A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. It is a deformable material that is used to create a static seal and maintain that seal under various operating conditions in a mechanical assembly. <Reference from Wikipedia>
Functions of Gaskets:
Sealing: The primary function of gaskets is to create a tight seal between joined components and prevent leakage of fluids(gases or liquids), even at extreme temperatures and pressures.
Compensation for Surface Irregularities: Gaskets compensate for imperfections or irregularities in mating surfaces, ensuring a uniform distribution of pressure for an effective seal.
Vibration Dampening: Gaskets can dampen vibrations and absorb shocks, reducing the risk of damage to equipment or machinery.
Safety Components: Gaskets are crucial safety components, designed to be the weakest link so they fail first in case of excessive pressure buildup, preventing catastrophic failures.
They allow for disassembly and maintenance by enabling the separation and reassembly of sealed surfaces.
Common Materials of Gasket
Gaskets are mechanical seals used in fluid processing and handling equipment to prevent leakage of process fluids and entry of contaminants. Here are some common gasket materials and their key properties:
Rubber Materials
Neoprene (Chloroprene): Resistant to acids, alkalis, oils, ozone, sunlight, and weathering. Good resistance to flexing and twisting. Temperature range: -40°F to 230°F (intermittent up to 250°F).
Nitrile (Buna-N, NBR): Excellent resistance to oils, fuels, hydraulic fluids, and petroleum-based compounds. Good gas and water impermeability. Temperature range: -40°F to 212°F.
EPDM (Ethylene Propylene Diene Monomer): Resistant to acids, alkalis, aging, heat, ozone, steam, and water. Suitable for outdoor environments. Temperature range: -40°F to 250°F (intermittent up to 275°F).
Silicone Rubber: Excellent high and low-temperature properties, resisting temperatures from -75°F to 500°F. Resistant to aging, oxygen, ozone, UV light, and weathering.
Viton® (Fluorocarbon): Outstanding resistance to high temperatures, chemicals, and solvents. Good tensile strength and low compression set. Temperature range: -20°F to 450°F.
Other Materials
Fiber Gaskets: Made from compressed fibers like aramid, carbon, or cellulose. Good for high temperatures and chemical resistance.
PTFE (Polytetrafluoroethylene): Excellent chemical resistance, low friction, and high temperature tolerance up to 500°F. Often filled with silica, barium sulfate, or glass microspheres.
Graphite: Suitable for high temperatures up to 1000°F and resistant to most chemicals except strong oxidizers.
Mica: Good for high temperatures and pressures, resistant to chemicals and corrosion
Key Selection Considerations for Gasket Materials
Temperature Range: Consider the temperature range of the application, including both operating and intermittent temperatures. Choose a gasket material that can withstand the temperature extremes without losing its sealing properties or deforming.
Chemical Compatibility: The gasket material must be chemically resistant to the fluids or gases it will be in contact with, such as acids, alkalis, oils, solvents, and other chemicals.
Pressure Range: Different gasket materials can withstand varying pressure levels. Metallic gaskets are suitable for high-pressure applications, while non-metallic gaskets like rubber are better for low to medium pressures. Ensure that the selected material can handle the pressure without extrusion or blowout, which can lead to leakage.
Environmental Factors: Consider the specific application environment such as exposure to UV radiation, ozone, weathering, and other environmental conditions, especially for outdoor applications. Materials like EPDM and neoprene exhibit good weather and ozone resistance.
Compressibility and Resilience: Assess the compressibility and resilience of the gasket material. The material should be able to conform to mating surfaces under compression to create a tight seal. Additionally, it should have the resilience to maintain its sealing properties over time and under varying pressures.
Industry Standards and Regulations: Certain industries like food and beverage or pharmaceutical may require gaskets made from FDA-compliant materials like EPDM or silicone.
Cost and Application Requirements: While performance is important, cost and application-specific requirements like ease of installation, reusability, and maintenance should also be evaluated.
Conclusion
In one word, the gasket is a deformable seal that fills the gaps between mating surfaces, creating a tight barrier to prevent leakage while also enabling maintenance access and acting as a safety release in overpressure situations. The gasket materials are various, and each material has its own set of advantages, making them suitable for various applications depending on factors such as temperature, pressure, fluid type, and environmental conditions.
By considering these key factors, along with consulting experienced gasket manufacturers, the optimal gasket material can be selected to ensure reliable sealing, extended service life, and compliance with industry standards.
