JPH0646077B2 - Electrically insulating joint - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrically insulating pipe joint for incorporation in a piping system to prevent corrosion of the piping system.

[Prior Art] Various types of electrically insulating pipe joints to be incorporated into a part of a piping system have been proposed, but all of them have a disadvantage in terms of performance or manufacturing such as those having a peculiar structure or complicated structure. There were many.

For example, the one disclosed in Japanese Patent Laid-Open No. 52-129013 discloses an insulating element such as an O-ring that hermetically closes one engaging end between an inner and an outer cylindrical coupling member that engages with each other in a fitting manner. Is provided, and a sealing material containing a compound for bonding an epoxy resin and a curing agent is poured into the space between the both cylindrical members from the other engaging end to bond the outer and inner cylindrical coupling members.

In addition, the one disclosed in Japanese Utility Model Application Laid-Open No. 57-10583, which is filed by the present applicant, has an outer cylinder tube on the outside and an inner cylinder tube on the inside through a resin bush provided with male and female threads for engagement on the inner and outer surfaces. Are engaged with each other to hold a space in the inner and outer cylindrical tubes, and a refractory cement having insulation and fire resistance is filled in the space between both members and solidified integrally.

[Problems to be Solved by the Invention]

In the former prior art, the work of pouring the sealing material containing the bonding compound between the inner and outer cylindrical members is very complicated and difficult. Further, a size interval is required for pouring the sealing material between both members. For example, when the sealing material made of epoxy resin disappears in a fire, there is a problem that the inner and outer cylindrical coupling members come out and a large amount of gas is ejected.

The latter conventional technique has fire resistance in the event of fire by filling with fire-resistant cement, but the work of pouring the cement into the space between the inner tube and the outer tube is complicated and difficult. Further, the cement in a dry state has hygroscopicity, and there is a problem that the insulating property is deteriorated by the cement that has adsorbed moisture.

The present invention solves the above problems and provides an electrically insulating joint that has a simple structure, is excellent in insulation performance and mechanical strength, has fire resistance during a fire, is easy to manufacture, and can be mass-produced. It is a thing.

[Means for Solving the Problems]

The gist of the present invention is to provide a pair of an outer tube and an inner tube having a gap between the female thread and the male thread in a state where the female thread of the metallic outer tube and the male thread of the metal inner tube are screwed together. A pipe, an insulating member coated on at least one surface of the female screw and the male screw, and a state in which the coated insulating member is present in a screwed gap between the female screw and the male screw, the female screw and the male screw are An electrical insulating joint characterized by comprising: an adhesive that seals and fixes a space between the screwed parts.

In the above, a conventional threaded joint can be used for the outer tube and the inner tube.

In order to provide a gap between the male screw and the female screw, the male screw may be made thin and the female screw may be made thick, but at that time, the outer diameter of the male screw should not be smaller than the inner diameter of the female screw.

As the insulating member that covers the surface of the screw, glass lining (enameled) or epoxy resin coating is used.

[Work]

The outer cylindrical tube and the inner cylindrical tube are insulated by the insulating member with which the thread surface is covered with the female thread and the male thread in a screwed state, and the airtightness is maintained by the adhesive.

Due to this screw-threaded coupling, the coupling strength between the outer tubular pipe and the inner tubular pipe is high, and it has sufficient strength even when used for general pipes such as gas and water.

Even if the insulating material disappears due to a fire in the indoor gas pipe, it will be retained by the male and female threads being screwed together.
The pipe will not come out of the joint or a large amount of gas will not be ejected.

Also, because it is insulated with an insulating member that covers the surface of the screw,
In manufacturing, it is possible to uniformly interpose the insulating member instead of pouring the insulating material into the space between both members as in the conventional case.
A joint having uniform insulation performance can be easily manufactured.

〔Example〕

 Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention.
Trapezoidal screw 1 so that the outer tube 2 has a gap of 1 mm on each side.
b and 2b are formed, and the insulating member 3 is sandwiched between them to be screwed together to be assembled. Inner tube 1 and outer tube 2
Is provided with taper screws 1a and 2a for connecting to a pipe.

The insulating member 3 and the trapezoidal screws 1b and 2b are fixed to each other with an adhesive to prevent the insulating member 3 from loosening during screwing in connection with the pipe. Insulating packing 4 is sandwiched between the inner cylindrical tube 1 and the outer cylindrical tube 2 at the inner end of the inner cylindrical tube 1 to maintain insulation and airtightness.

Since the above insulating joint has a small number of parts, it is easy to assemble, has sufficient mechanical strength as a pipe joint, and leaks of internal fluid are minimal even in the event of a fire.

FIG. 2 shows a second embodiment of the present invention, in which a powder coating (hereinafter referred to as an insulation coating) 7 by an insulating member of the male thread portion 5b of the inner cylindrical pipe 5 using a pipe fitting female-male socket is applied, It is an electrically insulative joint that is fitted and assembled to the female thread portion 6b of the outer cylinder pipe 6 using a pipe joint socket.

Tapered screws 5a, 6a for connecting the pipes are provided at the ends of the assembled inner pipe 5 and outer pipe 6. The insulating coating 7 is coated with not only the taper male screw portion 5b of the inner cylindrical tube 5 but also the excess coating portions 7a and 7b having a length both on the inner and outer surfaces. There is.

The taper male threaded portion 5b of the inner tubular tube 5 and the taper female threaded portion 6b of the outer tubular tube 6 after the insulation coating are fitted with a sufficient tightening torque so that the screwed-in portion does not become loose. It is assembled. Therefore, the fitting portion does not loosen even when connected to the pipe, and the airtightness is maintained.

The electrically insulating joint described above is capable of sufficiently satisfying the electrical insulating property and the function as the pipe joint similarly to the electrically insulating joint of the first embodiment, and since the conventional screw-in type pipe joint can be used, It is easy to manufacture and has excellent mass productivity.

As can be understood from the above description, the screw of the insulating portion of the electrically insulating joint of the present invention may be a trapezoidal screw, a triangular screw, a square screw, a round screw, and a screw structure in which a male screw and a female screw are screwed with each other. If so, the thread shape is not restricted.

Further, in the above-mentioned embodiment, the connecting portion with the pipe is the female thread 1a,
Although the screwing type of a, 5a, and 6a has been described, a connecting portion of another connecting type such as a mechanical type may be used.

Further, in the above embodiment, the pipe joint shape of the straight pipe connection has been described, but an elbow connection, a tee or other connection structure may be used.

〔The invention's effect〕

As described above, the electric insulating joint of the present invention can use an existing pipe joint, and by coating the surface of the screw with an insulating member, an insulating joint having uniform insulating performance can be easily manufactured. And is excellent in mass productivity.

Further, since the insulating portion is screw-coupled, high mechanical strength peculiar to screw-joint can be maintained.

In addition, since it is held in a narrow insulation gap between screw threads, even if the insulation member disappears in the event of a fire, the piping will not come out and a large amount of internal fluid will not be ejected, which is safe for the sealing property in the event of a fire. is there.

[Brief description of drawings]

FIG. 1 is a sectional view of an electrically insulating joint showing a first embodiment of the present invention. FIG. 2 is a sectional view of an electrically insulating joint showing a second embodiment of the present invention. 1: Inner tube tube, 2: Outer tube tube, 3: Insulating member, 4: Insulating packing, 5: Inner tube tube, 6: Outer tube tube, 7: Insulation coating.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Iwamura 3-3, Kumomidai, Isogo-ku, Yokohama-shi, Kanagawa (56) References JP-A-58-170991 (JP, A)

Claims (1)

[Claims] 1. A pair of an outer tube and an inner tube having a gap between the female thread and the male thread in a state where the female thread of the metallic outer tube and the male thread of the metal inner tube are screwed together. And an insulating member coated on at least one surface of the female screw and the male screw, and with the coated insulating member interposed in a threaded gap between the female screw and the male screw, the female screw and the male screw are screwed together. An electrically insulative joint comprising: an adhesive that seals and fixes the gap between the mated parts.