JP2001280506A - Gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gasket preventing leakage of steam or the like by low fastening pressure for a long period, generating no rust on a flange face. SOLUTION: This gasket comprises a joint-sheet gasket A2 and a spiral gasket B1, installed inside the joint-sheet gasket A2 through fitting. The spring gasket B1 functions as a primary seal for the steam to prevent contact of the joint-sheet gasket A2 with the steam, while the joint-sheet gasket A2 function as a secondary seal for stopping the leakage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a gasket used in a wide range of fields such as petrochemical plants, various industrial machinery, automobiles, and home appliances.

[0002]

2. Description of the Related Art A gasket is used for preventing leakage from a joint portion of a pipe, and a gasket made of a joint sheet or a spiral-wound gasket is used depending on the application. Of these, the joint sheet is made of
A rubber material swollen in a solvent (or a mixture of powdered rubber or latex and a solvent) is thoroughly kneaded with a filler / rubber chemical using a Henschel mixer or the like to form a composition for forming a joint sheet (hereinafter abbreviated as a kneading material). Then, the kneaded material is put between a pair of rolls (calender rolls) composed of a hot roll (about 150 ° C.) and a cold roll (about 20 ° C.), and the solvent is evaporated while being laminated on the hot roll side.・ Vulcanization is performed by peeling the sheet that has reached a predetermined thickness from the hot roll, depending on the product. In some cases, vulcanization is performed. In addition,
Depending on the intended use, the kneading material may be a softener or
A small amount of a plasticizer, a water swelling agent, an oil swelling agent, or the like is added, and a pigment may be blended for storage and identification.

[0003] Conventionally, asbestos joint sheets using asbestos as a base fiber have been widely used. By utilizing the unique shape and excellent heat resistance of asbestos, pipes and equipment for water, oil, air, steam, etc. are used. It was stamped and used as a gasket.

The above-mentioned asbestos joint sheet contains about 60 to 85% by weight of asbestos which is inorganic but very flexible and highly fibrillated, and the asbestos fibers are sufficiently dispersed and entangled in the joint sheet. Because it has a large tensile strength, it is flexible and can maintain flexibility by entanglement of asbestos even after heating,
It has excellent properties that can maintain the sealing property stably for a long time.

As shown in FIGS. 5 to 6, a gasket formed by punching the asbestos joint sheet has a flat gasket A disposed between the flat seat flanges 2 and 2 which are fastened by bolts 1. As shown in FIG. ₁ and FIG.
As shown in FIG. 8, there is a full face gasket A ₂ having bolt holes 4 disposed between the entire seat flanges 3,3 which are bolted 1. These gaskets are flexible and can be sufficiently tightened with low bolt stress. Of these, full face gasket A ₂ having a bolt hole for the flange faces can be completely sealed, it is often used in piping rust prone ship.

Another type of gasket is:
There are spiral wound gaskets. This has a configuration in which a hoop material and a filler material of a metal thin plate having a substantially V-shaped cross section are superimposed on each other and wound in a spiral shape, and this structure is called a basic shape. In addition, for the purpose of preventing deformation and inward centering of the gasket main body due to the tightening pressure, a metal reinforcing ring is provided on the inner and / or outer side of the gasket main body, with an inner ring, with an outer ring,
Various types called with inner and outer rings are used,
Generally, it is widely used as a gasket for high temperature and high pressure.

FIG. 9 shows an example of use of a basic spiral wound gasket among the above spiral wound gaskets. In the figure, B ₁ is a basic spiral wound gasket, which is used by being inserted into the grooves of the grooved flanges 5, 5 which are fastened by bolts 1.
Moreover, and raised face flanges 2,2 shown in FIG. 10, the entire surface seat flange 3, 3 shown in FIG. 11, but the outer ring 6 or the inner and outer rings with spiral wound gasket B ₂ is used, a completely leak In order to prevent the generation, a high-strength bolt to which a high tightening pressure is applied and a high-rigidity flange are required.

[0008]

The asbestos used for the asbestos joint sheet is a natural mineral, and there is a concern that resources may be depleted. Recently, asbestos has not been used at all and inorganic and organic fibers other than asbestos have been used. A joint sheet using both or any one of them (referred to as an asbestos-free joint sheet or a non-asbestos joint sheet, hereinafter abbreviated as an NA joint sheet) has been used.

However, in the NA joint sheet, the base fiber used is an inorganic fiber or an organic fiber other than asbestos, and the fiber diameter is large and rigid as compared with the asbestos fiber. Addition amount is 60 ~ like asbestos
Since it cannot be added up to 85% by weight, the tensile strength is inferior to that of the asbestos joint sheet. further,
It has been pointed out that organic fibers used as base fibers have poor heat resistance, and that aramid pulp, which has relatively excellent heat resistance, has a problem with steam resistance, and is used in environments such as steam. In such a case, the aramid pulp is deteriorated, the sealing property is reduced, and it cannot be used for a long time.

Further, as described above, the spiral wound gasket requires a rigid flange to which a high tightening pressure can be applied in order to completely prevent the occurrence of leakage. In many cases, it cannot be used for low rigidity flanges. Further, when used for the entire seat flange, as shown in FIG. 11, the flange surface cannot be completely sealed, so that generation of rust on the flange surface cannot be prevented. Furthermore, since the outer ring and the inner ring, which are the reinforcing rings, are made of metal, they are expensive, heavy and easily rusted, so that they have poor handling properties during storage and the like.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to provide a gasket which prevents leakage of steam or the like for a long time at a low tightening pressure and does not generate rust on the flange surface. It is in.

[0012]

In order to achieve the above object, a gasket according to the present invention comprises a sheet gasket,
The gist of the present invention consists of a spiral-wound gasket fitted and fitted inside the inside.

According to the research experiments conducted by the present inventors, the use of a gasket made of an NA joint sheet for a low-rigidity full-face seat flange in which a gasket made of an asbestos joint sheet was conventionally used in a ship piping line or the like was examined. However, the heating of the gasket made of the NA joint sheet alleviated the stress, and it was not possible to completely stop high-pressure steam at a low tightening pressure.

Therefore, as a result of further intensive studies, it was found that the steam can be completely stopped by assembling the basic shape of the spiral wound gasket inside the gasket made of the NA joint sheet.

In other words, the spiral wound gasket assembled inside the gasket made of the NA joint sheet may buckle when used alone, but may be buckled by tightening with a bolt. It will not be tightened more than a certain thickness.

The spiral gasket assembled as described above serves as a primary seal for steam,
The A-joint sheet gasket prevents the gasket from coming into contact with steam, and even if the pipe is temporarily twisted due to vibration or the like and leaks from the spiral wound gasket, the NA-joint sheet gasket disposed outside the gasket does not It acts as a next seal and stops leaks.

Further, by forming the joint sheet gasket into a full-face gasket with bolt holes, the flange face can be completely sealed when used as a full-face seat flange, thereby preventing the generation of rust and the like. it can.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a preferred embodiment of the present invention, as shown in FIGS. 1 and 2, a thickness composed of a composition comprising a base fiber other than asbestos, rubber, a filler, a rubber chemical and the like is used. 430m outside diameter from 3mm NA joint sheet
m, an inner diameter of 280 mm, punched into a full-face gasket A ₂ having a bolt hole 4, a metal hoop material 7 and a filler material 8 are superimposed on the inside, and spirally wound so as to project inward. Outer diameter 280mm, inner diameter 27
Constitute in combination 0mm basic shape Spiral Wound gasket B ₁ in fitting.

As the filler material used in the spiral wound gasket constituting the gasket of the present invention, non-asbestos paper or expanded graphite mainly composed of inorganic fibers can be used depending on the application.

The shape of the gasket of the present invention is not limited to a full-face gasket, as shown in FIGS.
Planar gasket A ₁ can also be used, in spiral wound gasket B _1, not only the shape of inwardly convex, it can also be used those which is convex in shape on the outside.

Further, the gasket of the present invention is not limited to a steam pipe, and it is needless to say that the gasket of the present invention can be used in a place where a fluid flows such that the joint sheet gasket is significantly deteriorated. Further, the sheet gasket is not limited to the joint sheet, and a rubber sheet gasket or the like can be selectively used.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. Example 1 In this example, a sheet composition material was prepared by kneading a base fiber other than asbestos, rubber, a filler, a rubber chemical, and the like with a Henschel mixer for 80 minutes, and heating the mixture to 150 ° C. It is put between a roll and a cold roll maintained at 20 ° C., and is pressed and vulcanized while being laminated on the hot roll side to form a 3 mm thick N
Make an A joint sheet, 430mm outside diameter,
It was punched into a full-face gasket having an inner diameter of 280 mm. Further, a hoop material obtained by drawing a SUS304 tape-shaped thin plate into a substantially V-shape is set in a winding form having a circumferential cross-section having the same shape as the substantially V-shape of the hoop material so that the inside becomes convex, and is symmetric with the winding form. The hoop material is wound once while applying pressure with a holding piece having such a shape, and then spot-welded to form a three-turn inner-circumferential-winding portion. The filler material has a thickness of 0.38 mm and a width of 6. A 2 mm expanded graphite tape (manufactured by UCAR Co., Ltd., phosphate-containing expanded graphite tape GTK) is manufactured, sandwiched between the hoop materials, superimposed on each other and wound five times, and finally only the hoop material is wound four times free. Then, spot welding was performed in the same manner as at the beginning of winding to obtain a basic spiral wound gasket having an outer diameter of 280 mm and an inner diameter of 270 mm. Then, the spiral wound gasket was fitted into the inside of the gasket made of the NA joint sheet and assembled to obtain a gasket of JIS16K, 250A size.

Comparative Example 1 In Comparative Example 1, a sheet composition material was prepared by kneading a base fiber other than asbestos, rubber, a filler, a rubber chemical, and the like with a Henschel mixer for 80 minutes, and heating this to 150 ° C. Between the heated hot roll and the cold roll maintained at 20 ° C., and press-vulcanizing while laminating on the hot roll side to form a 3 mm thick N
Manufacture A joint sheet, outer diameter 430mm, inner diameter 2
JIS16
K, 250A size NA joint sheet was obtained.

Comparative Example 2 In Comparative Example 2, a SUS304 tape-shaped thin plate was drawn into a substantially V-shape, and then a substantially V-shaped hoop material was formed so that the outside became convex.
The hoop material is set on a winding form having the same cross-section as the shape of the letter, and the hoop material is wound once while applying pressure with a holding piece having a shape symmetrical to the winding form. A circumferentially wound portion was formed, and as a filler material, an expanded graphite tape 0.38 mm in thickness and 6.2 mm in width (manufactured by UCAR, phosphate-containing expanded graphite tape GTK) was manufactured, and this was sandwiched between the hoop materials. It is superposed on each other and wound 10 times. Finally, only the hoop material is wound 4 times, and spot-welded in the same way as at the beginning of the winding to produce a spiral-wound gasket of 328 mm in outer diameter and 288 mm in inner diameter. An outer ring made of SUS304 having an outer diameter of 354 mm, an inner diameter of 328 mm, and a thickness of 3 mm was fitted into the spiral to obtain a spirally wound gasket of JIS16K, 250A size.

The weight of the gasket itself of Example 1 and Comparative Examples 1 and 2 and the surface pressure of 29.4M were applied to the pipe with the entire seat flange.
Table 1 shows the results of visually confirming the leakage after flowing saturated steam of 16K in an 8-hour cycle for 200 days and the presence or absence of rust on the flange surface after removing the gasket in a state where the assembly was performed at Pa. As a result of the measurement, Example 1 had better sealing performance than Comparative Examples 1 and 2, and Comparative Example 2
It can also be seen that the weight is light and no rust is generated on the flange surface.

[0026]

[Table 1]

[0027]

As described above, according to the present invention,
Since it is composed of a sheet-like gasket and a spiral-wound gasket that is fitted and assembled inside,
A gasket that can prevent leakage of steam or the like for a long time at a low tightening pressure and that does not generate rust on the flange surface can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of a gasket showing an embodiment of the present invention.

FIG. 2 is a sectional view of the gasket.

FIG. 3 is a plan view of a gasket showing another embodiment of the present invention.

FIG. 4 is a sectional view of the gasket.

FIG. 5 is a sectional view showing a state in which a conventional joint sheet gasket is mounted on a flat seat flange.

FIG. 6 is a plan view of a gasket made of a flat joint sheet.

FIG. 7 is a cross-sectional view of a state in which a conventional joint sheet gasket is mounted on an entire seat flange.

FIG. 8 is a plan view of a gasket made of a full-face joint sheet.

FIG. 9 is a cross-sectional view showing a state in which a spiral gasket is mounted on a grooved flange.

FIG. 10 is a cross-sectional view showing a state in which a spiral wound gasket is mounted on a flat seat flange.

FIG. 11 is a cross-sectional view showing a state in which a spiral gasket is attached to a whole surface seat flange.

[Explanation of symbols]

A ₁ planform joint sheet gasket 1 volt 2 raised face flange A ₂ full face joint sheet gasket 3 entire seat flange 4 bolt holes B ₁ Basic Spiral Wound Gasket B ₂ outer ring with spiral wound gasket 5 grooved flange 6 outer ring 7 Hoop material 8 Filler material

Claims (3)

[Claims] 1. A gasket comprising: a sheet-like gasket; and a spiral-wound gasket fitted inside the gasket. 2. The gasket according to claim 1, wherein a bolt hole is provided in the sheet-like gasket. 3. The sheet gasket is a joint sheet formed of a composition comprising a base fiber other than asbestos, rubber, a filler, a rubber chemical, and the like.
Or the gasket according to claim 2.