JP2001056077A - Insulating union joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain reliability of sealing performance and insulating performance by providing a packing concentrically having a portion whose axial thickness is larger than the depth of a concentric groove and a portion whose axial thickness is smaller than the above thick portion, and setting the thick portion to such dimensions as to be inserted in the concentric groove. SOLUTION: This insulating union joint has a groove 114' concentric with an opposite face 114 near the outer periphery of the opposite face 114 of a joint body 11, and the base of the groove 114' is parallel to the opposite face 114. A packing 14 inserted in the groove 114' is concentrically provided with a portion 141 whose axial thickness is larger than the depth of the concentric groove 114' and a portion 142 whose axial thickness is smaller than the thick portion 141, and the thick portion 141 is set to such dimensions as to be inserted in the concentric groove 114'. Thus, reliability of sealing performance and insulating performance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulated union joint and, more particularly, to an insulated union joint having a packing having high reliability in both sealing performance for preventing water leakage and the like and insulating performance.

[0002]

2. Description of the Related Art In order to prevent electric corrosion in a water supply pipe, an insulating pipe joint is inserted into the pipe so that electricity does not flow between connected pipes. ing. One of such insulated pipe joints is an insulated union joint.

FIG. 5 shows an example of an insulated union joint.
(A) and (b). FIG. 5 is a sectional view of the insulated union joint showing the upper half in section.
(A) shows a state where the union nut is manually tightened,
(B) shows a state in which the union nut is tightened with almost standard tightening torque.

In this figure, reference numeral 51 denotes a joint body which can be connected to a pipe end, has a flange 512 on the outer periphery, and is provided on an end face opposite to a side connected to the pipe end. It has an opposing surface 514. Reference numeral 52 denotes an attachment which can be connected to another pipe end, and has an opposing surface 524 on an end surface opposite to the side connected to the pipe end, and the opposing surface 524 is a joint body. The packing 54 is configured to be held between the gasket 51 and the opposing surface 514. The attachment 52 has an external thread 526 on the outer periphery near the facing surface 524. Union nut 53
Has an inner peripheral flange 532 that is hooked on the outer peripheral flange 512 of the joint body 51, and has a female screw 536 that is screwed into a male screw on the outer periphery of the attachment. In the insulated union joint, in order to insulate between the joint body 51 and the attachment 52, the insulating body is insulated by a packing 54 held between the facing surfaces 514 and 524, and the outer peripheral flange 512 of the joint body is Inner circumference collar 53 of union nut
2, an insulating ring 55 is interposed.

[0005] The packing 54 is an annular flat sheet, and is made of an elastic material such as rubber or resin.
The packing 54 needs to have insulation and to maintain elasticity in order to have a sealing performance of a fluid such as water between the opposing surfaces. In particular, when the connected insulating union joint is disassembled and reconnected, if the packing loses elasticity, the sealing performance will also be lost.

[0006]

FIG. 5B shows a state in which the union nut is strongly tightened by the insulated union joint. The packing 54 between the joint body 51 and the attachment 52 is crushed by its opposing surfaces 514 and 524 and becomes very thin. If the packing 54 is within the elastic deformation range when the thickness is reduced in this manner, the packing can elastically seal between the opposing surfaces. However, since the normal tightening is performed slightly over the standard tightening torque, once tightened, it is often deformed beyond the elastic deformation range. Even if the packing is not deformed to the point where the packing is cut by tightening, the sealing performance may be low because the elasticity may be lost due to the deformation.

When the union nut 53 is tightened with a considerably larger tightening force than the standard tightening torque, the packing 54
Of the joint body 51 and the attachment 52 may come into contact with each other between the opposing surfaces, and the insulation performance may be lost.

An object of the present invention is to provide an insulated union joint having a packing with high reliability in both sealing performance and insulating performance.

[0009]

The insulated union joint of the present invention can be connected to a pipe end, and can be connected to a joint body having a flange on the outer periphery and another pipe end. In addition, an attachment having an external thread on the outer periphery, an inner peripheral flange hooked on the flange of the joint body, a union nut having an internal thread screwed into the external thread of the attachment, a flange of the joint body and a union nut An insulating ring inserted between the inner peripheral flanges, and a packing held between the joint body and the opposed surface of the attachment, wherein at least the opposed surface of the joint body and the opposed surface of the attachment On the other hand, the packing has a groove concentric with the facing surface, and the packing has a portion whose axial thickness is thicker than the depth of the concentric groove, Together have a thin portion of the countercurrent thickness concentrically, the thick portion is characterized in that has a size that can enter said concentric grooves.

[0010] When the insulating union joint holds the packing between opposing surfaces of the joint body and the attachment, and tightens the joint body and the attachment with a union nut, the thick part of the packing is It is preferable that the thin portion of the packing does not reach breaking deformation while being within the elastic deformation range.

Further, in the insulating union joint, it is preferable that a tightening torque at which a thin portion of the packing reaches a breaking deformation is 2.5 times or more of a standard tightening torque.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is an insulated union joint according to an embodiment of the present invention, and is a side view showing an upper half in cross section.
(A) shows a state where the union nut is manually tightened, and (b) shows a state where the union nut is tightened with the standard tightening torque. FIG. 2 is an insulated union joint according to another embodiment of the present invention, and is a side view similarly showing a cross section of an upper half, and FIG.
(B) shows a state where the union nut is tightened with the standard tightening torque. FIG. 3 is a side view of the insulated union joint shown in FIG. 1 in which the thickness of the thin portion of the packing is thin, and also shows the upper half, and (a) shows the union nut manually tightened. (B) shows a state where the union nut is excessively tightened. FIG. 4 shows the thickness t of the thin portion of the packing in the insulated union joint of the present invention.
7 is a graph showing the tightening torque with respect to the rotation speed of the union nut, using the parameters as parameters.

FIG. 1 shows an insulated union joint for steel pipes according to one embodiment of the present invention. In this figure, 11 is a joint body, 12 is an attachment, 13 is a union nut, 14 is packing,
Reference numeral 15 denotes an insulating ring, and the basic configuration of the joint is the same as that shown in FIG. That is, the joint body 11
Has a flange 112 on the outer periphery and a facing surface 114 on an end surface opposite to the side connected to the piping end. The attachment 12 can be connected to another pipe end, and has an opposing surface 124 on an end surface opposite to the side connected to the pipe end. The packing 14 is held between itself and the facing surface 114. The attachment 12 has an external thread 126 on the outer periphery near the facing surface 124. The union nut 13 has an inner peripheral flange 132 that is hooked on the outer peripheral flange 112 of the joint body 11, and has a female screw 136 that is screwed to a male screw on the outer periphery of the attachment 12. The insulating ring 15 is interposed between the outer peripheral flange 112 of the joint body and the inner peripheral flange 132 of the union nut.

In the insulated union joint shown in FIG.
A groove 114 'concentric with the facing surface is provided near the outer periphery of the facing surface 114, and the bottom surface of the groove 114' is parallel to the facing surface 114. In addition, packing 14
Has a portion 141 thicker than the depth of the concentric groove 114 ′ in the axial direction and a portion 142 thinner in the axial direction than the thicker portion, and the thick portion 141 has the concentric groove 114. 'Is large enough to fit in.

FIG. 1A shows a state in which the union nut 13 is tightened by hand, and FIG. 1B shows a state in which the union nut 13 is further tightened with a tool to have a substantially standard tightening torque. ing. From the state of FIG.
When the union nut is tightened to the state of (b), the joint body 11 advances with respect to the attachment 12 and the packing 1
4 between its opposing surfaces. At this time, the joint body 1
The displacement of the opposing surface 114 is the same as the displacement of the groove 114 ', but the ratio of the displacement is larger in the opposing surface 114. Therefore, the thin portion 142 of the packing is deformed more than the elastic deformation and is not deformed any more, and has a stopper function for the joint body. However, since the rate of deformation of the thick portion 141 of the packing is small, it is still within the elastic deformation range and has sealing performance.

In the present invention, the thin portion 1 of the packing is used.
42 is preferably deformed more than elastic deformation and has not yet reached destructive deformation even though it has a stopper function. In the state where the fracture deformation has not been reached, the opposing surfaces 114 and 124
Since no mutual contact occurs, the insulation performance is maintained.

FIG. 3 shows the insulated union joint shown in FIG. 1 in which the thin portion 142 of the packing is thinned, and the thickness t of the thin portion 142 is reduced so that the force is larger than the standard tightening torque. If it is tightened, the thin portion 142 of the packing is broken as shown in FIG.

An insulating union joint having a nominal diameter of 3/4 ", wherein the thickness t of the thin portion 142 of the packing is 0.5 to 2.0 m.
FIG. 4 shows the state of the occurrence of dielectric breakdown when the tightening torque is increased for the ones changed to m.
Here, the standard tightening torque is a value described in the materials of the Japan Water Pipe Association and the Iron Pipe Fitting Association, and is 58.8 Nm (6 kgf · m) in the case of a nominal diameter of ／ ″. When the thickness t of the thin portion of the packing is 0.5 mm, dielectric breakdown occurs at twice the standard tightening torque. Dielectric breakdown did not occur up to 2.5 times, and when the thickness t was 1.5 mm or more,
Dielectric breakdown did not occur up to three times or more. As described above, it is preferable that the thin portion of the packing does not undergo destructive deformation up to at least 2.5 times the standard tightening torque.

Next, in another embodiment of the insulated union joint of the present invention shown in FIG. 2, a core 26 is provided on the inner surface of the union screw of the attachment 22, and is used for a resin-lined steel pipe. This is the same as the insulated union joint of the embodiment shown in FIG. In this case, the facing surface 224 of the attachment 22 is made of the attachment and the core 26.

In the above description, the groove 11 is formed on the facing surface 114.
4 'is provided, and the thick portion 141 of the packing 14 is provided.
Was provided on the joint body 11 side, but a groove may be provided on the facing surface on the attachment side, or a groove may be provided on both facing surfaces, and a thick portion of the packing may project on both sides. However, the function of the present invention is the same.

[0021]

As described above in detail, in the insulated union joint of the present invention, the packing has a thick portion and a thin portion, and the thick portion maintains elasticity even when the thin portion exerts a stopper function. Therefore, it exhibits sealing performance. As described above, the insulating union joint of the present invention has high reliability in both sealing performance and insulating performance.

[Brief description of the drawings]

FIG. 1 is a side view of an insulated union joint according to one embodiment of the present invention, in which an upper half is shown in cross section, (a) showing a state in which a union nut is manually tightened, and (b) showing a union nut. It shows a state in which it is tightened with a standard tightening torque.

FIG. 2 is a side view showing an upper half of an insulated union joint according to another embodiment of the present invention in cross section, in which (a) shows a state where the union nut is manually tightened, and (b) shows a state where the union nut is used. It shows a state in which it is tightened with the standard tightening torque.

FIG. 3 is a side view of the insulated union joint shown in FIG. 1 in which the thickness of a thin portion of the packing is thin, and also shows the upper half, and (a) shows the union nut manually tightened. (B) shows a state where the union nut is excessively tightened.

FIG. 4 is a graph showing the tightening torque with respect to the rotation speed of the union nut, with the thickness t of the thin portion of the packing in the insulating union joint of the present invention as a parameter.

5A and 5B are cross-sectional views of an example of an insulated union joint in which the upper half is shown in cross section, wherein FIG. 5A shows a state in which the union nut is manually tightened, and FIG. It shows the state where it was turned on.

[Explanation of symbols]

 11, 51 Joint body 112, 512 Flange 114, 514 Opposing surface 114 'Groove 12, 22, 52 Attachment 124, 224, 524 Opposing surface 126, 526 Male thread 13, 53 Union nut 132, 532 Inner circumference flange 136, 536 Female thread 14, 54 Packing 141 Thick section 142 Thin section 15, 55 Insulation ring 26 Core

Claims (3)

[Claims] 1. A joint body that can be connected to a pipe end and has a flange on the outer circumference, and an attachment that can be connected to another pipe end and has a male thread on the outer circumference, An inner peripheral flange hooked on the flange of the joint body, a union nut having an internal thread screwed into the male screw of the attachment, and an insulating ring inserted between the flange of the joint body and the inner peripheral flange of the union nut. An insulating union joint having the joint body and a packing held between opposed surfaces of the attachment, wherein at least one of the opposed surface of the joint body and the opposed surface of the attachment has a groove concentric with the opposed surface. The packing has a concentric portion with a portion having an axial thickness greater than the depth of the concentric groove and a portion having an axial thickness smaller than the thick portion. And the thicker portion is sized to enter the concentric groove. 2. When the packing is held between facing surfaces of the joint body and the attachment and the joint body and the attachment are tightened with a union nut, the thick portion of the packing is within an elastic deformation range. The insulated union joint according to claim 1, wherein the thin portion of the packing does not reach breaking deformation. 3. The insulated union joint according to claim 2, wherein a tightening torque at which the thin portion of the packing reaches a breaking deformation is 2.5 times or more of a standard tightening torque.