(I) Common Materials for Valve Body 1. Carbon Steel (WCB, ZG230-450) Application: Suitable for non-corrosive/weakly corrosive, medium-temperature and high-pressure working conditions such as water, air, steam, with low cost. 2. Stainless Steel 304: General-purpose type, resistant to medium corrosion, suitable for dilute acids, alkalis, and organic acids. 316/316L: Contains molybdenum, resistant to chloride ions, seawater, sulfuric acid, commonly used in chemical and pharmaceutical industries. Duplex Stainless Steel (2205/2507): Resistant to chloride ion stress corrosion, ideal for seawater and high-salt working conditions. 3. High Temperature Alloy Steel (Cr-Mo Steel, 12Cr1MoV) Application: Suitable for high temperature (>450℃), high-pressure steam, and petroleum refining. 4. Special Alloys Hastelloy (C-276): Resistant to strong corrosion (wet chlorine, mixed acid, high-temperature strong acid). Monel Alloy: Resistant to hydrofluoric acid, lye, and seawater. Titanium / Tantalum: Super corrosion resistance, suitable for extreme corrosion such as aqua regia and concentrated hydrochloric acid. 5. Non-Metallic Lining PTFE (Teflon), PFA, FEP: Lined for strong corrosive media (concentrated acid, strong alkali), temperature resistance ≤180℃. Rubber (EPDM, Butyl): For weak acid and weak alkali, slurry, with low cost. (II) Materials for Internal Parts (Valve Core / Valve Seat) Commonly used: 17-4PH, 316, 440C stainless steel, with surface hardfacing of Stellite hard alloy (wear-resistant, erosion-resistant). Strong corrosion working conditions: Hastelloy, titanium alloy, PTFE-lined.