JP5031659B2 - Composite gasket - Google Patents

Description

  The present invention relates to a composite gasket, and more particularly to a composite gasket that exhibits high sealing performance even when the initial clamping pressure is low and can be used in a wide range from low temperature to high temperature and from vacuum to high pressure.

  In recent years, various plants capable of operating under high-temperature conditions have been developed in order to save energy in the chemical industry. In petrochemical plants, liquefied petroleum gas and liquefied natural gas plants, etc., penetration leaks that leak through the gasket body, interface leaks that leak from the interface between the gasket surface and the flange surface, and permeation that leaks through the flange, pipe or container, etc. Although leakage occurs, since most of the leakage (about 80%) is osmotic leakage, sealing materials such as gaskets used to prevent fluid leakage at the piping connection part of the plant are problematic. In addition, actual leakage accidents are also caused largely by tightening work such as insufficient bolt tightening, excessive tightening, or one-side tightening.

Conventionally, asbestos products have been widely used as gaskets, especially as high-temperature gaskets, but since the adverse effects on asbestos health became apparent, it was urged to discontinue use and develop alternatives. Non-asbestos-based gaskets have been developed, and as typical gaskets, rubber gaskets in which a rubber-based material such as chloroprene rubber, fluorine rubber, or silicone rubber is molded into a ring shape (for example, see Patent Document 1), fluorine resin, or expanded graphite A non-asbestos-based sheet formed by solidifying a non-asbestos-based powder with a binder into a sheet-like shape and overlapping with a thin strip steel plate such as stainless steel having a corrugated cross-section, and a spiral gasket (for example, ), And an inorganic fiber sheet covered with a metal jacket made of a heat-resistant and corrosion-resistant alloy. Comprising a metal jacketed gasket (e.g., see Patent Document 3) are proposed.
JP-A-5-287205 Rubber JP, 2004-3264706, A Swirl + Reinforcement ring JP 2006-226456 A

  However, since the rubber gasket is a rubber material, the heat resistance is low, and there is a problem that the rubber gasket cannot be used as a high-temperature gasket at 200 ° C. or higher. That is, the rubber gasket has fluidity when the temperature is high, and the sealing performance is lowered. Therefore, in order to maintain the sealing performance even at a high temperature, it is desired to prevent the fluidity of the rubber material at a high temperature. .

  On the other hand, the spiral gasket has a small clamping pressure and exhibits a good sealing property. Therefore, the swirl gasket is widely used in fields such as petrochemical plants, liquefied petroleum gas and liquefied natural gas plants, but an expanded graphite sheet is used as a core material. For gaskets, if the temperature exceeds 300 ° C, the entire gasket is likely to deteriorate due to thermal decomposition of the binder, overload on the metal plate or the mechanical strength of the expanded graphite sheet, and for fluororesin sheets, the pressure is higher than 350 ° C. In such a case, it melts and fluidizes, so it undergoes severe plastic deformation, temporarily showing good sealing properties, but it cannot withstand long-term use, causing gas leakage in a short period of time, and in some cases causing a fire. It became clear that there was.

Furthermore, the metal jacket type gasket has good durability in a wide temperature range of −200 ° C. to 1000 ° C., and exhibits a high sealing performance of 10 ⁻⁷ Pam ³ / sec. Although widely adopted in fields that require heat resistance, durability, and sealing ability, such as intake / exhaust gaskets for generation systems, there are the following disadvantages when applied to petrochemical plants and the like. That is, (1) Since the metal jacket type gasket has a small effective seal area, it must be a full contact type so as to withstand vibrations and surface pressures. (2) The metal jacket type gasket has no permeation but has a predetermined sealing performance between the flange surface and the gasket surface. It takes a long time to reach this point, and in order to increase the operation efficiency, it is a cause of refusal from an economical point of view in a petrochemical plant or the like in which it is important to shorten the test period after mounting the gasket.

  As a means for solving the problem related to the tightening pressure of the metal jacket type gasket, the width of the gasket (half the difference between the outer diameter and the inner diameter of the gasket) can be narrowed, that is, the width can be reduced. Even if the total tightening force of the gasket can be reduced to a fraction, leakage due to flange loading occurs, making it difficult to center the center of the flange inner diameter and the center of the gasket in extreme cases. May burn due to the heat of the fluid flowing in the pipe, making it impossible to seal, and if the gasket is narrowed, the surface pressure is too high and the gasket is destroyed when tightening. . In addition, in order to facilitate positioning, it can be solved by forming a groove of a predetermined depth in the flange of a pipe or the like, and fitting a ring gasket to it and tightening it. However, forming a groove in the flange is very expensive. It is not economical because it requires.

  Therefore, the problem of the present invention is that the total tightening pressure can be lowered, the handling is easy, the test period can be shortened, it can be used in a petrochemical plant, etc. It is to obtain a non-asbestos-based gasket excellent in heat resistance, durability and sealability.

  The present invention basically adopts a metal jacket type gasket structure as means for solving the above-mentioned problems, and by reducing the width of the metal jacket type gasket, the contact area with the pipe flange is reduced. While reducing the tightening pressure, the metal jacket type gasket having the narrow width is used as a gasket body, and a metal ring is fitted to at least one of the outer periphery and inner periphery of the gasket body to form a composite gasket. New problems caused by narrowing of jacket type gaskets, such as leakage due to flange loading, gasket workability deterioration, tightening work efficiency reduction, heat damage due to poor centering, and strength reduction Solves problems such as gasket destruction during tightening, and has sufficient heat resistance and durability Fine sealing performance is obtained by the so can be ensured.

  Therefore, the present invention is fitted to a narrow ring-shaped metal jacket type gasket body in which a core material mainly composed of a non-asbestos material is wrapped with a metal jacket, and at least one of an outer periphery and an inner periphery of the gasket body. A composite gasket characterized by comprising a metal ring.

  However, if the gasket does not require heat resistance, instead of adopting a metal jacket type gasket structure as the gasket body, rubber materials such as silicone rubber, chloroprene rubber and fluorine-based rubber, fluorine resin fibers, aromatic polyamide resin fibers, etc. A narrow ring-shaped rubber jacket type or resin jacket type gasket in which a core mainly composed of at least one material selected from the group consisting of synthetic resin fibers is wrapped with the rubber material or resin material, an expanded graphite sheet, and Narrow ring-shaped gaskets made by processing sheet materials such as joint sheets into ring shapes, or ring-shaped gaskets with grommets fitted to their inner edges, and metal rings are fitted to at least one of the outer circumference and inner circumference Thus, a composite gasket may be configured. By adopting such a composite structure with a metal ring, problems caused by the material of rubber gaskets and resin gaskets, such as plastic deformation and fluidization at high temperatures in rubber materials and fluororesin gaskets. The deterioration of the sealing performance can be prevented, and sufficient heat resistance, durability and sealing performance can be ensured.

  Therefore, from another viewpoint, the present invention is characterized in that a narrow ring-shaped gasket body made of a non-asbestos material and a metal ring is fitted to at least one of the outer periphery and the inner periphery of the gasket body. A composite gasket is provided.

  The ring-shaped gasket body is different from the conventional full-surface metal jacket type gasket, and is formed with a narrow width. Usually, the width of the pipe flange to which the gasket is applied (that is, half the difference between the inner diameter and the outer diameter of the flange). ) Of 2/3 or less, preferably 1/2 to 1/20, more preferably 1/3 to 1/16. Specifically, for example, a gasket having a nominal pressure of 5K and a nominal diameter of 25A (referred to as 5K-25A, hereinafter the same) (inner diameter 40 mm, outer diameter 95 mm, thickness 2 mm, PC (gasket center-bolt hole center diameter) 75 mm. In the case of a bolt hole diameter of 12 mm (× 4), the gasket width is 4 to 8 mm, and a 5K-100A gasket (inner diameter 118 mm, outer diameter 200 mm, thickness 2 mm, PC165 mm, bolt hole diameter 19 mm (× 8)). If the gasket width is 5 to 10 mm and the 5K-750A gasket (inner diameter 780 mm, outer diameter 945 mm, thickness 2.5 mm, PC 880 mm, bolt hole diameter 27 mm (× 24)), the gasket width is 15 to 30 mm. It is preferable to set to.

  Examples of the non-asbestos material include rubber materials such as silicone rubber, chloroprene rubber, and fluorine rubber, and heat-resistant resin fibers such as polyparaphenylene benzobis oxazole (PBO) fiber, Kevlar fiber, fluorine resin, and aromatic polyamide resin. , Expanded graphite, glass fiber, rock wool, ceramic fiber, alumina silica fiber, alumina fiber, calcium carbonate fiber, ceviolite, attapulgite, wollastonite, clay, etc., these may be used alone or in combination it can. The fluororubber includes vinylidene fluoride rubber, tetrafluoroethylene-propylene rubber, tetrafluoroethylene-purple chlorovinyl ether rubber, and the like. When the non-asbestos material does not require much heat resistance, for example, when a heat resistant temperature of 200 ° C. or lower is sufficient, a rubber material such as silicone rubber, chloroprene rubber, or fluorine rubber, when a heat resistant temperature of 260 ° C. or lower is required Organic materials such as heat-resistant fluororubber, fluororesin, and aromatic polyamide resin can be used. At higher temperatures, expanded graphite, glass fiber, rock wool, ceramic fiber, alumina silica fiber, alumina fiber, calcium carbonate fiber, ceviolite It is preferable to use non-asbestos inorganic materials such as attapulgite, wollastonite and clay (clay). When a heat resistant temperature exceeding 500 ° C. is required, it is preferable to use a non-asbestos high heat resistant inorganic material such as rock wool, ceramic fiber, alumina silica fiber or alumina fiber. Non-asbestos formed by adding high heat-resistant inorganic short fibers to high heat-resistant inorganic long fibers, adding inorganic fine powder, and bonding them with a binder to form a sheet when a heat-resistant temperature exceeding that is required It is preferable to use a material using an inorganic fiber sheet. In addition, as a core material, it is also possible to use a commercially available expanded graphite sheet or a joint sheet.

  Typical examples of the heat-resistant inorganic long fibers include rock wool (including in vivo soluble rock wool), alumina silica fiber, alumina fiber, boron fiber, carbon fiber, and the like. Commercially available products include, for example, Fineflex (registered trademark) bulk fiber (for example, TOMBO (registered trademark) No. 5100 / 5200-Z) manufactured by NICHIAS Corporation, RUBERU (registered trademark) manufactured by the same company. Denka Alsene (trade name) manufactured by Denki Kagaku Kogyo Co., Ltd., Isowool (registered trademark) 1400, 1500, 1600 manufactured by Isolite Kogyo Co., Ltd., and Nichibi Alfic Fiber (registered trademark) manufactured by Nichibi Corporation.

  The longer the fiber length of the inorganic fiber, the better the handleability and sheet strength in the process of manufacturing the inorganic fiber sheet, but it is sufficient if the average fiber length is 1 mm or more, and the average fiber length is usually 2 mm to It is preferable to use a fiber having a small fiber diameter of 40 mm, for example, a fiber diameter of 0.2 to 12 μm, preferably 0.2 to 7 μm. The inorganic long fiber may be any amorphous or crystalline.

  The inorganic short fibers are added to reduce the cost of the core material, and at the same time, ensure the uniformity of the product and prevent the wear of the Thomson blade when the inorganic fiber sheet is punched into a predetermined shape. In this case, the inorganic short fibers are preferably added in an amount of 5 to 35%, preferably 10 to 20%. This is because if the amount added is less than 5%, a sufficient effect cannot be obtained, and if it exceeds 35%, the difficulty in the manufacturing process increases, and the handleability and the sheet strength decrease.

  The inorganic short fibers are used alone or in combination with inorganic long fibers, and the same materials as the inorganic long fibers, for example, short fibers such as alumina silica short fibers, alumina short fibers, boron fibers, carbon fibers, etc. Alternatively, they may be used in combination, but from an economical viewpoint, it is preferable to use fine inorganic fibers such as clay mineral (magnesium silicate ore), for example, inorganic short fibers such as sepiolite (hydrous magnesium silicate). Examples of the inorganic short fibers include Hayashi Kasei Co., Ltd.'s Milcon LS (trade name), SS, E, LS-2, SS-2, and MS-2, as well as NICHIAS Corporation. Fine Flex (registered trademark), Ruby (registered trademark), Denka Arsene (trade name) manufactured by Denki Kagaku Kogyo Co., Ltd., Isowool (registered trademark) 1400, 1500, 1600 manufactured by Isolite Kogyo Co., Ltd., and the like can be mentioned. In general, inorganic fibers having an average fiber length of 30 μm or less are short fibers, but those having an average fiber length of less than 1 mm may be used as the short fibers. Sepiolite usually contains 0.1 to 0.3% of tremolite asbestos, so it is preferable to use attapulgite, wollastonite, calcium carbonate short fibers, and the like.

  Further, inorganic fine powder is added to the inorganic fiber composition, and the density of the inorganic fiber sheet is made uniform by utilizing the elasticity of the fine powder, and the load applied to the inorganic long fibers is dispersed to seal at a high temperature. It may be possible to homogenize the sex. In this case, the inorganic fine powder is preferably added in an amount of 10 to 60%, preferably 20 to 50%. This is because a sufficient effect cannot be expected if the added amount of the inorganic fine powder is less than 10%, and if it exceeds 60%, the sheet strength is lowered.

  The inorganic fine powder is added for the purpose of preventing the inorganic long fibers from breaking or breaking by filling the gaps between the inorganic long fibers and the inorganic short fibers and dispersing the load applied to the inorganic long fibers. The inorganic long fibers and the short inorganic fibers have a melting point equal to or higher than the maximum use temperature, and have an average particle diameter substantially equal to or smaller than the diameter of the inorganic long fibers, specifically, the melting point is 1300. A material having an average particle diameter of 0.1 to 10 μm, preferably 0.2 to 6 μm may be used at a temperature equal to or higher than C.

  Examples of the inorganic fine powder include rock fine powder such as clay and talc, oxide fine powder such as alumina, titanium oxide, silica, mullite, cordierite, ferrite, and magnesium oxide; silicon nitride, aluminum nitride, boron nitride, and the like. Nitride fine powder: carbide fine powder such as silicon carbide, titanium carbide, tungsten carbide, etc., and commercially available products include micelleton (trade name), Hayashi Kasei Co., Ltd., micron white (trade name) 5000S, 5000P, 5000SD, 5000A, 5000B, Showa Mining Co., Ltd. Milcon MS (trade name), Kyocera Corporation Silicon Nitride SN281 (trade name) and other fine powder talc, Hayashi Kasei Co., Ltd. Milcon (trade name) LS, SS, Shin-Etsu Chemical Co., Ltd. silicon nitride KSN-10SU, KSN-10SP, KSN- 0M-TX, KSN-10L, Showa Denko Co., Ltd. Boron Nitride powder Sho BN (registered trademark) UHP, Ruby En (registered trademark) LBN, Sumitomo Chemical Co., Ltd. high purity alumina AKP-20, AKP-30, AKP-50, activated alumina KHA-46, KHA-24, KHO-46, KHO-24, KHD-46, KHD-24, NKHD-46, NKHD-24, etc. Silicon nitride powder HM-5, HM-5MF, Boron nitride powder GP, SP-1, SP-2, manufactured by Denki Kagaku Kogyo Co., Ltd. Powder), silicon nitride manufactured by the same company, aluminum nitride powder manufactured by Tokuyama Corporation. It should be noted that talc may contain asbestos of about 0.5% or less.

  The core material is usually formed by adding 15 to 60% inorganic fine powder and 5% or less binder to the inorganic fiber component composed of the inorganic long fibers and inorganic short fibers, and then laminating them. Is done. If necessary, 2 to 10% of organic fiber may be added. As the organic fiber, polyparaphenylene benzoxador (PBO) fiber, aramid fiber, polyamide synthetic fiber, acrylic fiber and other artificial fibers, pulp, Manila hemp and other natural fibers can be used.

  As the binder, either an organic binder or an inorganic binder may be used, and the organic binder includes a natural binder and a synthetic binder typified by starch paste. As the inorganic binder, in addition to a heat-resistant inorganic adhesive mainly composed of alumina or silica, a silane compound inorganic binder, fibrous sepiolite, or the like can be used. Examples include Alumina BK-112, BK-103, Betak # 1300 manufactured by TA Chemical Co., Ltd., # 1550B, Showa Mining Co., Ltd., Milcon SP, LS, Asahi Chemical Industry Co., Ltd.

  As a material of the metal jacket, a known material adopted for a conventional metal jacket, for example, a cold rolled steel plate (SPCC) or a stainless steel plate (for example, SUS304, SUS304L, SUS316, etc.) may be used. When heat resistance or corrosion resistance of ℃ or higher is required, it is preferable to use heat resistant and corrosion resistant stainless steel or nickel base heat resistant alloy. Examples of the heat and corrosion resistant stainless steel include high chromium high nickel low carbon stainless steel, and commercially available products include SUS310, SUS309S, SUS321, SUS347, Incoloy (registered trademark) 800, and the like. Further, the nickel-base heat-resistant alloy includes a nickel-base heat-resistant alloy containing Cr 15-30%, Ni 10-80%, C 0.4% or less, and Mo 10% or less, and commercially available products include Inconel (registered trademark) 600. 601, 625, 718, and the like. These metal jacket materials may be sheets having a thickness of 0.1 to 1.0 mm.

  Further, the metal jacket type gasket main body does not necessarily have to be a full coating type, and may be a double coating type, a single side coating type (French type) or a round shape (ring joint type). Each has a slightly thicker wall thickness than the metal ring described later when not in use, and is compressed to the thickness of both the inner and outer metal rings by tightening.

  Note that when heat resistance is not required, a metal jacket is not necessarily required. For example, when the heat resistant temperature may be 260 ° C. or less, a sheet mainly composed of silicone rubber, chloroprene rubber, fluororubber, fluororesin, or the sheet is used. A narrow ring-shaped gasket obtained by processing a sheet such as a resin-coated sheet, an expanded graphite sheet, or a joint sheet as a core material into a disk shape, or the gasket as a core material (medium cushion material), and the rubber or A ring-shaped rubber or resin jacket type gasket wrapped with a resin material may be used as the gasket body. As the resin jacket material, a resin having a wide use temperature range and excellent chemical resistance, non-adhesiveness, weather resistance, flame retardancy, etc. may be used. An aromatic polyamide resin is mentioned. In particular, polytetrafluoroethylene (PTFE) is suitable because it can be used in a wide temperature range from -180 ° C to + 260 ° C and has excellent properties such as chemical resistance, non-adhesiveness, weather resistance, and flame resistance. is there. In addition, the joint sheet refers to a heat-resistant organic fiber such as an aramid fiber (aromatic polyamide fiber) and an inorganic fiber mixed with graphite and other fillers and a rubber material, mixed and pressed, A commercially available product may be used.

  The outer metal ring fitted to the outer periphery of the gasket body has the same inner diameter as the outer diameter before finishing the gasket, and the outer diameter is the outer diameter of the pipe flange to which the gasket is applied, or the outer surface of the flat seat portion. It is preferable to set the same as the diameter, but it is set in consideration of the strength. Moreover, the plate | board thickness of an outer side metal ring is set to the thickness of the gasket compressed by the surface pressure required for a gasket pressure. Further, the outer metal ring may have a bolt hole corresponding to the bolt hole of the flange.

  The inner metal ring fitted to the inner periphery of the gasket body is usually a donut shape, and its inner diameter is set to be the same as or slightly larger than the inner diameter of the pipe and flange of the piping system to which the gasket is applied, The outer diameter is set to be approximately the same as the inner diameter before gasket finishing.

  The outer metal ring and the inner metal ring may be formed of the same material as the metal jacket, for example, a cold rolled steel plate (SPCC) or a general-purpose stainless steel plate (SUS304, SUS304L, SUS316, etc.). When an overload prevention or positioning function is required, it is preferable to use a rust-proof plated material on a stainless steel plate (SUS) or a cold rolled steel plate (SPCC). In addition to the rust preventive plating material on the outer metal ring and the inner metal ring, when a secondary seal or tertiary seal is required to further increase the sealing performance, SUS, SPCC, Cu, Al, Zn, It is preferable to use a metal plate of Ni, Sn, Si, Ti or an alloy plate thereof in combination. Furthermore, when reinforcing heat resistance and corrosion resistance, it is preferable to use a metal or alloy plate such as Fe, Cr, Ni, Ti, Nb, Si, C, Mo, W, and Co.

  The metal ring is a surface treatment for forming a film by preventing the corrosion and coating the metal plating or at least one material selected from the group consisting of fluororesin, fluororubber and silicon resin in order to improve the sealing performance. It is preferable to apply.

  When quick sealing is required at a low temperature, for example, 250 ° C. or less, a thin organic paper of 0.2 mm or less, a sealing tape such as vinyl, fluororesin paper, or silicon paper, a liquid packing, etc. are used for the outer metal ring. And / or it is preferable to stick or apply | coat to both surfaces of an inner side metal ring. Further, when the use temperature is in the range of 200 to 400 ° C., it is preferable to adhere carbon paper, aluminum foil, ceramic paper, etc. on both sides of the inner metal ring.

  The gasket according to the present invention can be manufactured, for example, as follows. First, when manufacturing an inorganic fiber sheet made of an inorganic material, high heat-resistant inorganic long fibers 10 to 40% and high heat-resistant inorganic short fibers 5 to 40% in order to increase the strength in the manufacturing process and improve handleability Inorganic fine powder 15 to 60% is added to this, organic fiber 2 to 20% and / or organic and inorganic binder 10% or less is blended, and after these are dispersed in water, they are made into a sheet by papermaking. None, this is dried, and further cut into a ring shape to prepare a raw sheet for core material.

  On the other hand, a metal sheet for a metal jacket is cut into a ring shape by a die, a Thomson die, a circular cutter, a laser, an electron beam, or other means, and this is pressed with a die or a simple die to make a U-shaped cross section or After forming a U-shaped ring-shaped jacket body member and an I-shaped ring-shaped jacket lid member, the raw sheet is placed in a recess of the jacket body member, and a jacket lid member is placed thereon, The inner edge and the outer edge of the jacket body member are caulked to obtain a metal jacket type gasket body.

  Separately, a metal sheet having a thickness equal to the thickness at the time of tightening the gasket is processed into a ring shape to produce an outer metal ring and / or an inner metal ring. Next, the inner metal ring is fitted inside the gasket main body, while the metal jacket type gasket main body is fitted inside the outer metal ring and flatly integrated.

  The gasket body is usually used as it is without heat treatment, and the starch paste and natural fibers of the organic material that is the internal material of the gasket body are gradually burned off at about 300 ° C. by heating during use. PBO fiber, Kepla fiber and other heat-resistant synthetic fibers remain in an environment of use at 500 to 600 [deg.] C. without deterioration by burning, although the strength deteriorates significantly in one to two years. On the other hand, in the metal jacket type gasket, the leak is only the interface leak, but it is greatly influenced by the flange surface roughness and the hardness of the gasket contact surface. Therefore, it is necessary for the metal jacket type gasket to determine the annealing temperature in accordance with the metal used for the jacket. For example, when the jacket is made of copper, softening starts at 180 ° C. or higher, but industrially 400 to 600 ° C. Becomes the annealing temperature. However, in the gasket according to the present invention, when the flange surface roughness is the top finish (finish symbol ▽▽▽ (three peaks)), about 180 ° C is sufficient, but the flange surface roughness is medium. In the case of finishing (finish symbol ▽▽ (two peaks)) or finish symbol ▽ (one mountain)), about 500 ° C is preferable. In this case, the annealing atmosphere requires a reducing atmosphere that does not contain hydrogen, and is performed in a gas atmosphere such as nitrogen or argon or in a vacuum. Moreover, since copper changes into annealed copper by annealing, it becomes impossible to press work. Therefore, it is performed after the gasket body is integrated with the inner metal ring and the outer metal ring. The same applies when the jacket material is iron or aluminum. In the latter case, annealing is preferably performed at 200 to 500 ° C. Furthermore, in the case of stainless steel, it is usually carried out by a blunting method in which it is heated to 1000 to 1200 ° C. and then cooled in water, or in a quenching method in which it is rapidly cooled with nitrogen. In the present invention, the hardness of the gasket is softened. Therefore, it is sufficient to rapidly cool after heating to about 600 ° C.

Moreover, when manufacturing the gasket which has the bolt hole 6a in the outer ring 6, the said gasket should just be punched with a metal mold | die, a Thomson type | mold etc., and a bolt hole should be drilled, and the said heat processing and finishing press should be performed after that. If necessary, the grommets may be fitted in the bolt holes after heat-treating the gasket. In addition, when a certain pressure is applied to the gasket and the gasket is left in that state for a predetermined time, for example, 10 hours or more, the sealing performance can be improved. In general, metal jacket type gaskets have no penetration leakage and only interface leakage, so it is necessary to allow the gasket surface to adjust to the roughness of the flange surface, but high temperature, vibration, clamping pressure and clamping time are required. It becomes clear that it is more familiar than expected, and when the metal jacket is made of Cu, a state in which no gas leaks of 10 ⁻⁷ Pa · m ³ / sec is achieved.

  According to the present invention, (a) by combining the metal jacket type structure and the metal ring structure, the metal jacket type gasket is made small by making use of the excellent heat resistance, durability and sealing properties characteristic of the metal jacket type gasket. In other words, problems such as flange loading leakage, gasket positioning difficulty, gasket destruction, bolt tightening and excessive or insufficient tightening pressure can be solved. Specifically, since the ring-shaped metal jacket type gasket body can be formed with a smaller width than the width of the pipe flange, the contact area with the pipe flange can be reduced, and a sufficient seal can be secured with a low clamping pressure. (B) The gasket body has a metal jacket type structure, so it can withstand vibrations and reduce leakage due to flange loading. (C) The gasket body is narrow. Since the strength of the gasket body is compensated by a metal ring located on at least one of the outer periphery and inner periphery of the gasket body, it is not destroyed even by the high gas internal pressure of the piping system. (E) The thickness of the gasket body that can prevent the thermal destruction of the gasket body due to misalignment. Because it is guaranteed by the metal ring, overtightening can be prevented, and the gasket body is not destroyed when tightening. (F) The gasket body has a metal jacket type structure and is small in width, so it is determined early. Therefore, the test can be completed immediately and the operation can be started immediately. (G) Since the gasket body has a narrow metal jacket type structure, if the gasket is enlarged, the contact of the gasket body Even if the pressure resistance of the gasket body alone is lower than that of the full surface contact type metal jacket gasket, for example, even if the operating pressure of the gasket body alone is about 10 MPa, the inner and outer metal rings fit into the gasket body. As a result, the gasket as a whole has a pressure resistance of 50 MPa or more, and it has a high operating pressure. Also improves the Le resistance, excellent effects such as obtained.

  As shown in FIG. 1, a metal ring / metal jacket composite gasket 1 according to the present invention includes a metal jacket type gasket body 2, an outer ring 6 fitted to the outer periphery of the gasket body 2, and a gasket body 2. It is comprised from the inner ring 7 inserted by the inner peripheral part. The metal jacket type gasket body 2 includes a U-shaped jacket body member 3, an I-shaped jacket cover member 4, and an inorganic fiber sheet 5, and its width is 1 / of the width of a pipe flange to which the composite gasket 1 is applied. In addition, the thickness of the outer ring 6 and the inner ring 7 is slightly thicker.

  The outer ring 6 and the inner ring 7 are made of stainless steel SUS304. The outer ring 6 has an outer diameter that is the same as the outer diameter of the pipe flange, and the inner diameter of the gasket main body 2 so that the gasket main body 2 can be inserted. The outer diameter of 2 is slightly smaller than the outer diameter. The outer ring 6 has bolt holes 6a formed at positions corresponding to the bolt holes of the pipe flange, as shown in FIG. The inner ring 7 is formed to have an outer diameter slightly larger than the inner diameter of the gasket body 2 so that the outer diameter can be fitted inside the gasket body 2, and the inner diameter is the same as or slightly larger than the inner diameter (pipe diameter) of the pipe flange. It is formed in the diameter.

  The metal ring / metal jacket composite gasket 1 can be manufactured, for example, by the following method. First, a core material 5 is prepared by cutting a commercially available expanded graphite sheet (thickness 3 mm) into a ring shape (r1 × r2).

  On the other hand, a stainless steel (SUS304) sheet having a thickness of 0.2 to 0.3 mm is cut to form a ring-shaped jacket cover member 4 having a diameter r1 and an inner diameter r2, and a ring-shaped jacket body having a diameter r1 + 10 mm and an inner diameter r2 to 10 mm. The member 3 is prepared, and the ring-shaped jacket body member 3 is pressed to form a U-shaped or U-shaped cross section.

  Next, after placing the core material 5 in the recess of the jacket body member 3 and placing the jacket lid member 4 thereon, the inner edge and the outer edge of the jacket body member 3 are caulked to 2.5-3.3 mm. A thick metal jacket type gasket body 2 is obtained.

  Separately, a stainless steel plate (SUS304) with a thickness of 2 to 2.5 mm is cut into a ring shape to form an outer metal ring 6 and an inner metal ring 7 having bolt holes 6a at positions corresponding to the bolt holes of the flange. To do. Next, the metal jacket type gasket main body 2 is fitted into the outer metal ring 6, the inner metal ring 7 is fitted inside the gasket main body 2, and then flattened to be integrated. A metal jacket composite gasket 1 is obtained. In the present embodiment, the outer diameter of the inner metal ring 7 and the inner diameter of the outer metal ring 6 are formed in a straight line, but these outer surfaces are formed as necessary as shown in FIGS. Alternatively, a groove or a recess having a semicircular, semi-elliptical, trapezoidal, triangular or rectangular cross section in the circumferential direction along the inner surface may be provided to facilitate fitting into the gasket body.

  When high heat resistance is required, for example, heat resistant and corrosion resistant stainless steel SUS310 is used as a metal ring material, and inorganic fine powder and a binder are added to an inorganic fiber component consisting of inorganic long fibers and inorganic short fibers as a core material. Then, it may be produced by the above method using an inorganic fiber board which is formed into a sheet shape, laminated and dried. In this case, the inorganic fiber board can be manufactured as follows. For example, Isowool (registered trademark) 1400 manufactured by Isolite Industry Co., Ltd. is used as the inorganic long fiber, and Milcon SL (fiber length: 50 μ, fiber diameter: 0.2 μ) manufactured by Hayashi Kasei Co., Ltd. is used as the inorganic short fiber. As shown in Table 1, talc is prepared together with organic fibers (pulp) and binder (starch paste), and dispersed in water to obtain a papermaking solution. The papermaking liquid is made with a papermaking machine to prepare a sheet having a thickness of 2.4 to 2.6 mm, and this sheet is cut into a predetermined shape with a Thomson mold to obtain an inorganic fiber raw sheet.

  After placing the raw inorganic fiber sheet in a U-shaped metal jacket main body member 2 formed in advance with heat-resistant and corrosion-resistant stainless steel, an I-shaped metal jacket cover member 3 formed of the same material is disposed thereon. The inner edge 2a and the outer edge 2b of the metal jacket main body member 2 having a U-shaped cross section are crimped and integrated to obtain a metal jacket type raw gasket. Next, after fitting both the inner and outer metal rings made of the same kind of heat-resistant and corrosion-resistant stainless steel plate having a thickness of 2 to 2.5 mm, and adjusting the gasket thickness to 2.5 to 3.3 mm by a finishing press, the metal ring -The metal jacket composite gasket 1 can be obtained. This composite gasket can be used even at a temperature of 900 ° C. or higher. Internal organic matter is decomposed at the start of use or by heating in advance, and cushioning properties are improved.

1 is a perspective view of a metal ring / metal jacket composite gasket according to the present invention. It is sectional drawing in the AA of FIG. It is sectional drawing similar to FIG. 2 which shows the other Example which concerns on this invention. It is sectional drawing similar to FIG. 2 which shows the other Example which concerns on this invention.

Explanation of symbols

1: Metal ring / metal jacket composite gasket 2: Metal jacket type gasket body 3: Metal jacket body member 4: Metal jacket lid member 5: Core material 6: Outer ring 6a: Bolt hole 7: Inner ring

Claims (8)

  It consists of a narrow ring metal jacket type gasket body made by wrapping a core material mainly composed of non-asbestos material with a metal jacket, and a metal ring fitted to at least one of the outer periphery and inner periphery of the gasket body. A composite gasket characterized by that.   The composite gasket according to claim 1, wherein a width of the gasket body is 2/3 or less of a width of a pipe flange to which the composite gasket is applied.   The composite gasket according to claim 1 or 2, wherein the metal jacket is in a form selected from the group consisting of a full-covered type, a double-covered type, a single-sided covered type, and a round shape.   The composite gasket according to any one of claims 1 to 3, wherein the metal ring has a coating made of at least one material selected from the group consisting of metal plating or fluororesin, fluororubber, and silicon resin.   The composite gasket according to any one of claims 1 to 4, which is a full surface contact type gasket in which the metal ring is fitted on the inner periphery and the outer periphery of the gasket body.   The gasket body has an outer diameter equal to or less than the diameter of a circle inscribed in a plurality of bolt holes provided in the pipe flange, and a metal ring fitted to the outer periphery of the gasket body corresponds to the bolt hole of the pipe flange. The composite gasket according to any one of claims 1 to 5, which has a bolt hole.   The composite according to any one of claims 1 to 6, wherein the gasket body has a thicker thickness than the metal ring when not fastened, and is compressed to the same thickness as the thickness of the metal ring when tightened. gasket. The non-asbestos material is silicone rubber, chloroprene rubber, fluororubber, fluororesin, aromatic polyamide resin, expanded graphite, glass fiber, rock wool, ceramic fiber, alumina silica fiber, alumina fiber, calcium carbonate fiber, ceviolite, attapulgite, The composite gasket according to any one of claims 1 to 7 , which is at least one selected from the group consisting of wollastonite and clay.

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