention, a blower for sending air into the fluidized tank and a blower for suctioning air from the fluidized tank are installed together, and by switching a switch, the flow of resin powder and the air from the fluidized tank are controlled. The suction may be performed continuously.

[Brief explanation of drawings]

The figures show one mode of carrying out the method of the present invention. Fig. 1 shows a state in which resin powder is fluidized; and Fig. 2 shows a state in which air in the fluidization tank is sucked. 1...Fluidized tank, 2...Resin powder, 3.
...Piping, 3a...Nozzle, 4...
...Blower, 5...Air suction pipe, 6...
・Opening/closing damper, 7... Piping, 8... Opening/closing damper, 9... Switching damper, 10, 11...
...Piping, 12...Exhaust pipe, P...
- Lined pipe.

Claims (1)

[Claims] 1. After heating the pipe to be lined to a temperature higher than the melting point of the resin powder serving as the lining material and immersing it in a fluidized tank where the resin powder flows, the flow of the resin powder is stopped and the resin powder is welded to the outer surface of the pipe. A method for lining the outer surface of a metal tube, the method comprising: sucking air in the fluidized tank after stopping the flow of the resin powder.