tiivîteitä

Tiivisteet, commonly known as gaskets, are seals that fill gaps between mating surfaces to prevent leakage of liquids or gases. They compensate for surface roughness, misalignment, and thermal expansion, making them essential in piping, engines, and many types of equipment.

Gasket types include static gaskets, which seal fixed joints such as flanged connections, and dynamic seals, used in moving assemblies. Static gaskets are often flat rings cut from sheet materials such as elastomer, graphite, PTFE, or metal. O-rings are circular cross‑section seals placed in grooves, while metallic gaskets such as spiral-wound or corrugated metal provide strength at high pressure. Dynamic seals include lip seals and mechanical seals for rotating shafts.

Materials are chosen for chemical compatibility, temperature, and pressure. Common classes are elastomers (NBR, EPDM, silicone, FKM), PTFE, graphite, and metals. Temperature and chemical exposure determine the best material; for example, FKM resists oils and high temperatures, while EPDM offers good resistance to water and polar substances.

Selection and design consider operating pressure and temperature, the fluid being sealed, flange standards and dimensions, surface finish (roughness), gasket thickness, and the required compression. Proper installation is essential to prevent leaks, including cleaning faces, correct orientation, and applying manufacturer-recommended bolt load.

Maintenance and failure prevention include routine inspection, timely replacement, and avoiding reusing gaskets. Typical failure modes are chemical attack, aging and compression-set, extrusion at high pressure, and improper installation.

Standards and testing rely on national and international bodies. Common references include ISO and ASME standards for gasket materials and performance, and leak-testing methods to verify integrity.