JPH0221675Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a corrosion-resistant pipe joint that improves the sealing performance of the inner surface of the threaded joint between a synthetic resin-lined metal pipe body and the pipe joint, thereby preventing corrosion of the joint. Regarding.

Conventionally, steel pipes such as water supply pipes have been mainly galvanized or coated with vinyl chloride resin, and joints have generally been made of screw-in malleable cast iron. Fig. 3 is a vertical cross-sectional view of the joint between a conventional bush, a straight pipe, and a socket, and shows a female thread 42 and a male thread 43 on both ends.
The inner surface of the bushing 41 is formed with
A synthetic resin coating 44 is applied to the parts other than the female thread 42, and a synthetic resin coating 44 is applied to the inner surface of the straight pipe 45 that is threadedly connected to the female thread 42 and the male thread 43 of the bush 41, respectively, and the entire inner surface of the socket 46 except for the threaded part. Resin coatings 47 and 48 are applied. However, in this case, each coating is formed from the threaded end and is formed only up to the edge of each member, so that the threaded ends 49 and 50 of each joint are There was a problem with oxidation corrosion and red water eventually forming. Therefore, conventional pipe joints cannot withstand long-term use, and even if replacement work is carried out, they have drawbacks such as being extremely difficult if they are embedded in a concrete wall, etc. It was hot.

In view of the above-mentioned problems and drawbacks, the present invention has been developed by integrally forming the male threaded end of the joint with an extended part of a synthetic resin body lined on the inside, and forming the female thread into a cylindrical extending part with a predetermined interval. It is an object of the present invention to provide a corrosion-resistant pipe joint which is covered with a metal pipe to improve the sealing performance of the joint part and more reliably prevent corrosion of the metal part of the main body.

Hereinafter, the present invention will be described in further detail based on the illustrated embodiments. Fig. 1 is a longitudinal cross-sectional view of an example of a bushing as a corrosion-resistant pipe joint according to the present invention, and Fig. 2 shows the embodiment of Fig. 1 for straight pipes. and a vertical cross-sectional view when connected to a socket. In Figures 1 and 2, 1 is a bush as a pipe joint, and the main body 2 is made of malleable cast iron, for example.
has a tapered male thread 3 on the outer surface of one end.
However, a tapered internal thread 4 is formed on the inner surface of the other end. On the other hand, the flat part 5 on the inner surface is lined with a synthetic resin body 6 of an appropriate thickness, and the male thread forming side end thereof extends further integrally from the main body 2, and the threaded part of the male thread 3 is extended at the outer periphery. The synthetic resin body 6 is integrally formed with a male screw tip 7 having about two threads so as to form the same shape. Further, on the side of the female thread 4, the synthetic resin body 6 extends integrally to the end edge of the main body 2 in a floating state with respect to the female thread 4, and forms a cylindrical extension portion 9 with a gap 8. . The synthetic resin body 6 is formed by injection molding, for example, from a thermoplastic resin such as vinyl chloride resin, polyethylene, polypropylene, or nylon, or a thermosetting resin such as phenolic resin or melamine.

Therefore, for such a bush 1, as shown in FIG. 2, for the male thread 3 side of the bush 1,
When the socket 10 whose inner surface is lined with synthetic resin is screwed together, the synthetic resin body 1 lined with the inner surface between the female threads 11 at both ends of the socket 10 is preliminarily inserted.
By forming a cylindrical extension part 14 at both ends of the bushing 1 in a floating state with a gap 13 corresponding to each screw 11, the end of the bush 1 fits into the gap 13. The cylindrical extending portion 14 is pressure-bonded to the inner surface of the synthetic resin body 6, thereby providing good sealing performance at this portion. The male thread 3 of the bush 1 and the female thread 11 of the socket 10 are screwed together using Teflon sealing tape or a sealant as appropriate.
It is preferable to apply an adhesive, a sealant, etc. between the synthetic resin body 6 and the cylindrical extension part 14.
Further, the end of the male thread 3 of the bush 1 forms a male thread tip 7 that is integrated with the synthetic resin body 6, so that the internal synthetic resin of the bush 1 is connected to the female thread 11 of the socket 10 in this part. The bodies 6 are brought into pressure contact with each other, and the sealing performance at the threaded portion is perfect. Therefore, the threaded portion is not affected by water flowing inside the pipe or the like, and the threaded portion is not oxidized and corroded, so that the generation of red water due to corrosion can be reliably prevented.

On the other hand, when a straight pipe 15 whose inner surface is lined with synthetic resin is threadedly connected to the female thread 4 side of the bush 1, the straight pipe 15 is connected to the cylindrical extension part 9 of the bush 1.
As a result, the synthetic resin body 16 lining the inner surface is pressed against the inner surface, resulting in an integrally joined state. In this case, it is preferable to apply an adhesive or a sealant to the joint surface between the cylindrical extension part 9 and the synthetic resin body 16, but even if no adhesive is applied, the sealing performance in this part is sufficient. will be secured. Therefore, there is no corrosion at this threaded portion due to the influence of water flowing inside the pipe, and no generation of red water occurs at this connection portion. In this case, the threaded end of the straight pipe 15 also has a synthetic resin body 16 lined inside.
If a bushing 1 is extended and has a male threaded end portion similar to the male threaded end portion 7 of the bush 1, the anticorrosion effect will be more complete. Further, in this case, a straight pipe or the like having a diameter different from the straight pipe 15 is connected to the other side of the socket 10.

By the way, the outer diameter of the cylindrical extension extending from the synthetic resin body in the above embodiment is set to be slightly smaller than the inner diameter of the welded member to be screwed together, and as it goes deeper, By increasing the size and tapering the innermost part so that it is slightly larger than the inner diameter, a good joining condition with the part to be joined can be obtained, and sufficient sealing performance can be obtained. In addition, if a relief part is formed as a recess deeper than the innermost part of the cylindrical extension part, when the anti-corrosion pipe joint of the present invention is screwed together, the male thread tip will penetrate sufficiently deep into the part.
This ensures a secure threaded fit. Furthermore, even if the tip of the male screw comes into contact with the lined synthetic resin body, elastic contact between the synthetic resins occurs, which improves the sealing performance and further improves the anti-corrosion effect.

As described above, according to the corrosion-resistant pipe joint of the present invention, there is no need to perform any special anti-corrosion treatment during construction, and the sealing of the joints is ensured by simply threading the required connections. Since this process completely prevents corrosion, it is possible to completely eliminate the generation of red water from corrosion at the joint, and even if the joint is buried inside a concrete wall, it will not deteriorate over time. It has the characteristics that it does not cause any problems and is extremely effective in construction.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of an example of a bushing as a corrosion-resistant pipe joint according to the present invention, Fig. 2 is a longitudinal sectional view of the embodiment shown in Fig. 1 when connected to a straight pipe and a socket, and Fig. 3 is a longitudinal sectional view of an example of a bushing as a corrosion-resistant pipe joint according to the present invention. FIG. 3 is a longitudinal cross-sectional view of a joint between a bush, a straight pipe, and a socket. 1...Button, 2...Body, 3...Male thread,
4... Female thread, 6... Synthetic resin body, 7... Male thread tip, 8... Gap, 9... Cylindrical extension, 10...
...Socket, 15...Straight pipe.

Claims (1)

[Scope of utility model registration request] In a pipe joint in which a metal fitting body has a male thread at one end and a female thread at the other end, the inner surface of the fitting body except for the female thread is lined with a synthetic resin body, and the synthetic resin body is attached to the male thread end. A cylindrical extension part is formed integrally with a male screw tip that extends to the side and continues to the male screw, and extends from the synthetic resin body and has a predetermined gap between it and the female screw. Corrosion-resistant pipe fittings.