The materials for manufacturing valve parts should be selected according to the following factors
1. The pressure, temperature and characteristics of the working medium.
2. The force of the part and its function in the valve structure.
3. It has better manufacturability.
4. If the above conditions are met, there must be a lower cost.
Stem material
During the opening and closing of the valve, the valve stem bears the forces of tension, pressure and torsion, and is in direct contact with the medium. At the same time, there is relative frictional movement with the packing. Therefore, the valve stem material must be sufficient at the specified temperature. Strength and impact toughness, a certain degree of corrosion resistance and scratch resistance, and good manufacturability.
Commonly used valve stem materials are as follows
01 Carbon steel
When used in water and steam medium with low pressure and medium temperature not exceeding 300℃, A5 ordinary carbon steel is generally used.
When used in water and steam medium with medium pressure and medium temperature not exceeding 450℃, 35 high-quality carbon steel is generally used.
02 Alloy steel
40Cr (chrome steel) is generally used when it is used for medium pressure and high pressure, and the medium temperature does not exceed 450 ℃ in water, steam, petroleum and other media.
38CrMoALA nitriding steel can be used when it is used in water, steam and other media with high pressure and medium temperature not exceeding 540℃.
25Cr2MoVA chromium molybdenum vanadium steel is generally used when used in high pressure steam medium with medium temperature not exceeding 570℃.
03 Stainless acid-resistant steel
It is used for non-corrosive and weakly corrosive media with medium pressure and high pressure, and the medium temperature does not exceed 450°C. 1Cr13, 2Cr13, 3Cr13 chromium stainless steel can be selected.
When used in corrosive media, stainless acid-resistant steel such as Cr17Ni2, 1Cr18Ni9Ti, Cr18Ni12Mo2Ti, Cr18Ni12Mo3Ti, and PH15-7Mo precipitation hardening steel can be selected.
04 Heat-resistant steel
When used for high-temperature valves whose medium temperature does not exceed 600℃, 4Cr10Si2Mo martensitic heat-resistant steel and 4Cr14Ni14W2Mo austenitic heat-resistant steel can be selected.
