JPH0211675Y2 - - Google Patents

Description

[Detailed description of the invention] This invention lines the inner surface of the metal joint body with a synthetic resin, and improves the sealing performance of the inner surface at the joint with the joint pipe, water faucet, etc. This invention relates to anti-corrosion pipe fittings that prevent corrosion.

Conventionally, galvanized steel pipes or vinyl chloride resin-lined steel pipes have been mainly used for water supply pipes in buildings, for example, and threaded malleable cast iron joints have generally been used as joints. First, this will be briefly explained with reference to FIGS. 4 and 5. FIG. 4 is a longitudinal cross-sectional view of a conventional malleable cast iron hydrant elbow, with the inner surface 22 of the elbow 21 exposed. It was just as it was. As shown in FIG. 5 as a sectional view of the water supply piping to a concrete wall, conventionally the elbow 21 has a straight pipe 10 made of galvanized or vinyl chloride resin lined steel pipe, and a water tap 11 made of gunmetal. were directly screwed together, and the straight pipe 10 and elbow 21 were buried in a concrete wall 23. Therefore, the inner surface 22 of the elbow 21 and the threaded joint are oxidized and corroded, causing so-called red water. In particular, the joint 24 with the faucet 11 is corroded due to the potential difference that occurs when joining dissimilar metals. There was a problem. If such a problem occurs, it is difficult to replace the joint because it is inside the concrete wall.
Such a piping system had to be discarded while being buried, and newly exposed piping had to be installed on the wall surface, which had disadvantages such as an undesirable appearance.

In view of the above-mentioned problems and drawbacks, the present invention has been developed by lining the inner surface of the joint with a synthetic resin material, and forming a cylindrical extension at one end with a predetermined gap from the screw formed at the end of the joint body. It is fitted to the inner surface of the joint pipe to ensure sealing at the joint and prevent corrosion, and the other end is threaded directly onto the lined synthetic resin body to attach a water tap, etc. It is an object of the present invention to provide a corrosion-resistant pipe joint which prevents dissimilar metals from being joined and which reliably prevents the occurrence of electrolytic corrosion.

The present invention will be described in more detail below based on the illustrated embodiment. FIG. 1 is a longitudinal cross-sectional view of an example of the corrosion-resistant pipe fitting according to the present invention, and FIG. 2 is a diagram of a piping system using the embodiment shown in FIG. FIG. 2 is a front view of a main part, partially shown in cross section.

In Figures 1 and 2, 1 is an elbow as a joint, and a tapered thread 3 is formed on the inner surface of one end of a main body 2 made of malleable cast iron, and a flange 4 is integrally formed on the outer surface edge of the other end. has been done. 5 is the main body 2
A synthetic resin body is lined with an appropriate thickness on the inner surface of the body other than the thread 3, and one end corresponding to the tapered thread 3 is placed in a floating state with a gap 6 between the ends of the main body 2. It extends integrally to a position corresponding to the edge, forming a cylindrical extension 7, and the other end side is formed with a slightly thinner wall of a certain width from the edge, and a parallel thread 8 is formed on its inner surface. has been done. Further, it is preferable that the synthetic resin body 5 on the side of the parallel screw 8 further has an extending portion 9 formed along the end face of the flange 4 of the main body 2, but the extending portion 9 may not necessarily be provided. The synthetic resin body 5 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, but preferably a hard synthetic resin. It is best to form it with

Therefore, if the end of the aforementioned straight pipe 10 whose inner surface is lined with synthetic resin is screwed into the tapered screw 3 as shown in FIG. 2, the inner surface of the elbow 1 will be lined. The outer diameter of the cylindrical extension part 7 of the synthetic resin body 5 is set in advance to be somewhat smaller than the inner diameter of the straight pipe 10 to which it is screwed at its end, and is made larger as it goes deeper. By tapering it to be somewhat larger than the inner diameter, the outer surface of the cylindrical extension 7 and the inner surface of the straight pipe 10 are reliably joined and sealed. The innermost part of the cylindrical extension part 7 in the synthetic resin body 5 of the elbow 1 is formed with a deeper concave part, so that when the connection with the straight pipe 10 is constructed on site, the threaded connection is prevented. If the threaded portion is longer than a predetermined length, it is preferable to prevent the tip from hitting the synthetic resin body 5 and damaging it.

On the other hand, if the above-mentioned water tap 11 is screwed into the parallel thread 8 formed on the synthetic resin body 5 on the other end side using Teflon sealing tape, sealant, etc., the water tap 11 will be completely attached to the elbow 1. Since it is attached separately from the metal part of the main body 2, electrolytic corrosion, so-called macro cell corrosion, that accompanies joining between dissimilar metals can be completely prevented. Note that if there is an extension 9 of the synthetic resin body 5 at the flange 4 part, the contact between the flange part of the faucet 11 and the flange 4 can be completely cut off, but if the extension part 9 is If not, a rubber gasket may be placed on the extending portion 9 for attachment.

FIG. 3 is a longitudinal cross-sectional view of another embodiment of the anti-corrosion pipe fitting according to the present invention, in which the entire outer surface of the pipe fitting of the embodiment in FIG. 1 has also been subjected to anti-corrosion treatment. Components that are the same as those in the embodiment shown in FIG. In this case, the entire outer surface of the elbow 1' of the main body 2 is lined with a suitably thick synthetic resin material 12 similar to the synthetic resin material 5 on the inner surface, and one end on the tapered screw 3 side is lined with a synthetic resin material 12 similar to the synthetic resin material 5 on the inner surface. A socket 13 is formed coaxially protruding outward from the end face of the main body 2, and the inner surface of the socket 13 has a tapered shape whose diameter increases from the middle part of the end face thickness of the main body 2 toward the open end side. ing. Further, the other flange 4 portion is formed continuously and integrally with the extending portion 9 of the synthetic resin body 5 on the inner surface.

Thus, according to the elbow 1', in the same manner as in the previous embodiment, the ends of the corrosion-proof pipe 14, whose inner and outer surfaces are lined with synthetic resin, are attached to the tapered screw 3 as shown by the dashed line. If you screw together,
The tube end and the elbow 1' are reliably sealed on the inner surface by the cylindrical extension 7 as in the case described above, and on the outer surface by the tapered socket 13. As a result, the space between the tube end and the outer surface is reliably sealed, and both the inner and outer surfaces can be completely protected from corrosion. In addition, if the water tap 11 is screwed to the other end of the elbow 1' as shown by the two-dot chain line, in this case, the connection between the main body 2 and the water tap 11 is completely the same as in the above embodiment. Since it is completely insulated, electrolytic corrosion due to bonding between dissimilar metals cannot occur. The anticorrosion effect in this case is thus more complete.

The present invention is not limited to the above-mentioned embodiments, and can of course be applied to other joints such as sockets and T-type joints, and the objects to be connected can be arbitrarily selected. It can also be used for other fluids, and the shape, wall thickness, degree of taper, etc. of each part of the synthetic resin body can be set as appropriate, and it goes without saying that various modifications can be made within the gist of the present invention. be.

As described above, according to the anti-corrosion pipe joint of the present invention, there is no need for special anti-corrosion treatment at the time of construction, and the piping system can be easily connected by simply threading or connecting joint pipes, water faucets, etc. The inner surface of the fitting is completely coated and sealed to prevent corrosion, completely eliminating the occurrence of red water caused by corrosion.Moreover, the fitting body and the joint between dissimilar metals such as the faucet are completely separated. Since there are no contact surfaces, there is no electrical corrosion phenomenon, and even if the piping system is buried inside a concrete wall, no problems will occur over time, which is extremely advantageous in terms of construction. It has the following characteristics.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of a corrosion-resistant pipe joint as an embodiment of the present invention, Fig. 2 is a front view of main parts showing a part of the piping system using the embodiment of Fig. The figure is a longitudinal cross-sectional view of another different embodiment of the anti-corrosion pipe joint according to the present invention, Fig. 4 is a longitudinal cross-sectional view of a conventional hydrant elbow, and Fig. 5 is a conventional piping system using the elbow of Fig. 4. It is a partial front view showing a part of as a cross section. 1, 1'... Elbow, 2... Main body, 3... Tapered screw, 5, 12... Synthetic resin body, 7... Cylindrical extension, 8... Parallel thread, 10, 14... Straight pipe ,1
1... Water tap.

Claims (1)

[Scope of utility model registration request] The inner surface of a metal joint body having a thread on the inner surface of one end is lined with a synthetic resin body except for the screw, and the one end side of the synthetic resin body extends between the thread and the thread. A corrosion-resistant pipe joint comprising a cylindrical extension with a predetermined gap and a thread formed on the inner surface of the other end.