The choice of gasket materials

A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression.

Gaskets allow "less-than-perfect" mating surfaces on machine parts where they can fill irregularities. Gaskets are commonly produced by cutting from sheet materials.

Gaskets for specific applications, such as high pressure steam systems, may contain asbestos. However, due to health hazards associated with asbestos exposure, non-asbestos gasket materials are used when practical

The choice of gasket materials that depends on the following three factors: temperature, pressure and medium.

1. Carbon Steel: Recommended maximum working temperature does not exceed 538 ℃, especially when the medium having oxidation time. Quality thin carbon steel plate ground is not suitable for the manufacture of inorganic acid, neutral or acidic salt solution equipment, if subjected to the stress of carbon steel, the accident rate for equipment under hot working conditions is very high. Carbon steel gaskets are usually used for high concentrations of acid and alkaline solution many. Brinell hardness of about 120.

2. 304 stainless steel (18-20% chromium, nickel, 8-10%), the recommended maximum operating temperature does not exceed 760 ℃. Within a temperature range of -196 ~ 538 ℃, prone to stress corrosion and intergranular corrosion. Brinell hardness of 160.

3. 304L stainless steel carbon content of not more than 0.03%. Recommended maximum working temperature does not exceed 760 ℃. Corrosion resistance similar to 304 stainless steel. Low carbon content reduces the precipitation of carbon from the lattice, intergranular corrosion resistance can be higher than 304 stainless steel. Brinell hardness of about 140.

4. 316 stainless steel (chromium 18%, nickel 12%), an increase of about 2% molybdenum in the 304 stainless steel, when the temperature increases strength and corrosion resistance can be improved. When the temperature is higher than other ordinary stainless steel has a higher creep resistance. Recommended maximum working temperature does not exceed 760 ℃. Brinell hardness of about 160.

5. 316L stainless steel recommended maximum continuous operating temperature does not exceed 760 ℃ ~ 815 ℃. With respect to the carbon content of not more than 316 stainless steel has better resistance to stress and intergranular corrosion. Brinell hardness of about 140.

6. Alloy of 45% iron, 24% nickel, 20% chromium and small amounts of molybdenum and copper. Recommended maximum working temperature does not exceed 760 ℃ ~ 815 ℃. Particularly suitable for the manufacture of sulfuric acid corrosion resistance equipment, Brinell hardness of about 160.

7. Aluminum (containing not less than 99%). Aluminum has excellent corrosion resistance and processing properties, for the manufacture of double-clip gasket. Brinell hardness of about 35. Recommended maximum continuous operating temperature does not exceed 426 ℃.

8. Copper copper composition close, it contains trace amounts of silver to increase its continuous work degree. Recommended maximum continuous operating temperature does not exceed 260 ℃. Brinell hardness of about 80.

9. Brass (66% copper, 34% zinc), in most operating conditions with good corrosion resistance, but not suited ammonium acetate, salt and acetylene. Recommended maximum continuous operating temperature does not exceed 260 ℃. Brinell hardness of about 58.

10. Hastelloy B-2 (26-30% molybdenum, 4-6% nickel and 62% iron). Recommended maximum working temperature does not exceed 1093 ℃. The concentration of hydrochloric acid which has excellent heat resistance. It has excellent moisture hydrogen chloride gas corrosion, sulfuric acid, phosphoric acid and reducing salt solution corrosion performance. Having high strength at high temperatures. Brinell hardness of about 230.

11. Hastelloy C-276 16-18% molybdenum, 13-17.5% chromium, 3.7-5.3% tungsten, 4.5-7% iron, the rest are a nickel). Recommended maximum working temperature does not exceed 1093 ℃. It has excellent corrosion resistance. Try a variety of cold or nitric acid concentration of 70% boiling nitric acid has excellent corrosion resistance, has good resistance to hydrochloric acid and sulfuric acid corrosion resistance and excellent resistance to stress corrosion. Brinell hardness of about 210.

12. Inconel 600 nickel-base alloy (77% Ni, 15% Cr and 7% Fe). Recommended maximum working temperature does not exceed 1093 ℃. Having high strength at high temperatures, typically used need to address the problem of stress corrosion equipment. At low temperatures, with excellent workability. Brinell hardness of about 150.

13. Monel 400 (30% copper, nickel recommended maximum continuous operating temperature does not exceed 815 ℃. In addition to strong oxidizing acid, the most acids and alkalis have excellent corrosion resistance in hydrofluoric acid, mercuric chloride, mercury medium easy to produce stress corrosion cracking, therefore, not suited for the medium. hydrofluoric acid is widely used in the manufacture of equipment. Brinell hardness of about 120.

14. The titanium Recommended maximum working temperature does not exceed 1093 ℃. At high temperatures, it has excellent corrosion resistance.

Source: Yaang Pipe Industry Co., Limited (www.yaang.com)

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