What are the material requirements of the valve sealing surface?
Sealant, liquid sealant, anaerobic adhesive gasket, pipe connection, thread sealInorganic materials, flexible graphite, natural graphite gasket, soft packing, sealing partsCarbon graphite baking carbon, anodized graphite, mechanical seal, hard packing, power seal, gap sealEngineering ceramics, alumina ceramics, talc ceramics, cermets, silicon oxide and chromium borideMetal, nonferrous metal, copper, aluminium, lead, zinc, tin and its alloy gasket, soft packing, mechanical seal, labyrinth seal, hard packing and gap sealFerrous metal, carbon steel, cast iron, stainless steel, surfacing alloy, spraying powder gasket, hard packing, mechanical seal, piston ring, gap seal, dust-proof seal, full closed seal, forming fillerTungsten carbide, cobalt carbide, tungsten cobalt titanium carbide mechanical sealPrecious metals, gold, silver, indium, tantalum, high vacuum sealed, high pressure sealed, low temperature sealedThe performance of the sealing material is an important factor to ensure effective sealing, selection of sealing materials, sealing element is mainly based on the working environment, working medium such as temperature, pressure, use and movement etc.. The basic requirements for sealing materials are as follows:I have certain mechanical properties such as tensile strength, elongation, etc.;
Table 29.2-2 characteristics of commonly used sealing methodsCategory material useLiquid polymer material, liquid sealant, anaerobic adhesive and hot-melt sealantFiber, plant fiber, cotton, linen, paper, cork gasket, soft packing, dust-proof seals, cloth rubber sealsAnimal hair fiber, felt, leather gasket, soft packing, molding filler, oil seal, dust-proof sealFiber, mineral fiber, asbestos gasket, soft packingArtificial fibres, organic synthetic fibres, glass fibres, carbon fibres, ceramic fibres, soft packing, cloth, rubber sealsElastomer, rubber, synthetic rubber, natural rubber gasket, molding filler, oil seal, soft packing, dust-proof sealing parts, fully enclosed sealsFluorine plastic, plastic nylon, polyethylene, phenolic plastic, chlorinated polyether, polyphenylene sulfide, oil seal, gasket, packing filler, soft hard packing, piston ring, mechanical seal and dustproof seals, fully enclosed seal
Sealing materials should meet the requirements of sealing function. Due to the different sealing medium and different working conditions of the equipment, sealing materials are required to have different applicability. The sealing material requirements are: the material density, not easy leakage; the appropriate mechanical strength and hardness; and good elasticity, compression, permanent deformation is small; the high temperature softening, decomposition, low temperature, non hardening embrittlement; the good corrosion resistance in the long-term work of acid and alkali, oil medium, the volume of a small change in hardness, and adhesion to the metal surface; the low friction coefficient, good wear resistance; with the sealing surface with soft and full; the good anti-aging, durable; to facilitate manufacturing, price cheap, easy. Obviously, it is impossible for any material to meet the above requirements completely, but the material with excellent sealing performance can meet most of the above requirements.Rubber is the most commonly used sealing material, in addition to rubber, suitable for sealing materials as well as graphite band, PTFE and various sealants, etc. table 29.2-4 lists the classification and use of sealing materials.
