JPS5934474B2 - Manufacturing method for internally coated steel pipe with flanges - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a flanged inner-coated steel pipe in which an annular body is welded without damaging the inner-coated layer of the inner-coated steel pipe.

Conventionally, when forming a flange by welding an annular body to the outside of the tube end of an inner-coated steel pipe, the inner coating layer at the tube end is damaged by the heat during welding, so the inner coating layer at that part is removed.
A short tube is inserted there to cover that part, but
This work was complicated, and the short tubes were not sufficiently covered, so there was a drawback that this part could not be sufficiently protected against corrosion.

The purpose of the present invention is to eliminate the conventional drawbacks such as sloping.The gist of the present invention is to close the inside of the pipe end of an inner-coated steel pipe, cool the inside with a fluid, and cool the inner-coated steel pipe. The present invention relates to a method for manufacturing a flanged inner-coated steel pipe, characterized in that a flange portion is formed by welding an annular body to the outside of the pipe end of the steel pipe.

Hereinafter, the present invention will be explained by way of examples with reference to the drawings.
1 is an inner-coated steel pipe, and a corrosion-resistant coating layer 12 made of synthetic resin or the like is provided on the inner surface of the steel pipe 11.

Reference numeral 2 denotes a closure device that closes a certain section inside the pipe end of the internally coated steel pipe 1. Discs 22 and 22' are fixed to the left and right middles of the shaft 21, respectively, and internally threaded parts 211 and 211' are provided at both ends of the shaft 21. is provided, and the disc 2 of the shaft 21
2 and 21', annular packing 23,
Push plates 24, 24' are inserted through 23', and the fastener 2
5 and 25' are internally threaded parts 211 and 211' of the shaft 21.
I'm being squeezed.

One end of the obturator 2 can be inserted into the end of the internally coated steel pipe 1 by sliding the outer periphery of the annular packing 23, and the other end of the obturator 2 is inserted into the end surface of the internally coated steel pipe 1. The inner side surface of the annular packing 23' can be brought into contact with the annular packing 23', and a certain section inside the pipe end of the internally coated steel pipe 1 can be closed off.
Inlet 26 and outlet 2 for cooling fluid such as water to the section
7 is the other push plate 24', annular packing 23', disk 2
2'. Reference numeral 3 denotes a flange-forming annular body, the inner diameter of which is the same as or slightly larger than the outer diameter of the inner-coated steel pipe to be welded.

The annular body 3 is attached to a predetermined position on the outside of the inner-coated steel pipe 1 where a flange portion is to be formed, and one end of the obturator 2, which is diagonally upward, is attached to the outer periphery of the annular packing 23 inside the inner-coated steel pipe 1. Then, the fastener 25' is tightened so that the inner surface of the other annular packing 23' comes into contact with the pipe end surface, thereby closing a certain section inside the pipe end. Inlet 26 and outlet 2T for cooling water to that section
is circulated to sufficiently cool the coating layer 12 at the end of the inner-coated steel pipe 1.

In this state, the annular body 3 is welded to a predetermined position outside the end of the inner-coated steel pipe 1 to form a flange portion without damaging the coating layer 12. Thereafter, the circulation of the cooling water is stopped, the cooling water is discharged through the discharge port 2T, the obturator 2 is removed, and the formation of the flange portion is completed. Note that the obturator is not limited to the oblique embodiment, but any obturator can be used as long as it can close the inside of the end of the internally coated steel pipe 1 and cool the inside with fluid.

Further, cooling does not necessarily have to be carried out in a circulation manner as described above, but may be carried out in any manner in which the cooling fluid is filled and sealed.

Since the present invention has a similar structure, when a flange portion is formed by welding an annular body to the outside of the pipe end of an internally coated steel pipe,
The inner coating layer at the tube end is in a cooled state, and the inner coating layer is not damaged by absorbing heat during welding, and welding can be performed quickly and reliably by a simple means.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view illustrating an embodiment of the present invention. Explanation of symbols, 1... Internally coated steel pipe, 2...
... Obturator, 3... Annular body, 11...
Steel pipe, 12... Coating layer, 23, 23'...
...Annular packing.

Claims (1)

[Claims] 1. An internally coated steel pipe characterized in that the inside of the pipe end of the internally coated steel pipe is closed, the inside of the pipe is cooled by a fluid, and an annular body is welded to the outside of the pipe end of the internally coated steel pipe to form a flange part. Production method.