Diaphragm valve parts materials: Diaphragm valve parts materials, including a variety of different grades of ferrous and non-ferrous metals and their alloys, all kinds of non-metallic materials. Diaphragm valve parts manufacturing materials to be selected according to the following factors: 1, the use of mining conditions (working medium pressure, temperature and characteristics). 2, the force of the parts and the role in the diaphragm valve structure. 3, a better technology. 4, to meet the above conditions, to have a lower cost. Body, bonnet, and disc (disc) Materials: The body, bonnet, and disc are one of the main components of diaphragm valves that directly withstand media pressure. Materials used must comply with "Diaphragm Pressure and Temperature Ratings" Provisions. Commonly used materials are the following: 1, gray cast iron: gray cast iron for nominal pressure PN ≤ 1.0MPa, the temperature of -10 ℃ ~ 200 ℃ water, steam, air, gas and oil media. Gray cast iron commonly used brands: HT200, HT250, HT300, HT350. 2, malleable iron: for nominal pressure PN ≤ 2.5MPa, the temperature of -30 ~ 300 ℃ water, steam, air and oil media, commonly used brands are: KTH300-06, KTH330-08, KTH350-10. 3, ductile iron: for PN ≤ 4.0MPa, the temperature of -30 ~ 350 ℃ water, steam, air and oil media. Common brands are: QT400-15, QT450-10, QT500-7. In view of the current domestic technological level, the factory is uneven, the user often is not easy to test. According to experience, it is recommended PN ≤ 2.5MPa, diaphragm valve or the use of steel diaphragm valve for safety. 4, acid-resistant high-silicon ductile iron: for nominal pressure PN ≤ 0.25MPa, the temperature below 120 ℃ corrosive media. 5, carbon steel: for nominal pressure PN ≤ 32.0MPa, temperature -30 ~ 425 ℃ water, steam, air, hydrogen, ammonia, nitrogen and petroleum products and other media. Common brands WC1, WCB, ZG25 and high-quality steel 20, 25, 30 and low alloy steel 16Mn. 6, Copper alloy: Suitable for media such as water, seawater, oxygen, air and oil with PN≤2.5MPa and steam medium with temperature of -40 ~ 250 ℃. Commonly used brands are ZGnSn10Zn2 (tin bronze), H62, Hpb59-1 (Brass), QAZ19-2, QA19-4 (aluminum bronze). 7, high temperature steel: for nominal pressure PN ≤ 17.0MPA, temperature ≤ 570 ℃ steam and petroleum products. Common brands are ZGCr5Mo, 1Cr5M0. ZG20CrMoV, ZG15Gr1Mo1V, 12CrMoV, WC6, WC9 and other brands. The specific choice must be in accordance with the diaphragm pressure and temperature specifications. 8, low temperature steel, suitable for nominal pressure PN ≤ 6.4Mpa, temperature ≥ -196 ℃ ethylene, propylene, liquid natural gas, liquid nitrogen and other media, commonly used brands) ZG1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Ti, ZG0Cr18Ni9. 9, stainless steel, suitable for nominal pressure PN ≤ 6.4Mpa, temperature ≤ 200 ℃ nitric acid, acetic acid and other media, commonly used brands ZG0Cr18Ni9Ti, ZG0Cr18Ni10, ZG0Cr18Ni12Mo2Ti, ZG1Cr18Ni12Mo2Ti. Diaphragm valve sealing surface Material: Sealing surface is the most critical face of the diaphragm valve, the quality of the sealing surface is related to the life of the diaphragm valve, the sealing surface material to be considered corrosion resistance, scratch resistance, erosion resistance, resistance Oxidation and other factors. Generally divided into two categories: (a) soft materials 1, rubber (including NBR, fluorine rubber, etc.) 2, plastic (PTFE, nylon, etc.) Low pressure diaphragm valve) 2, chrome stainless steel (for ordinary high pressure diaphragm valve) 3, Stellite alloy (for high temperature and high pressure diaphragm valve and strong corrosion diaphragm valve) 4, nickel-based alloys (for corrosive media)
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