Valve material selection

In the industrial field, the valve is a key component to control the flow of fluid, which is widely used in many industries such as petroleum, chemical, electric power, metallurgy and so on. Its performance is directly related to the safety, stability and efficient operation of the whole system. If the material is not selected properly, the valve may have corrosion, wear, deformation and other problems, which will lead to leakage, blockage and even system failure, which will not only cause huge economic losses, but also may cause serious safety accidents. Therefore, an in-depth understanding of the temperature resistance and media characteristics of various valve materials is an essential skill for industrial practitioners to ensure the smooth progress of production.
Metal materials are one of the most commonly used materials in valve manufacturing, and there are many kinds of different metal materials with different temperature resistance properties.
Gray cast iron valves have low cost and simple manufacturing process, but their temperature resistance is relatively limited, and are generally suitable for working environments ranging from -15 ° C to 250 ° C. At temperatures beyond this range, gray cast iron may fail due to excessive thermal stress.
Due to its better mechanical properties and corrosion resistance, the temperature range of ductile iron valves is extended to -30 ° C to 350 ° C. This makes ductile iron valves used in more fields.
The temperature range of carbon steel valves is -29 ℃ to 450℃, and the recommended temperature t<425℃ is in the JB/ T3595-93 standard. In this temperature range, carbon steel can maintain good strength and toughness, and meet the requirements of most conventional working conditions.
Alloy steel valves show more excellent high temperature resistance, for example, the maximum use temperature of 1Cr5Mo alloy steel valves is 550 ° C, and the maximum use temperature of 12Cr1MoVA alloy steel valves is 570 ° C, which plays an important role in high temperature steam, petroleum, chemical and other industries.
Stainless steel valves are known for their excellent corrosion resistance and high and low temperature resistance. Among them, 1Cr18Ni9Ti and 1Cr18Ni12Mo2Ti stainless steel valves have a very wide temperature range, from -196 ° C to 600 ° C. This makes the stainless steel valve in extremely cold and high temperature environment can maintain stable performance, widely used in food, pharmaceutical, petroleum, chemical and other fields.
Different metal materials have different tolerance to various media due to their differences in chemical composition and physical properties.
Gray cast iron valve
It is suitable for water, steam, air, gas, oil and other media with nominal pressure PN≤1.0MPa and temperature -10 ℃ ~ 200℃. This is because gray cast iron can maintain relatively stable properties in these media, without serious corrosion or chemical reactions. However, gray cast iron is not resistant to strong corrosive media such as hydrochloric acid and nitric acid.
Malleable cast iron valve
It is suitable for water, steam, air and oil medium with nominal pressure PN≤2.5MPa and temperature -30 ~ 300℃. The toughness and plasticity of malleable cast iron is superior to that of gray cast iron, allowing it to work stably over a wider range of pressures and temperatures, as well as in the medium environments described above.
Ductile iron valve
It is suitable for water, steam, air, oil and other media with PN≤4.0MPa and temperature of -30 ~ 350℃. The unique spherical graphite structure of ductile iron gives it good mechanical properties and corrosion resistance, so that it can operate reliably in a variety of media and working conditions.
Carbon steel valve
It is suitable for water, steam, air, hydrogen, ammonia, nitrogen and petroleum products with nominal pressure PN≤32.0MPa and temperature -30 ~ 425℃. In such a pressure and temperature range, carbon steel valves can withstand the pressure of the medium, and it is not easy to react with the medium, to ensure the normal use of the valve.
Copper alloy valve
Suitable for PN≤2.5MPa water, sea water, oxygen, air, oil and other media, as well as the temperature of -40 ~ 250℃ steam medium. Copper alloys have good corrosion resistance and thermal conductivity, especially in seawater and other corrosive media.
High temperature copper
Suitable for steam and petroleum products with nominal pressure PN≤17.0MPA and temperature ≤570℃. High temperature copper material can still maintain good strength and stability in high temperature environment, and can meet the requirements of valve use in the process of high temperature steam and petroleum products.
Low-temperature steel
Suitable for nominal pressure PN≤6.4Mpa, temperature ≥-196℃ ethylene, propylene, liquid natural gas, liquid nitrogen and other low temperature media. Low temperature steel through special alloying and heat treatment process, so that it has good toughness and impact resistance in low temperature environment, effectively prevent the valve in low temperature conditions brittle fracture.
Stainless acid resistant steel
Suitable for nominal pressure PN≤6.4Mpa, temperature ≤200℃ nitric acid, acetic acid and other corrosive media. The stainless acid-resistant steel contains high alloying elements such as chromium and nickel, forming a dense oxide film, which makes it have excellent corrosion resistance and can work stably in highly corrosive media such as nitric acid and acetic acid.