There are many materials used to manufacture valve components, including various grades of black and non-ferrous metals and their alloys, as well as various non-metallic materials.
The material for manufacturing valve components should be selected based on the following factors:
1. The pressure, temperature, and characteristics of the working medium.
2. The force situation of the component and its role in the valve structure.
3. Has good processability.
4. Under the above conditions, there should be lower costs.
Materials for valve body, valve cover, and valve plate (disc)
The valve body, valve cover, and gate (valve disc) are one of the main components of the valve, which directly bear the pressure of the medium. The materials used must comply with the regulations of the "pressure and temperature rating of the valve". There are several commonly used materials, including:
1、 Gray cast iron: Gray cast iron is suitable for media such as water, steam, air, gas, and oil with nominal pressure PN ≤ 1.0MPa and temperature ranging from -10 ℃ to 200 ℃. The commonly used grades of gray cast iron are HT200 HT250、HT300、HT350。
2、 Forged cast iron: suitable for water, steam, air, and oil media with nominal pressure PN ≤ 2.5MPa and temperature ranging from -30 to 300 ℃. Commonly used grades include KTH300-06 KTH330—08、KTH350—10。
3、 Ductile iron: suitable for media such as water, steam, air, and oil with PN ≤ 4.0MPa and temperature ranging from -30 to 350 ℃. Common grades include: QT400-15 QT450—10、QT500—7。
Given the current level of domestic technology, factories vary greatly, and users often find it difficult to inspect. Based on experience, it is recommended to use steel valves for safety when PN ≤ 2.5MPa.
4、 Acid resistant high silicon ductile iron: suitable for corrosive media with nominal pressure PN ≤ 0.25MPa and temperature below 120 ℃.
5、 Carbon steel: suitable for media such as water, steam, air, hydrogen, ammonia, nitrogen, and petroleum products with nominal pressure PN ≤ 32.0MPa and temperature ranging from -30 to 425 ℃. Common grades include WC1, WCB, ZG25, high-quality steel 20, 25, 30, and low-alloy structural steel 16Mn.
6、 Copper alloy: suitable for media such as water, seawater, oxygen, air, oil, etc. with PN ≤ 2.5MPa, as well as steam media with temperature -40~250 ℃. Commonly used grades are ZGnSn10Zn2 (tin bronze), H62, Hpb59-1 (brass), QAZ19-2, QA19-4 (aluminum bronze).
7、 High temperature copper: suitable for steam and petroleum products with nominal pressure PN ≤ 17.0MPA and temperature ≤ 570 ℃. The commonly used grades are ZGCr5Mo and 1Cr5M0 ZG20CrMoV, ZG15Gr1Mo1V, 12CrMoV, WC6, WC9 and other grades. The specific selection must comply with the valve pressure and temperature specifications.
8、 Low temperature steel, suitable for media such as ethylene, propylene, liquid natural gas, liquid nitrogen, etc. with nominal pressure PN ≤ 6.4Mpa and temperature ≥ -196 ℃, commonly used grades include ZG1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Ti, ZG0Cr18Ni9
9、 Stainless acid resistant steel, suitable for media such as nitric acid and acetic acid with nominal pressure PN ≤ 6.4Mpa and temperature ≤ 200 ℃. Commonly used grades include ZG0Cr18Ni9Ti, ZG0Cr18Ni10<nitric acid resistance>, ZG0Cr18Ni12Mo2Ti, ZG1Cr18Ni12Mo2Ti<acid and urea resistance>
Sealing surface material
The sealing surface is the most critical working surface of the valve, and the quality of the sealing surface is related to the service life of the valve. Generally, the sealing surface material should consider factors such as corrosion resistance, abrasion resistance, erosion resistance, and oxidation resistance.
Usually divided into two categories:
（1） Soft materials
1. Rubber (including nitrile rubber, fluororubber, etc.)
2. Plastic (PTFE, nylon, etc.)
（2） Hard sealing material
1. Copper alloy (used for low-pressure valves)
2. Chromium stainless steel (used for ordinary high and medium pressure valves)
3. Si Tai Li alloy (used for high temperature and high pressure valves and strongly corrosive valves)
4. Nickel based alloys (for corrosive media)
Valve stem material
The valve stem bears tensile, compressive, and torsional forces during the opening and closing process of the valve, and is in direct contact with the medium. At the same time, there is relative frictional motion between the valve stem and the packing. Therefore, the valve stem material must ensure sufficient strength and impact toughness at the specified temperature, have certain corrosion resistance and abrasion resistance, and have good processability.
There are several commonly used valve stem materials.
1、 Carbon steel
When used for water and steam media with low pressure and medium temperature not exceeding 300 ℃, A5 ordinary carbon steel is generally selected.
When used for water and steam media with medium pressure and medium temperature not exceeding 450 ℃, 35 high-quality carbon steel is generally selected.
2、 Alloy steel
When used for medium and high pressure media such as water, steam, and petroleum with a medium temperature not exceeding 450 ℃, 40Cr (chromium steel) is generally selected.
When used for high-pressure media such as water and steam with a medium temperature not exceeding 540 ℃, 38CrMoALA nitriding steel can be selected.
When used for steam media with high pressure and medium temperature not exceeding 570 ℃, 25Cr2MoVA chromium molybdenum vanadium steel is generally selected.
3、 Stainless acid resistant steel
For non corrosive and weakly corrosive media with medium and high pressure and medium temperature not exceeding 450 ℃, 1Cr13, 2Cr13 chromium stainless steel can be selected.
When used in corrosive media, stainless acid resistant steels such as Cr17Ni2, 1Cr18Ni9Ti, Cr18Ni12Mo2Ti, Cr18Ni12Mo3Ti, and PH15-7Mo precipitation hardening steels can be selected.
4、 Heat-resistant steel
When used for high-temperature valves with medium temperatures not exceeding 600 ℃, 4Cr10Si2Mo martensitic heat-resistant steel and 4Cr14Ni14W2Mo austenitic heat-resistant steel can be selected.
Valve stem nut material
The valve stem nut directly bears the axial force of the valve stem during the opening and closing process, so it must have a certain strength. At the same time, it is threaded with the valve stem, requiring a low coefficient of friction, no rust, and avoiding biting.
1、 Copper alloy
Copper alloy has a low coefficient of friction and does not rust, making it one of the commonly used materials at present. For low-pressure valves with Pg<1.6Mpa, ZHMn58-2-2 cast brass can be used. For medium pressure valves with Pg16-6.4Mpa, ZQAL9-4 Wuxi Bronze can be used. For high-pressure valves, ZHAL66-6-3-2 cast brass can be used.
2、 Steel
When working conditions do not allow the use of copper alloys, high-quality carbon steels such as 35 and 40, and stainless acid resistant steels such as 2Cr13, 1Cr18Ni9, and Cr17Ni2 can be selected.
The working conditions do not allow for the following situations.
1. There are many materials used to manufacture valve parts with melon shaped clutches for electric valves, including various grades of black and non-ferrous metals and their alloys, as well as various non-metallic materials.
The material for manufacturing valve components should be selected based on the following factors:
1. The pressure, temperature, and characteristics of the working medium.
2. The force situation of the component and its role in the valve structure.
3. Has good processability.
4. Under the above conditions, there should be lower costs.
Materials for valve body, valve cover, and valve plate (disc)
The valve body, valve cover, and gate (valve disc) are one of the main components of the valve, which directly bear the pressure of the medium. The materials used must comply with the regulations of the "pressure and temperature rating of the valve". There are several commonly used materials, including:
1、 Gray cast iron: Gray cast iron is suitable for media such as water, steam, air, gas, and oil with nominal pressure PN ≤ 1.0MPa and temperature ranging from -10 ℃ to 200 ℃. The commonly used grades of gray cast iron are HT200 HT250、HT300、HT350。
2、 Forged cast iron: suitable for water, steam, air, and oil media with nominal pressure PN ≤ 2.5MPa and temperature ranging from -30 to 300 ℃. Commonly used grades include KTH300-06 KTH330—08、KTH350—10。
3、 Ductile iron: suitable for media such as water, steam, air, and oil with PN ≤ 4.0MPa and temperature ranging from -30 to 350 ℃. Common grades include: QT400-15 QT450—10、QT500—7。
Given the current level of domestic technology, factories vary greatly, and users often find it difficult to inspect. Based on experience, it is recommended to use steel valves for safety when PN ≤ 2.5MPa.
4、 Acid resistant high silicon ductile iron: suitable for corrosive media with nominal pressure PN ≤ 0.25MPa and temperature below 120 ℃.
5、 Carbon steel: suitable for media such as water, steam, air, hydrogen, ammonia, nitrogen, and petroleum products with nominal pressure PN ≤ 32.0MPa and temperature ranging from -30 to 425 ℃. Common grades include WC1, WCB, ZG25, high-quality steel 20, 25, 30, and low-alloy structural steel 16Mn.
6、 Copper alloy: suitable for media such as water, seawater, oxygen, air, oil, etc. with PN ≤ 2.5MPa, as well as steam media with temperature -40~250 ℃. Commonly used grades are ZGnSn10Zn2 (tin bronze), H62, Hpb59-1 (brass), QAZ19-2, QA19-4 (aluminum bronze).
7、 High temperature copper: suitable for steam and petroleum products with nominal pressure PN ≤ 17.0MPA and temperature ≤ 570 ℃. The commonly used grades are ZGCr5Mo and 1Cr5M0 ZG20CrMoV, ZG15Gr1Mo1V, 12CrMoV, WC6, WC9 and other grades. The specific selection must comply with the valve pressure and temperature specifications.
8、 Low temperature steel, suitable for media such as ethylene, propylene, liquid natural gas, liquid nitrogen, etc. with nominal pressure PN ≤ 6.4Mpa and temperature ≥ -196 ℃, commonly used grades include ZG1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Ti, ZG0Cr18Ni9
9、 Stainless acid resistant steel, suitable for media such as nitric acid and acetic acid with nominal pressure PN ≤ 6.4Mpa and temperature ≤ 200 ℃. Commonly used grades include ZG0Cr18Ni9Ti, ZG0Cr18Ni10<nitric acid resistance>, ZG0Cr18Ni12Mo2Ti, ZG1Cr18Ni12Mo2Ti<acid and urea resistance>
Sealing surface material
The sealing surface is the most critical working surface of the valve, and the quality of the sealing surface is related to the service life of the valve. Generally, the sealing surface material should consider factors such as corrosion resistance, abrasion resistance, erosion resistance, and oxidation resistance.
Usually divided into two categories:
（1） Soft materials
1. Rubber (including nitrile rubber, fluororubber, etc.)
2. Plastic (PTFE, nylon, etc.)
（2） Hard sealing material
1. Copper alloy (used for low-pressure valves)
2. Chromium stainless steel (used for ordinary high and medium pressure valves)
3. Si Tai Li alloy (used for high temperature and high pressure valves and strongly corrosive valves)
4. Nickel based alloys (for corrosive media)
Valve stem material
The valve stem bears tensile, compressive, and torsional forces during the opening and closing process of the valve, and is in direct contact with the medium. At the same time, there is relative frictional motion between the valve stem and the packing. Therefore, the valve stem material must ensure sufficient strength and impact toughness at the specified temperature, have certain corrosion resistance and abrasion resistance, and have good processability.
There are several commonly used valve stem materials.
1、 Carbon steel
When used for water and steam media with low pressure and medium temperature not exceeding 300 ℃, A5 ordinary carbon steel is generally selected.
When used for water and steam media with medium pressure and medium temperature not exceeding 450 ℃, 35 high-quality carbon steel is generally selected.
2、 Alloy steel
When used for medium and high pressure media such as water, steam, and petroleum with a medium temperature not exceeding 450 ℃, 40Cr (chromium steel) is generally selected.
When used for high-pressure media such as water and steam with a medium temperature not exceeding 540 ℃, 38CrMoALA nitriding steel can be selected.
When used for steam media with high pressure and medium temperature not exceeding 570 ℃, 25Cr2MoVA chromium molybdenum vanadium steel is generally selected.
3、 Stainless acid resistant steel
For non corrosive and weakly corrosive media with medium and high pressure and medium temperature not exceeding 450 ℃, 1Cr13, 2Cr13 chromium stainless steel can be selected.
When used in corrosive media, stainless acid resistant steels such as Cr17Ni2, 1Cr18Ni9Ti, Cr18Ni12Mo2Ti, Cr18Ni12Mo3Ti, and PH15-7Mo precipitation hardening steels can be selected.
4、 Heat-resistant steel
When used for high-temperature valves with medium temperatures not exceeding 600 ℃, 4Cr10Si2Mo martensitic heat-resistant steel and 4Cr14Ni14W2Mo austenitic heat-resistant steel can be selected.
Valve stem nut material
The valve stem nut directly bears the axial force of the valve stem during the opening and closing process, so it must have a certain strength. At the same time, it is threaded with the valve stem, requiring a low coefficient of friction, no rust, and avoiding biting.
1、 Copper alloy
Copper alloy has a low coefficient of friction and does not rust, making it one of the commonly used materials at present. For low-pressure valves with Pg<1.6Mpa, ZHMn58-2-2 cast brass can be used. For medium pressure valves with Pg16-6.4Mpa, ZQAL9-4 Wuxi Bronze can be used. For high-pressure valves, ZHAL66-6-3-2 cast brass can be used.
2、 Steel
When working conditions do not allow the use of copper alloys, high-quality carbon steels such as 35 and 40, and stainless acid resistant steels such as 2Cr13, 1Cr18Ni9, and Cr17Ni2 can be selected.
The working conditions do not allow for the following situations.
1. The valve stem nut with a melon shaped clutch used on electric valves requires heat treatment to obtain high hardness or surface hardness.
2. When the working medium or surrounding environment is not suitable for using copper alloy, such as ammonia medium that corrodes copper.
When selecting steel valve stem nuts, special attention should be paid to the phenomenon of thread biting.
Valve stem nuts require heat treatment to obtain high hardness or surface hardness.
2. When the working medium or surrounding environment is not suitable for using copper alloy, such as ammonia medium that corrodes copper.
When selecting steel valve stem nuts, special attention should be paid to the phenomenon of thread biting.