JPH067272Y2 - Electrically insulated pipe fittings for gas pipes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a screw-in type electrical insulating pipe joint for a gas pipe.

[Conventional technology]

As this kind of conventional electrical insulation pipe joint, an outer cylinder and an inner cylinder each having a predetermined standard diameter screw for screwing a gas pipe to a gas pipe connection portion are formed, and an alumina cement or the like is fitted to a fitting portion of both cylinders. It is well known that the electrical insulating material is filled in and integrated with each other by filling it with an electrically insulating filler. However, such a material has an extremely complicated structure and the number of parts is also large. There is a problem that many of them cannot be made light and compact and cannot be provided at low cost.

For this reason, recently, as disclosed in Japanese Patent Laid-Open No. 61-153091, for example, as shown in FIG.
In addition, a different-diameter female thread 103 having a diameter different from a predetermined standard female thread diameter to which the pipe 105 to be connected can be screwed is formed, and a high-diameter female thread 103 is formed on the surface of the different-diameter female thread 103 to correct it to a standard diameter 102a thread. An electrically insulated joint for gas pipes has been proposed, in which a screw-shaped electrically insulating member 104 made of a composite material of a molecular material and an inorganic fiber material having electrical insulation is adhered in a threaded manner. According to such an electrically insulated joint for a gas pipe, it is possible to achieve various effects such as a great reduction in the number of parts, an extremely simple structure, and a great weight and compactness.

[Problems to be solved by the invention]

However, in the electrically insulating joint for gas pipes disclosed in the above-mentioned JP-A-61-153091, the screw at the tip of the pipe 104 shown in FIG. 3 has a threaded tubular shape.
Immediately before reaching the incomplete thread portion 104a, the thread 105a on the base side of the pipe 104 scrapes the opening end surface 104c of the electric insulating member 104, and in particular, the outer diameter of the thread 105a is large in the tolerance range, and therefore the opening end surface 104c. When scratched, the screw thread 105a may come into contact with the metal part of the joint body 102 and cause dielectric breakdown.

In the case of the electrically insulating joint of FIG. 3, when it is connected to the pipe 104 and buried in the ground, it exists in the ground because the surface of the opening end face 102b of the joint body 102 is exposed to the outside. Foreign matter capable of electrical conduction may straddle between the surface of the opening end face 102b and the threaded portion 105b on the base side of the pipe 104 and become clogged, so that the joint body 102 and the pipe 104 are electrically conducted and insulated. There was also the problem of causing destruction.

The present invention has been made in view of the above circumstances, and provides an electrically insulating pipe joint for a gas pipe capable of preventing the above-mentioned dielectric breakdown without impairing the characteristics of the conventional electrically insulating joint shown in FIG. The purpose is to do.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the electrical insulation pipe joint for gas pipes of the present invention is configured such that the gas pipe is screwed to at least one gas pipe connection portion of the metal joint body. A different diameter female thread having a diameter different from the predetermined standard female thread diameter is formed, and a tapered surface that expands toward the opening end face side is formed over the entire circumference in the opening of the joint body that is continuous with this different diameter female thread. On the surface of this female screw with a different diameter, in order to correct it to the standard female screw diameter, a threaded tubular portion of an electrically insulating member made of a composite material having electrical insulation between a polymer material and an inorganic fiber material is screw-bonded. In addition, the ends of the electrically insulating member that are continuous from the threaded tubular portion are also bonded to the surfaces of the tapered surface and the opening end surface.

[Operation] According to the present invention, as in the case of the conventional electrically insulated joint shown in FIG. 3, the electrically insulating member is screwed on the surface of the female screw of different diameter of the joint body to correct it to the standard female screw diameter. Since they are bonded together, the electrically insulating member can electrically insulate the connecting gas pipe from the joint body.

Moreover, in the case of the present invention, a taper surface that expands toward the opening end face side is formed over the entire circumference in the opening of the joint body that is continuous with the female screw of different diameter, and the end of the electrical insulating member is formed on the surface of this taper surface. Since the parts are bonded, even if the screw thread on the base side of the gas pipe hits the opening end of the electric insulating member, the screw thread on the base side hits the opening end of the tapered electric insulating member, The screw thread on the root side bites into the open end of the electric insulating member to some extent, and is stopped without reaching the metal portion of the joint body. Therefore, the screw thread on the root side does not scratch the opening end surface of the electrical insulating member and come into contact with the metal portion of the joint body, causing dielectric breakdown.

Further, in the case of the present invention, since the end of the electrically insulating member is adhered to the surface of the opening end face of the joint body, the electrically conductive foreign matter existing in the ground is buried in the joint body so that the electrically conductive foreign matter exists in the joint body. Even if there is a clogging between the surface of the opening end face of and the threaded portion on the root side of the gas pipe, the end of the electrical insulating member adhered to the surface of the opening end face of the fitting body causes The electrical connection with the gas pipe can be cut off.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

That is, in the gas pipe electrically insulated pipe joint 1 of this embodiment, first, the threaded portion of each pipe 5 is screwed to each end inner peripheral portion of the cylindrical joint body 2 made of a metal material such as malleable cast iron. Different diameter internal thread 2a with a diameter larger than the standard internal thread diameter
Is formed as a taper screw, and at the opening of the joint body 2 that is continuous with each female screw 2a having a different diameter, approximately 4 mm toward the opening end side.
A tapered surface 2b that spreads at an angle of 5 ° is formed over the entire circumference. Then, on the surface of each of the different-diameter female threads 2a, there is provided a threaded tubular portion 4a having an outer peripheral shape having a thread shape that can be tightly screwed into the different-diameter female thread 2a and an inner peripheral shape having a thread shape that matches a standard female thread diameter. Each gas pipe connecting portion 1a is formed by adhering the electrical insulating member 4 in a threaded manner, and is connected to the threaded tubular portion 4a of the electrical insulating member 4 on the surfaces of the tapered surface 2b and the opening end surface 2c. The end 4b is adhered.

The electrical insulating member 4 is a composite material (prepreg treated with inorganic fiber material such as glass fiber, aromatic polyamide fiber, etc.) containing epoxy resin and other semi-cured thermosetting polymer material that has not been thermoset. One or a plurality of the composite materials are laminated depending on the thickness of the electric insulating member 4. The thickness of the electric insulating member 4 is set to a substantially uniform thickness smaller than the depth of each female screw 2a having a different diameter, and is set to 0.1 to 0.8 mm.

The electrical insulation member 4 is adhered to the joint body 2 by first applying an epoxy resin to the adhesive surface and then joining the electrical insulation member 4 to the joint body 2 and impregnating the electrical insulation member 4 with a polymer material. It is performed by thermosetting the epoxy resin applied to the adhesive surface. However, when the aromatic polyamide fiber is used as the inorganic fiber material, it is not necessary to separately apply the epoxy resin to the adhesive surface as described above because the fiber material has a porous shape and the amount of the polymer material impregnated is large.

The gas pipe electrically insulated joint 1 as described above has a small number of parts and a simple structure, is lightweight and compact, and when the gas pipe 5 is joined, the tip of the gas pipe 5 is electrically connected. Even if stress may be applied to the end 4b side of the electrically insulating member 4 by reaching the incomplete threaded portion 4c of the threaded tubular portion 4a of the insulating member 4, the end 4b is not the end surface of the joint body 2. By being bonded to 2c, the mechanical strength is enhanced, and the end 4b is less likely to peel off from the joint body 2.

The polymer material and the inorganic fiber material may be, for example, polyester resin or phenol resin as the polymer material, while alumina oxide fiber may be used as the inorganic fiber material, which is not necessarily limited to the above embodiment. Absent. Also,
As the polymer material and the inorganic fiber material, it is preferable to use a prepreg-treated material as described above, and particularly as the inorganic fiber material, a knit-woven material having some elasticity is preferable, but the inorganic fiber material is contained. Engineering, plastic sheets, etc. may be used, or BM
C, SMC, etc. can also be used.

However, if a thermosetting resin such as the above-mentioned epoxy resin is adopted as the polymer material, the hardness of the electric insulating member 4 after being bonded to the joint body 2 is high, and therefore the electric insulating member at the time of gas pipe bonding is used. Due to the elasticity of No. 4, the gas pipe is not screwed in more than desired, and there is an advantage that the joining is carried out by a predetermined rotation torque without excessive threading.

Further, the pipe joint to which the present invention is applied is not limited to the socket type as in each of the above embodiments, but an elbow type or a T type.
It may have a letter shape. The standard female thread diameter 3 formed by the electrical insulating member 4 may be a taper thread or a parallel thread.

Further, in a socket type or elbow type pipe joint having two gas pipe connecting portions, it is not necessary to apply the configuration of the present invention to all the gas pipe connecting portions. This is because in order to electrically insulate the two gas pipes from each other, at least one of the gas pipes should be connected to the pipe joint in an electrically insulated state.
This also applies to T-shaped pipe joints and the like.

If necessary, the female screw of different diameter and the electrical insulating member may be bonded using an adhesive or may be baked.

Furthermore, the thickness of the electrically insulating member is not necessarily required to be smaller than the root depth of the female screw with a different diameter if it has sufficient mechanical strength against the pulling force of the gas pipe, but That is, since the screw strength of the electrical insulating member is reinforced by the different diameter female thread of the metal joint body,
If the mechanical strength of the electric insulation member itself is set to such a degree that the member is not scraped off when the gas pipe is screwed, the connection strength of the gas pipe can be sufficiently secured, and when the electric insulation member burns. Further, it is possible to prevent the gas pipe from being pulled out, and it is possible to widen the selection range of the constituent material of the electrical insulating member, which is advantageous.

[Effect of device]

As is apparent from the above description, according to the electric insulation pipe joint for gas pipes of the present invention, the thread on the base side of the gas pipe is electrically insulated without impairing the characteristics of the conventional electric insulation joint shown in FIG. The problem of scratching the opening end face of the member and contacting the metal part of the joint body to cause dielectric breakdown, and the electrically conductive foreign substance existing in the ground due to being buried in the ground is the surface of the opening end face of the joint body. To effectively solve the problem that the fitting main body and the gas pipe are electrically connected to each other to cause electrical breakdown between the pipe part and the threaded portion on the base side of the gas pipe, causing dielectric breakdown with a simple configuration. Is something that can be done.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of an electrically insulating pipe joint for a gas pipe according to the present invention, and FIG. 2 is an enlarged view of a portion II of FIG.
FIG. 3 is a vertical sectional view of a conventional example. 1 …… Pipe joint 1a …… Gas pipe connection part 2 …… Coupling body 2a …… Deformed female screw 2b …… Tapered surface 2c …… Opening end face of joint body 3 …… Standard female screw diameter 4 …… Electrical insulating member 4a …… Threaded tubular portion 4b ... End portion of the electrically insulating member continuous from the threaded tubular portion 5 ... Gas pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shozo Fujisawa 5-1, Hirano-cho, Higashi-ku, Osaka City, Osaka Prefecture Osaka Osaka Gas Co., Ltd. Steel Pipe Fitting Co., Ltd. (72) Inventor Masachika Inoue 1 day at 153 Tajime-cho, Kishiwada City, Osaka Prefecture Steel Pipe Fitting Co., Ltd. (72) Hideo Hirabayashi, 1 day at 153 Tajime-cho, Kishiwada City, Osaka Main Steel Pipe Fitting Incorporated (56) References JP 61-153091 (JP, A) Actually 61-190093 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A female thread having a diameter different from a predetermined standard female thread diameter with which the gas pipe can be screwed is formed on at least one gas pipe connecting portion of a metal joint body, and the female thread is continuous with the female thread. To form a taper surface that expands toward the opening end face side in the opening of the joint body to be formed over the entire circumference, and to correct this to the standard internal thread diameter on the surface of this different diameter internal thread,
The electrical insulation member is made to adhere to the threaded tubular portion of the electrical insulation member made of a composite material having an electrical insulation property of a polymer material and an inorganic fiber material in a threaded manner, and also on the surfaces of the tapered surface and the opening end surface. An electrically insulating pipe joint for a gas pipe, characterized in that a continuous end portion of the threaded tubular portion is adhered.