JPH09317894A - Spiral gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spiral gasket which is used in a high temperature oxidizing atmosphere such as a gas turbine by using an expansion graphite tape in which oxidant suppressing agent of a mineral system as a filler material, in the spiral gasket formed by laminating a hoop material and the filler material alternately and winding it in a spiral shape. SOLUTION: In a stainless steel made hoop material 1 wound in a spiral shape, the inner circumferential part 1a and an outer peripheral part 1b are vacantly wound in a condition in which they are brought into contact with each other, and they are fixed by a spot welding work. At this time, a filler material 2 is wound by laminating with the hoop material 1. An expansion graphite tape in which oxidant suppressing agent of a mineral system is used as the filler material 2. An inner wheel 3 and the outer wheel 4 which are made of stainless steel are arranged to prevent deformation caused by surface pressure and carry out centering when they are installed on a joint part. Phosphate, zinc powder, aluminum powder, and boron nitride powder, are used as the oxidant suppressing agent mixed with the filler material 2, its adding rate is set to 0.1 to 10 weight %, more preferably, it is set to 0.3 to 0.5 weight %.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is designed to be sandwiched between fixed joining surfaces such as joining surfaces of machinery, pressure vessels, pipes, etc.
Tighten with bolts or other means to get hot steam, gas,
The present invention relates to a spiral gasket used for preventing leakage of fluids such as oil and water, and more particularly to improvement of a spiral gasket suitable for a high temperature oxidizing atmosphere such as air of a gas turbine or a joint portion of an exhaust gas pipe.

[0002]

2. Description of the Related Art Conventionally, spiral gaskets have been used as hoop materials.
We use a stainless steel strip that is easy to weld, and use a flexible cushioning material such as asbestos paper, non-asbestos fiber paper, expanded graphite, tetrafluoroethylene resin, etc. for the filler material, and wrap them both At the inner peripheral portion and the outer peripheral portion, a structure is often used in which only the hoop material is idled in a state of being in contact with each other and fixed by spot welding.

The spiral gasket having the above structure is suitable as a gasket for high temperature and high pressure. For this reason, as a gasket for air and exhaust gas pipe joints of gas turbines, which is a typical application of high-temperature and high-pressure gaskets, expanded graphite fillers, asbestos paper fillers, non-asbestos paper fillers, and swirls containing fillers combining these Shaped gaskets are used. Further, as other gaskets for the same purpose as described above, metal-coated gaskets, flat metal gaskets, etc. are also used.

[0004]

DISCLOSURE OF THE INVENTION The spiral gasket is
Although it is sometimes used in the pipe of the gas turbine as described above, in the case of being used in the gas turbine, the fluid with which the gasket contacts is a high-temperature oxidizing gas such as air or exhaust gas flowing in the pipe of the gas turbine. Further, this air flow frequently undergoes a thermal cycle due to rapid start and stop of the gas turbine. Furthermore, vibration due to rotation of the gas turbine is applied to this gasket. On the other hand, asbestos paper impairs the health of the operator, and therefore development of one that does not use asbestos paper is desired.

However, in the spiral gasket having the graphite tape as the filler material, the graphite is oxidized from about 400 ° C. in the fluid containing oxygen such as air and exhaust gas, and the graphite tape disappears as carbon monoxide and carbon dioxide. Therefore, the temperature limit for long-term use is 400 to 450 ° C. For this reason, there is a problem that the flow of increasing temperature of the gas turbine cannot be followed.

Further, a gasket containing asbestos paper or non-asbestos paper as a filler material and containing an organic substance as a binder, a filler or the like has a problem that the organic substance is decomposed and disappears from around 200 ° C. and the sealing property is deteriorated. Further, if organic substances are not included as a binder or a filler to avoid this, there is a problem that the sealing property is poor from the beginning.

Further, the spiral wound gasket in which the expanded graphite filler and the asbestos paper filler are combined or the non-asbestos paper filler is used, when used in a high temperature atmosphere of 200 ° C. or higher, the sealing property is deteriorated for the same reason as above, or From the beginning, there was the problem of poor sealing.

Further, the metal-coated gasket and the flat metal gasket have sufficient heat resistance, but since a very large load is required for sealing, the gasket itself is crushed by the tightening force of the flange, Since the amount of restoration is smaller than that of the spiral wound gasket, there is a problem that leakage tends to occur when a heat cycle or vibration is applied.

The present invention has been made by paying attention to the problems existing in such conventional techniques. The purpose is to use high temperature steam, gas,
It is an object of the present invention to provide a spiral gasket that can be used in an atmosphere of oil, water, etc., particularly, in a high temperature oxidizing atmosphere in a gas turbine or the like.

[0010]

In order to achieve the above-mentioned object, in the invention according to claim 1, in the spiral gasket, the hoop material and the filler material are superposed and wound in a spiral shape. An expanded graphite tape containing an inorganic oxidation inhibitor is used as.

According to the second aspect of the invention, phosphate, zinc powder, aluminum powder or boron nitride powder is used as the oxidation inhibitor.

According to a third aspect of the invention, 0.1 to 10% by weight of the oxidation inhibitor is blended.

According to a fourth aspect of the present invention, a metal inner ring and an outer ring are provided.

According to a fifth aspect of the present invention, the materials of the hoop material, the inner ring and the outer ring are the same.

Therefore, the spiral gasket constructed as described above does not use the asbestos paper as the filler material, so that there is no problem of pollution. In addition, the elasticity of the hoop material makes it possible to immediately respond to sudden changes in usage conditions and expansion and contraction due to heat.

Particularly, in the spiral gasket according to the first to fifth aspects, in a fluid containing oxygen such as air and exhaust gas,
The action of the antioxidant prevents the graphite from being oxidized at about 400 to 450 ° C. and prevents the expanded graphite tape from disappearing as carbon monoxide or carbon dioxide.

Further, in the spiral gasket according to the fourth aspect, even if the surface pressure increases due to the high pressure fluid or the tightening force,
Does not deform due to inner and outer rings. Also, there is no concern that hoop material damaged by the inner ring will enter the piping.
In addition, even if leakage occurs due to damage to the hoop material, etc., the outer ring can be used as a second-stage sealing mechanism by tightening the outer ring to the full extent, and operation can be continued without stopping the machine such as the gas turbine. .

In the spiral gasket according to the fifth aspect of the invention, the hoop material, the inner ring and the outer ring are made of the same material, for example, stainless steel, so that the deformation of the hoop material due to the difference in elongation due to heat of different materials can be prevented. , The inner ring and the outer ring are always held in place and the sealing function is improved.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a partial vertical cross-sectional view of a spiral gasket according to the present invention, showing a left half of the center line. In the figure, reference numeral 1 denotes a spirally wound hoop material made of stainless steel (SUS316), and an inner peripheral portion 1a and an outer peripheral portion 1b thereof are idled in a state of being in contact with each other and fixed by spot welding. ing.
Reference numeral 2 is a filler material that is wound on the hoop material 1 in an overlapping manner. In the present invention, an expanded graphite tape containing an inorganic oxidation inhibitor is used as the filler material 2. 3
And 4 are provided with an inner ring and an outer ring for the purpose of preventing deformation due to surface pressure and centering at the time of attachment to the joint portion. Further, the inner ring and the outer ring are made of stainless steel like the hoop material 1.

As the above-mentioned oxidation inhibitor, for example, phosphate, zinc powder, aluminum powder and boron nitride powder are used, and the addition amount thereof is 0.1 to 10% by weight, preferably 0.3 to. 0.5% by weight.

As described above, since the spiral wound gasket 5 uses the expanded graphite tape containing the inorganic oxidation inhibitor such as phosphate as the filler material 2, it cannot be used for a long time conventionally. Even in an atmosphere of air, exhaust gas, or the like having a high temperature of 400 to 450 ° C. or higher, the sealing property and the restoring property similar to the normal temperature can be maintained.

Further, in the gasket 5 having the above structure, even if the hoop material 1 is damaged and fluid such as gas leaks, the hoop material 1 is formed by the inner ring 3.
Are prevented from scattering into the pipe. Also, by tightening the pipe joint part to the full extent of the outer ring 4,
A fluid leakage prevention function of the second stage can be performed. Further, the hoop material 1, the inner ring 3 and the outer ring 4 are all made of stainless steel and made of the same material, so that the hoop material 1 can be prevented from being deformed due to the difference in thermal expansion and contraction.

[0023]

Since the present invention is constructed as described above, it has the following effects. According to the invention of claims 1 to 5, since the expanded graphite tape containing an inorganic oxidation inhibitor is used as a filler material, the use limit in an oxidizing atmosphere can be raised to about 500 to 600. it can. Therefore, it is suitable as a gasket for a joint portion to which vibration is frequently applied, especially in a gas turbine, where frequent heat cycles occur.

Further, according to the invention of claim 4, by having the inner ring and the outer ring, it is possible to prevent the deformation due to the high-pressure fluid and the tightening force. Further, the inner ring can prevent the damaged hoop material or filler material from entering the inside of the pipe. Further, even if fluid leakage occurs, fluid leakage can be prevented by tightening the joint portion to the full extent of the outer ring.

Further, since the hoop material is made of the same material as the inner ring and the outer ring, there is no deformation due to the difference in thermal expansion and contraction, and the hoop material, the inner ring and the outer ring are always held at the prescribed positions, so that the sealing function is improved. Therefore, it is particularly suitable as a gasket for piping of a gas turbine whose usage conditions such as rapid start and rapid stop change drastically.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of the left half of a spiral gasket according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Hoop material, 2 ... Filler material, 3 ... Inner ring, 4 ... Outer ring,
5 ... Spiral gasket.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akinori Owaki 3365, Foxhole, Takehana Town, Hashima City, Gifu Prefecture Nichias Corporation Hashima Factory

Claims (5)

[Claims] 1. A spiral gasket formed by stacking a hoop material and a filler material and winding them in a spiral shape, wherein an expanded graphite tape containing an inorganic oxidation inhibitor is used as the filler material. Spiral type gasket. 2. Phosphate, zinc powder as the oxidation inhibitor,
The spiral gasket according to claim 1, wherein aluminum powder or boron nitride powder is used. 3. The spiral gasket according to claim 1, wherein the oxidation inhibitor is blended in an amount of 0.1 to 10% by weight. 4. The spiral gasket according to claim 1, wherein an inner ring and an outer ring made of metal are provided. 5. The spiral gasket according to claim 1, wherein the hoop material, the inner ring and the outer ring are made of the same material.