When something works well, you barely notice how it works. Today's manufacturing and engineering techniques make so many machines and devices run dependably and silently. When you need to build those machines, things get a lot more interesting.
You need to understand both the purpose of a design and the tolerances it requires and the conditions under which it operates. The more demanding the specifications, the more precise the component materials. This precision explains why there are so many different gasket materials.
Whether you need a material to last a long time, resist a lot of heat and pressure, or avoid conducting electromagnetic resonance, a gasket exists to meet the need. That's why gaskets and seals are a $25 billion industry that continues to grow.
Before you get started on your next engineering project, it's important to have an idea of the scope of gasketing materials and their uses. Strap in and get excited for the slew of information.
While the purpose of a gasket is to maintain a seal between two elements, a variety of shapes and types of gaskets are employed depending on the situation.
Rigid objects require gaskets that fit a set shape. Doors and moving structures need something flexible that can deform and then reform to fill a gap. Some objects have large, noticeable gaps, while others seem to fit tightly but feature irregularities and unconformities.
Gaskets prevent matter from passing through. The matter may be a liquid or a gas. In some cases, gaskets need to keep energy discharges from crossing thresholds.
Simple joints, like those found in pipes, use pipe gaskets. These are circular in shape and usually require a higher tolerance for compression. A pipe gasket also needs to resist corrosion and temperatures to maintain its shape over time.
Pipe joints aren't one solution fits-all, either. A combination of metallic, non-metallic, and composite materials are used to ensure that each joint remains sealed.
The best gasket type is the one that does the job. That said, the most employable of gaskets are the jacketed type. These gaskets provide flexibility from a soft core and resilience with an external coating.
With jacketing, one surface of a gasket may be covered with a metal material or both sides. A product is referred to as a double jacketed when both sides are wrapped around a softer core. Double jacketed gaskets provide better corrosion resistance over single jacketed as there is less possibility of material seeping into the core.
Corrugated jacketed gaskets interweave materials in layers, making for specialized combinations of flexibility and durability.
Like a jacketed gasket, spiral wound seeks to combine the best of both worlds. These use a combination of metal and plastics(or rubber) wound around layers of metal.
The resulting gasket yields acute physical resistance to stress and high thermal resistance. The gasket remains rubbery, so it seals well in moving joints and where fluids, gases, or heat exchange is needed.
Kammprofile gaskets can be thought of as a jacketed spiral wound gasket. A corrugated core of metal is covered in a sealing material. This sealing material is always on both sides.
The gasket uses physic stress to focus tension into the surface sealant and form a seal.
With the seal being created by the pressure around the gasket it leverages the different materials of the core to the sealing material to effectively reduce stress and transfer heat without further deformation.
Metal gaskets (typically) that are inexpensive and easy to use. They are used in high thermal and high-pressure situations. Solid gaskets require a lot of compression force to properly form a seal.
Solid gaskets are most commonly used between two other dense surfaces harder than the gasket material. The majority of solid gaskets are formed from metals.
Gasketing Tape/Gasketing Adhesive
Not all gaskets fit into a contained system. Doors and windows need to retain tight steals when closed but also allow free movement to be opened.
Threads and other locking components need help to reinforce mechanical seals and reduce friction that creates unconformities.
Gasketing tape or pressure-sensitive tape can be applied in these situations. The material expands to create a type seal and deforms to allow the seal to break with mechanical motion.
These tapes are made of a variety of polymers and even metals. They reduce noise, contain fluids, gasses, and heat while remaining flexible through weathering and impacts.
Thread tape fills in gaps to create a tighter seal while also reducing the friction that can create locks that split or break the threads from vibrations or percussive force.
Foam gaskets are another option for applying seals to materials with irregular shapes or that cover large surface areas.
In some cases, foam is applied much like tape, where a backing layer is attached to one surface and the foam is uncovered from a surface protection film before the seal is completed.
Another form of gasket foam application is through spraying. This puts the maximum amount of material into a gap between two other materials. Foam gaskets of this persuasion do well for projects requiring noise and impact reduction. The seals made are less tight than those created through other types and the material is far less dense.
Heating, Ventilating, and Air Conditioning (HVAC) industries use foam gaskets to reduce heat exchange between components or to provide extra seals at vents. These gaskets slow leaks of refrigerants and gasses without preventing them altogether. Fluids are also slowed but not blocked by foam gaskets.
The lack of durability of foam types is made up for by the ease of reapplying. Foam gaskets work well in conditions were other components need frequent repair or replacement.
The material used to create a gasket aids in the final function.
Some gaskets offer a higher level of resilience to a particular damaging agent or force. Others offer durability and flexibility to create a tight seal and stay operations over a lot of iterations or time.
It's important to remember that there are enough combinations of types and material for gaskets that not everything has been tried. A novel engineering problem requires a novel solution.
The purpose of understanding gasket materials is to gain an insight into what you need to tackle your particular challenge. We offer samples on a quick turn around to test new innovations and ideas.
Silicone materials are created from silica sands. They excel at a wide temperature range. You'll find them serviceable from 400 F all thew ay down to -67 F.
Silicone gaskets withstand aging and weathering well. The high elasticity of silicone makes it great for troublesome angles.
If you need a seal against solvents, fuels, or silicone-based fluids, then silicone seals are a poor choice. Each of these materials quickly degrades the gasket.
Neoprene is a synthetic polymer rubber. As a gasket material, it provides high tensile strength for areas that move often, even under stress.
It features a solid temperature range from 230 F to -40 F. Not as high or low as silicone but still useable in a wide variety of environments. Neoprene, as a rubber polymer, does well with compression but isn't as tough as other materials.
Neoprene ages well and won't crack or bleach under sunlight. It resists oils including grease and silicone oil. The tight pores of the polymer are excellent at resisting damage from gases such as refrigerants, carbon dioxide, and ammonia.
Neoprene has no specific weaknesses but also is middle of the road on many of its benefits.
Another synthetic rubber polymer offering a variety of resistances. The material is made from polyethylene and propylene with a crystallinity that gives it its elastic properties.
EPDM offers excellent resistance against oxygenation, weathering, ozone, and heat. EPDM also makes an excellent electrical insulator.
Its operation temperature range goes from 250 F to -40 F.
It doesn't do well with petroleum fluids or oils.
Given that Teflon is a brand name, you'll also see PTFE gaskets listed. PTFE (polytetrafluoroethylene) offers extreme resistance to corrosion as it offers a tight surface that restricts the ripping and tearing of bonds.
PTFE also provides incredible heat resistance ranging from 500 F down to -328 F. The material is non-flammable, and weathers exceptionally well.
The low coefficient of friction and lack of adhesivity can be useful or a pain depending on the need.
PTFE does have a perceived drawback when used in water transportation and food devices. Older productions of PTFE utilizes PFOA which released a toxic gas at high temperatures. Current PTFE manufacturing uses alternative chemicals to avoid this problem.
Like Teflon, Gore-Tex is a named brand ePTFE material. It has many of the same properties as PTFE but expands to provide better compression and expansion. Gore-TEx ePTFE is used in places where stability is key as it avoids intrusions and flaring.
It operates at the same temperature ranges.
The material is strong to corrosion and solvents.
The material's notable weakness is that it can't survive exposure to alkali metals and elemental fluorine.
Graphite is another strong, non-porous material that works well for gaskets. It provides excellent compression characteristics and transfer performance.
Graphite offers a strong temperature range of 950 F to -400 F. Graphite's lattice structure and density make it excellent for reducing danger from gasses and particulates.
Nuclear grade graphite is used to slow reactions in reactors. When made into gasket material it is combined with polymers and metal cores to provide flexibility and reduce brittleness.
Graphite can be interwoven with a large number of secondary materials to create the desired product. These include wire mesh, steel foil, tinplated carbon steel, and stainless steel foil.
Butyl rubber polymer combines isoprene and isobutylene.
Butyl rubber gaskets provide low moisture and gas permeability. They do well with aging, abrasion, weathering, and ozone.
The material operates well at temps between 248 F and -67 F. It's also an excellent electrical isolator.
Though good against hydraulic fluid, it is not recommended for contact with petroleum fluids.
Nitrile is the go-to for petroleum oils and gasoline. Other acids, bases, and especially aliphatic hydrocarbons are resisted.
Nitrile polymer has a lower temperature tolerance between 212 F and -40 F. The compression resistance is high to permanent compression but has low reformation properties.
Nitrile does poorly against weathering, ozone, and sunlight.
Natural rubber is both difficult to come by and of mild performance. Its best characteristic is its high tensile strength and tear resistance. It's hard to beat the water-resistance of natural rubber.
It operates between a scant 122 F and -67 F, so it can be handy for some lower temp conditions.
It ages and heats lest well than polymers and synthetic rubbers.
If you need a natural rubber feel with enhanced characteristics, SBR (Buna S) is the way to go.
It provides even better water resistance but still lacks in resistance to solvents and related chemicals. It ages better and performs at higher temps ranging from 158 F to -67 F.
In excessive heat, it hardens and becomes brittle.
A synthetic fiber material composed of elastomeric binders and fillers. This material creates high heat resistance and long-term sealability.
It offers a safe temperature range of 400 F to -40 F with an operation spike survivability of 700 F.
Compressed asbestos-free gaskets do well against water, hydrocarbons, and inert gases.
It makes a solid general-purpose material but only excels in temperature resistance in comparison to other materials.
A Thousand Uses
With so many gasket materials to chose from you can expect the best results with the right combination. The shapes, sizes, and combinations of materials that you require are all supported by Strouse.
We've worked with many companies over the years to deliver on difficult problems with precise specifications. Contact us with questions and let us create the gasket that you need.