JPH078943Y2 - Pipe fitting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an intermediate joint used when connecting a metal pipe and a pipe member made of a dissimilar metal.

<Prior Art> When a metal pipe, for example, a steel pipe whose inner surface is coated with plastic (hereinafter, simply referred to as a lining steel pipe) and a pipe member made of a different metal from the metal pipe, for example, a bronze valve, are used, the different metal is used. Electrolytic erosion due to contact, so-called galvanic corrosion becomes a problem, and to prevent such corrosion,
It is known that a packing is mounted between the front end surface of the lining steel pipe and the inner part of the piping member to cover the contact boundary between the lining steel pipe and the piping member in a watertight manner with the packing.

<Problems to be solved> However, there is a risk that the packing may be deformed abnormally or the packing may be damaged due to the amount of screwing of the tip of the lining steel pipe into the piping member. In contact with water cannot escape galvanic corrosion.

For this reason, it is known to use an intermediate joint made of metal having an intermediate potential between the metal and the piping member. In this intermediate joint, the potential difference between dissimilar metal contacts is halved due to the intermediate potential medium. However, it cannot completely prevent carbanic corrosion and only delay corrosion damage.

It is an object of the present invention to provide a joint that can prevent corrosion almost completely in the medium joint between the metal pipe and the piping member.

<Means for Solving the Problem> A pipe joint according to the present invention is a joint for intermediating connection between a metal pipe and a pipe member made of a dissimilar metal, and the pipe member is watertightly screwed to the pipe member. A portion of the male screw portion closer to the tip than the middle is made of a metal having a potential substantially equal to that of the metal forming the piping member, and an anticorrosion coating is provided on the inner peripheral surface. .

<Description of Embodiments> Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory view showing an embodiment of the present invention, in which an upper half portion is shown in a longitudinal section and a lower half portion is shown in a side surface.

In FIG. 1, reference numeral 1 denotes a male screw portion on the tip side, which is screwed into the piping member A. Reference numeral 2 denotes a female screw portion on the rear end side, into which the front end of the metal tube B is screwed. Reference numeral 10 denotes a tip member that constitutes the tip side from the middle of the male screw portion 1, and uses a metal having a potential substantially equal to the potential of the metal that constitutes the piping member A. Reference numeral 20 denotes a joint body, which is made of metal having a potential substantially equal to that of the metal tube B. Reference numeral 3 is an anticorrosion coating layer provided on the inner peripheral surface, which is usually formed by powder coating using a resin such as polyolefin sulfide.

In the above description, the boundary P ₁ between the tip member 10 and the joint body 20 on the outer surface of the male threaded portion 1 is at a position where almost all of the internal pressure water and the external water can be stopped, and on the inner peripheral surface of the joint. The boundary P ₂ between the tip member 10 and the joint body 20 is the anticorrosion layer 3
Since the boundary P ₂ does not come into contact with the liquid by being coated with, the dissimilar metal corrosion does not occur even though the tip member 10 and the joint body 20 are dissimilar metals. Further, between the tip member 10 and the piping member A, and between the joint body 20 and the metal pipe B,
Since it is the contact of the same kind of metal having almost the same electric potential, corrosion of different kinds of metal can be eliminated even between them.

The tip member 10 and the joint body 20 on the outer periphery of the male screw portion 1
The boundary position P _{1 with} is usually ₁ to 9 threads from the tip,
Preferably, the number of threads should be 2 to 6. Further, the anticorrosion coating layer 3 on the inner peripheral surface does not have to be provided over the entire length, and may be any one that can seal the boundary between the tip member and the joint body on the inner peripheral surface in a watertight manner.

It is desirable that the tip member 10 and the joint main body 20 be connected by a step surface as shown in FIG. Bonding can be by gluing, reverse screw threading, quenching, or caulking. The male thread processing of the tip portion is usually performed after this connection.

In the above description, it is ideal to use the same metal as the pipe member A for the tip member 10 and the same metal as the metal pipe B for the joint body 20 from the viewpoint of preventing corrosion of dissimilar metal contacts,
It is necessary to take into consideration the joint strength between the tip member 10 and the joint body 20, the joint workability, and the like. For example, when the pipe member A is made of bronze and the metal pipe B is a lining steel pipe, it is desirable to use gun metal for the tip member 10 and malleable or ductile for the joint body 20.

FIG. 3 shows the connection between the bronze valve A and the lining steel pipe B using the joint of the present invention. The tip member 10 of the joint is a gun metal of the same material as the bronze valve A, and the joint body 20 has a potential almost equal to that of steel. I'm using Marable. When the lining steel pipe B and the joint body 20 are screwed together, the packing 4 is mounted in the packing mounting groove 21 of the joint, and the packing 4 is compressed by screwing the tip of the lining pipe.
The metal exposed portion on the pipe end surface of the lining steel pipe B is prevented from being corroded by the liquid contact. 41 is a corrosion resistant core for packing support, and b is a plastic lining. The male screw portion 1 of the joint and the valve A are watertightly screwed together via a tape seal.

<Effect of the Invention> The intermediary joint according to the present invention is configured as described above,
Since the pipe member and the intermediate joint and the intermediate joint and the metal pipe can be in the same kind of metal contact, the dissimilar metal corrosion between them can be almost completely eliminated. In addition, the boundary between the joint tip portion and the other joint portion (joint body), which have almost the same potential as the piping member, is a contact with different metals, but the boundary on the outer peripheral side exists at the watertight screwing interface with the piping member, Since the boundary on the peripheral side is covered with the anticorrosion layer, the corrosion at the boundary between different metals can be eliminated.

Therefore, according to the intermediary joint of the present invention, dissimilar metal pipes and piping members can be connected without fear of galvanic corrosion.

[Brief description of drawings]

1 and 2 are explanatory views showing an embodiment of the present invention, and FIG. 3 is an explanatory view showing a connecting portion between a pipe member and a metal pipe using the pipe joint of the present invention. 1 ... Male screw part, 10 ... Part closer to the tip side than the middle of the female screw part,
3 ... Anticorrosion coating layer.

Claims (1)

[Scope of utility model registration request] 1. A joint for interposing a metal pipe and a pipe member made of a dissimilar metal between the metal pipe and a portion closer to the tip than the middle of a male threaded portion which is water-tightly screwed to the pipe member. A pipe joint made of a metal having an electric potential substantially equal to that of the metal forming the piping member, and having an inner peripheral surface provided with an anticorrosion coating.