阅读说明：本技术 金属垫圈 (Metal gasket ) 是由 佐藤广嗣 于 2019-09-24 设计创作，主要内容包括：一种金属垫圈(1),其具有：金属制的垫圈主体(2),其在外周面具有凹部状的圆周槽(3)；以及弹性体(4),其特征在于,在垫圈主体(2)的圆周槽(3)中插入有弹性体(4),在金属垫圈(1)的纵截面中,在与被密封件接触的垫圈主体(2)的上表面形成有朝向上部具有鼓起的圆弧状的上部密封面(2a),在与被密封件接触的垫圈主体的下表面形成有朝向下部具有鼓起的圆弧状的下部密封面(2b),在上部密封面(2a)设置有上部平面(5c)或者上部切口部(5a),在所述下部密封面(2b)设置有下部平面(5d)或者下部切口部(5b)。(A metal gasket (1) having: a metal gasket main body (2) having a concave circumferential groove (3) on the outer circumferential surface; and an elastic body (4) inserted into the circumferential groove (3) of the gasket main body (2), wherein, in the longitudinal section of the metal gasket (1), an arc-shaped upper sealing surface (2a) having a bulge toward the upper part is formed on the upper surface of the gasket main body (2) in contact with the object to be sealed, an arc-shaped lower sealing surface (2b) having a bulge toward the lower part is formed on the lower surface of the gasket main body in contact with the object to be sealed, an upper flat surface (5c) or an upper notched portion (5a) is provided on the upper sealing surface (2a), and a lower flat surface (5d) or a lower notched portion (5b) is provided on the lower sealing surface (2 b).)

1. A metal gasket, having:

a metal gasket main body having a concave circumferential groove on an outer circumferential surface thereof; and

an elastic body is arranged on the upper surface of the shell,

it is characterized in that the preparation method is characterized in that,

an elastic body is inserted into the circumferential groove of the gasket main body,

in the vertical cross section of the metal gasket, an arc-shaped upper sealing surface having a bulge toward the upper part is formed on the upper surface of the gasket main body contacting with the sealed material,

an arc-shaped lower sealing surface bulging toward the lower part is formed on the lower surface of the gasket main body contacting with the sealed piece,

the upper sealing surface is provided with an upper flat surface or an upper cutout portion, and the lower sealing surface is provided with a lower flat surface or a lower cutout portion.

2. The metal gasket of claim 1,

the surface hardness of the gasket main body is 15HV to 250 HV.

3. The metal gasket according to claim 1 or 2,

the metal constituting the gasket main body is a metal selected from the group consisting of aluminum, aluminum alloy, stainless steel, inconel, carbon steel, lead, gold, silver, copper, and magnesium alloy.

Technical Field

The present invention relates to metal gaskets. More specifically, the present invention relates to a metal gasket used for connecting pipes to each other in, for example, a steam plant, a nuclear power plant, a steam turbine ship, an oil refinery line, a petrochemical industry production line, a semiconductor manufacturing line, and the like.

Background

As metal gaskets having excellent heat resistance, metal hollow O-rings, metal C-rings, and the like have been proposed (for example, see patent documents 1 and 2). However, these metal gaskets have a drawback that a fastening force required for sealing between flanges is large. Therefore, in order to reduce the fastening force of the metal gasket, it is conceivable to form a protrusion on the sealing surface of the metal gasket, but when the metal gasket having the protrusion is attached between the flanges and the flanges are fastened, the protrusion is crushed to reduce the sealing property, and it is difficult to manufacture the protrusion with high accuracy, and therefore it is difficult to ensure high sealing property, and further, stress is concentrated on the protrusion, and therefore, the flange may be damaged.

As a metal gasket having a small tightening force and excellent sealing performance without providing a protrusion on a sealing surface of the metal gasket, a metal gasket having a groove on an outer diameter side surface or an inner diameter side surface of the metal gasket has been proposed (for example, see patent document 3). However, although the metal gasket is attached between the flanges, and the fastening force when fastening the flanges is small and the sealing property is excellent, there is a possibility that the sealing property is lowered when the metal gasket is subjected to a heat history.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 9-177976

Patent document 2: japanese patent laid-open publication No. 11-30333

Patent document 3: japanese patent laid-open publication No. 2003-156147

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above-described conventional technology, and an object thereof is to provide a metal gasket that can secure sealing performance by fastening flanges with a small fastening force and can secure sealing performance even when subjected to a heat history.

Means for solving the problems

The present invention relates to:

(1) a metal gasket, having: a metal gasket main body having a concave circumferential groove on an outer circumferential surface thereof; and an elastic body inserted into the circumferential groove of the gasket main body, wherein an upper sealing surface having a circular arc shape bulging upward is formed on an upper surface of the gasket main body contacting the object, a lower sealing surface having a circular arc shape bulging downward is formed on a lower surface of the gasket main body contacting the object, an upper flat surface or an upper cutout portion is provided on the upper sealing surface, and a lower flat surface or a lower cutout portion is provided on the lower sealing surface;

(2) the metal gasket according to the above (1), wherein the surface hardness of the gasket main body is 15HV to 250 HV; and

(3) the metal gasket according to the above (1) or (2), wherein the gasket main body is formed of a metal selected from the group consisting of aluminum, aluminum alloy, stainless steel, inconel, carbon steel, lead, gold, silver, copper, nickel, tantalum, chrome molybdenum steel, monel, titanium, and magnesium alloy.

Effects of the invention

According to the present invention, there is provided a metal gasket capable of securing sealability by fastening flanges with a small fastening force and capable of securing sealability even when subjected to a thermal history.

Drawings

Fig. 1 (a) is a schematic side view showing an embodiment of the metal gasket of the present invention, and fig. 1 (b) is a schematic plan view showing the embodiment of the metal gasket.

Fig. 2 is a schematic sectional view showing an embodiment of a metal gasket of the X-X portion shown in fig. 1 (b).

Fig. 3 is a schematic cross-sectional view showing one embodiment of the gasket main body of the X-X portion shown in fig. 1 (b).

Fig. 4 is a schematic sectional view showing another embodiment of the metal gasket of the X-X portion shown in fig. 1 (b).

Fig. 5 is a schematic sectional view showing still another embodiment of the metal gasket of the X-X portion shown in fig. 1 (b).

Fig. 6 is a schematic explanatory view of an evaluation test apparatus for a gasket used in each example and each comparative example.

Detailed Description

As described above, the metal gasket of the present invention is a metal gasket including a metal gasket main body having a concave circumferential groove on an outer circumferential surface thereof and an elastic body.

In the metal gasket of the present invention, the elastic body is inserted into the circumferential groove of the gasket main body, and in the longitudinal section of the metal gasket, an arc-shaped upper sealing surface having a bulge shape toward the upper portion is formed on the upper surface of the gasket main body that contacts the object to be sealed, an arc-shaped lower sealing surface having a bulge shape toward the lower portion is formed on the lower surface of the gasket main body that contacts the object to be sealed, an upper flat surface or an upper cutout portion is provided on the upper sealing surface, and a lower flat surface or a lower cutout portion is provided on the lower sealing surface.

Since the metal gasket of the present invention has the above-described structure, the following excellent effects are exhibited: the sealing performance can be ensured by fastening the flanges with a small fastening force, and the sealing performance can be ensured even when the heat history is applied.

Hereinafter, the metal gasket of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the embodiments shown in the drawings.

Fig. 1 (a) is a schematic side view showing an embodiment of the metal gasket of the present invention, and fig. 1 (b) is a schematic plan view showing the embodiment of the metal gasket. Fig. 2 is a schematic cross-sectional view showing an embodiment of the metal gasket 1 at the X-X portion shown in fig. 1 (b).

As shown in fig. 1 (a) and 2, a metal gasket 1 of the present invention includes: a metal gasket body 2 having a concave circumferential groove 3 on an outer circumferential surface thereof; and an elastic body 4. An elastic body 4 is inserted into the circumferential groove 3 of the gasket main body 2.

In the embodiment shown in fig. 2, an arc-shaped upper sealing surface 2a having a bulge toward the upper part is formed on the upper surface of the gasket main body 2 contacting the object to be sealed, and an arc-shaped lower sealing surface 2b having a bulge toward the lower part is formed on the lower surface of the gasket main body contacting the object to be sealed. An upper cut portion 5a and a lower cut portion 5b are provided in the upper seal surface 2a and the lower seal surface 2b, respectively.

From the viewpoint of securing the sealing performance by fastening the flanges with a small fastening force, the surface hardness (vickers hardness) of the gasket main body 2 is preferably 15HV or more, and more preferably 19HV or more. From the viewpoint of securing the sealing performance by fastening the flanges together with a small fastening force, the surface hardness (vickers hardness) of the gasket main body 2 is preferably 250HV or less, more preferably 220HV or less, still more preferably 175HV or less, and still more preferably 170HV or less.

From the viewpoint of securing the sealing property by fastening the flanges with a small fastening force, the material of the gasket main body 2 is preferably a metal selected from the group consisting of aluminum, aluminum alloy, stainless steel, inconel, carbon steel, lead, gold, silver, copper, nickel, tantalum, inconel, monel, titanium, and magnesium alloy, more preferably a metal selected from the group consisting of aluminum, aluminum alloy, stainless steel, and inconel, and still more preferably aluminum or stainless steel.

Examples of the aluminum alloy include an aluminum-iron alloy, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-magnesium alloy, an aluminum-zinc alloy, and an aluminum-nickel alloy, but the present invention is not limited to the above examples.

Examples of stainless steel include SUS304, SUS316, SUS430, SUS630, SUS631, SUS633, and SUS420J2, but the present invention is not limited to these examples.

Examples of the metal other than magnesium used for the magnesium alloy include lithium, calcium, aluminum, zinc, titanium, manganese, zirconium, yttrium, tantalum, neodymium, niobium, and the like, but the present invention is not limited to the above examples.

As shown in fig. 1 (b), the planar shape of the metal gasket 1 may be a ring shape or a polygonal shape such as a quadrangular shape, but is usually a ring shape. The outer diameter L of the metal gasket 1 varies depending on the application of the metal gasket 1 and cannot be determined in a general manner, and therefore is preferably determined appropriately depending on the application of the metal gasket 1, but is usually about 2mm to 3 m.

As shown in fig. 2, the cross-sectional shape of the gasket main body 2 at the X-X portion shown in fig. 1 (b) is substantially circular, but the present invention is not limited to this cross-sectional shape and may be polygonal. The cross-sectional shape of the gasket body 2 is preferably circular. The circular shape is not only a perfect circle but also a circular shape including concepts of a vertically long elliptical shape, a horizontally long elliptical shape, and an elliptical trajectory shape.

As described above, in the metal gasket 1 of the present invention, the upper surface of the gasket main body 2 is formed with the arc-shaped upper sealing surface 2a having a bulge upward, and the lower surface of the gasket main body 2 is formed with the arc-shaped lower sealing surface 2b having a bulge downward. The arc shape is not limited to a perfect circle arc, but may be an arc shape including a concept of a vertically long oval-shaped arc, a horizontally long oval-shaped arc, and an oval locus-shaped arc, as in the sectional shape of the gasket main body 2.

The gasket main body 2 will be described below with reference to fig. 3. Fig. 3 is a schematic cross-sectional view showing an embodiment of the gasket main body 2 of the X-X portion shown in fig. 1 (b).

In the metal gasket 1 of the present invention, an upper cutout portion 5a is provided on an upper sealing surface 2a of a gasket main body 2, and a lower cutout portion 5b is provided on a lower sealing surface 2b of the gasket main body 2.

The depths D of the upper cut portion 5a and the lower cut portion 5b are different depending on the material of the gasket body 2, the size of the gasket body 2, and the like, and therefore cannot be determined in a lump, but from the viewpoint of obtaining a metal gasket 1 capable of securing sealability by fastening the flanges with a small fastening force and also capable of securing sealability even when subjected to a heat history, the depths D of the upper cut portion 5a and the lower cut portion 5b are preferably 0.1mm to 3mm, more preferably 0.3mm to 2mm, and further preferably 0.5mm to 1mm, respectively. As shown in fig. 3, parallel lines are drawn out so that a tangent line is drawn out from the end portions of the upper cutout portion 5a and the lower cutout portion 5b and a straight line contacting the bottom portions of the upper cutout portion 5a and the lower cutout portion 5b is parallel to the tangent line, and the depth D of the upper cutout portion 5a and the lower cutout portion 5b is a distance between the tangent line and the parallel lines.

The widths W of the upper notch 5a and the lower notch 5b are different depending on the material of the gasket body 2, the size of the gasket body 2, and the like, and therefore cannot be determined in a lump, but from the viewpoint of obtaining a metal gasket 1 capable of securing sealability by fastening the flanges with a small fastening force and ensuring sealability even when subjected to a heat history, the widths W of the upper notch 5a and the lower notch 5b are preferably 0.1mm to 3mm, more preferably 0.3mm to 2mm, and further preferably 0.5mm to 1mm, respectively. As shown in fig. 3, a tangent line is drawn at the end of each of the upper cutout portion 5a and the lower cutout portion 5b, 2 straight lines perpendicular to the tangent line are drawn from the end of each of the upper cutout portion 5a and the lower cutout portion 5b, and the width W of each of the upper cutout portion 5a and the lower cutout portion 5b is a distance between 2 perpendicular lines.

In order to obtain the metal gasket 1 capable of securing the sealing property by fastening the flanges with a small fastening force and securing the sealing property even when the metal gasket is subjected to a heat history, each of the upper notch portion 5a and the lower notch portion 5b is preferably a V-shaped notch portion as shown in fig. 3. From the viewpoint of obtaining a metal gasket 1 that can secure sealing properties by fastening flanges with a small fastening force and can secure sealing properties even when subjected to a heat history, the angle θ formed by the groove portions of the V-shaped notch portions is preferably 20 ° or more, more preferably 40 ° or more, and still more preferably 45 ° or more, and from the viewpoint of obtaining a metal gasket 1 that can secure sealing properties by fastening flanges with a small fastening force and can secure sealing properties even when subjected to a heat history, the angle θ formed by the groove portions of the V-shaped notch portions is preferably less than 180 °, more preferably 160 ° or less, more preferably 140 ° or less, and still more preferably 120 ° or less.

In the upper cutout portion 5a and the lower cutout portion 5b, as shown in fig. 3, the bottom of the V-shaped cutout portion may be acute-angled, flat, or arcuate. From the viewpoint of securing the sealing property by fastening the flanges with a small fastening force, the bottom of the V-shaped notch portion is preferably at an obtuse angle.

From the viewpoint of obtaining the metal gasket 1 capable of securing the sealing property by fastening the flanges with a small fastening force and also securing the sealing property even when the metal gasket is subjected to a heat history, as shown in fig. 3, the position of the deepest portion of the upper cutout portion 5a and the deepest portion of the lower cutout portion 5b in the horizontal direction of the metal gasket 1 is preferably present between the deepest end P of the inner side wall of the circumferential groove 3 and the inlet portion Q of the circumferential groove 3.

The upper cutout portion 5a and the lower cutout portion 5b may be provided not only on the upper sealing surface 2a and the lower sealing surface 2b, respectively, but also on an upper wall surface (not shown) and a lower wall surface (not shown) inside the circumferential groove 3 for inserting the elastic body 4 described later, respectively, as necessary.

A circumferential groove 3 for inserting an elastic body 4 is formed inside the gasket main body 2. In the embodiment shown in fig. 2 and 3, both the upper wall surface (not shown) and the lower wall surface (not shown) inside the circumferential groove 3 are formed as planes horizontal to the gasket main body 2, but need not necessarily be formed as planes horizontal to the gasket main body 2, and may be planes inclined (tapered) with respect to the horizontal direction of the gasket main body 2.

The minimum thickness of the gasket main body 2 at the innermost end P of the inner side wall of the circumferential groove 3 is not determined in a lump because it differs depending on the application or the like of the metal gasket 1 of the present invention, but from the viewpoint of obtaining a metal gasket 1 capable of securing sealability by fastening the flanges with a small fastening force and also capable of securing sealability even when subjected to a thermal history, the minimum thickness of the gasket main body 2 at the innermost end P of the inner side wall of the circumferential groove 3 is preferably 1mm or more, more preferably 1.5mm or more, and still more preferably 2mm or more, respectively. The maximum thickness of the gasket main body 2 at the innermost end P of the circumferential groove 3 is preferably 15mm or less, more preferably 10mm or less, and still more preferably 5mm or less, from the viewpoint of obtaining a metal gasket 1 that can secure sealing properties by fastening flanges with a small fastening force and can secure sealing properties even when subjected to a thermal history, although the maximum thickness of the gasket main body 2 at the innermost end P of the circumferential groove 3 cannot be determined in a lump depending on the application and the like of the metal gasket 1 of the present invention.

The inner surfaces (not shown) of the circumferential groove 3 of the gasket main body 2 shown in fig. 3 are formed of flat surfaces, but need not necessarily be formed of flat surfaces, and may be formed of curved surfaces such as circular arc-shaped curved surfaces, wave-shaped curved surfaces, and concave-convex curved surfaces.

The width S of the opening of the circumferential groove 3 is preferably 30% to 85% of the thickness T of the gasket main body 2 of the metal gasket 1 shown in fig. 1 (a), from the viewpoint of obtaining a metal gasket 1 capable of securing sealability by fastening the flanges with a small fastening force and securing sealability even when subjected to a thermal history, although the width S of the opening of the circumferential groove 3 cannot be determined in a lump depending on the application or the like of the metal gasket 1 of the present invention.

The thickness T of the gasket main body 2 varies depending on the application of the metal gasket 1 and the like, and cannot be determined in a general manner, and therefore is preferably determined appropriately depending on the application of the metal gasket 1, but is usually about 1.5mm to 15 mm.

In fig. 3, the horizontal length B of the gasket main body 2 differs depending on the application of the metal gasket 1 and the like, and cannot be determined in a general manner, and therefore, it is preferably determined appropriately depending on the application of the metal gasket 1 and the like, but is usually about 1mm to 15 mm.

From the viewpoint of securing the sealing property by fastening the flanges with a small fastening force, the value of the ratio of the depth a of the circumferential groove 3 of the gasket main body 2 to the length B of the gasket main body 2 in the horizontal direction (the depth a of the circumferential groove/the length B of the gasket main body in the horizontal direction) is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, still more preferably 0.4 or more, still more preferably 0.5 or more, and from the viewpoint of improving the mechanical strength of the gasket main body 2 and securing the sealing property by fastening the flanges with a small fastening force, the ratio is preferably 0.95 or less, more preferably 0.9 or less, still more preferably 0.88 or less, and still more preferably 0.86 or less.

As shown in fig. 2, an elastic body 4 is disposed in the circumferential groove 3 of the gasket main body 2. Examples of the material constituting the elastomer 4 include rubbers such as fluororubber, silicone rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, chloroprene rubber, and natural rubber, thermoplastic elastomers such as olefin thermoplastic elastomers, ester thermoplastic elastomers, styrene thermoplastic elastomers, and vinyl chloride thermoplastic elastomers, and highly flexible thermoplastic resins such as fluororesins such as polytetrafluoroethylene. Among the materials constituting the elastic body 4, fluororubber and silicone rubber are preferable, and fluororubber is more preferable, from the viewpoint of obtaining a metal gasket 1 which has excellent heat resistance, can secure sealing properties by fastening the flanges with a small fastening force, and can secure sealing properties even when subjected to heat history. In addition, a coil spring can be used as the elastic body 4.

The elastic body 4 has a shape corresponding to the inner shape of the circumferential groove 3 of the gasket main body 2. The elastic body 4 shown in fig. 2 is disposed in the circumferential groove 3 so as to be in contact with the inner wall of the circumferential groove 3 of the gasket main body 2, but for example, a gap may be provided between the elastic body 4 and the inner surface of the circumferential groove 3 by forming a concave-convex shape on the surface of the elastic body 4 or forming the sectional shape of the elastic body 4 into a circular shape, a triangular shape, or the like. From the viewpoint of improving the flexibility of the elastic body 4, as shown in fig. 4, the elastic body 4 may be provided with a cutout 6 as needed. Fig. 4 is a schematic cross-sectional view showing another embodiment of the metal gasket 1 at the X-X portion shown in fig. 1 (b).

The elastic body 4 may be disposed so as to fill the entire inner portion of the circumferential groove 3 of the gasket main body 2, or may be disposed in the circumferential groove 3 so that a brim portion 2c is formed at an inlet portion Q of the circumferential groove 3 of the gasket main body 2, as shown in fig. 2.

As another embodiment of the metal gasket 1 of the present invention, a metal gasket 1 shown in fig. 5 can be mentioned. Fig. 5 is a schematic sectional view showing still another embodiment of the metal gasket of the X-X portion shown in fig. 1 (b).

While the embodiment shown in fig. 2 to 4 has an upper cutout portion 5a provided in the upper sealing surface 2a and a lower cutout portion 5b provided in the lower sealing surface 2b, the embodiment shown in fig. 5 has an upper flat surface 5c provided in the upper sealing surface 2a and a lower flat surface 2d provided in the lower sealing surface 2 b. In these embodiments, from the viewpoint of securing the sealing performance by fastening the flanges with a small fastening force, it is preferable that the upper seal surface 2a is provided with an upper notched portion 5a and the lower seal surface 2b is provided with a lower notched portion 5 b.

The upper flat surface 5c and the lower flat surface 5d may be provided in parallel with the upper sealing surface 2a and the lower sealing surface 2b, respectively, as shown in fig. 5, or may be provided in an inclined manner with respect to the upper sealing surface 2a and the lower sealing surface 2b, respectively. In these embodiments, from the viewpoint of securing the sealing performance by fastening the flanges with a small fastening force, the upper flat surface 5c and the lower flat surface 5d are preferably provided to be inclined with respect to the upper sealing surface 2a and the lower sealing surface 2b, respectively. In this case, from the viewpoint of securing the sealing property by fastening the flanges with a small fastening force, the length E from the upper end to the lower end in the vertical direction of the upper flat surface 5c and the length F from the upper end to the lower end in the vertical direction of the lower flat surface 5d are preferably 0.1mm to 3mm, more preferably 0.3mm to 2mm, and further preferably 0.5mm to 1mm, respectively. From the viewpoint of securing the sealing performance by fastening the flanges with a small fastening force, the length G from the upper end to the lower end of the upper flat surface 5c in the horizontal direction and the length H from the upper end to the lower end of the lower flat surface 5d in the horizontal direction are each preferably 0.1mm to 3mm, more preferably 0.3mm to 2mm, and further preferably 0.5mm to 1 mm.

The metal gasket 1 of the present invention configured as described above can secure sealing performance by fastening the flanges with a small fastening force, and can secure sealing performance even when subjected to a thermal history. Therefore, the metal gasket 1 of the present invention can be suitably used for connecting pipes to each other in, for example, a steam plant, a nuclear power plant, a steam turbine ship steam facility, an oil refinery line, a petrochemical industry production line, a semiconductor manufacturing line, and the like.

Next, an embodiment of the metal gasket of the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples.

Example 1

As the gasket body, an aluminum gasket body (surface hardness: 22HV) having the shape shown in FIGS. 1 to 3 was used.

More specifically, the following gasket main body 2 is used: in the metal gasket 1 shown in fig. 1 (a) and (b), the outer diameter L of the planar shape of the gasket main body 2 was 75mm, the thickness T was 3.5mm, in the metal gasket 1 shown in fig. 2, the width S of the opening portion of the circumferential groove 3 is 2.5mm in length, the minimum thickness of the gasket body 2 at the innermost end P of the inner side wall of the circumferential groove 3 is 0.3mm, in the gasket main body 2 shown in fig. 3, the depth a of the circumferential groove 3 is 3mm, the length B in the horizontal direction is 3.5mm, the ratio of the depth a to the length B in the horizontal direction (the depth a of the circumferential groove 3/the length B in the horizontal direction) is 0.86, the widths W of the upper cutout portion 5a and the lower cutout portion 5B are 4mm, the depths D of the upper cutout portion 5a and the lower cutout portion 5B are 2mm, and the angles θ formed by the groove portions 3 of the V-shaped cutout portions of the upper cutout portion 5a and the lower cutout portion 5B are 110 °.

The metal gasket 1 was manufactured by fitting the fluororubber elastomer 4 having the shape shown in fig. 2 into the circumferential groove 3 of the gasket main body 2.

As the physical properties of the metal gasket 1 obtained as described above, the required fastening force, the sealing property, and the sealing property after the heat history were evaluated by the following methods. The results are shown in table 1.

(1) Required fastening force

The required fastening force was evaluated using the evaluation test apparatus 7 for a gasket shown in fig. 6. Fig. 6 is a schematic explanatory view of the evaluation test device 7 for a gasket.

The gasket 8 is mounted between the test plates 9a and 9b, and the amount of movement of the test plate 9a is measured by a dial gauge while compressing the gasket 8, and the gasket is measured according to the following equation:

[ compression ratio ]/[ height of initial gasket 8) - (height of gasket 8 after compression) ]/[ height of initial gasket 8 ] × 100

The compression load when the obtained compression ratio reached 17% was measured, and the compression load was used as the required tightening force, and the required tightening force was evaluated according to the following evaluation criteria. In addition, the compression load when the compression rate reaches 17% is a compression load (required fastening force) required to eliminate the gap between the gasket 8 and the test plates 9a, 9 b.

[ evaluation criteria ]

Very good: the required tightening force (compressive load) is less than 50 kN/m.

Good: the required fastening force (compressive load) is 50kN/m or more and less than 80 kN/m.

And (delta): the required fastening force (compressive load) is 80kN/m or more and less than 100 kN/m.

X: the required fastening force (compressive load) is 100kN/m or more.

(2) Sealing property

For the evaluation of the sealing property of the gasket, the gasket evaluation test apparatus 7 shown in fig. 6 was used.

First, in the evaluation test device 7 for sealing property, a gasket 8 was mounted between the test boards 9a and 9b, and after a compressive load of 25kN/m was applied to the gasket 8, helium gas was injected from a nozzle 10a of a helium tank 10 so that the evaluation test device 7 was filled with helium gas at atmospheric pressure.

Next, the inside of the gasket 8 was depressurized until the degree of vacuum became 0.1Pa using the helium leak detector 11, and the amount of leakage of helium gas flowing from the outside of the gasket 8 into the space inside the gasket 8 was measured at the time when 5 minutes elapsed from the reaching of the degree of vacuum.

Based on the measured helium gas leakage amount, the sealing performance was evaluated according to the following evaluation criteria.

[ evaluation criteria ]

Very good: leakage of helium less than 4 x 10^-11Pa·m³S · m (detection limit).

Good: leakage of helium gas was 4X 10^-11Pa·m³A number of m is not less than 1X 10^-10Pa·m³/s·m。

And (delta): leakage of helium gas is 1X 10^-10Pa·m³A number of m is not less than 1X 10^-9Pa·m³/s·m。

X: leakage of helium gas is 1X 10^-9Pa·m³More than s.m.

(3) Sealing after thermal history

After a thermal history was given to the gasket by placing the gasket in a thermostatic bath at a temperature of 100 ℃ for 24 hours and heating, the gasket was cooled to room temperature and taken out from the thermostatic bath.

The heat history-imparted gasket was used to investigate the sealing property in the same manner as described above, and whether or not the leakage amount of helium gas was increased as compared with the case of measuring the sealing property was examined, and the sealing property after the heat history was evaluated based on the following evaluation criteria.

[ evaluation criteria ]

Very good: the amount of helium leakage is not considered to increase.

X: the amount of helium leakage is believed to increase.

(4) Comprehensive evaluation

In the evaluation results of the required fastening force, the sealing property, and the sealing property after the heat history of the gasket, the evaluation of ∈ was regarded as 100 points, the evaluation of good was regarded as 80 points, the evaluation of Δ was regarded as 60 points, and the evaluation of × was regarded as 0 points, and the respective scores of the required fastening force, the sealing property, and the sealing property after the heat history of the gasket were summed up, and the total score was described in the column of the comprehensive evaluation in table 1.

In addition, when there is an evaluation of x in any one of the evaluation results of the required fastening force of the gasket, the sealability and the sealability after the heat history, the column of the comprehensive evaluation indicates "failure".

Comparative example 1

In example 1, a gasket main body in which an elastomer is not used is used as a metal gasket.

The required fastening force, sealing property, and sealing property after heat history of the metal gasket were evaluated in the same manner as in example 1. The results are shown in table 1.

Comparative example 2

A conventional gasket was evaluated for required fastening force, sealing property, and sealing property after heat history in the same manner as in example 1 using an O-ring made of fluororubber (product No.4640, manufactured by Walker Kasei corporation). The results are shown in table 1.

Comparative example 3

A spring-equipped metal C-ring (product No. 3645, manufactured by Walker Karl) was used as a conventional metal gasket, and the required fastening force, sealing property and sealing property after heat history were evaluated in the same manner as in example 1. The results are shown in table 1.

Comparative example 4

As a conventional gasket, a metal hollow O-ring (product No. 3640, manufactured by Walker Kasei corporation) made of stainless steel (SUS304) was used, and the required fastening force, sealing property and sealing property after heat history were evaluated in the same manner as in example 1. The results are shown in table 1.

[ Table 1]

As is apparent from the results shown in table 1, the metal gasket obtained in example 1 can eliminate the gap between the metal gasket and the test plate with a low fastening force such that the required fastening force is 35kN/m, and therefore, even when used for fastening a flange made of a soft metal such as an aluminum flange, for example, a seal can be improved when the flange is used without leaving any fastening mark on the flange.

The metal gasket obtained in example 1 is excellent in sealing properties and does not change in sealing properties after being subjected to a thermal history, and therefore, it is considered that the metal gasket can be suitably used for connecting pipes to each other in a steam facility of a thermal power plant, a nuclear power plant, a steam turbine ship, an oil refinery line, a production line of a petrochemical industry, a semiconductor manufacturing line, and the like.

In contrast, the physical properties of the gasket used in each comparative example were found to be inferior in any of the required fastening force, the sealing property, and the sealing property after the heat history.

Description of the reference symbols

1: a metal washer; 2: a gasket body; 2 a: an upper sealing surface; 2 b: a lower sealing surface; 2 c: an eave portion; 3: a circumferential groove; 4: an elastomer; 5 a: an upper cut-out portion; 5 b: a lower cut-out portion; 5 c: an upper plane; 5 d: a lower plane; 6: a cutout portion; 7: a sealing performance evaluation test device; 8: a gasket; 9 a: a test board; 9 b: a test board; 10: a helium tank; 11 a: a nozzle; 12: a helium leak detector.