CN108474476B

CN108474476B - Spiral wound gasket

Info

Publication number: CN108474476B
Application number: CN201580085532.2A
Authority: CN
Inventors: 中里聪; 黑河真也
Original assignee: Nippon Valqua Industries Ltd
Current assignee: Nippon Valqua Industries Ltd
Priority date: 2015-12-28
Filing date: 2015-12-28
Publication date: 2020-03-06
Anticipated expiration: 2035-12-28
Also published as: WO2017115400A1; CN108474476A

Abstract

The invention provides a spiral wound gasket which can exert sealing performance even after being used in a high-temperature atmosphere for a long time and has low possibility of filler loss. The spiral wound gasket has a gasket main body formed by overlapping a filler material and a hoop material and winding the overlapped filler material into a spiral wound shape, wherein the filler material is composed of a sheet material mixed with inorganic fibers; a rectangular parallelepiped test piece having a length of a long side of 30mm x a short side of 15mm and a thickness of 0.5 + -0.05 mm was sampled from a filler, the test piece was heated at 500 ℃ for 96 hours, the heated test piece was placed on two bars spaced at a distance of 14mm such that the short sides were parallel to the bars and the center of the test piece overlapped with the center of the space, a rectangular parallelepiped weight having a length of a short side of 9mm x a long side of 15mm or more was placed at the center of the test piece such that the center axes of the long sides of the test piece and the weight were orthogonal to each other, the strength was set to 1g when the test piece could be held without breaking for 5 to 10 seconds, the weight of 1g was placed further, the holding was repeated for 5 to 10 seconds, and the strength was set to 9g or more when the weight of the weight which could be held until the test piece just before breaking was set to the strength of the filler.

Description

Spiral wound gasket

Technical Field

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

Background

A Spiral Wound Gasket (SWG) used under high temperature and high pressure is formed in a structure as shown in fig. 1. That is, in the spiral wound gasket, the packing material 1 and the hoop material 2 are overlapped and wound in a spiral wound shape, the winding start part and the winding end part are wound only with the hoop material 2 for 2 to 3 weeks (japanese: hollow き), and the wound gasket is fixed by spot welding or the like to form the gasket main body 10; the hoop material 2 is made of a thin metal strip having a V-shaped cross section.

Then, an inner ring member 3 made of an annular metal plate is fitted and fixed as a guide member to the inner peripheral edge of the pad main body 10. An outer ring member 4 made of an annular metal plate is fitted and fixed to the outer peripheral edge of the gasket main body 10 as a guide member.

Typical examples of such fillers include expanded graphite sheets (e.g., patent document 1: Japanese patent laid-open publication No. 2011-144881), sheets mainly composed of mica (e.g., patent document 2: Japanese patent laid-open publication No. 2007-127178), and sheets containing inorganic fibers (e.g., patent document 3: Japanese patent laid-open publication No. Hei 7-305772).

The maximum service temperature and the sealability under prolonged heating conditions of these filler materials are generally shown in the following table.

[ TABLE 1]

	Maximum temperature of use	Sealing property
			Expanded graphite sheet	～450℃	◎
Sheet mainly composed of mica	～750℃	×
			Sheet material blended with inorganic fiber	～500℃	○

The expanded graphite sheet has problems such as the following: the sheet is difficult to use in a high temperature environment, and is oxidized or deteriorated when exposed to a high temperature, and therefore, the sheet mainly composed of mica has a narrow range of use and is not versatile.

The sheet containing inorganic fibers has an advantage of having high sealability in a high region at a high temperature of 500 ℃, but has a problem that the sealability is lowered when the sheet is used at a high temperature for a long period of time.

Prior Art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-144881

Patent document 2: japanese patent laid-open No. 2007-127178

Patent document 3: japanese patent laid-open No. Hei 7-305772

Disclosure of Invention

Technical problem to be solved by the invention

Under such circumstances, the present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a spiral wound gasket which can exhibit sealing properties even after long-term use in a high-temperature atmosphere and which is less likely to cause a loss of a filler.

Technical scheme for solving technical problem

The factors for the reduction of the sealability of the spirally wound gasket generally consider the following mechanisms:

(i) the interface between the gasket and the flange leaks,

(ii) by means of the permeation leakage inside the filling material,

(iii) permeation leakage through the interface of 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, it is considered that the sealability is lowered by (i) when the gasket is used under heating for a long period of time.

The reason is considered to be: when the sheet surface pressure is lowered by using a spirally wound mat containing "a sheet containing inorganic fibers" as a filler in a high-temperature state for a long period of time or by repeating heating and cooling, the binder component in the filler disappears by heat; then, when the binder component disappears, the strength of the filler itself decreases, and the shape of the seal surface as a filler cannot be maintained; the result is: the inorganic fibers in the filler fall off from the sealing surface due to negative pressure or vibration in the pipe, and a leak path is formed at the contact surface between the gasket and the flange, thereby causing a reduction in sealing performance. In addition, when the strength of the filler is reduced, the detached inorganic fibers scatter, and may affect the environment.

Thus, the inventors further studied intensively to find that: the present inventors have completed the present invention by using a filler material that can suppress the loss of filler due to the action of external factors such as pipe stress or internal pressure during the use of a spirally wound gasket; the filler is a filler having a filler strength after heating within a specific range, measured under a predetermined heating condition.

The constitution of the present invention is as follows:

[1] a spiral wound gasket having a gasket main body formed by overlapping a filler material and a hoop material and winding them in a spiral wound shape;

the filler is composed of a sheet material blended with inorganic fibers;

a rectangular parallelepiped test piece having a length of 30mm long by 15mm short and a thickness of 0.5 + -0.05 mm was sampled from the filler, the test piece was heated at 500 ℃ for 96 hours, the heated test piece was placed on two bars spaced at a distance of 14mm so that the short sides were parallel to the bars and the center of the test piece overlapped with the center of the space, a rectangular parallelepiped weight having a size of 9mm short by 15mm long is placed at the center of the test piece so that the center axes of the long sides of the test piece and the weight were orthogonal to each other, the strength was set to 1g when the test piece could be held without breaking for 5 to 10 seconds, a weight of 1g was placed further, the holding was repeated for 5 to 10 seconds, and the weight which could be held until the test piece just before breaking was set to the strength of the filler, and the strength was set to 9g or more.

[2] [1] the composition of the filler in the spiral wound gasket is in the range of 74 to 85 wt% of the inorganic filler, 2 to 20 wt% of the inorganic fiber, 2 to 20 wt% of the organic fiber, and 4 to 12 wt% of the organic binder (however, the total is 100 wt%).

[3] The spiral wound gasket of [1] or [2] contains rock wool as an inorganic fiber.

[4] [3] the spiral wound gasket wherein 75% by weight or more of the inorganic fibers are rock wool.

[5] The spiral-wound gasket according to any one of [1] to [4], wherein the inorganic fibers have an average fiber diameter in the range of 11 to 20 μm.

[6] The spiral wound gasket of any one of [1] to [5], wherein the average aspect ratio of the inorganic fibers is in the range of 70 to 115.

ADVANTAGEOUS EFFECTS OF INVENTION

The spiral-wound gasket of the present invention uses a filler having a high filler strength evaluated under predetermined conditions, and therefore has high sealability when used under high temperature conditions for a long period of time.

Specifically, the filler having a certain strength or more after heating under a predetermined condition is used, and as a result: when used at high temperature for a long period of time, loss of the filler due to external factors such as internal pressure load can be suppressed, and the fluid can be sealed even when used at high temperature for a long period of time.

Drawings

FIG. 1 is a partial cross-sectional view showing a substantial portion of a spiral wound gasket.

FIG. 2 is a schematic diagram of the measurement of the strength of the filling material.

Detailed Description

The spiral wound gasket of the present invention is described in further detail below.

The spiral-wound gasket of the present invention has a ring-shaped gasket main body formed by overlapping and winding a filler and a hoop material in a spiral wound shape, as shown in fig. 1.

[ Filler ]

The filler material is composed of a sheet material in which inorganic fibers are blended.

In the present invention, as the inorganic fibers to be blended in the filler, it is preferable to use fibers having a small fiber length (short) and a large fiber diameter (thick), that is, fibers having a small aspect ratio. Consider that: by using the inorganic fiber, the inorganic fiber is hardly broken, and the strength as a filler is enhanced while maintaining the normal properties.

As the inorganic fiber, inorganic fibers other than asbestos may be used, and specific examples thereof include ceramic fibers, rock wool, glass fibers, and titanate fibers. As such inorganic fibers, those having flexibility but no rigidity are preferable, 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, more preferably 70 to 115. The average fiber length is appropriately selected from the aforementioned fiber diameter and aspect ratio.

When the inorganic fibers having an aspect ratio and a fiber diameter in these ranges are used, a predetermined filler strength can be obtained.

The shape of the inorganic fibers was observed with a microscope on 100 samples, and the fiber diameter and the fiber length were measured by the methods described in examples, and the aspect ratio was calculated while obtaining the average value.

In the present invention, one or two of such inorganic fibers may be used in combination.

In the present invention, it is preferable to include rock wool as the inorganic fiber because it does not adversely affect the environment from the viewpoint of biodegradability or the like. More preferably, the rock wool is made of inorganic fibers in an amount of 75% by weight or more.

The filler is preferably a filler containing an organic fiber, an inorganic filler, an inorganic binder and an organic binder in addition to the inorganic fiber.

Examples of the organic fiber include natural fibers such as plant fibers, synthetic fibers such as aramid fibers, carbon fibers, and graphitized fibers. These organic fibers may be used singly or in combination.

These organic fibers serve to reinforce the strength of the filler material, such as to prevent the filler material from breaking, when the filler material and the hoop material are wound to produce a spiral wound gasket. Such organic fibers are preferably organic fibers having high flexibility and not deteriorating the air tightness of the spirally wound gasket produced. The fiber diameter is 10 μm or less, preferably 0.2 μm or more. For this reason, at least one of such organic fibers is preferably a pulp-like aramid fiber obtained by fibrillating the 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 have a function of improving the sealing (airtightness) between fibers, the flexibility of the filler, and the shape retention (cohesiveness) of the filler at high temperature, and a function of maintaining the sealing property without being lost even at high temperature. The particle size of such an inorganic filler is preferably very small, and particularly preferably 5 μm or less in particle size, and has a particle size distribution in which particles of 1 μm or less are present at 5% or more. In the present invention, it is preferable to use two or more types of fillers having mutually different particle size distributions in combination. When two or more fillers having different particle size distributions are used in combination, a gasket having excellent airtightness and flexibility can be obtained.

The binder combines with the fibers and the inorganic filler to improve sealability and impart mechanical strength to the filler. Either an organic binder or an inorganic binder may be used, or a combination of an organic binder and an inorganic binder may be used. Specific examples of such inorganic binders include polyphosphates and water glass. Specific examples of the organic binder include: heat-resistant elastomer organic adhesives such as NBR, SBR, acrylates, fluororubbers, silicone adhesives such as methyl silicone adhesive and phenyl silicone adhesive, or phenol adhesives such as water-dispersible phenol resin.

The filler may contain, in addition to the above components, a water-repellent and oil-repellent agent such as paraffin, if necessary. When such a water-repellent and oil-repellent agent is used, the sealing properties at room temperature can be improved.

The filler of the present invention may further contain various vulcanizing agents, vulcanization accelerators, vulcanization auxiliaries, age resistors, colorants, and the like in addition to the above components.

The filler is preferably a filler having a range of 74 to 85 wt% of an inorganic filler, 2 to 20 wt% of an inorganic fiber, 2 to 20 wt% of an organic fiber, and 4 to 12 wt% of an organic binder (however, the total is 100 wt%), because the filler can achieve a predetermined strength.

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

The inorganic fibers in the filler are 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 fibers are contained in an amount of 1.8 parts by weight or more, preferably 3.5 parts by weight or more, based on 100 parts by weight of the total amount of the inorganic substances.

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

The organic fiber is preferably contained in the filler 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 containing the inorganic substance comprising the inorganic fiber, the inorganic binder and the inorganic filler in the total amount is excellent in airtightness at high temperatures. In the filler containing less than 76% by weight of inorganic substances, since the organic substances are large, they are decomposed at high temperature, and the weight is remarkably reduced, so that the sealing effect of the adhesive is not achieved.

As described above, the filler containing the inorganic fibers and the organic fibers in an amount of 3 to 20 wt% in total has strength required for manufacturing the filler and strength required for manufacturing the spiral wound gasket. The spiral-wound gasket having the filler is excellent in sealing properties at room temperature, and does not deteriorate in airtightness due to a reduction in its heat weight even when used at high temperatures.

The filler can be produced by a conventionally known method such as a papermaking method, and for example, the filler can be produced by the papermaking method as follows: first, a predetermined amount of organic fibers, inorganic fibers and an inorganic filler are dispersed in water using a Haydra pulper (Hidra pulp) or a heater, then a predetermined amount of organic binder and inorganic binder, and if necessary, various auxiliary materials such as a vulcanizing agent, a vulcanization accelerator and a water repellent agent are added to adjust the slurry concentration as appropriate, then a fixing agent is added as necessary to adhere the organic binder and the inorganic binder to the fibrous material, the inorganic filler and the like, and then the obtained slurry is sequentially introduced into a box and a paper machine to obtain a sheet for a filler. If necessary, the slurry may be diluted to a concentration at which the slurry can be made into paper by using a coagulant in the paper making stage to maintain uniform dispersibility of the slurry.

The filler used in the present invention has a strength of 9g or more, preferably 10g or more, more preferably 11g or more, as measured by the following evaluation. If a filler having such strength is used, long-term sealing under heating becomes possible. Since the strength of the filler after heating is high, the filler loss 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 the filler strength, the fiber diameter, aspect ratio, fiber length, and content of the filler of the inorganic fibers are important, and can be adjusted by using a material that satisfies the above-mentioned predetermined ranges.

Measurement of the intensity

Rectangular test pieces having a size of 30mm long side by 15mm short side and a thickness of 0.5. + -. 0.05mm were collected from the filler, and the test pieces were heated at 500 ℃ for 96 hours in an air atmosphere. Upon heating, the binder and organic fibers disappear. The heated test piece was placed on two round bars (made of stainless steel having a diameter of about 2.4mm (2.4 to 2.6 mm)) spaced at a distance of 14mm, and the short sides of the test piece were placed so that the center of the rectangle of the test piece overlapped the center of the gap between the bars.

A rectangular parallelepiped weight having a dimension of short side 9mm x long side 15mm or more and a weight of 1g is placed on the center of a test piece, the center axes of the long sides of the test piece and the weight are made orthogonal to each other, and when the test piece can be held for 5 seconds without breaking, the strength is set to 1g, and the weight placed with 1g is further repeatedly held for 5 seconds. If the test piece is broken, the weight of 1g is added and the holding operation is repeated, and when the test piece is broken, the weight of the weight which can be held until just before the test piece is broken is determined as the strength of the filling material of the present invention.

The holding time is preferably fixed to 5 seconds, but even if it exceeds 5 seconds, the strength of measurement is not affected as long as it does not exceed 10 seconds. For this purpose, the holding time may be set to 5 to 10 seconds.

The long side of the weight is not particularly limited as long as it is 15mm or more, and a weight of 25mm is generally used. 5 tests were performed and the average of 5 tests was evaluated.

[ hoop Material ]

As the hoop material, a tape-like hoop material used for a general spiral-wound gasket can be used.

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

The thickness of the hoop material may vary depending on the size of the pad, the use purpose, the required performance, and other conditions, but is usually set in the range of 0.1 to 0.3 mm.

The cross-sectional shape of the hoop material may be formed in a curved shape such as an arc shape or a wave shape, or a combination of a straight portion and a curved portion, in addition to a shape formed in a bent line such as a V shape or an M shape.

[ spiral wound gasket ]

The spiral-wound gasket of the present invention has a gasket main body formed by winding the filler and the hoop material into a spiral-wound shape by a conventionally known method.

The gasket main body may be used together with a filler other than the above filler. For example, the gasket main body is formed by using the filler only in the inner peripheral portion and the outer peripheral portion and using a conventional expanded graphite filler in the central portion.

The spiral wound gasket of the present invention may further have the following members: an inner ring member fitted to an inner periphery of the pad main body and/or an outer ring member fitted to an outer periphery of the pad main body.

The spiral wound gasket of the present invention has the above-described structure, and therefore exhibits excellent sealing properties even in a highly oxidizing atmosphere, and is therefore useful for applications such as petrochemical seals and seals for petroleum purification machinery.

Examples

The spiral-wound gasket of the present invention is explained in more detail below by way of examples, but the present invention is not limited to these examples at all.

< method for evaluating fiber diameter and fiber length >

An optical microscope photograph of the inorganic fiber was taken, and the diameter and length were measured.

The fiber length may be shortened by breaking the inorganic fiber. For this reason, in the case of performing the fiber length evaluation, a broad distribution appears. To exclude these effects, 100 fibers were randomly drawn out from the optical microscope photograph and evaluated. The data of the first 50% of the fiber length after evaluation was used as the evaluation target (table 2).

The fiber diameter was calculated from the fibers evaluated for excess fiber length. The respective aspect ratio is also determined by the respective fiber diameter and fiber length. The measured data are shown in the following table. The evaluation results are also shown in the following table.

The measurement apparatus was a KEYENCE VHX-D510(VHX digital microscope), and was evaluated with an optical magnification of 150 to 200 times.

[ example 1]

Use of a mixture containing an inorganic filler (talc, clay, etc.): 78 wt%, inorganic fibers (rock wool): 6 wt%, organic fiber (aromatic amide fiber): 8 wt%, organic binder (NBR): 8% by weight of filler material. The filling material is made of paper, and the thickness of the filling material is 0.5 +/-0.05 mm. The average diameter of the fiber diameter of the rock wool was 11.05 μm and the average length of the fiber length was 774.05 μm. The average value of the aspect ratio was 72.48.

In the above method, the weight was repeatedly held for 5 seconds to evaluate the filler strength. After heating to eliminate the binder and organic fibers, the filler strength was measured. The heating conditions in examples and comparative examples were 500 ℃ for 96 hours under air.

The result is: the filler strength was 13.0 g.

Comparative example 1

Use of a mixture containing an inorganic filler (talc, clay, etc.): 78 wt%, inorganic fibers (ceramic fibers): 6 wt%, organic fiber (aromatic amide fiber): 8 wt%, organic binder (NBR): 8% by weight of filler material. The filling material is made of paper, and the thickness of the filling material is 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 mm. The average value of the aspect ratio was 117.80.

The filler strength was evaluated in the same manner as in example 1. After heating to eliminate the binder and organic fibers, the filler strength was measured.

The result is: the filler strength was 8.8 g.

[ TABLE 2]

Description of the symbols

1 … … filling material

2 … … hoop Material

3 … … inner race ring member

4 … … outer race ring member

10 … … pad body

Claims

1. A spiral wound gasket having a gasket body formed by overlapping a filler material and a hoop material and winding them in a spiral wound shape,

the filler is composed of a sheet material blended with inorganic fibers;

2. The spiral wound gasket of claim 1 wherein the filler material comprises 74 to 85 wt% inorganic filler material, 2 to 20 wt% inorganic fiber, 2 to 20 wt% organic fiber, and 4 to 12 wt% organic binder, the total being 100 wt%.

3. The spiral wound gasket of claim 1 or 2 comprising rock wool as the inorganic fiber.

4. The spiral wound gasket of claim 3 wherein greater than 75% by weight of the inorganic fibers are rock wool.

5. The spiral wound gasket of claim 1, 2 or 4 wherein the inorganic fibers have an average fiber diameter in the range of 11 to 20 μm.

6. The spiral wound gasket of claim 1, 2 or 4 wherein the inorganic fibers have an average aspect ratio in the range of 70 to 115.