IQS Newsroom Articles on 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 which prevents gases or fluids 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); these are EMI gaskets, which are made from special EMI-blocking materials (such as nickel). Gaskets must be more pliable than the two adjoining surfaces in order for gaskets to work properly; this allows them to mold to the groves of both components, creating a seal. For this reason, most gaskets are made from synthetic or natural rubbers; rubber gaskets may include viton gaskets, EPDM gaskets, silicone gaskets and a number of other rubber materials. Additionally, gaskets must be chemically compatible with the two joining surfaces. This ensures a tight seal with no fluid or gas leaks. While most gaskets used in low to mid demand applications are die cut rubber, spiral wound gaskets, metal jacketed gaskets and coated teflon gaskets are used as high temperature gaskets or chemically resistant gaskets in high demand applications.
Gaskets of various materials, sizes and configurations are used for sealing applications across 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. Seals between joints are critical in many hydraulic, pneumatic and aerospace applications responsible for maintaining air or fluid pressure; in a commercial flight, gaskets throughout the aircraft keep the cabin from depressurizing. For especially high demand applications, particularly where high levels of pressure are applied to the seal, metal 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. Single jacket gaskets are the most basic type, while double jackets gaskets are available for extra rigid applications, and french style jacket gaskets with two- or three-piece construction have irregular shapes.
Most rubber gaskets are die cut from flat rubber or metal sheets. Die cutting allows gasket manufacturers significant design flexibility, and gaskets are cut in shapes as simple as basic rings or as complex as head gaskets automotive engine blocks. For applications which require simple gaskets with thick, structurally sound construction, rubber molding is used as an alternative to die cutting. Gasket manufacturers use a wide number of both natural and synthetic rubbers to manufacture gaskets with application-specific tolerances. Common elastomeric materials include silicone, neoprene, nitrile, EPDM and Viton. Plastics commonly used for either gasket material or for jacketing include Teflon, nylon, polyethylene (PE), polyurethane and mylar. Sponge rubber, such as open or closed cell silicone, is also used for applications requiring a more flexible seal. Gaskets may be made out of non-asbestos sheets, such as carbon filament, fiberglass, ceramic and Kevlar. Metal gaskets and shims, which are flat metal gaskets similar to washers, are used alone or in combination with rubber gaskets to fill additional gaps that may
occur within flanges, similarly to the way metal jacketed gaskets are
used to create extra seal strength and corrosion resistance.
Gaskets are molded, die cut and roll formed into configurations to meet every possible sealing application, and there are few ways to substitute the efficiency and function of a gasket seal. O-rings are specific types of circular molded gaskets which are used in simple, primarily static sealing applications; while o-rings can provide an exceptionally strong seal around simple ring flanges, they cannot provide the kind effective seal in non-circular or complex flanges that die cut and molded gaskets are capable of providing. Soft non-polymer materials, are sometimes die cut into gaskets to create a breathable seal; these materials include cork sheet, felt, vegetable fiber, vulcanized hard fiber, chipboard and fishpaper.
Types of 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.
- 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 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.
- consist of a gasket of one material and a continuous
layer of another material, typically Teflon, which completely encloses
the gasket.
- consist of a gasket of one material and an envelope
of another material, typically Teflon, which covers the gasket.
- 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 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.
- 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 plastic.
- combine the durability of a metal jacket with the
sealing capability of a soft gasket.
- consist of two or more layered materials and are
often enclosed in an envelope.
- 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.
- 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.
- are rubber components that create a seal between two parts.
- (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.
- 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.
- 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.
- are gaskets designed to resist sticking to the adjoining
materials.
- are
made of a synthetic tube that is resistant to heat, oil, and various
acids.
Gaskets Terms
- 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.
- A lightweight metal that resists corrosion and
is used in aerospace materials, springs and gaskets.
- The internal forces that exert pressure against
a gasket, which may cause the unsealing of the gasketed joint.
- Flat steel washers in the center of which a rubber
sealing ring is molded to fit over a bolt, providing a seal.
- Cutting
shapes out of material using a die. The die is a pre-formed stencil.
- An interruption produced
by an electric current, which can be filtered out by some gaskets.
- The total force that creates a seal through compression
of the gasket.
- The
internal forces working against the flanges holding the gasket in place.
- The unevenness of
a seal due to differences in the two adjoining surfaces.
- A specialized gasket material that is used in electrical
transformers.
- A rubber used in weather resistant products, adhesives,
paints, rocket fuel and gaskets.
- A back-up ring that is used as an anti-extrusion ring
for an o-ring. Parbacks are concave-shaped on one side.
- Circular sealing devices.
- Strips comprised of multiple layers of metal that
are welded together to allow gaskets to be used in extreme heat or pressure.
- A type of ring that relieves friction by fitting
over an o-ring.
- Used as spacers between a gasket and the
adjoining material.
- A seal, created by a gasket, between
two unmoving parts.
- Flat, circular rings placed under
the head of a bolt to serve as spacers, gaskets or slip devices.