JP2017120102A - Spiral type gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spiral type gasket capable of exerting sealability and reduced in a risk of filler defect even after being used under a high temperature atmosphere for a long period.SOLUTION: In a spiral type gasket 10 formed by superposing a filler material 1 and a hoop material 2 and spirally winding them, inorganic fiber is blended in the filler material, and strength of the filler is 9 g or more, when a rectangular parallelepiped specimen having long side 30 mm×short side 15 mm, and thickness of 0.5±0.05 mm is collected from the filler material, the specimen is heated for 96 hours at 500°C, then the specimen is placed on two rods of 14 mm interval while aligning a center of the specimen to a center of the interval of the rods, a rectangular parallelepiped weight having a weight of 1 g, and a dimension of 9 mm×15 mm or more is placed on the center of the specimen in a state that central axes of long sides of the specimen and the weight are orthogonal to each other, strength of 1 g is determined when the specimen can be held without broken for 5-10 seconds, further the holding of 5-10 seconds is repeated by further placing the weight of 1 g, and the weight of the weight capable of being held just before breaking of the specimen is regarded as the strength of the filler.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a spiral wound gasket, and more particularly to a spiral wound gasket using inorganic fibers as a filler material of a gasket body.

  A spiral wound gasket (SWG) used at high temperature and high pressure has a structure as shown in FIG. That is, in the spiral wound gasket, the filler material 1 and the hoop material 2 made of a thin metal tape having a V-shaped cross section are overlapped and wound in a spiral shape, and the winding start and end are wound. The gasket body 10 is formed by performing idle winding of 2 to 3 rounds with only 2 and fixing this by spot welding or the like.

  And it fixes to the inner periphery of this gasket main body 10 by fitting the inner ring ring member 3 which consists of a cyclic | annular metal plate as a guide member. Further, an outer ring member 4 made of an annular metal plate is fixed to the outer peripheral edge of the gasket body 10 as a guide member by fitting.

As such a filler material, typically, an expanded graphite sheet (for example, Patent Document 1: Japanese Patent Application Laid-Open No. 2011-144881) and a sheet mainly composed of mica (for example, Patent Document 2: Japanese Patent Application Laid-Open No. 2007-127178). ), Inorganic fibers (for example, Patent Document 3: JP-A-7-305772).
The sealing properties of these filler materials under the maximum use temperature and long-term heating conditions are roughly shown in the following table.

The expanded graphite sheet is difficult to use in a high temperature environment, and is oxidized and deteriorates when exposed to a high temperature, and the sheet mainly composed of mica has a problem that its use range is narrow and its versatility is poor.
The sheet | seat which mix | blended the inorganic fiber has the advantage which has the sealing performance in a high area | region in the high temperature area | region to 500 degreeC. However, when used at a high temperature for a long period of time, there is a problem that the sealing performance is lowered.

JP 2011-144881 A JP 2007-127178 A Japanese Patent Application Laid-Open No. 7-307772

  Under such circumstances, the present invention has been made in view of the problems in the prior art as described above, and not only exhibits sealing properties even after use under a long-term high-temperature atmosphere, but also lacks filler defects. An object of the present invention is to provide a spiral wound gasket that has a low risk of occurrence.

In general, the following mechanism can be considered as a cause of a decrease in sealing performance of a spiral wound gasket.
(i) Contact surface leakage between gasket and flange
(ii) Permeation leakage through the filler material
(iii) Permeation leakage through the interface between the filler material and the hoop material In particular, in the case of a spiral wound gasket using a sheet containing inorganic fibers as a filler material, when it is used for a long time under heating conditions, the sealing performance is reduced by (i) It is considered to be.

  The reason for this is that the spiral wound gasket using “sheets containing inorganic fibers” as a filler material, when the surface pressure of the gasket is reduced by repeated long-term use and heating / cooling at high temperatures, The binder component disappears due to heat. And when a binder component lose | disappears, the intensity | strength of filler material itself falls and it becomes impossible to hold | maintain the shape as a filler material of a sealing surface. As a result, it is considered that the inorganic fiber or the like in the filler material falls off from the sealing surface due to pressure or vibration in the pipe, and a leak path is generated at the contact surface between the gasket and the flange, resulting in a decrease in sealing performance. Further, when the strength of the filler material is lowered, the dropped inorganic fibers are scattered, so there is a concern about the influence on the environment.

  And the present inventors have further studied earnestly, by using a filler material whose filler strength after heating measured in a predetermined heating condition is in a specific range, such as pipe stress and internal pressure during use of the spiral wound gasket The present inventors have found that filler deficiency due to the action of external factors can be suppressed and have completed the present invention.

The configuration of the present invention is as follows.
[1] A spiral wound gasket including a gasket body formed by overlapping a filler material and a hoop material and winding them in a spiral shape,
The filler material comprises a sheet containing inorganic fibers,
A rectangular parallelepiped test piece having a length of 30 mm × short side of 15 mm and a thickness of 0.5 ± 0.05 mm is collected from the filler material, and the test piece is heated at 500 ° C. for 96 hours. On two bars with a distance of mm, the short side is parallel to the bars and the center of the test piece is overlapped with the center of the distance, the weight of the test piece is 1 g, and the dimensions are short. Put a cuboid weight with a side of 9 mm x longer side of 15 mm or more so that the central axes of the long sides of the test piece and the weight are orthogonal to each other. As described above, when the weight of the weight that was able to be held before the test piece breaks was used as the strength of the filler, the strength was 9 g or more. Spiral wound gasket.
[2] The composition of the filler material ranges from 74 to 85% by weight of the inorganic filler, 2 to 20% by weight of the inorganic fiber, 2 to 20% by weight of the organic fiber, and 4 to 12% by weight of the organic binder (the total is 100% by weight) %)). The spiral wound gasket according to [1].
[3] The spiral wound gasket according to [1] or [2], wherein rock wool is included as the inorganic fiber.
[4] The spiral wound gasket according to [3], wherein 75% by weight or more of the inorganic fiber is rock wool.
[5] The spiral wound gasket according to any one of [1] to [4], wherein the average fiber diameter of the inorganic fibers is in the range of 11 to 20 μm.
[6] The spiral wound gasket according to any one of [1] to [5], wherein the average aspect ratio of the inorganic fibers is in the range of 70 to 115.

Since the spiral wound gasket of the present invention uses a filler material having a high filler strength evaluated under predetermined conditions, the sealability when used for a long time under high temperature conditions is high.
Specifically, after heating under predetermined conditions, a filler material having a certain strength or more is used. As a result, the loss of the filler material due to external factors such as internal pressure load is suppressed during high-temperature long-term use, and the fluid can be sealed for a long time even in a high-temperature environment.

FIG. 1 is a partial cross-sectional view schematically showing a spiral wound gasket. FIG. 2 is a schematic view of measuring the strength of the filler material.

Hereinafter, the spiral wound gasket of the present invention will be described in more detail.
The spiral wound gasket of the present invention includes an annular gasket body formed by overlapping a filler material and a hoop material and winding them in a spiral shape as shown in FIG.

[Filler material]
A filler material consists of a sheet | seat which mix | blended inorganic fiber.
In the present invention, with respect to the inorganic fibers blended in the filler material, fibers having a small fiber length (short) and a large fiber diameter (thick) are preferably used. That is, the fiber has a small aspect ratio. By using the inorganic fiber, it was considered that the inorganic fiber is not easily broken and normality is maintained, and the strength as a filler is increased.

  Inorganic fibers other than asbestos are used as the inorganic fibers, and specific examples include ceramic fibers, rock wool, glass fibers, titanate fibers, and the like. Such inorganic fibers are preferably flexible and not rigid, and the average fiber diameter is 20 μm or less, preferably 11 to 20 μm. The average aspect ratio is 150 or less, preferably 115 or less, and more preferably in the range of 70 to 115. The average fiber length is appropriately selected from the fiber diameter and aspect ratio described above.

When inorganic fibers having an aspect ratio and a fiber diameter in this range are used, a predetermined filler strength is exhibited.
As for the shape of the inorganic fiber, the fiber diameter and the fiber length are measured by the method shown in Examples by microscopic observation of 100 samples, and the average value is obtained and the aspect ratio is calculated.

In the present invention, such inorganic fibers may be used alone or in combination of two or more.
In the present invention, it is preferable that rock wool is included as the inorganic fiber without adversely affecting the environment from the viewpoint of biodegradability. Furthermore, it is preferable that 75% by weight or more of the inorganic fiber is rock wool.

The filler material is preferably formed by including organic fibers, an inorganic filler, an inorganic binder, and an organic binder together with the inorganic fibers.
Examples of organic fibers include natural fibers such as plant fibers, synthetic fibers such as aramid fibers, carbonized fibers, carbon fibers, and graphitized fibers. These organic fibers may be used alone or in combination of two or more.

  These organic fibers play a role of increasing the strength of the filler material such that the filler material does not break when the spiral wound gasket is manufactured by winding the filler material and the hoop material. Such an organic fiber is desirably flexible and does not deteriorate the airtightness of the spiral wound gasket obtained, and the fiber diameter is preferably 10 μm or less and preferably 0.2 μm or more. Therefore, as such an organic fiber, it is desirable to use at least one kind of fibrillated pulp-like aramid fiber having a fiber diameter as described above.

  Examples of the inorganic filler include talc, clay, calcium carbonate, barium sulfate, zinc oxide, titanium oxide, and silica. These inorganic fillers play a role in increasing the clogging (airtightness) between fibers, the flexibility of the filler, and the shape retention (aggregation) of the filler at high temperatures, and remain without disappearing even at high temperatures. And plays a role in maintaining the sealing performance. The particle size of such an inorganic filler is preferably fine, and specifically, it is desirable to have a particle size distribution in which the particle size is 5 μm or less and the particle size of 1 μm or less is 5% or more. In the present invention, it is desirable to use two or more kinds of fillers having different particle size distributions in combination, and when two or more kinds of fillers having different particle size distributions are used in combination as described above, A gasket having excellent flexibility can be obtained.

  The binder combines the fiber and inorganic filler, plays a role in enhancing the sealing performance and giving the filler material mechanical strength, and can be either organic or inorganic, or a combination of organic and inorganic binders. Also good. Specific examples of such an inorganic binder include polyphosphate and water glass. Specific examples of organic binders include, for example, NBR-based, SBR-based, acrylic ester-based, fluorine-based rubber-based elastomer-based organic binders, methylsilicone-based binders, phenylsilicone-based binders, and other silicone-based binders. Or a binder of phenol such as a water-dispersed phenol resin.

  In addition to the above-described components, the filler material may contain a paraffin wax-based water / oil repellent as necessary. When such a water / oil repellent is used, the sealing property at room temperature can be improved.

In addition to the above components, the filler material of the present invention may further contain various vulcanizing agents, vulcanization accelerators, vulcanization aids, anti-aging agents, colorants and the like.
The filler material is in a range of 74 to 85% by weight of an inorganic filler, 2 to 20% by weight of inorganic fibers, 2 to 20% by weight of organic fibers, and 4 to 12% by weight of an organic binder (however, the total is 100% by weight). It is preferable in order to express the strength.

  In the filler material used in the present invention, when the inorganic fiber and the inorganic filler as described above and an inorganic binder are further included, the total amount of inorganic substances is 76 to 94% by weight, preferably 85 to 90% by weight (however, When the inorganic binder is included, the total of the inorganic filler, the inorganic fiber, the organic fiber, the organic binder, and the inorganic binder is 100% by weight).

  The inorganic fiber in the filler material is contained in an amount of 2 to 20% by weight, preferably 2 to 19% by weight, particularly preferably 2 to 18% by weight, and the inorganic fiber is contained in a total amount of 100 parts by weight of the above-mentioned inorganic substances. It is desirable that it is contained in an amount of 1.8 parts by weight or more, preferably 3.5 parts by weight or more.

  In the filler material, the total amount of the inorganic binder and the organic binder is 5 to 20% by weight, preferably 7 to 17% by weight, and the total amount of the inorganic fiber and the organic fiber is 4 to 20% by weight, preferably Is preferably contained in an amount of 5 to 15% by weight.

The organic fiber is desirably contained in the filler material in an amount of 2 to 20% by weight, preferably 2.0 to 13.7% by weight, particularly preferably 2.0 to 9.7% by weight.
The filler material containing the inorganic material composed of the inorganic fiber, the inorganic binder, and the inorganic filler in the total amount as described above is excellent in airtightness at a high temperature. Note that the filler material having an inorganic content of less than 76% by weight contains a large amount of organic matter, so that it is decomposed at a high temperature, the weight loss becomes significant, and the effect of sizing the binder is lost.

  In addition, the filler material containing the inorganic fiber and the organic fiber in a total amount of 3 to 20% by weight as described above has a strength required when manufacturing the filler material and a strength required when manufacturing the spiral wound gasket. ing. Moreover, the spiral wound gasket having the filler material is excellent in sealing properties at room temperature, and does not impair airtightness even when used at high temperatures due to its heat loss.

  The filler material can be produced by a conventionally known method such as a papermaking method. For example, the filler material can be produced by the papermaking method as follows. First, after a predetermined amount of organic fiber, inorganic fiber and inorganic filler are dispersed in water using a hydra pulper or a heater, a predetermined amount of organic / inorganic binder and, if necessary, a vulcanizing agent, a vulcanization accelerator, and a water repellent It was obtained after adding various auxiliary materials such as agents to adjust the slurry concentration as appropriate, then adding a fixing agent as necessary, and attaching the organic / inorganic binder to the fibrous material, inorganic filler, etc. The slurry is sequentially guided to a chest and then to a paper machine to obtain a filler material sheet. If necessary, by using a flocculant at the paper making stage, the slurry may be diluted to a concentration capable of making paper while maintaining the uniform dispersibility of the slurry.

  The filler material used in the present invention has a strength evaluated below of 9 g or more, preferably 10 g or more, and more preferably 11 g or more. When a filler material having such strength is used, long-term sealing is possible under heating conditions. Since the strength of the filler material after heating is high, the loss of the filler can be suppressed, and long-term sealing can be achieved. The upper limit of the strength is not particularly limited as long as it can be processed.

  In order to adjust to such filler strength, the fiber diameter, aspect ratio, fiber length, and content in the filler material of the inorganic fiber are important, and adjustment is possible by using the one in the predetermined range described above. It becomes.

A rectangular parallelepiped test piece having a length of 30 mm × short side of 15 mm and a thickness of 0.5 ± 0.05 mm is taken from the strength measurement filler material and heated at 500 ° C. for 96 hours. By heating, the binder and the organic fiber disappear. The test specimen after heating is placed on two round bars (made of stainless steel having a diameter of about 2.4 mm (2.4 to 2.6 mm)) with an interval of 14 mm, and the rectangular center of the test piece is the center of the interval between the bars. Place the short side to overlap.

  Place the weight of a rectangular parallelepiped with a weight of 1 g and a dimension of 9 mm short side x 15 mm long side at the center of the test piece so that the central axes of the long sides of the test piece and the weight are orthogonal to each other. When it is not broken and can be held for 2 seconds, the strength is set to 1 g, and a weight of 1 g is further applied and the holding for 5 seconds is repeated. If not broken, the operation of adding and holding a 1 g weight is repeated, and when the test piece breaks, the weight of the weight that can be held immediately before breaking is taken as the strength of the filler in the present invention.

Note that the holding time is desirably constant at 5 seconds, but the measured intensity is not affected as long as it is 10 seconds after 5 seconds. For this reason, what is necessary is just to hold | maintain for 5 to 10 second.
The long side of the weight is not particularly limited as long as it is 15 mm or more, but a 25 mm length is usually used. The test is performed 5 times, and the average value of 5 times is evaluated.

[Hoop material]
As the hoop material, a tape-shaped hoop material used for a normal spiral wound gasket can be used.

  Examples of the material of the hoop material include stainless steel materials such as SUS304, SUS304L, SUS316, and SUS316L, and simple metals and alloys such as aluminum, inconel, and hastelloy.

The thickness of the hoop material is usually set in the range of 0.1 to 0.3 mm, although it varies depending on conditions such as gasket dimensions, usage, and required performance.
The cross-sectional shape of the hoop material is not only a curved line shape such as a V shape or M shape, but also a curved shape such as an arc shape or a wave shape, or a combination of a straight portion and a curved portion. it can.

[Spiral wound gasket]
The spiral wound gasket of the present invention includes a gasket body formed by winding the filler material and the hoop material in a spiral manner by a conventionally known method.

  Moreover, in the said gasket main body, filler materials other than the said filler material may be used together. For example, the gasket main body may be formed using the filler material only in the inner peripheral portion and the outer peripheral portion and using a conventional expanded graphite filler material in the central portion.

  The spiral wound gasket of the present invention may further include an inner ring member that is fitted to the inner periphery of the gasket body and / or an outer ring member that is fitted to the outer periphery of the gasket body.

  Since the spiral wound gasket of the present invention has the above-described structure, it exhibits good sealing performance even in a highly oxidizing atmosphere, so that it can be used for petrochemical sealing materials, oil refining plant sealing materials, and the like. Useful.

[Example]
Hereinafter, the spiral wound gasket according to the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

<Evaluation method of fiber diameter and fiber length>
Optical micrographs of inorganic fibers were taken and the diameter and length were measured.
Regarding the fiber length, there are those in which inorganic fibers break and become shorter. Therefore, when performing fiber length evaluation, a wide distribution occurs. In order to eliminate these effects, 100 optical fibers are randomly picked up and evaluated. Evaluation is made using the data of the top 50 percent with the longest fiber length (Table 2).

Moreover, the average of the fiber diameter was computed from the fiber which evaluated fiber length. Each aspect ratio was also determined from each fiber diameter and fiber length. The measured data is listed in the table below. The evaluation results are also described below.
The measuring instrument was KEYENCE VHX-D510 (VHX DIGITAL MICROSCOPE), and the optical magnification was evaluated at 150 to 200 times.

[Example 1]
Inorganic filler (talc, clay, etc.): 78% by weight, inorganic fiber (rock wool): 6% by weight, organic fiber (aramid fiber): 8% by weight, organic binder (NBR): 8% by weight used. The form of the filler material was papermaking, and the thickness was 0.5 ± 0.05 mm. The average diameter of the rock wool fibers was 11.05 μm, and the average fiber length was 774.05 μm. The average aspect ratio was 72.48.

By holding the weight for 5 seconds by the above method, the filler strength was evaluated. After heating to remove the binder and organic fibers, the strength of the filler was measured. In addition, the heating conditions in the Examples and Comparative Examples were performed at 500 ° C. for 96 hours under air.
As a result, the filler strength was 13.0 g.

[Comparative Example 1]
Inorganic filler (talc, clay, etc.): 78% by weight, inorganic fiber (ceramic fiber): 6% by weight, organic fiber (aramid fiber): 8% by weight, organic binder (NBR): 8% by weight used. The form of the filler material was papermaking, and the thickness was 0.5 ± 0.05 mm. The average fiber diameter of the ceramic fiber was 8.73 μm, and the average fiber length was 996.50 mm. Moreover, the average value of the aspect ratio was 117.80.

In the same manner as in Example 1, the filler strength was evaluated by the method described above. After heating to remove the binder and organic fibers, the strength of the filler was measured.
As a result, the filler strength was 8.8 g.

DESCRIPTION OF SYMBOLS 1 ... Filler material 2 ... Hoop material 3 ... Inner ring ring member 4 ... Outer ring ring member 10 ... Gasket body

The configuration of the present invention is as follows.
[1] A spiral wound gasket comprising a gasket body formed by overlapping a filler material and a hoop material and winding them in a spiral shape ,
The filler material comprises a sheet containing inorganic fibers,
A rectangular parallelepiped test piece having a length of 30 mm × short side of 15 mm and a thickness of 0.5 ± 0.05 mm is collected from the filler material, and the test piece is heated at 500 ° C. for 96 hours. On two bars with a distance of mm, the short side is parallel to the bars and the center of the test piece is overlapped with the center of the distance, the weight of the test piece is 1 g, and the dimensions are short. Place a cuboid weight with a side of 9 mm × long side of 15 mm or more so that the central axes of the long sides of the test piece and the weight are orthogonal to each other. When the test piece is not broken or held for 5 to 10 seconds, the strength is 1 g. As described above, when the weight of the weight that was able to be held by the weight of the filler was set to the strength of the filler until just before the test piece broke, the strength was 9 g or more.
A spiral wound gasket characterized in that the average fiber diameter of the inorganic fibers is in the range of 11 to 20 μm and the average aspect ratio is in the range of 70 to 115 .
[2] The composition of the filler material ranges from 74 to 85% by weight of the inorganic filler, 2 to 20% by weight of the inorganic fiber, 2 to 20% by weight of the organic fiber, and 4 to 12% by weight of the organic binder (the total is 100% by weight) %)). The spiral wound gasket according to [1].
[3] The spiral wound gasket according to [1] or [2], wherein rock wool is included as the inorganic fiber.
[4] The spiral wound gasket according to [3], wherein 75% by weight or more of the inorganic fiber is rock wool.

Spiral wound gasket of the present invention may further comprise a inner ring member and / or the outer ring a ring member fitted on the outer periphery of the gasket main body is fitted to the inner periphery of the gasket body.

[Comparative Example 1]
Inorganic filler (talc, clay, etc.): 78% by weight, inorganic fiber (ceramic fiber): 6% by weight, organic fiber (aramid fiber): 8% by weight, organic binder (NBR): 8% by weight used. The form of the filler material was papermaking, and the thickness was 0.5 ± 0.05 mm. The average fiber diameter of the ceramic fibers was 8.73 μm, and the average fiber length was 996.50 μm . Moreover, the average value of the aspect ratio was 117.80.

Claims (6)

A spiral wound gasket comprising a gasket body formed by overlapping a filler material and a hoop material and winding them in a spiral shape,
The filler material comprises a sheet containing inorganic fibers,
A rectangular parallelepiped test piece having a length of 30 mm × short side of 15 mm and a thickness of 0.5 ± 0.05 mm is collected from the filler material, and the test piece is heated at 500 ° C. for 96 hours. On two bars with a distance of mm, the short side is parallel to the bars and the center of the test piece is overlapped with the center of the distance, the weight of the test piece is 1 g, and the dimensions are short. Place the weight of a rectangular parallelepiped with a side of 9 mm × long side of 15 mm or more so that the central axes of the long sides of the test piece and the weight are orthogonal to each other. 1g, repeat the holding for 5 seconds to 10 seconds with a further 1g of weight, and the strength of the filler is the weight of the weight that can be held just before the test piece breaks, and the strength is 9g or more. Spiral wound gasket characterized by.   The composition of the filler material is in the range of 74 to 85% by weight of inorganic filler, 2 to 20% by weight of inorganic fiber, 2 to 20% by weight of organic fiber, and 4 to 12% by weight of organic binder (the total is 100% by weight) The spiral wound gasket according to claim 1.   The spiral wound gasket according to claim 1 or 2, wherein rock wool is included as the inorganic fiber.   The spiral wound gasket according to claim 3, wherein 75% by weight or more of the inorganic fibers is rock wool.   The spiral wound gasket according to any one of claims 1 to 4, wherein the average fiber diameter of the inorganic fibers is in the range of 11 to 20 µm.   The spiral wound gasket according to any one of claims 1 to 5, wherein the average aspect ratio of the inorganic fibers is in the range of 70 to 115.