 About Gaskets
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Gaskets are used to create a tight seal |
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between two parts. The seal prevents gas or
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| fluid from leaking. A proper seal will prevent |
| leakage during temperature or pressure |
| changes. Some gaskets are made to withstand |
| electromagnetic and radio frequency |
| interference (EMI and RFI). Gaskets should be |
| more pliable than the two adjoining surfaces. |
| In order for gaskets to work properly, they must mold to the groves of both components. |
| Additionally, gaskets must be chemically compatible with the two joining surfaces. This |
| ensures a tight seal with no fluid or gas leaks. Gaskets are used in the aerospace, |
| automotive, aviation, electronics, military and transportation industries. Some |
| applications include air frames, appliances, business machines, compressors, elevators, |
| escalators, medical equipment, meters, turbines and valves. |
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| While there are many types of gaskets, jacketed gaskets optimize temperature and the |
| chemical performance. These gaskets combine the temperature resistance of a metal |
| jacket with the sealing performance of a soft filler. Pressure needs, gasket geometry and |
| sealing issues are factors in selecting types of jacketed gaskets. Single jacket gaskets are |
| most basic type. Double jackets gaskets are available with double shell and corrugation |
| options. French style jacket gaskets with two- or three-piece construction have irregular |
| shapes. |
| Determining whether or not a gasket and its accessories are necessary and, if so, what a |
| type of material should be used can be confusing. If the application is calling for |
| something to be sealed in or out between environments (e.g. to prevent leakage of a fluid |
| from one area to another), then it is necessary to use a seal, o-ring or gasket. If there is |
| gap between two assemblies or surfaces, then a shim is required. Shims act as leveling |
| devices or as seals to prevent leakage. Whether or not to use a metallic or non-metallic |
gasket depends on the substance being contained and the ambient environment. Other
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| factors include internal forces such as blowout pressure and hydrostatic end force, the |
| flange load, the temperature and the liquid or gas medium against which the gasket is to |
| seal. |
| There are many, many materials out of which gaskets may be manufactured. Types of |
| rubber include Neoprene, PVC, Hypalon, pure gum, Viton and food grade (FDA). Plastics |
| commonly used include Teflon, nylon, polyethylene (PE), polyurethane and Mylar. Sponge |
| rubber, such as silicone and open- and closed-cell rubber, is also used. Gaskets may be |
| made out of non-asbestos sheets, such as carbon filament, fiberglass, ceramic and Kevlar. |
| There many types of available soft materials, including the following: compressed sheet, |
| composition cork, felt, vegetable fiber, vulcanized hard fiber, chipboard and fishpaper. |
| Polyether, polyester and filter foam are three types of foam rubber. Of course, gaskets |
| can also be made of metal, some of which are carbon steel, stainless steel, nickel, |
| aluminum, brass and copper. |
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| Types |
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| a gasket dressing or adhesive in assembly and sealing. Composite gaskets are made from |
| any combination of the following materials: cork, rubber, paper and felt. |
| are metal gaskets that may be surface-treated with ceramic, non- |
| asbestos or flexible graphite. Corrugated gaskets, which may be used with Teflon |
| envelopes, provide a seal at low seating stress. are made of materials that |
| can be cut before assembly. |
| are diecut, water-jet cut or formed gaskets or rings that provide a seal |
| between two surfaces. |
| have protruding rims or lips that aid in the attaching process. |
| are made out of strips of plastic, foam or rubber |
| are inserted between the cylinder head and the engine block. Head gaskets |
| prevent coolant from entering the cylinders. |
| have a tubular cross section that is typically made out of rubber or |
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| combine the durability of a metal jacket with the sealing capability of a |
| soft gasket. |
| Silicone gaskets: (formed-in-place) are made from an uncured blend of a silicone |
| compound that is applied to the mating parts and allowed to cure after assembly. |
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