JP2007232133A - Spiral gasket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spiral gasket including an outer ring at least on the outer diameter side of a gasket body, restraining deterioration of sealing performance as the whole gasket even if a gap is caused in the sealing surface of the body part when a bending phenomenon is caused by a fastening load. <P>SOLUTION: In this spiral gasket 20, a metal-made corrugated thin plate 4 and a cushioning material 5 such as asbestos paper are spirally wound to construct a gasket body 6, and the metal-made outer ring 24 having a thickness smaller than that of the body 6 is fitted to at least the outer peripheral side thereof. The surface hardness of the outer ring is set smaller than that of a flange member 1 abutting thereto. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a spiral wound gasket preferably used, for example, for sealing a pipe joint portion such as a steam whose fluid becomes high temperature and high pressure.

  Spiral wound gasket is designed for high temperature and high pressure. It has rich elasticity and can regulate the tightening force with the mounting thickness, and does not require precise finishing of the flange surface. Because it has the advantages of being hard to fix and easy to clean, it is widely used not only in steam systems of thermal power / nuclear power plants and steam turbine ships, but also in process lines of the petroleum refining and petrochemical industries.

  In a pipe joint portion of a pipe in which such a gasket is used, for example, as shown in FIG. 3, a spiral wound gasket G is interposed between both flanges 1, 1 and tightened by a plurality of bolts 2. The gasket G and the flanges 1 and 1 are in close contact with each other and sealed so that high-pressure fluid flowing through the inner passage 3 does not leak to the outside (for example, Patent Document 1).

In this way, when the gasket G is attached to the joint portion and an appropriate surface pressure is applied, the gap d is secured on both sides of the gasket G.
As shown in FIG. 2, for example, the spiral wound gasket G is configured by winding a metal corrugated thin plate 4 having a V-shaped cross section and a filler material (buffer material) 5 selected according to specifications into a spiral shape. The gasket main body 6 is provided. In the case of a large-diameter size, both the inner ring 7 and the outer ring 8 that are smaller than the thickness of the gasket body 6 or the inner and outer rings are formed on the inner diameter side or the outer diameter side of the gasket body 6. Either one of 7, 8 is mounted as necessary.

  By the way, the flanges 1 and 1 of the pipe joint to which such a spiral wound gasket G is mounted are provided with flat seats 1a and 1a inside the holes through which the bolts 2 are inserted as shown in FIG. (Patent Document 2).

When the gasket G is attached to the pipe joint provided with such flat seats 1a and 1a and tightened by the bolt 2, the gasket main body 6 that produces a sealing effect is first tightened.
On the other hand, when the applied fluid flowing through the inner passage 3 is at a high pressure, a large tightening force is required. Therefore, the bolt 2 is excessively tightened so as to reduce the gap d shown in FIG. If the bolt 2 is tightened excessively or the strength of the flanges 1 and 1 is weakened in this way, the so-called point 6a and 6a of the gasket body 6 with which the flanges 1 and 1 are first brought into contact with each other at the time of tightening. Bending occurs, and as a result, there is a risk of fluid leaking from a gap generated on the inner diameter side. Such a tendency is more remarkable as the inner passage 3 has a larger diameter.
Japanese Patent Laid-Open No. 3-117778 Japanese Utility Model Publication No. 60-58961

  In view of such a situation, in the spiral wound gasket in which at least the outer ring is provided on the outer diameter side of the gasket main body, when a bending phenomenon occurs due to a tightening load, a gap is generated on the sealing surface of the main body portion. However, an object of the present invention is to provide a spiral wound gasket that can suppress a decrease in sealing performance as a whole gasket.

To achieve the above object, the spiral wound gasket according to the present invention is:
A metal outer ring having a thickness smaller than the thickness of the main body is fitted on at least the outer peripheral side of the gasket main body formed by winding a corrugated thin metal plate and a cushioning material such as asbestos paper in a spiral shape. In the combined spiral wound gasket,
The surface hardness of the outer ring is set to be smaller than the hardness of the flange member in contact with the outer ring.

  According to the present invention having such a configuration, even if the outer ring is strongly tightened by the flat seat provided on the inner surface of the flange member, the surface of the outer ring is soft with respect to the flat seat, so the flat seat is on the surface of the outer ring. I start to bite. Therefore, even if a gap is generated on the sealing surface of the main body due to the bending phenomenon, it is possible to suppress the deterioration of the sealing performance of the gasket as a whole.

Here, in the present invention, the outer ring may have a surface hardness smaller than that of the central portion by forming a plating layer made of a soft metal on the surface.
Further, the outer ring may have a surface hardness reduced by attaching a soft metal to the surface of a metal plate material as a core material. Or the said outer ring | wheel is comprised by joining of two members with a radial direction inner peripheral side and a radial direction outer peripheral side, and the outer ring | wheel of the part contact | abutted to the said flange member among these may be formed from the soft material.

In this way, the surface hardness of the outer ring can be reduced.
Furthermore, in the present invention, the height of the outer ring may be set to be substantially the same as the height of the gasket body when the gasket body is tightened with an appropriate pressure.

  If the height of the outer ring is set in this way, excessive deformation of the gasket body can be prevented, and the sealing surface and the flange surface are hardly separated by bending. Similarly, at this time, the flange flat seat end face bites into the outer ring surface during bending, so that the familiarity can be secured.

  According to the spiral wound gasket according to the present invention, since the hardness of the outer ring is set to be smaller than the hardness of the flat seat of the flange member, the biting of the flat seat is good. Therefore, a sealing effect can be obtained between the outer ring and the flange plane seat when bending occurs. As a result, even when a gap is generated on the sealing surface of the main body portion during bending, it is possible to suppress a decrease in sealing performance as a whole gasket.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a pipe joint employing a spiral wound gasket 20 according to an embodiment of the present invention.

  The gasket body 22 of the spiral wound gasket 20 according to the present embodiment is formed in substantially the same manner as the gasket body 6 of FIG. That is, the gasket main body 22 is configured by the metal corrugated thin plate 4 and the filler material 5 being wound tightly. And the outer ring | wheel 24 is installed in the outer peripheral side of this gasket main body 22, and the inner ring | wheel 26 is installed in the inner peripheral side. If the outer ring 24 is provided on the outer peripheral side of the gasket body 22, the inner ring 26 may not be provided. That is, the inner ring 26 is not an essential component of the present invention.

On the other hand, examples of the corrugated thin plate 4 made of metal include SUS304, SUS316, SUS321, and aluminum, and examples of the filler material 5 include non-asbestos inorganic paper. The inner ring 26 is exemplified by carbon steel, SUS304, SUS316, SUS321, SUS430, and the outer ring 24 is exemplified by carbon steel SUS304.

  In the present embodiment, the surface of the outer ring 24 is formed softer than the flat seat 1 a of the flange 1. Thus, in order to make the surface of the outer ring 24 soft with respect to the plane seat 1a, a soft layer may be formed by plating.

  In addition to plating, in order to make the surface of the outer ring 24 soft with respect to the plane seat 1a, two disk-shaped plate materials are prepared, and one plate material made of a soft material is bonded to the other plate material, and the outer ring 24 is bonded. May be configured.

Furthermore, the portion to be softened may not be the entire outer ring 24 but only the portion with which the flat seat 1a hits. In short, when the outer ring 24 is tightened by the flat seat 1 a of the flange 1, the end of the flat seat 1 a may bite into the surface of the outer ring 24.
In this way, even when bending occurs, the sealing performance can be secured on the outer peripheral side. Thereby, the fall of a sealing performance as the whole gasket can be prevented.

  As mentioned above, although one Example of this invention was described, this invention is not limited to this. For example, the inner ring 26 is not essential. Further, the use conditions are not limited to high temperature and high pressure, but can be used under normal temperature and normal pressure.

Further, the height of the outer ring 8 can be set in the same manner as the height of the gasket body 6 at the time of tightening as shown by the wavy line in FIG. 4 so that bending does not easily occur.
In order to prevent the occurrence of bending in this way, the gap d shown in FIG. 3 may be eliminated, but this may be done as follows.

  That is, by preliminarily measuring the sealing performance with respect to the gasket surface pressure and the strain amount with respect to the gasket surface pressure, the strain amount of the gasket when obtaining a desired sealing performance is assumed. If the height of the outer ring 8 is set to the same height as the initial height of the gasket minus the amount of distortion, the height of the gasket body 6 and the height of the outer ring 8 become the same during tightening.

If the height of the outer ring 8 is set in advance in this way, it becomes difficult for the sealing surface and the flange surface to be separated by bending.
As described above, in this embodiment, the flange flat seat end face bites into the outer ring surface during bending, and the sealability can be obtained.

FIG. 1 is a sectional view showing a flange joint equipped with a spiral wound gasket according to an embodiment of the present invention. FIG. 2 is a perspective view showing a part of a conventional spiral wound gasket. FIG. 3 is a sectional view of a flange joint equipped with a conventional spiral wound gasket. FIG. 4 is a schematic cross-sectional view when bending occurs in the spiral wound gasket.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flange 1a Plane seat 2 Bolt 3 Inner channel | path 4 Metal corrugated sheet 5 Filler material 6 Gasket body 7, 8 Inner / outer ring 22 Gasket body 24 Outer ring 26 Inner ring G Gasket

Claims (5)

A metal outer ring having a thickness smaller than the thickness of the main body is fitted on at least the outer peripheral side of the gasket main body formed by winding a metal corrugated thin plate and a cushioning material such as asbestos paper in a spiral shape. In the combined spiral wound gasket,
A spiral wound gasket characterized in that a surface hardness of the outer ring is set to be smaller than a hardness of a flange member in contact with the outer ring. 2. The spiral ring according to claim 1, wherein the outer ring has a surface hardness smaller than that of a central portion by forming a plating layer made of a soft metal on a surface of a metal plate material as a core material. Shape gasket. 2. The spiral wound gasket according to claim 1, wherein the outer ring has a surface hardness reduced by attaching a soft metal to a surface of a metal plate material as a core material. The outer ring is configured by joining two members on the radially inner peripheral side and the radially outer peripheral side. Of these, the outer ring of the portion that comes into contact with the flange member is formed of a soft material, so that the surface hardness is increased. The spiral wound gasket according to claim 1, wherein the spiral wound gasket is small. 5. The spiral wound gasket according to claim 1, wherein a height of the outer ring is set to be substantially the same as a height of the gasket body when the gasket body is tightened with an appropriate pressure. .

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