Full definition
A flat sealing element die-cut, waterjet-cut, or stamped from elastomer sheet and compressed between two mating flanges or surfaces to create a static (non-moving) seal against fluids or gases. The gasket material must be chemically compatible with the sealed medium, withstand the operating temperature and pressure, and have adequate compression set resistance for sustained sealing force. Selection criteria: (1) chemical compatibility (consult compatibility charts for elastomer vs fluid), (2) temperature range, (3) pressure (determines minimum bolt load and gasket stress), (4) surface finish of flanges. Common materials: NR/SBR (water, air — economical), NBR (oil, fuel), EPDM (water, steam, chemicals), neoprene CR (moderate oil + weather), silicone (high temperature, food), and FKM (aggressive chemicals). Thicknesses: 1.5-6 mm standard. Bolt torque must achieve minimum gasket seating stress without exceeding maximum compressive stress. For ASME flanges, compressed fiber and spiral-wound gaskets are more common; rubber gaskets dominate in low-pressure applications (<10 bar) and custom equipment. Per ASME B16.21 for non-metallic gasket dimensions.