When something works well, you likely won’t even notice. In the manufacturing world, well-running machines result from precise engineering with the right components to make for a smooth, dependable, and quiet experience. When it comes time to build those machines and consider such parts as an industrial gasket, it’s vital to ensure the right pieces are in the right spots and made to tight tolerances for the most accurate fit.
In your search for the right gasket material, you’ll find an abundance of options. What is gasket material, and what material will you need? Before you engineer your next flexible material, read our overview of gasket materials to see what might work best.
At its core, a gasket is meant to prevent matter from passing from one place to another, be it a liquid, gas, or energy discharge. Whether you need something to last a long time, resist heat and pressure, or avoid conducting electromagnetic resonance, a gasket exists to meet that need. While the purpose of any gasket is to maintain a seal between two elements, a variety of shapes and types of gaskets are employed depending on the situation.
Common Types of Gaskets
Simple joints, like those found in pipes, use pipe gaskets. These are circular and usually require a higher tolerance for compression. A pipe gasket also needs to resist corrosion and extreme temperatures to maintain its shape over time.
A combination of metallic, non-metallic, and composite materials is used to ensure that each joint remains sealed. As versatile as they are, pipe gaskets aren't a one-solution-fits-all endeavor, so you’ll still need to ensure the measurements and materials are appropriate.
The most employable of gaskets is the jacketed type. Jacketed 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 on both sides. A product is referred to as “double-jacketed” when both sides are wrapped around a softer core. Double-jacketed gaskets provide better corrosion resistance over single-jacketed gaskets, as there is less possibility of material seeping into the core.
Another type of jacketed gasket is the corrugated jacketed gasket, which interweaves materials in layers, making for specialized combinations of flexibility and durability.
Spiral Wound Gaskets
Like a jacketed gasket, spiral wound gaskets seek to combine the best of both worlds. These use a combination of metals and plastics (or rubber) wound around layers of metal.
The resulting gasket yields acute physical resistance to stress and high heat. 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 metal core is covered in a sealing material on both sides with this type of gasket.
The kammprofile gasket uses physic stress to focus tension onto the surface sealant to form a seal. This process leverages the different core materials to the sealing material to effectively reduce stress and transfer heat without further deformation.
Solid gaskets are metal gaskets that are inexpensive and easy to use. They are used in high-thermal and high-pressure situations and require immense compression force to form a seal properly.
Solid gaskets are most commonly used between two other dense surfaces that are harder than the gasket material, and the majority of solid gaskets are formed from metals.
Other Gasket Materials
The material used to create a gasket aids in the final function. Some gaskets offer a higher level of resilience to a particularly damaging agent or force. Others provide durability and flexibility to create a tight seal and keep operations running for a long time.
It's important to remember that there are enough combinations of types and materials for gaskets that not everything has been tried. If you’re facing a novel engineering problem, it will require a novel solution, which could even mean a custom gasket that isn’t commonly used.
Take a look at the following gasket materials, which can further assist your manufacturing project development.
Gasketing Tape and Adhesive
Not all gaskets fit into a contained system. Doors and windows need to retain tight seals when closed while allowing people to open them freely. Threads and other locking components need help to reinforce mechanical seals and reduce friction that creates unconformities.
Gasketing tape or pressure-sensitive tape made from a various polymers and metals can be applied in these situations. The material expands to create a seal and deforms to allow the seal to break with mechanical motion. The result: a reduction in noise and the containment of fluids, gases, and heat while remaining flexible through weathering and impact.
On the other hand, 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, particularly irregular shapes or covering large surface areas. In some cases, foam is used 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.
Spraying is another form of gasket foam application. This puts the maximum amount of material into a gap between two other materials. Foam gaskets applied this way do well for projects requiring noise and impact reduction. The seals made are less tight than those created by other gasket 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 provide extra seals on vents. These gaskets can slow refrigerant and gas leaks, though not prevent them altogether. Fluids are also slowed down but may not be blocked entirely.
Though foam may lack some durability, that’s made up for by the ease of reapplication. Foam gaskets work well in conditions where other components need frequent repair or replacement.
Silicone materials are created from silica sands and can be used at a wide temperature range, from 400˚ F all the way down to -67˚ F.
Silicone gaskets withstand aging and weathering well. The high elasticity of silicone makes it great for troublesome angles. That said, if you need a seal against solvents, fuels, or silicone-based fluids, then silicone seals won’t cut it. Each of these materials quickly degrades a silicone gasket.
Neoprene is a synthetic polymer rubber. It provides high tensile strength for areas that often move, even under stress, as a gasket material.
Neoprene gasketing works in a temperature range of 230˚ F to -40˚ F. While not as high or low as silicone, it is still usable in a wide variety of environments. Neoprene does well with compression as a rubber polymer but isn't as tough as some 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. While there may not be particular weaknesses to pinpoint, neoprene stands as a middle-of-the-road option for many of its benefits.
Ethylene propylene diene monomer, or EPDM, is 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./p>
EPDM offers excellent resistance against oxygenation, weathering, ozone, and heat, and it makes an excellent electrical insulator. Its operational temperature range goes from 250˚ F to -40˚ F, but it doesn't do well with petroleum fluids or oils, which is something you’ll need to keep in mind.
Teflon (PTFE) Gasketing
Teflon is technically a brand name, but it’s a common shorthand for polytetrafluoroethylene, or PTFE. PTFE provides extreme resistance to corrosion as it offers a tight surface that restricts the ripping and tearing of bonds.
PTFE also provides remarkable temperature 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 may be helpful or may be an obstacle depending on how you’ll need it.
PTFE does have a perceived drawback when used in water transportation and food devices. Older production runs of PTFE utilize PFOA (perfluorooctanoic acid), which releases a toxic gas at high temperatures. Current PTFE manufacturing, however, uses alternative chemicals to avoid this problem.
Like Teflon, Gore-Tex is a name-brand ePTFE (expanded polytetrafluoroethylene) material. It has many of the same properties as PTFE but expands to provide better flexibility. Gore-Tex ePTFE is used in places where stability is critical since it avoids intrusions and flaring.
This gasketing material operates at the same temperature ranges as standard PTFE—500˚ F to -328˚ F—and it’s strong against corrosion and solvents. You’ll want to consider this material's notable weakness, which is its trouble with exposure to alkali metals and elemental fluorine.
Graphite is another robust and non-porous material that works well for gaskets. It provides excellent compression characteristics and transfer performance, and it offers a substantial temperature range of 950˚ F to -400˚ F. Its lattice structure and density make it ideal 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, tin-plated carbon steel, and stainless steel foil.
Butyl rubber polymer combines isoprene and isobutylene. Butyl rubber gaskets provide low moisture and gas permeability and do well against aging, abrasion, weathering, and ozone.
The material operates well at temperatures between 248˚ F and -67˚ F and is an excellent electrical isolator. While it works well 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 than many options, ranging between 212˚ F and -40˚ F.
Nitrile offers high compression resistance against permanent compression, but it has low reformation properties and 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. Plus, it's hard to beat the water resistance it provides.
Natural rubber operates between 122˚ F and -67˚ F, which can be helpful in some moderate or lower temperature conditions. While it offers certain benefits, it generally doesn’t age or heat as well as polymers and synthetic rubbers.
If you need a natural rubber feel with enhanced characteristics, styrene-butadiene rubber (SBR, or Buna S) is the way to go. SBR provides better water resistance but still lacks resistance to solvents and related chemicals. It tends to age well and perform at higher temperatures ranging from 158˚ F to -67˚ F. In excessive heat, however, it can harden and become brittle.
Compressed Asbestos-Free Gasketing
Compressed asbestos-free material is a synthetic fiber composed of elastomeric binders and fillers. This material creates high heat resistance and long-term sealability and has 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 and make a solid general-purpose material. However, they only excel in temperature resistance in comparison to other materials.
The Importance of the Right Gasket Material and Tight Tolerances
How can you use all these different gasket materials? The possibilities are too numerous to count. With so many gasket materials to choose from, you can expect the best results and cost-effectiveness with the right combination your projects need.
Precision is critical in selecting the right gasketing applications and materials. Each type of gasket has its unique set of specifications, and it’s vital to use the right one and have the correct measurements in place. You want the kind of seal that works so well you won’t even notice it.
To help you consider the importance of some of these factors, we’ve developed a guide to the hidden costs of tight tolerances, which you can reference as you develop your projects. Click the link below for your copy, or give Strouse a call at (800)-410-8273.