JP4423265B2 - Spiral wound gasket - Google Patents

Description

  The present invention relates to a spiral wound gasket formed by winding a metal strip having a corrugated cross section and a strip-like filler material in a state of being polymerized to each other in a spiral manner.

  This type of spiral wound gasket is suitable for applications that require high airtightness, such as LNG and LPG, such as piping systems for fluids such as gases and liquids, or for applications where it is difficult to ensure a large tightening pressure. It is used. For example, as disclosed in Patent Document 1, there is known a structure in which a filler material made of expanded graphite and a metal band are polymerized and wound in a spiral shape.

  When the spiral gasket is used, the end face of the metal strip is mainly in contact with the surface to be sealed, but the compression rigidity of the metal strip is large (because it is used at a relatively high tightening pressure). The low tightening pressure has a feature that it tends to cause poor adhesion to the surface to be sealed. In addition, due to the structure in which the end surface of the metal band is in contact with the surface to be sealed in this way, when the undulation or unevenness of the surface to be sealed is significant, or in a spiral gasket with a small amount of compression, the metal band and the surface to be sealed are in close contact. Defects tend to occur.

  Conventionally, in order to deal with the adhesion failure, as disclosed in Patent Document 2, the end face of the filler material interposed between the metal bands adjacent in the radial direction is protruded from the end face of the metal band. A spiral wound gasket is known. In other words, in a state where the spiral gasket is tightened between the surfaces to be sealed, the metal band end surface is operated so that the unevenness is filled with the filler material, thereby improving the familiarity and improving the degree of adhesion. is there. A spiral wound gasket having such a structure is called a filler exposed type.

However, in the above-described filler-exposed spiral gasket, the strength of the filler material that spreads on the surface to be sealed is low, so that it tends to cause blow-out breakage due to internal pressure, which tends to impair the sealing function. New problems arise. Therefore, in order to improve the familiarity with the surface to be sealed when the spiral wound gasket is employed, there remains room for further improvement.
JP-A-60-188664 Japanese Patent Laid-Open No. 02-266164

  In view of the above circumstances, an object of the present invention is to realize and provide a spiral wound gasket in which the familiarity with the surface to be sealed is improved, the adhesion failure is eliminated, and the sealing property is improved.

The invention according to claim 1 is a spiral gasket formed by winding a metal strip 1 having a corrugated cross section and a strip-like filler material 2 in a state of being polymerized with each other in a spiral manner.
An annular groove 3 concentric or substantially concentric with the seal surface S is formed on the annular seal surface S formed at the respective end portions of the metal strip 1 and the filler material 2 in the gasket thickness direction, and the metal A soft seal material 7 is filled in the annular groove 3 in a closed loop state straddling both the belt 1 and the filler material 2 .

  The invention according to claim 2 is the spiral wound gasket according to claim 1, wherein a plurality of the annular grooves 3 have different diameters and are concentrically formed. Is characterized by being filled with a soft sealing material 7.

  The invention according to claim 3 is the spiral gasket according to claim 1 or 2, characterized in that the annular groove 3 is formed by pressing using a pressing die. .

  The invention according to claim 4 is the spiral wound gasket according to claim 1 or 2, wherein the annular groove 3 is formed by mechanically cutting off the end portions of the metal strip 1 and the filler material 2. It is characterized by being.

  The invention according to claim 5 is the spiral wound gasket according to any one of claims 1 to 4, wherein the seal surface S is concentric or substantially concentric with the seal surface S and the annular groove 3. An annular and flat sheet-like soft sealing material 8 covering the soft sealing material 8 filled in is installed.

  The invention according to claim 6 is the spiral wound gasket according to any one of claims 1 to 5, characterized in that the soft sealing material 8 is expanded graphite or ceramic paper.

  According to the first aspect of the present invention, in the use state in which the seal is compressed by being assembled between the surfaces to be sealed, the soft seal material filled in the annular groove is provided with undulations on each seal surface and each surface to be sealed. It can be provided as a spiral wound gasket that acts to fill the unevenness, thereby improving the familiarity between the sealing surface and the surface to be sealed, improving the adhesion, and further improving the sealing performance. And since the soft sealing material of the annular groove is constrained as a closed loop of the concentric circular groove, it is possible to prevent the pressure resistance from being lowered and the exposed filler material (surface) in the spiral wound gasket of the type in which the filler material is exposed to the sealing surface. The sticking out of the sealing material can be prevented.

  As a result, a device that provides an annular groove filled with a soft sealing material on the sealing surface improves the familiarity with the surface to be sealed, eliminates or reduces adhesion failure, and realizes a spiral wound gasket that can improve sealing performance. Can be provided. In this case, if a plurality of annular grooves filled with the soft sealing material are formed concentrically as in the second aspect, there is an advantage that the conformability is further improved and the sealing performance is further improved.

  According to the invention of claim 3, since the annular groove is formed by press molding, the processing time for the annular groove can be shortened, and the spiral wound gasket to which the advantages of enabling production efficiency and cost reduction are added. Can be provided. The annular groove can also be formed by mechanically cutting the end portions of the metal strip and the filler material so as to eliminate expensive press dies and reduce capital investment.

  According to invention of Claim 5, it is a means which attaches a flat sheet-like soft sealing material to a sealing surface in the state which covers the soft sealing material with which an annular groove is filled, In the above-mentioned use state, it is a sheet-like soft sealing material Since it also compresses and extends to act to fill up the undulations and irregularities on each seal surface and each seal target surface, the spiral performance can be greatly improved by both the soft seal material and the sheet-like soft seal material. A gasket can be provided. In this case, as in the sixth aspect, the sheet-like soft sealing material can be appropriately selected and set from expanded graphite and ceramic paper.

  Embodiments of a spiral wound gasket according to the present invention will be described below with reference to the drawings. 1-3 is each figure regarding the spiral wound gasket and annular groove of Example 1, and FIG.4, 5 is a perspective view of the notch which shows the spiral wound gasket of Example 2,3. In each figure, the thickness of the filler material, the winding interval of the metal strip, etc. are exaggerated to be larger than the actual dimensional balance for understanding the drawings.

[Example 1]
As an example, the spiral gasket A according to the first embodiment is used at a connection location between the pipe flanges 4 and 5, as shown in FIG. That is, it is interposed between the flange portion 4A of the first piping flange 4 and the flange portion 5A of the second piping flange 5, specifically between each flange surface (an example of a surface to be sealed) 4b, 5b. Until the thickness of the spiral wound gasket A is compressed by a predetermined amount (or a specified tightening torque) by the plurality of bolts and nuts 6 arranged at equal angles in the circumferential direction on the flange portions 4A and 5A. The pipe flanges 4 and 5 are coupled to each other so that the internal flow paths 4a and 5a are connected in a sealed state.

  As shown in FIGS. 1 and 2, the spiral gasket A has a corrugated cross section, more specifically, a cross-section of a metal band 1 having a substantially “ku” (or “V”) shape and a band-shaped filler material 2. Each of the annular seal surfaces S formed at the ends of the metal strip 1 and the filler material 2 in the gasket thickness direction is wound on the seal surface S. And an annular groove 3 which is concentric or substantially concentric with the annular groove 3 and is filled with a soft seal material 7. As an example of the size of this spiral wound gasket A, an inner diameter of 90 mm, an outer diameter of 110 mm, and a thickness of 4.5 mm can be cited.

  As shown in FIGS. 1 to 3, a metal strip (called “hoop”) 1 is formed by press-forming a steel plate (eg, stainless steel plate) so that the cross-sectional shape is short straight portions 1 t and 1 t at both ends, The V-shaped portion 1A is formed into a substantially “<” (or “V”) shape, and each of the winding start and winding end points to the adjacent metal strip 1 on the outer diameter side or inner diameter side. It is fixed by spot welding. As an example of dimensions, there is one with a width of 6 mm. Various materials can be used as the filler material 2, but expanded graphite is used here. In addition, M in each figure is a spot welding mark.

  The annular grooves 3 are concentric with the shaft center P of the seal surface S, and are formed in three, that is, triple (with different diameters and concentric), and the three annular grooves 3 are soft. As an example of the sealing material, expanded graphite 7 is filled in a slightly raised state. Each annular groove 3 has a semicircular cross section with a width of 2 mm and a depth of 1 mm. These triple annular grooves 3, 3, and 3 are, for example, molds having triple annular protrusions (not shown). It is formed at a stretch on the seal surface S by press molding using. In this case, an annular ring groove 3 is formed by crushing the ends of the spiral metal strip 1 and the filler material 2.

  In this way, a plurality of annular grooves 3 are formed in a closed loop shape (concentric shape) that is not continuous (not spiral) from the inner diameter side to the outer diameter side of the seal surface S, and the expanded graphite 7 is filled therein. In the compressed state interposed between the flange portions 4A and 5A and tightened, the annular expanded graphite 7 is undulated or uneven on the seal surfaces S and S and the flange surfaces 4b and 5b (sealing target surfaces). As a result, the familiarity between the seal surface S and the flange surfaces 4b and 5b is improved, and the adhesion is improved. As a result, it can be provided as a spiral wound gasket with improved sealing performance.

  Since the expanded graphite 7 in the annular groove 3 is constrained as a closed loop of concentric grooves, the pressure resistance can be prevented from being lowered, and the exposed filler in a spiral wound gasket of the type in which the filler material 2 is exposed on the seal surface S. Protruding of the material (surface sealing material) can be prevented. In addition, in the lower annular groove 3 in FIG. 3, in order to facilitate understanding of the shape of the annular groove 3, the expanded graphite 7 is intentionally drawn as a virtual line.

[Example 2]
As shown in FIG. 4, the spiral wound gasket A <b> 2 according to the second embodiment is a soft seal that is concentrically or substantially concentric with the seal surfaces S and S and is filled in the annular groove 3. An annular flat sheet-like soft sealing material 8 covering the material 7 is provided. In other words, the flat expanded graphite sheet 8 having an annular shape and a small thickness is attached to each of the sealing surfaces S and S of the spiral wound gasket A of the first embodiment.

Example 3
The spiral wound gasket A2 according to Example 3 is obtained by changing the material of the sheet-like soft sealing material 8 of the spiral wound gasket A2 according to Example 2 from expanded graphite to ceramic paper, as shown in FIG. Is the same as in Example 2.

[Another Example]
The annular groove 3 may be formed by using mechanical cutting means such as a cutting process on the ends of the metal strip 1 and the filler material 2. The annular groove 3 may be a double one or a structure in which four or more layers are formed and the soft sealing material 7 is filled.

Partially cutaway perspective view showing the structure of a spiral wound gasket (Example 1) Sectional drawing which shows one use condition of the spiral wound gasket of FIG. Partial sectional view of the spiral wound gasket of FIG. The perspective view of a part notch which shows the spiral wound gasket by Example 2 The perspective view of a part notch which shows the spiral wound gasket by Example 3

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal strip 2 Filler material 3 Annular groove 7 Soft sealing material 8 Sheet-like soft sealing material S Seal surface

Claims (6)

A spiral gasket formed by winding a metal strip having a corrugated cross section and a strip-shaped filler material in a state of being polymerized with each other in a spiral shape,
An annular groove concentric with or substantially concentric with the seal surface is formed in an annular seal surface formed at each end of the metal band and the filler material in the gasket thickness direction, and the metal band and the filler material A spiral wound gasket in which a soft seal material is filled in the annular groove that is in a closed loop state across both .   2. The spiral wound gasket according to claim 1, wherein a plurality of the annular grooves have different diameters and are concentrically formed, and the plurality of annular grooves are filled with a soft seal material.   3. The spiral wound gasket according to claim 1, wherein the annular groove is formed by pressing using a pressing die.   3. The spiral wound gasket according to claim 1, wherein the annular groove is formed by mechanically cutting the metal band and the end of the filler material.   The sealing surface is equipped with an annular and flat sheet-like soft sealing material that is concentric or substantially concentric with the sealing surface and covers the soft sealing material filled in the annular groove. The spiral wound gasket according to any one of the above. The spiral wound gasket according to any one of claims 1 to 5, wherein the soft sealing material is expanded graphite or ceramic paper.

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