The choice of gasket material mainly depends on the following three factors

The choice of gasket material mainly depends on the following three factors: temperature pressure medium

I Metal gasket material

1. Carbon steel: the recommended maximum working temperature shall not exceed 538 ℃, especially when the medium is oxidizing. High quality thin carbon steel plate is also not suitable for equipment manufacturing inorganic acid, neutral or acid salt solution. If carbon steel is subject to the stress of, the equipment accident rate under hot water working condition is very high. Carbon steel gaskets are usually used for high concentrations of acid and many alkaline solutions. The Brinell hardness is about 120.

2. 304 stainless steel 18-8 (chromium 18-20%, nickel 8-10%), the recommended maximum working temperature shall not exceed 760 ℃. In the temperature range of - 196~538 ℃, stress corrosion and grain boundary corrosion are easy to occur. Brinell hardness 160.

3.304L stainless steel carbon content shall not exceed 0. 03%。 The maximum recommended operating temperature shall not exceed 760 ℃. Corrosion resistance is similar to 304 stainless steel. The low carbon content reduces the precipitation of carbon from the lattice, and the grain boundary corrosion resistance is higher than 304 stainless steel. The Brinell hardness is about 140.

4. 316 stainless steel 18-12 (18% chromium, 12% nickel), increase about 2% molybdenum in 304 stainless steel, and its strength and corrosion resistance will be improved when the temperature increases. When the temperature increases, it has higher creep resistance than other ordinary stainless steels. The maximum recommended operating temperature shall not exceed 760 ℃. The Brinell hardness is about 160.

5. The maximum continuous working temperature of 316L stainless steel shall not exceed 760 ℃~815 ℃. The carbon content shall not exceed that of 316 stainless steel, which has better stress resistance and grain boundary corrosion resistance. The Brinell hardness is about 140.

6.20 Alloy 45% iron, 24% nickel, 20% chromium and a small amount of molybdenum and copper. The maximum recommended operating temperature shall not exceed 760 ℃~815 ℃. It is especially suitable for manufacturing equipment resistant to sulfuric acid corrosion. The Brinell hardness is about 160.

7. Aluminum (the content shall not be less than 99%). Aluminum has excellent corrosion resistance and processing performance, suitable for manufacturing double clip gaskets. The Brinell hardness is about 35. The recommended maximum continuous operating temperature shall not exceed 426 ℃.

8. The composition of red copper is close to that of pure copper, which contains trace silver to increase its continuous working temperature. The recommended maximum continuous operating temperature shall not exceed 260 ℃. The Brinell hardness is about 80.

9. Brass (66% copper and 34% zinc) has good corrosion resistance under most working conditions, but is not suitable for acetic acid, ammonia, salt and acetylene. The recommended maximum continuous operating temperature shall not exceed 260 ℃. The Brinell hardness is about 58.

10. Hastelloy B-2 (26-30% molybdenum, 62% nickel and 4-6% iron). The maximum recommended operating temperature shall not exceed 1093 ℃. It has excellent corrosion resistance to heat resistant hydrochloric acid. It also has excellent corrosion resistance to wet hydrogen chloride gas, sulfuric acid, phosphoric acid and reducing salt solution. It has high strength at high temperature. Brinell hardness is about 230.

11. Hastelloy C-276 16-18% molybdenum, 13-17.5% chromium, 3.7-5.3% tungsten, 4.5-7% iron, and the rest are nickel). The maximum recommended operating temperature shall not exceed 1093 ℃. It has excellent corrosion resistance. It has excellent corrosion resistance to cold nitric acid or boiling nitric acid with concentration up to 70%, good corrosion resistance to hydrochloric acid and sulfuric acid, and excellent stress corrosion resistance. The Brinell hardness is about 210.

12. Inconel 600 nickel base alloy (77% nickel, 15% chromium and 7% iron). The maximum recommended operating temperature shall not exceed 1093 ℃. It has high strength under high temperature conditions and is usually used for equipment that needs to solve stress corrosion problems. Under low temperature conditions, it has excellent processing properties. The Brinell hardness is about 150.

13. Monel 400 (copper 30%, nickel) is recommended to have a maximum continuous working temperature of no more than 815 ℃. Except for strong oxidizing acids, it has excellent corrosion resistance to most acids and alkalis. It is easy to produce stress corrosion cracks in fluoric acid, mercuric chloride, and mercury media, so it is not suitable for the above media. It is widely used in equipment manufacturing hydrofluoric acid. The Brinell hardness is about 120.

14. Titanium

The maximum recommended operating temperature shall not exceed 1093 ℃. It has excellent corrosion resistance under high temperature. It is well known that it is resistant to chloride ion corrosion and has excellent nitric acid corrosion resistance in a wide range of temperatures and concentrations. Titanium materials are rarely used in most alkaline solutions and are suitable for oxidation conditions. The Brinell hardness is about 216.

2、 Non metallic gasket materials

1. Natural rubber NR has good corrosion resistance to weak acid and alkali, salt and chloride solutions, but poor corrosion resistance to oil and solvent. It is not recommended for ozone media. The recommended working temperature is - 57 ℃~93 ℃.

2. Neoprene rubber CR Neoprene rubber is a synthetic rubber, which is suitable for resisting the corrosion of medium corrosive acid, alkali and salt solutions. Good corrosion resistance to commercial oils and fuels. However, the corrosion resistance of strong oxidizing acids, aromatic hydrocarbons and chlorinated hydrocarbons is poor. The recommended working temperature is - 51 ℃~121 ℃.

3. Cyanobutadiene rubber NBR Cyanobutadiene rubber is a kind of synthetic rubber, which is suitable for having good corrosion resistance to oil, solvent, aromatic hydrocarbon, alkaline hydrocarbon, oil and natural gas in a wide temperature range. It has good corrosion resistance to hydroxide, salt and near neutral acid. However, the corrosion resistance of strong oxidizing medium, chlorinated hydrocarbons, ketones and lipids is poor, and the recommended working temperature is 51 ℃~121 ℃.

4. Fluoroelastomer Fluoroelastomer compound is made of binary and ternary raw fluorine rubber by mixing with compounding agent and curing agent. In addition to excellent heat resistance, medium resistance, and good physical and mechanical properties, it also has low compression permanent deformation, good elasticity, and ultra long service life. Fluorine rubber has outstanding heat resistance (200~250 ℃) and oil resistance. It can be used to manufacture cylinder liner sealing ring, rubber bowl and rotary lip sealing ring, and can significantly improve the service time. The recommended working temperature is - 40 ℃~232 ℃.

5. Chlorosulfonated polyethylene synthetic rubber has good corrosion resistance to acid, alkali and salt solutions, and is not affected by climate, light, ozone and commercial fuels (such as diesel and kerosene). But it is not suitable for aromatic hydrocarbons, chlorinated hydrocarbons, chromic acid and nitric acid. The recommended working temperature is - 45 ℃~135 ℃.

6. Silicon rubber Silicon rubber has outstanding high and low temperature resistance, and can be used for a long time at 150 ℃ without performance change; It can be used continuously for 10000 hours at 200 ℃, and can maintain its unique use elasticity, ozone resistance, weather resistance and other advantages within the working temperature range of - 70~260 ℃. It is suitable for making the sealing gasket required in the thermal mechanism, such as sealing lining ring, valve gasket, oil seal (applicable to water medium), etc. Special silicone rubber can be used to make oil seal.

7. Ethylene propylene rubber has good corrosion resistance to strong acid, alkali, salt and chloride solutions. But it is not suitable for oil, solvent, aromatic hydrocarbon and hydrocarbon. The recommended operating temperature is - 57 ℃~176 ℃.

8. Graphite This material contains no resin or inorganic matter, and can be divided into metal doped or non metal element doped graphite materials. The material can be bonded to make gaskets for pipes with a diameter of more than 600 mm. It has excellent corrosion resistance to many acids, bases, salts, organic compounds, heat transfer solutions, and even high temperature solutions. It cannot melt, but will sublimate when it exceeds 3316 ℃. Under high temperature conditions, the material should be used with caution in strong oxidizing media. In addition to being used for gaskets, the material can also be used to make non-metallic winding tapes in packing and spiral wound gaskets.

9. Ceramic fiber and ceramic fiber formed on the strip are excellent gasket materials suitable for high temperature and low pressure working conditions and light flange conditions. The recommended working temperature is 1093 ℃, which can be used to make non-metallic winding tape in spiral wound gasket.

10. PTFE combines the advantages of most plastic gasket materials, including temperature resistance from - 95 ℃ to 232 ℃. In addition to free fluorine and alkali metals, it has excellent corrosion resistance to chemicals, solvents, hydroxides and acids. PTFE material can be filled with glass, and its purpose is to reduce the cold fluidity and creep of PTFE.