A gasket is a ring made of a material that can produce plastic deformation and has a certain strength. Most gaskets are cut from non-metallic plates, or made by professional factories with specified dimensions. The materials are asbestos rubber plates, asbestos plates, PTFE plates, polyethylene plates, etc .; thin metal plates (tinplate, Stainless steel) A metal-clad gasket made of asbestos and other non-metal materials; there is also a wound gasket made of a thin steel tape wound with asbestos tape. The most commonly used is a stainless steel tape and graphite wound. As for the metal wound gasket, asbestos can be used for the wound tape according to the different use environment. Ordinary rubber gaskets are suitable for applications where the temperature is lower than 120 ℃; asbestos rubber gaskets are suitable for applications where the water vapor temperature is lower than 450 ℃, the oil temperature is lower than 350 ℃, and the pressure is lower than 5MPa. Medium, the most commonly used is acid-resistant asbestos board. In high-pressure equipment and pipelines, lens type or other shape metal gaskets made of copper, aluminum, No. 10 steel, and stainless steel are used. The contact width between the high-pressure gasket and the sealing surface is very narrow (line contact), and the processing finish of the sealing surface and the gasket is high.
Low-pressure small diameter wire-connected flanges, high-pressure and low-pressure large diameters are welded flanges. The thickness of flange plates and the diameter and number of connecting bolts are different at different pressures.