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          • Introduction to common materials of valve stem

            The commonly used stem materials are as follows:

             

             

            Carbon steel. Generally choose A5, 35 steel, after nitriding treatment, suitable for nominal pressure less than or equal to 2.5MPa of ammonia valve, water, steam and other medium low and medium pressure valve. A5 steel is suitable for valves with temperature not exceeding 300℃; 35 steel is suitable for valves with temperature not exceeding 450℃.

             

            Copper alloy. The brands are qa19-2 and hpb59-1-1. Suitable for valve with nominal pressure less than or equal to 1.6MPa and temperature less than or equal to 200℃.

             

            Stainless steel. Generally, 2Cr13, 3Cr13, 1Cr17Ni2, 1Cr18Ni12Mo2Ti and other materials are selected. 2Cr13, 3Cr13 stainless steel is suitable for nominal pressure less than or equal to 32MPa, temperature less than or equal to 450℃ of water, steam and mildly corrosive media, can be strengthened by chromium plating, high-frequency quenching and other methods. 1Cr17Ni2 stainless steel valve, low temperature valve, can resist corrosive medium. 1Cr18Ni9Ti and 1Cr18Ni12Mo2Ti stainless steel are used for high temperature valves with nominal pressure less than or equal to 6.4mpa and temperature less than or equal to 600℃, as well as stainless steel valves with temperature less than or equal to -100℃ and low temperature valves. 1Cr18Ni9Ti can withstand nitric acid and other corrosive media; 1Cr18Ni12Mo2Ti can resist acetic acid and other corrosive media. When 1Cr18Ni9Ti and 1Cr18Ni12Mo2Ti are used for high temperature valve, nitriding treatment can be adopted to improve anti-abrasion performance.

             

            Alloy steel. Generally choose 40Cr, 38CrMoA1A, 20CrMo1V1A and other materials. After chromium plating, 40Cr is suitable for water, steam, petroleum and other media with nominal pressure less than or equal to 32MPa and temperature less than or equal to 450℃. 38CrMoA1A can withstand 10MPa pressure at the working temperature of 540℃ after nitriding treatment, which is often used on power station valves. 20CrMo1V1A can withstand the pressure of 14MPa under the working temperature of 570℃ after nitriding treatment, which is often used on power station valves.

             

            Bearing chromium steel. GCr15 is selected for ultra-high pressure valve with nominal pressure less than or equal to 300MPa and temperature less than or equal to 300℃. For the production of stem materials, and 4Cr10Si2Mo martensitic heat resistant steel, 4Cr14Ni14W2Mo austenitic heat resistant steel. Stem nut and stem with thread, direct bearing stem axial force, and brand and support in the friction of the valve. Therefore, the stem nut in addition to a certain strength, also requires a small friction coefficient, not rust, not with the stem bite performance.

             

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