What material are gaskets made of?
Gaskets are made from a broad range of materials, including elastomeric rubbers, PTFE, graphite, and metals, chosen for chemical compatibility, temperature, and pressure.
Gasket material selection hinges on the sealing environment: the fluid or gas being sealed, operating temperature and pressure, chemical exposure, and the flange design. This article surveys the main material families used in gasket manufacture and how they are applied across industries.
Elastomeric gasket materials
Elastomeric gaskets are widely used for their ability to deform and recover under compression, providing reliable seals in many applications. Common elastomeric materials include:
- Nitrile rubber (NBR) — good oil resistance; widely used in automotive and hydraulic systems.
- Ethylene propylene diene monomer (EPDM) — excellent resistance to water, steam, and weathering; popular in HVAC and potable water systems.
- Fluorocarbon elastomers (FKM, e.g., Viton) — excellent chemical resistance and high-temperature stability;
- Silicone (VMQ) — broad temperature range; good for high/low temps but more limited chemical resistance.
- Neoprene (CR) — balanced temperature and chemical resistance; versatile for general sealing.
- Fluorosilicone (FVMQ) — combines silicone flexibility with fluorinated chemical resistance; used in fuel or solvent exposure.
Elastomeric gaskets cover a wide range of applications, but their chemical compatibility and temperature exposure are critical limits; verify suitability for the specific service to prevent swelling or degradation.
Non-elastomeric polymer and filler gasket materials
Non-elastomeric polymer gaskets and fillers provide higher temperature and chemical stability in some services and are chosen when elastomers would fail. Typical materials include:
- PTFE (polytetrafluoroethylene) — chemically inert and broad compatibility; limited resilience and cold flow under load.
- Expanded PTFE (ePTFE) — improved conformability and sealing under compression; often used for critical chemical processes.
- Graphite — flexible graphite sheets or fillers; excellent high-temperature and chemical resistance; common in high-pressure, high-temperature service when used with appropriate gaskets.
- Non-asbestos reinforced sheet materials — aramid/mineral fiber composites bound with elastomers or thermosets; used as a safer replacement for asbestos-containing sheets.
- Mineral or ceramic-filled composites — for specialized high-temperature or abrasive environments.
Non-elastomeric materials provide strong chemical resistance and heat tolerance, but they can be less forgiving in terms of conformability and may require careful flange preparation and seating design.
Metallic and composite gaskets
Metallic and composite gaskets deliver peak performance in extreme temperatures and pressures, and are widely used in critical industrial systems. Typical types include:
- Spiral wound gaskets — metal windings (usually stainless steel) with a soft filler such as graphite or PTFE; excellent for high pressure/temperature service and many chemical applications.
- Full-face metal gaskets — solid metal sheets used in specialized flange connections; rely on a soft seal at the interface.
- Corrugated metal gaskets — cam-profile or other corrugation to enhance sealing characteristics; used in heat exchangers and harsh environments.
- Ring joint (RJ) gaskets — hard metal rings (RJ, RX styles) used with RTJ flanges in oil, gas, and refinery service; designed for metal-to-metal seals at extreme conditions.
Metallic and composite gaskets excel under extreme pressures and temperatures, but their installation requires precise flange preparation and correct material pairing to prevent galling, creep, or leaks.
Regulatory context and safety considerations
Historically, asbestos-containing gaskets were common, but they pose serious health risks. Modern standards and regulations in many regions require non-asbestos materials for new equipment, and existing installations are often retrofitted or replaced to meet safety guidelines.
Non-asbestos alternatives, including aramid fiber-based, mineral fiber, and elastomer-reinforced composites, are now standard options. When ordering gaskets, specify non-asbestos materials and verify compatibility with the service fluids, temperatures, and pressures.
Non-asbestos alternatives
Non-asbestos gasket products rely on combinations of aramid fibers (such as Nomex), mineral fibers, cellulose, and elastomer binders to replicate sealing performance while meeting health and safety requirements.
In all cases, material selection should align with chemical compatibility, temperature and pressure limits, and the flange design to ensure a reliable, long-lasting seal.
Summary
Gasket material choice hinges on the sealing environment: elastomeric, non-elastomeric polymer and filler, and metallic/composite options cover most applications. Elastomers offer flexibility and resilience for many fluids; PTFE and graphite provide chemical and temperature resilience; metallic gaskets deliver maximum performance under extreme conditions, often with specialized flange designs. Increasingly, non-asbestos composites are used to meet safety regulations while delivering reliable seals. The best choice balances seal integrity, durability, process conditions, and safety compliance.
Do gaskets still contain asbestos?
Asbestos Rope Gaskets
Rope gaskets were convenient for sealing the doors of boilers, furnaces, and ovens. Asbestos rope gaskets are still used today but are made with fiberglass instead of asbestos. Some common characteristics of Asbestos rope gaskets include; Material: Soft, woven asbestos fibers.
What gasket material is FDA approved?
FDA-compliant gasket materials include silicone, PTFE, EPDM, Buna-N (Nitrile), and Neoprene, among others, which are used in food, beverage, and pharmaceutical applications. These materials must be manufactured from FDA-listed ingredients and meet specific composition and extraction test requirements. The FDA does not approve specific gasket products, but manufacturers can produce compliant gaskets using FDA-approved materials and processes.
Common FDA-approved gasket materials
- Silicone: Flexible, odorless, and resistant to a wide range of temperatures, making it ideal for food packaging and processing equipment.
- PTFE (Polytetrafluoroethylene): A chemically inert material that is resistant to aggressive chemicals and comes in both virgin and filled forms. Some filled PTFE gaskets are specifically designed for FDA applications.
- EPDM (Ethylene Propylene Diene Monomer): A durable and flexible rubber that is suitable for food and beverage, and dairy applications. It is resistant to oils and can be used in a wide temperature range.
- Buna-N (Nitrile): A rubber material that is resistant to oils and has good chemical resistance. It is suitable for food processing applications.
- Neoprene: A durable, off-white rubber known for preventing breakdown from exposure to various foods and oils, making it popular in the food and beverage industry.
Key compliance factors
- Composition: The material must be made from ingredients listed in the FDA's regulations (21 CFR).
- Extraction testing: The material must pass specific tests that measure the amount of substance that can be extracted from it.
- Manufacturing practices: The gaskets must be produced under good manufacturing practices and maintain documented traceability.
What material is used for gaskets?
Gaskets are normally made from a flat material, a sheet such as paper, rubber, silicone, metal, cork, felt, neoprene, nitrile rubber, fiberglass, polytetrafluoroethylene (otherwise known as PTFE or Teflon) or a plastic polymer (such as polychlorotrifluoroethylene).
Is a gasket a rubber seal?
A gasket, also known as an O-ring or washer, seals the gap between two surfaces. These items are usually made of rubber and are available in different sizes and shapes depending on their purpose.
