JP2007225050A - Insulating pipe joint and pipe end corrosion-proof insulating pipe joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulating pipe joint which can be easily manufactured while adequately securing sealing performance and insulating performance of a joint main body and a screw member screwed therein. <P>SOLUTION: An insulating pipe joint consists of a joint body 2 including a female screw part 22 in at least one end and an inner end contact surface 8 in a deep side of the female screw part, of a screw member 3 having a male screw part 31 screw-fitted in the female screw part 22, of an electric insulation layer 5 interposed between the joint body and the screw member and of a seal member 10 sandwiched by the joint body and screw member, wherein the female screw part and the male screw part screw-fitted in the female screw part are screw-fitted in each other through a parallel screw and the seal member covers the inner end contact surface 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an insulated pipe joint that electrically insulates a part of a pipe line in a water supply pipe or the like.

In water supply pipes, when connecting different materials such as steel pipes coated with resin on the inner surface and normal bronze faucets with pipe joints, the pipe joints are usually made of cast iron. In order to prevent corrosion caused by the battery action due to the potential difference between the two and the like, an insulating joint having a function of electrically insulating the two and preventing conduction between the pipe joint and the water faucet is used. Patent Document 1 discloses an outer joint body made of ordinary ferrous metal, an inner joint body made of a different metal, an inner surface resin coating formed inside the outer joint body, and an electrical insulation layer provided on the inner joint body male thread portion. And an electrical insulating pipe joint for water composed of an adhesive layer. Patent Document 2 includes a first joint member, a second joint member, and an electric insulating member sandwiched between the first joint member and the second joint member. The first joint member and the second joint member are electrically connected. There is described an electrical insulating pipe joint that is integrally joined by receiving a deformation force in a direction in which the insulating members are brought into close contact with each other. Patent Document 3 includes a metal joint main body and a bush threadedly connected via a seal member, and a water supply provided by molding an insulating material having a bush thread thickness of 0.4 to 1.5 mm. Insulated joints for stoppers are described.
Furthermore, in Patent Document 4, a resin ring body having a male thread portion is integrally formed on the outer peripheral surface of a cylindrical insert portion by injection molding, and the male thread portion of the resin ring body is replaced with a female thread portion for assembly of a joint body. The inner end contact surface of the insert part is in contact with the inner end face of the resin anticorrosion core, and a notch is provided along the circumferential direction at the corner of the inner end of the insert part. And an adhesive having electrical insulation in the gap between the outer peripheral surface of the insert part and the inner peripheral surface of the joint body. An intervening pipe joint is described.
Japanese Utility Model Laid-Open No. 2-136894 (pages 2 to 4, FIG. 1) Japanese Patent Laid-Open No. 7-35274 (pages 2 and 3, FIG. 1) JP-A-7-269754 (pages 2 to 4, FIG. 1) JP-A-8-93978 (pages 3 to 5, FIG. 1)

However, the adhesive layer described in Patent Document 1 needs to have both functions of an adhesive function for fixing the outer joint body and the inner joint body, and a sealing property between the outer joint body and the inner joint body. When the adhesive cannot be applied to the entire surface of the screw, there is a difficulty in causing water leakage. In particular, for long-term sealability, it is necessary to fill the adhesive to reach the female thread valley of the outer joint body and the male thread valley of the inner joint body, and there is a problem that workability is extremely low. Further, the outer joint member and the inner joint member are screwed together with a taper screw. Therefore, if the screwing is loose, the adhesive layer becomes thick, and if the screwing is tight, the adhesive layer becomes thin. Therefore, the adhesiveness and the sealing property are unstable, and there is a problem that the assembling property is low.
The electrical insulation joint described in Patent Document 2 has a sealing performance because it incorporates an O-ring. However, when the first joint member and the second joint member are joined together, Subjected to compressive deformation from the outside or enlarged deformation from the inside. In addition to the function that the second joint member does not come out of the first joint member, the pipe material and the second joint do not rotate together at this joint location when screwing the pipe material into the second joint member. The function to make is required. However, the strong deformation coupling has a drawback in that the insulating performance of the electrical insulating member may be impaired.
The insulating joint described in Patent Document 3 is not only difficult to form because the thickness of the electrically insulating bush is very thin, but when the pipe is screwed into the bush female thread portion during construction, a part of the bush is formed. There is also a problem that the insulating property is impaired.
The pipe joint described in Patent Document 4 is practically used as a joint in which the problems of Patent Documents 1 to 3 are improved. In other words, the resin ring body integrally formed by injection molding provides insulation performance, and the ring-shaped sealing material provides leakage performance. The adhesive is interposed in the gap between the outer peripheral surface of the insert portion and the inner peripheral surface of the joint body. It has a structure in which torque resistance is made to function by an agent. However, there is a difficulty in insulation between the surface portion on the other end side of the inner flange portion of the joint body and the inner end contact surface of the insert portion. That is, according to this configuration, the insert portion is screwed to secure the leakage performance of the seal material, and the seal material is crushed, so that the surface portion on the other end side of the inner flange portion of the joint body and the inner end of the insert portion The gap between the surfaces is extremely small. Or there exists a problem that the surface part of the other end side of a joint main body inner collar part and the inner end contact surface of an insert part contact | abut, and insulation performance is not ensured.

  Accordingly, an object of the present invention is to provide an insulated pipe joint that can be easily manufactured while sufficiently ensuring the sealing performance and the insulation performance of the joint body and the screw member screwed into the joint body.

In order to achieve the above object, the present invention has a joint body having a female threaded portion at least at one end, an inner end contact surface on the back side of the female threaded portion, and a male threaded portion that is screwed into the female threaded portion. In the insulated pipe joint having a screw member, an electrical insulating means interposed between the joint body and the screw member, and a seal member interposed between the joint body and the screw member, the female thread portion And a male screw portion screwed into the female screw portion are screwed in parallel threads, and the seal member covers the inner end contact surface.
With this configuration, since the seal member covers the inner end contact surface of the joint body, the joint body and the screw member are not directly in contact with each other. Therefore, the screwing accuracy between the joint body and the screw member is increased. Easy manufacture is possible without the need for management, and an insulating pipe joint with stable insulation and sealing properties is obtained.

  In the present invention, the seal member is an insulating material and preferably has a seal portion and a lip portion, and the lip portion preferably covers a part or the entire surface of the inner end contact surface. It is desirable that a taper portion is provided on the outer periphery of the screw member, and the seal member is sandwiched between the inner end contact surface and the taper portion. According to this configuration, it is possible to further stabilize the insulating performance and the sealing performance.

  In the present invention, an adhesive layer is interposed between the joint body and the screw member, and the adhesive layer preferably contains an epoxy resin as a main component, and the electrical insulating means includes the screw member. A resin coating layer formed on the outer peripheral surface or an electric insulator integrally formed on the outer peripheral surface of the screw member by injection molding is preferable. According to this configuration, the torque resistance of the screw member can be maintained and the insulation performance can be ensured.

  Further, in the present invention, the inner peripheral surface excluding the female thread portion at one end of the joint body and the pipe thread portion at the other end is coated with resin, and the inner periphery of the covering portion extends to the pipe thread portion side at the other end portion of the joint body. By having the inner surface resin-coated portion having the cylindrical portion that comes out, a pipe end anti-corrosion insulating pipe joint that prevents corrosion of the pipe end portion of the lining steel pipe is obtained.

  According to the present invention, since the sealing member is interposed between the joint body and the screw member screwed into the joint body, the sealing performance is stabilized, and the sealing member covers the inner end contact surface of the joint body. And the screw member are not in direct contact with each other, so that it is possible to easily manufacture without having to manage the screwing accuracy between the joint body and the screw member, and the insulation and the sealing performance are stable. A pipe joint can be obtained.

  Details of the present invention will be described below with reference to the accompanying drawings. 1 is a longitudinal sectional view of an insulating joint according to an embodiment of the present invention, FIG. 2 is an enlarged view of a main part of an embodiment of the present invention, and FIG. 6 is a longitudinal section of a seal member according to an embodiment of the present invention. FIG.

  The insulating pipe joint 1 shown in FIGS. 1 and 2 is bonded to a joint body 2 having a female thread portion 21 made of a pipe taper screw on the inner peripheral surface at one end and a female screw portion 22 made of a parallel screw on the inner peripheral surface of the other end. A screw member having a male screw part 31 composed of a parallel screw screwed to the female screw part 22 on the other end side through the layer 4 and the electrical insulating layer 5, and a female screw part 32 to which a water supply device or the like is connected to the inner peripheral surface thereof 3 is provided. An inner surface lining 6 is fixed to the inner peripheral surface of the joint body 2 via a primer (not shown) on the inner side of the screw member 3. Since a steel pipe whose inner surface is coated with resin is screwed into the female thread portion 21, the joint body 2 is formed of black core malleable cast iron, for example, in order to reduce the potential difference between them, and the screw member 3 is made of, for example, a material on the instrument side. It is made of bronze. In particular, it is preferable to use lead-free bronze (lead content: 0.25% or less) due to recent water quality problems. The seal ring 7 attached to the female screw portion 21 to prevent corrosion at the back of the screw is formed of an elastic body (rubber material) excellent in water resistance and calcification resistance such as EPDM, and the inner lining 6 generates dioxins during incineration. The primer which does not have the cause chlorine group, for example, is formed from polyethylene, and the joint body 2 and the inner surface lining 6 are bonded to each other is formed from an adhesive polyolefin. As shown in FIG. 2, an inner end contact surface 8 is formed at the inner end of the female screw portion 22 of the joint body 2, and a tapered surface 9 is formed on the outer periphery of the screw member 3. The seal member 10 is interposed by the inner end contact surface 8 and the tapered surface 9 in a substantially triangular cross section. The joint body 2 and the screw member 3 are both formed of a conductive material, but the adhesive layer 4 and the electrical insulating layer 5 are formed of a material having an insulating property, thereby preventing conduction between the two. can do.

The parallel screw is, for example, a general metric screw defined in Japanese Industrial Standard (JIS B0205). At this time, since the adhesive layer 4 and the electrical insulating layer 5 are provided between the joint body 2 and the screw member 3, the female thread portion 22 of the joint body 2 is increased or the male thread portion 31 of the screw member 3 is decreased. Provide. In that case, the internal diameter of the internal thread part 22 is provided smaller than the external diameter of the external thread part 31. However, this is not the case when the electrical insulating means is provided by injection molding described later. Needless to say, the parallel screw is not limited to a general metric screw as long as it is a parallel screw such as a pipe parallel screw, a unified screw, and a metric trapezoidal screw.
In order to prevent the electrical insulation means from being destroyed, the screwing with the pipe taper screw of the prior art requires, for example, screwing torque management. However, in the configuration of the parallel screw, it is not necessary and the assemblability is good.

Examples of the adhesive for forming the adhesive layer 4 include a thermosetting adhesive used by adding a curing agent to an epoxy resin, a thermosetting acrylic resin, polyaromatic, polyurethane, or the like, or a vinyl polymer (for example, ethylene- A commercially available adhesive such as a thermoplastic adhesive mainly composed of a thermoplastic polymer such as a vinyl acetate copolymer), a polyamide resin, or a thermoplastic polyester can be used. Among these adhesives, epoxy resins have excellent adhesion, low volume shrinkage when cured, excellent strength and toughness, excellent electrical properties, and excellent resistance to solvents and other chemicals It is known that it has characteristics such as having no volatile matter released during curing. The adhesive layer 4 is required to have an adhesive strength (for example, 180 Nm or more in the case of a 3 / 4B diameter) that can withstand torque several times (for example, three times) or more of the standard screwing torque. In view of material strength (about 19.6 N / mm ² or more), volume resistivity (1 × 10 ¹⁴ Ω · cm or more), and leachability when used as a pipe joint, an epoxy resin adhesive (for example, A bisphenol type epoxy resin adhesive) is preferred. The bisphenol type epoxy resin is cured by heating by mixing with a curing agent, and a predetermined adhesive strength and a predetermined hardness are obtained.

The electrical insulating layer 5 is obtained from ceramic, glass fiber, insulating polymer, etc., and is formed of insulating polymer especially considering the strength of the insulating layer, adhesion to metal, followability to complex shapes, etc. It is preferable to do. The electrical insulating layer made of an insulating polymer can be obtained by injection molding, liquid coating, powder coating, etc. For example, the screw member 3 is powder-coated with an epoxy resin, which is a thermosetting resin, and is heated in a heating furnace, for example, It can be obtained by heat curing at about 150 to 250 ° C. For powder coating, electrostatic powder coating or fluidized immersion powder coating can be used.
The electrical insulating layer 5 thus obtained has good adhesiveness to the screw member 3. That is, 11 cuts at 1 mm intervals are made in the thermosetting resin film with sharp edges to reach the base member to form 100 sections, and the section is rubbed several times with abrasive paper. Even if it peels off rapidly after sticking an adhesive tape on it, the said division does not peel.

Further, in the method of obtaining the electrical insulating means by injection molding, not only the thermosetting resin but also a thermoplastic resin can be used. As the thermoplastic resin, for example, a thermoplastic resin such as polyphenylene sulfide, polyamide, modified polyphenylene oxide, polyimide, polyetherimide, polyamideimide, or a glass fiber reinforced product thereof can be used. It is selected in consideration of adhesiveness with the agent.
The electrical insulating means obtained in this way can stably satisfy the insulation required for the water pipe (surface resistance of 10 × 10 ⁶ Ω at 1.5 V).

  Next, the configuration of the seal portion will be described with reference to FIGS. An inner end contact surface 8 is formed at the inner end of the female screw portion 22 of the joint body 2, and a tapered surface 9 is formed on the outer periphery of the screw member 3. The seal member 10 is interposed by the inner end contact surface 8 and the tapered surface 9 in a substantially triangular cross section. The seal member 10 is made of, for example, EPDM, and the seal performance is generally considered to be good when compressed by 30% with respect to the cross-sectional area before insertion. Therefore, when the female screw portion 22 and the male screw portion 31 are screwed together and the seal member 10 is compressed, the joint body 2 and the screw member 3 may come into contact with each other. In particular, in FIG. 2, it is conceivable that the tapered surface 9 contacts the inner end contact surface 81. At this time, there is a possibility that the electrical insulating layer 5 formed on the surface of the tapered surface 9 is destroyed and the insulating property is impaired. However, the seal member 10 shown in FIG. 6 is formed of a seal portion 101 and a lip portion 102. When the seal member 10 is assembled into an insulating pipe joint as shown in FIG. 8 is covered up to the surface corner portion 81 per inner end, so that the tapered surface 9 does not directly contact the surface corner portion 81 per inner end, thereby preventing the electrical insulating layer 5 from being broken. it can. Even if the electrical insulating layer 5 is broken by screwing, the sealing member has an insulating performance, so that the insulation between the joint body and the screw member can be ensured.

  In the assembly of the present invention, the seal member 10 is first mounted on the inner surface contact surface 8 of the joint body 2 or the tapered surface 9 of the screw member 3 provided with the electrical insulating layer 5. Subsequently, an appropriate amount of an epoxy resin adhesive is applied to the male thread portion 31 of the screw member 3, and the screw member 3 is screwed into the joint body 2. At this time, in order to ensure sealing performance, the epoxy resin adhesive is applied so as not to adhere to the seal member. In screwing, the screw member 3 may simply be brought into contact with the lip portion 102 covering the inner end contact surface 8 of the joint body 2 or until the seal portion 101 has an appropriate compression ratio. Easy to. Further, in the conventional technology expected to have a sealing property, the adhesive must be filled up to the back of the valley of the screw, whereas the application of the adhesive of the present invention is appropriately applied to the surface of the male screw 31. It is very easy to just do.

  3 to 5 are enlarged views of main parts of the second, third and fourth embodiments of the present invention. FIG. 3 shows an example in which a sealing member having a substantially triangular cross section is used and the inner end contact surface 8 is covered. FIG. 4 shows an example in which a contact portion 91 is provided in a part of the taper portion 9, and a lip portion 102 provided about 0.3 mm covers the inner end contact surface 8. FIG. 5 shows an example in which an abutment surface 91 and a seal member compression surface 92 are provided. Similarly, a lip portion 102 provided at about 0.3 mm covers the inner end contact surface 8. In addition to these, the seal member and its interposing form may be considered, but in any case, the portion where the inner end contact surface of the joint body 2 and the screw member 3 abut is covered with the seal member. Thus, it is possible to obtain an insulated pipe joint having a reliable electrical insulation performance with an easy assembly operation. Needless to say, the seal member is not limited to the embodiment as long as the seal member covers the inner end surface.

As described above, the insulating joint 1 is formed by coating the screw member 3 with powdered epoxy resin and curing it in a heating furnace to form an electrical insulating layer, which is then bonded to the inner peripheral surface of the female thread portion 22 of the joint body 2. The adhesive is applied, and then the screw member 3 having the external thread portion 31 is screwed on the outer peripheral surface, and the adhesive is heated and cured again in a heating furnace. Further, a pipe end anticorrosion type insulated pipe joint is manufactured by applying an adhesive primer to one end of the inner surface excluding the threaded portion of the joint body 2 and then injection molding the inner surface lining 6.
Therefore, the seal member 10 must be able to withstand the thermal effects in the heat curing process and the injection molding process of the manufacturing process. As the seal member having high heat resistance, ethylene propylene rubber, fluoro rubber, silicone rubber, acrylic rubber, and the like are preferable, and ethylene propylene rubber having heat resistance, water resistance, calc resistance, and economy is particularly preferable.

Returning to FIG. 1 again, the pipe end anti-corrosion insulating pipe joint of the present invention includes a joint main body 2 having a female thread portion 22 made of a parallel screw at one end portion and an inner end contact surface 8 on the inner side of the female thread portion 22. , A screw member 3 having a male screw portion 31 screwed into the female screw portion 22, an electrical insulating layer 5 interposed between the joint body 2 and the screw member 3, and the joint body 2 and the screw member. 3, the seal member 10 covers the inner end contact surface 8, and has a female screw portion 22 at one end of the joint body 2 and a female screw portion 21 for pipe at the other end. By forming the inner surface lining 6 having the cylindrical portion 61 in which the inner periphery of the lining extends toward the female thread portion 21 for the pipe at the other end of the joint body, the inner end surface of the lining steel pipe Prevents corrosion.
The inner lining 6 is fixed to the central recess 23 of the joint body 2 on the back side of the screw member 3 via a primer (adhesive polyolefin). The primer is obtained by electrostatic powder coating or the like, and the inner surface lining is obtained by injection molding.

In pipe end anti-corrosion insulated pipe joints, the leaching performance standard for tap water is less than 0.3 mg / L of iron, less than 1.0 mg / L of copper and its compound, less than 1.0 mg / L of zinc and its compound, lead and It is required to satisfy less than 0.01 mg / L of the compound, cadmium and less than 0.01 mg / L of the compound.
Since the pipe end of the pipe end anticorrosion insulation joint of the present invention corrodes the pipe end of the lining steel pipe with the seal ring 7 and the inner lining 6 lines the central recess 23 of the joint body 2, the joint body 2 made of black core malleable cast iron. However, it was confirmed that a pipe end anti-corrosion type insulated pipe joint that does not come into contact with tap water, sufficiently satisfies the above leaching performance standard, and has excellent insulation performance can be obtained.

As described above, according to the configuration of the present invention, since the joint body 2 and the screw member 3 are screwed in parallel threads, there is no need to manage the degree of screwing in the assembly operation, and the electric insulation layer The adhesive layer and the seal member share the functions of insulation, torque resistance, and leak resistance, respectively, and the seal member 10 covers the inner end contact surface of the joint body 2 so that predetermined insulation is ensured. From the above, it can be seen that an insulating pipe joint with good sealing performance can be easily obtained.

It is a longitudinal cross-sectional view of the insulated pipe joint which concerns on 1st embodiment of this invention. It is a principal part enlarged view of FIG. It is a principal part longitudinal cross-sectional view of the insulated pipe joint which concerns on the 2nd embodiment of this invention. It is a principal part longitudinal cross-sectional view of the insulated pipe joint which concerns on 3rd embodiment of this invention. It is a principal part longitudinal cross-sectional view of the insulated pipe joint which concerns on the 4th embodiment of this invention. It is a longitudinal cross-sectional view of the sealing member which concerns on the 1st embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Insulation pipe coupling, 2: Joint main body, 21, 22: Female thread part, 23: Center recessed part, 3: Screw member, 31: Male thread part, 32: Female thread part, 4: Adhesion layer, 5: Electrical insulation layer, 6 : Inner lining, 61: cylindrical portion, 7: seal ring, 8: inner end contact surface, 81: inner end contact corner, 9: taper surface, 91: contact surface, 92: compression surface, 10: seal member 101: Seal part, 102: Lip part

Claims (6)

A joint main body having an internal thread portion at least at one end, an inner end contact surface on the back side of the internal thread portion, a screw member having an external thread portion screwed into the internal thread portion, the joint main body, and the screw member; In an insulated pipe joint having an electrical insulating means interposed between and a seal member interposed between the joint body and the screw member, the female screw part and a male screw part screwed into the female screw part, Is an insulating pipe joint, wherein the sealing member covers the inner end contact surface. The seal member is an insulating material, and has a seal portion and a lip portion, and the lip portion is a seal member that covers a part or the entire surface of the inner end contact surface. The insulation joint according to 1. 3. The insulated pipe joint according to claim 1, wherein a taper portion is provided on an outer periphery of the screw member, and the seal member is sandwiched between the inner end contact surface and the taper portion. . The insulating pipe joint according to any one of claims 1 to 3, wherein an adhesive layer is interposed between the joint body and the screw member, and the adhesive layer contains an epoxy resin as a main component. 2. The electrical insulation means is a resin coating layer formed on the outer peripheral surface of the screw member or an electrical insulator integrally formed on the outer peripheral surface of the screw member by injection molding. 4. The insulating joint according to any one of 4. The insulating pipe joint according to any one of claims 1 to 5, wherein an inner peripheral surface excluding a female thread part at one end and a thread part for a pipe at the other end of the joint body is resin-coated, and the inner periphery of the covering part is the joint. A pipe end anti-corrosion insulating pipe joint having an inner surface resin coating part having a cylindrical part extending to the pipe thread part side of the other end of the main body.