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This post was last edited by yinkuilin6868 on 2015-11-17 at 14:59. Non-metallic materials: 1. Polytetrafluoroethylene, code F. Polytetrafluoroethylene is commonly used in stop valves, gate valves, ball valves, etc., in applications where the temperature is t≤232°C and the nominal pressure is PN≤6.4MPa. 2 Synthetic rubber, code X. The comprehensive properties of synthetic rubber, such as oil resistance, temperature resistance, and corrosion resistance, are superior to those of natural rubber. Generally, the operating temperature for synthetic rubber is t≤150°C, while for natural rubber it is t≤60°C. Rubber is used for sealing valves such as globe valves, gate valves, diaphragm valves, butterfly valves, check valves, and clamp valves with a nominal pressure of PN≤1MPa. 3 Nylon, code N. Nylon features a low coefficient of friction and good corrosion resistance. Nylon is mostly used in ball valves, globe valves, etc. for temperatures t≤90°C and nominal pressures PN≤32MPa. Metals: 4 Babbitt alloys, code B. Babbitt alloys are used in ammonia stop valves operating at temperatures of -70 to 150°C and with a nominal pressure of PN ≤ 2.5 MPa. 5-chromium stainless steel, code H. Common grades of chromium stainless steel include 2Cr13 and 3Cr13; after quenching and tempering, they exhibit good corrosion resistance. It is commonly used on valves for media such as water, steam, and oil at temperatures of t≤450°C and nominal pressures of PN≤32MPa. 6 chromium-nickel-titanium stainless steel, code R. The common grade of chromium-nickel-titanium stainless steel is 1Cr18Ni9Ti; it possesses good corrosion resistance, erosion resistance, and heat resistance. Suitable for use in media such as steam and *ao acid at temperatures of t≤600℃ and nominal pressures of PN≤6.4MPa, for use in stop valves, ball valves, etc. 7 Copper alloy, code T. Common copper alloy materials include 6-6-3 tin bronze and 58-2-2 manganese brass, etc. Copper alloys have good wear resistance and are suitable for use in water and steam at temperatures of t≤200°C and nominal pressures of PN≤1.6MPa. They are commonly used in gate valves, globe valves, check valves, plug valves, etc.