JPS5827186Y2 - Connection between internally coated steel pipe and pipe fitting - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a connecting portion between an internally coated steel pipe and a pipe joint.

Conventionally, when connecting internally coated steel pipes, in order to prevent corrosion of the pipe end and also to prevent liquid leakage from the joint, the inner pipe was covered with an iron gassho lid, as disclosed in Japanese Utility Model Publication No. 37-18144. A joint pipe joint has been proposed in which a backing is fitted into the inside of a joint pipe joint that is clamped and fixed into one piece so that the joint pipe can be inserted into the thread.

However, even if you try to tighten the joint pipe to the joint pipe joint, the backing is pressed between the end of the inner cylinder and the end of the joint pipe, and the joint between the joint pipe joint and the joint pipe is It bulges out in the inner circumferential direction of the pipe and easily falls off, and it is not possible to securely fasten it to the joint pipe joint through the backing, which prevents corrosion on the end surface of the joint pipe and prevents liquid from leaking from the joint. There was a drawback that it was not possible to do it adequately.

In order to improve this drawback, the present inventor first applied for
No. 5496, a pipe joint is made of an internally coated steel pipe whose end face is abutted with an annular elastic body and a flanged short pipe is crowned so as to cover the end face of the elastic body and the inner peripheral surface of the tube end. We proposed screwing them together, but if they are tightened tightly, there is no escape for the annular elastic body, which may push the short pipe part of the flanged short pipe inward and cause it to bulge. It is not necessarily sufficient to prevent liquid leakage.

The present invention has been made with the aim of solving the drawbacks of the conventional ones as mentioned above, and its gist is that a female thread is provided on the inner surface of the open end, and a female thread is provided on the inner circumferential surface of the deep part along the circumferential direction. A pipe joint is provided with a concave groove, and a protrusion is provided along the circumferential direction on the inner circumferential surface of the deep end of the concave groove. An inner surface formed by screwing together an internally coated steel pipe in which an annular elastic body with an outer diameter smaller than the groove is abutted, and a flanged short pipe is crowned so as to cover the end face of the elastic body and the inner peripheral surface of the tube end. Located at the connection between coated steel pipe and pipe fitting.

Hereinafter, the present invention will be explained with reference to an embodiment of the drawings.

Reference numeral 1 denotes a pipe joint, in which a tapered acid threaded portion 11 is provided on the inner circumferential surface of the end thereof, a groove 12 is provided along the circumferential direction on the inner circumferential surface of the deep part, and a groove 12 is provided in the deep inner circumferential surface of the groove. A protrusion 13 is provided on the circumferential surface along the circumferential direction.

Reference numeral 2 denotes an inner-coated steel pipe, in which a corrosion-resistant coating layer 22 made of synthetic resin or the like is provided on the inner surface of the steel pipe 21, and a tapered male threaded portion 23 is provided on the outer peripheral surface of the pipe end.

3 is an annular elastic body, which has an outer diameter smaller than the concave groove 12 of the pipe joint 1 before the internally coated steel pipe 2 is screwed into the pipe joint 1; They have approximately the same wall thickness.

Reference numeral 4 denotes a short pipe with a flange, and a flange 42 having an outer diameter substantially the same as the outer diameter of the annular elastic body 3 is provided at one end of the short pipe 41 having an outer diameter that is substantially the same as the inner diameter of the internally coated steel pipe 2. It is made of synthetic resin such as hard vinyl chloride resin to provide corrosion resistance and sealing performance.

One end surface of the annular elastic body 3 is brought into contact with the end surface of the internally coated steel pipe 2 on which the tapered salt threaded portion 23 is provided so as to cover the joint between the steel pipe 21 and the coating layer 22 .

A short flanged tube 4 is crowned so as to cover the other end surface of the elastic body 3 and the inner circumferential surface of the tube end of the internally coated steel tube 2.

With the flanged short pipe 4 mounted on the internally coated steel pipe 2 via the elastic body 3 in this manner, the tapered salt threaded portion 23 at the end of the pipe is screwed into the tapered female threaded portion 11 of the pipe fitting 1. When tightened, the outer surface of the flange 42 of the short pipe 4 with a housing and flange comes into contact with the protrusion 13 of the pipe joint 1, forming a part of the sealing surface.

The flat flanged short pipe 4 presses the elastic body 3 against the end face of the internally coated steel pipe 2, and seals the end face from the outside to prevent corrosion.
The elastic body 3 is surrounded by the flanged short tube 4 and will not fall off inward.

Moreover, the taper 1 threaded portion 11 and the tapered salt threaded portion 2
3, the threaded state of the two varies, and even if the compression conditions of the elastic body 3 fluctuate, the elastic body 31 that is about to be compressed excessively will not move the short tube 41 of the flanged short tube 4. The elastic body 3 is deformed by seeking refuge in the groove 12 without being pressed inward to bulge, and the elastic body 3 is more effectively pressed against the end face of the inner-coated steel pipe 2.

The housing elastic body 3 bulges in the outer circumferential direction, and a secondary sealing surface is formed in front of the threaded portion between the tapered female threaded portion 11 and the tapered salt threaded portion 23.

In the above embodiment, the female thread and the male thread are tapered threads, but they may be parallel threads.

However, tapered screws have the advantage of making the screwing state stronger.

As mentioned above, the connection between the internally coated steel pipe and the pipe fitting of the present invention is such that the pipe joint has a concave groove and a protrusion in the circumferential direction on the inner peripheral surface of the male threaded part, and a male thread is provided on the outer peripheral surface of the pipe end. An annular elastic body having an outer diameter smaller than the concave groove of the pipe joint is brought into contact with the end face of the annular elastic body, and the flanged short pipe is covered with the end face of the elastic body and the inner circumferential surface of the tube end. Since the crowned inner-coated steel pipe is screwed together, the annular elastic body is pressed against the end surface of the inner-coated steel pipe and does not fall off inward, and the elastic body that is about to be tightened by the excess neck is prevented. Presses the flanged short pipe inward, deforms it into a groove without causing it to bulge, and is pressed against the end surface of the internally coated steel pipe due to extra pressure, causing the steel pipe and the coating layer to separate. The pipe end face of the inner-coated steel pipe and the threaded joint between the female thread of the pipe joint and the male thread of the inner-coated steel pipe are completely sealed without any corrosion, and liquid leakage from the joints is sufficiently prevented. It can be carried out.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view of an example of a pipe joint used in the present invention, Fig. 2 is a partially cutaway front view showing one embodiment of the present invention, and Fig. 3 is another embodiment of the present invention. It is a partially cutaway front view showing an example. Explanation of symbols: 1...Pipe joint, 2...Inner coated steel pipe, 3...Elastic body, 4...Short pipe with flange, 11... ...Female thread part, 12...
Concave groove, 13... protrusion, 23... male threaded portion.

Claims (1)

[Scope of utility model registration request] A female thread is provided on the inner circumferential surface of the opening end, a groove is provided along the circumferential direction on the inner circumferential surface of the deep part, and a protrusion is provided along the circumferential direction on the inner circumferential surface of the deep end of the groove. The pipe fitting is provided with a male thread on the outer peripheral surface of the pipe end, and an annular elastic body having an outer diameter smaller than the concave groove of the pipe joint is brought into contact with the end face of the male thread, and the end face of the elastic body and the inner peripheral surface of the pipe end are in contact with each other. A connection between an inner-coated steel pipe and a pipe fitting, in which an inner-coated steel pipe is screwed together with a flanged short pipe.