Commonly‑Used Material Selection and Application Scope for Valves
Add time：2017/10/18 13:49:42 Page views：2297
Valve materials are selected according to different service media. Generally, material selection for valves covers normal‑temperature, high‑temperature and low‑temperature conditions, corrosion‑resistant requirements, as well as material options for low‑pressure, medium‑pressure and high‑pressure valves. Main materials include cast iron, cast steel, stainless steel, alloy steel, high‑temperature steel, low‑temperature steel, corrosion‑resistant plastics and others.
Common Valve Materials
1. Grey Cast Iron Valves
Grey cast iron is applicable for media such as water, steam, air, coal gas and oil products with nominal pressure PN ≤ 1.0 MPa and temperature ranging from ‑10 ℃ to 200 ℃.
Common grades: HT200, HT250, HT300, HT350.
2. Malleable Cast Iron
Suitable for media of water, steam, air and oil products with nominal pressure PN ≤ 2.5 MPa and temperature from ‑30 ℃ to 300 ℃.
Common grades: KTH300‑06, KTH330‑08, KTH350‑10.
3. Ductile Iron Valves
Applicable for media such as water, steam, air and oil products with PN ≤ 1.6 MPa and temperature between ‑5 ℃ and 80 ℃.
Common grades: QT400‑15, QT450‑10, QT500‑7.
In view of the uneven domestic manufacturing standards among different manufacturers and the difficulty for users to conduct inspection, experience suggests that steel valves shall be adopted for PN ≤ 2.5 MPa for safety reasons.
4. Acid‑Resistant High‑Silicon Ductile Iron
Applicable for corrosive media with nominal pressure PN ≤ 0.25 MPa and temperature below 120 ℃.
5. Carbon Steel Valves
Suitable for media including water, steam, air, hydrogen, ammonia, nitrogen and petroleum products with nominal pressure PN ≤ 32.0 MPa and temperature from ‑30 ℃ to 425 ℃.
Common grades: WC1, WCB, ZG25; high‑quality carbon steel 20#, 25#, 30#; low‑alloy structural steel 16Mn.
6. Copper Alloy Valves
Applicable for water, seawater, oxygen, air, oil products (PN ≤ 2.5 MPa) and steam media at ‑40 ℃ ~ 250 ℃.
Common grades: ZCuSn10Zn2 (tin bronze); H62, HPb59‑1 (brass); QAl19‑2, QAl9‑4 (aluminum bronze).
7. High‑Temperature Steel
Applicable for steam and petroleum products with nominal pressure PN ≤ 17.0 MPa and temperature ≤ 570 ℃.
Common grades: ZGCr5Mo, 1Cr5Mo, ZG20CrMoV, ZG15Cr1Mo1V, 12CrMoV, WC6, WC9. Specific selection shall comply with valve pressure‑temperature rating specifications.
8. Low‑Temperature Steel Valves
Applicable for ethylene, propylene, liquefied natural gas, liquid nitrogen and other media with nominal pressure PN ≤ 6.4 MPa and temperature down to ‑196 ℃.
Common grades: ZG1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Ti, ZG0Cr18Ni9.
9. Stainless Acid‑Resistant Steel Valves
Applicable for nitric acid, acetic acid and other media with nominal pressure PN ≤ 6.4 MPa and temperature ≤ 200 ℃.
Common grades: ZG0Cr18Ni9Ti, ZG0Cr18Ni10 (nitric‑acid resistant); ZG0Cr18Ni12Mo2Ti, ZG1Cr18Ni12Mo2Ti (acid‑ and urea‑resistant).
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