1, copper alloyGenerally selected grades are QA19-2, HPb59-1-1. Applicable to the nominal pressure is less than 1.6MPa, the temperature is less than or equal to 200 degrees of low pressure valve.2 carbon steelGenerally used A5, 35 steel, after nitriding treatment, applicable to the nominal pressure of less than 2.5MPa ammonia valve, water, steam and other medium low, medium pressure valve. A5 steel is suitable for valves with temperatures not exceeding 300 degrees; steel 35 is applicable to temperatures not exceeding 450 degrees. (Note: the actual route proves that the valve stem is made of carbon steel and can not solve the corrosion problem well and should be avoided
5, bearing steelSelection of GCr15, applicable to the nominal pressure is less than 300MPa, the temperature is less than or equal to 300 degrees of ultra-high pressure valve.Used to make the stem more materials, as well as 4Cr10Si2Mo martensitic heat-resistant steel, 4Cr14Ni14W2Mo austenitic heat-resistant steel.The stem nut and the valve stem match with the screw thread, and directly bear the axial force of the valve stem, and the friction between the plate and the support valve. Therefore, the stem nut in addition to a certain strength, but also requires a small friction coefficient, not rust, and stem does not bite and other performance.
3, alloy steelGenerally choose 40Cr, 38CrMoA1A, 20CrMo1V1A and other materials. 40Cr after chrome treatment, apply to nominal pressure is less than 32MPa, temperature less than 450 degrees of water, steam, oil and other media. 38CrMoA1A after nitriding treatment, can work temperature of 540 degrees under the pressure of 10MPa, often used in power plant valve. 20CrMo1V1A after nitriding treatment, can work at 570 degrees temperature under the pressure of 14MPa, often used in power plants valve.4,Generally choose 2Cr13, 3Cr13, 1Cr17Ni2, 1Cr18Ni12Mo2Ti and other materials. 2Cr13, 3Cr13 stainless steel for nominal pressure less than 32MPa, the temperature is less than or equal to 450 degrees of water, steam and weak corrosive medium, can be chromium plating, high frequency hardening and other methods to strengthen the surface. 1Cr17Ni2 stainless steel valves and cryogenic valves are resistant to corrosive media. 1Cr18Ni9Ti, 1Cr18Ni12Mo2Ti stainless acid resistant steel for nominal pressure less than 6.4MPa, temperature is less than or equal to 600 degrees of high temperature valve, can also be used for temperature less than -100 degrees of stainless steel valve, low temperature valve. 1Cr18Ni9Ti can resist corrosive medium such as nitric acid; 1Cr18Ni12Mo2Ti can resist corrosive medium such as acetic acid. When 1Cr18Ni9Ti and 1Cr18Ni12Mo2Ti are used in high temperature valves, nitriding treatment can be adopted to improve the scratch resistance.
