Gaskets

About Gaskets and Gasket Manufacturers Including: Head Gaskets, Rubber Gaskets, Silicone Gaskets, Spiral Wound Gaskets & Viton Gaskets.

Gaskets are used to create a tight seal between two parts. The seal prevents gas or 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. Gasket manufacturers produce gaskets to be 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.

While there are many types of gaskets, jacketed gaskets optimize temperature and 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 the 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 gaskets and their accessories are necessary and, if so, what 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 gaskets. If there is a 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 metallic or non-metallic gaskets depends on the substance being contained and the ambient environment. Other 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 gaskets are to seal.
 
Gasket manufacturers use many, many materials to make gaskets. 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, gasket manufacturers use metal to make gaskets, some of which are carbon steel, stainless steel, nickel, aluminum, brass and copper.
 

Gaskets and Gasket Manufacturers Images Provided by Reliant Rubber Company

Types of Gaskets

• Composite gaskets are custom-fit to individual applications and are typically applied with 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.
  
• Corrugated gaskets 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.
  
• Die cut gaskets are made of materials that can be cut before assembly.
  
• ElastaGraph gaskets are corrugated gaskets that are suitable for high temperature, high pressure applications and consist of a metallic core over which a seamless flexible graphite is applied. ElastaGraph gaskets have a high density inner ring to increase sealability and provide low minimum seating stress.
  
• Encapsulated gaskets consist of a gasket of one material and a continuous layer of another material, typically Teflon, which completely encloses the gasket.
  
• Envelope gaskets consist of a gasket of one material and an envelope of another material, typically Teflon, which covers the gasket.
  
• Fibre seal rings are diecut, water-jet cut or formed gaskets or rings that provide a seal between two surfaces.
  
• Flange gaskets have protruding rims or lips that aid in the attaching process.
  
• Flat solid metal gaskets are cut from sheet metal in an almost infinite variety of sizes and shapes.  Mating surfaces must be perfectly aligned for flat solid metal gaskets to provide good seals.
  
• Foam gaskets are made out of strips of plastic, foam or rubber.
  
• Head gaskets are inserted between the cylinder head and the engine block. Head gaskets prevent coolant from entering the cylinders.
  
• Hollow tube gaskets have a tubular cross section that is typically made out of rubber or plastic.
  
• Jacketed gaskets combine the durability of a metal jacket with the sealing capability of a soft gasket.
  
• Laminated gaskets consist of two or more layered materials and are often enclosed in an envelope.
  
• O-rings also referred to as “donut-shaped” gaskets, are circular rings, having a variety of cross-sectional configurations that are specified by their dimensions, material and hardness. O-rings are installed in a gland to close off a passageway, preventing the escape or loss of fluids or gases.
  
• Profiled and serrated gaskets are solid metal gaskets with surface grooves, which facilitate a good seal with low seating stress. To protect flange surfaces, profile and serrated gaskets can be jacketed.
  
• Rubber gaskets are rubber components that create a seal between two parts.
  
• 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.
  
• Solid metal gaskets are gaskets made out of solid metal, yet they must be softer than the materials of the two adjoining surfaces. Solid metal gaskets are used for extreme pressures or temperatures.
  
• Spiral wound gaskets are made of a thin metallic strip and a soft nonmetallic filler that are wound together. Spiral wound gaskets can withstand high pressure and extreme temperature.
  
• Teflon gaskets are gaskets designed to resist sticking to the adjoining materials.
  
• Viton gaskets are made of a synthetic tube that is resistant to heat, oil, and various acids.

Gaskets Terms

Anti-extrusion Rings – Also referred to as “back-up rings,” they are rings designed to fit behind rubber o-ring seals in order to prevent extrusion into the gap between the metal pieces.
 
Beryllium Copper – A lightweight metal that resists corrosion and is used in aerospace materials, springs and gaskets.
 
Blowout Pressure – The internal forces that exert pressure against a gasket, which may cause the unsealing of the gasketed joint.
 
Bonded Seals – Flat steel washers in the center of which a rubber sealing ring is molded to fit over a bolt, providing a seal.
 
Die Cutting – Cutting shapes out of material using a die. The die is a pre-formed stencil.
 
Electromagnetic Interference – An interruption produced by an electric current, which can be filtered out by some gaskets.
 
Flange Load – The total force that creates a seal through compression of the gasket.
 
Hydrostatic End Force – The internal forces working against the flanges holding the gasket in place.
 
Mismatch – The unevenness of a seal due to differences in the two adjoining surfaces.
 
Nebar – A specialized gasket material that is used in electrical transformers.
 
Neoprene – A rubber used in weather resistant products, adhesives, paints, rocket fuel and gaskets.
 
Parback – A back-up ring that is used as an anti-extrusion ring for an o-ring. Parbacks are concave-shaped on one side.
 
Rings – Circular sealing devices. Seal Strips – Strips comprised of multiple layers of metal that are welded together to allow gaskets to be used in extreme heat or pressure.

Slip O-ring – A type of ring that relieves friction by fitting over an o-ring.

Shims – Used as spacers between a gasket and the adjoining material.

Static Seal – A seal, created by a gasket, between two unmoving parts.

Washers – Flat, circular rings placed under the head of a bolt to serve as spacers, gaskets or slip devices.