The valve body, bonnet and wedge (disc) are the main parts of the valve, which directly bear the medium pressure. The materials used must comply with the provisions of "pressure and temperature rating of the valve". Common materials are as follows: 

1. Grey Cast Iron

Grey cast iron is suitable for water, steam, air, gas and oil media with nominal pressure PN ≤ 1.0MPa and temperature between - 10 ℃ ~ 200 ℃. Common marks: HT200, HT250, HT300, HT350.

2. Malleable Cast Iron

Malleable cast iron valve is suitable for water, steam, air and oil media with nominal pressure PN ≤ 2.5MPa and temperature between - 30 ℃ ~ 300 ℃. Common marks: KTH300-06, KTH330-08, KTH350-10.

3. Nodular Cast Iron

Nodular cast iron is suitable for water, steam, air and oil media with nominal pressure PN ≤ 4.0MPa and temperature between - 30 ℃ ~ 350 ℃. Common marks: QT400-15, QT450-10, QT500-7.

According to experience, if PN ≤ 2.5MPa, it is safer to use steel valves.

4. Acid Resistant High Silicon Nodular Cast Iron

Acid resistant high silicon nodular cast iron is suitable for corrosive medium with nominal pressure PN ≤ 0.25MPa and temperature below 120 ℃.

5. Carbon Steel

Carbon steel valve is suitable for water, steam, air, hydrogen, ammonia, nitrogen and petroleum medium with nominal pressure PN ≤ 32.0MPa and temperature between - 30 ℃ ~ 425 ℃. Common marks: WC1, WCB, ZG25, high-quality steel 20, 25, 30 and low-alloy structural steel 16Mn.

6. Copper Alloy

Copper alloy is suitable for water, seawater, oxygen, air and oil medium with nominal pressure PN ≤ 2.5MPa and temperature between - 40 ℃ ~ 250 ℃. Common marks: ZCuSn10Zn2(Tin Bronze), H62, Hpb59-1(Brass), QAZ19-2, QA19-4(Aluminum Bronze).

7. High Temperature Copper

High temperature copper is suitable for steam and petroleum products with nominal pressure PN ≤ 17.0MPa and temperature below 570 ℃. Common marks: ZGCr5Mo, 1Cr5M0, ZG20CrMoV, ZG15Gr1Mo1V, 12CrMoV, WC6, WC9.

The specific selection must be in accordance with the specifications of valve pressure and temperature.

8. Low Temperature Steel

Low temperature steel is suitable for ethylene, propylene, liquid natural gas and liquid nitrogen medium with nominal pressure PN ≤ 6.4MPa and temperature ≥ -196℃. Common marks: ZG1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Ti, ZG0Cr18Ni9.

9. Stainless Acid Resistant Steel

Stainless acid resistant steel is suitable for nitric acid and acetic acid medium with nominal pressure PN ≤ 6.4MPa and temperature ≤ 200℃. Common marks: ZG0Cr18Ni9Ti, ZG0Cr18Ni10(Nitric Acid Resistance), ZG0Cr18Ni12Mo2Ti, ZG1Cr18Ni12Mo2Ti(Acid Resistance and Urea).