How do you choose valve material? -CF8,WCB, ductile cast iron, or forged steel?

Valve is one kind of mechanical device which is used in pipeline system to connect, regulate and cut off the medium flow, which includes soft seal and hard seal gate valves, butterfly valves, check valves, globe valves, ball valves, hydraulic control valves, grooved valves, balance valves, throttle valves, etc. With different working conditions, like different working temperature, different working mediums, different medium pressure,etc, different materials are used for valve body, sealing material, and valve trim parts,etc. 

Today we are going t discuss how to select your valve materials: 

The valve body, bonnet, and valve disc are the main parts of one industrial valve, which directly bear the pressure of the mediums, so the material used for valve body, bonnet and valve disc must comply with the requirements of “Pressure and Temperature Rating of Valves”. 

Here are some common used materials for valves: 

1. Gray cast iron: 

Gray cast iron is suitable for water, steam, air, gas, oil and other mediums with nominal pressure PN≤1.0MPa, and working temperature is between －10℃～200℃. 

The common grade Nos of gray cast iron are: HT200,HT250,HT300,HT350. 

2. Malleable cast iron: 

Malleable cast iron is suitable for water, steam, air and oil medium with nominal pressure PN≤2.5MPa,working temperature is between －30～300℃.

The common grade Nos of malleable cast iron are KTH300—06,KTH330—08,KTH350—10.

3. Ductile cast iron: 

Ductile cast iron is suitable for water, steam, air, oils and other mediums with nominal pressure PN≤4.0MPa, working temperature is between -30～350℃. 

The common grade Nos for ductile cast iron are QT400—15,QT450—10,QT500—7. 

4. Acid-resistant high silicon ductile cast iron: 

Acid-resistant high silicon ductile cast iron is suitable for corrosive mediums with nominal pressure PN≤0.25MPa, and working temperature is lower than 120℃. 

5.Carbon steel: 

Carbon steel is suitable for mediums such as water, steam, air, hydrogen, ammonia, nitrogen and petroleum products with nominal pressure PN≤32.0MPa, working temperature is between -30～425℃. 

The common grade Nos for carbon steel are WC1、WCB、ZG25 and high quality steel 20, 25,30 and low alloy structural steel 16Mn. 

6. Brass alloy(copper alloy): 

Brass alloy material is suitable for water, seawater, oxygen, air, oil and other mediums with nominal pressure PN≤2.5MPa, and steam medium with working temperature is between -40～250℃. 

The common grade Nos for brass alloy are ZGnSn10Zn2(Tin bronze), H62, Hpb59-1(Brass), QAZ19—2, QA19—4(Aluminium bronze or Albronze) 

7. high temperature copper: 

High temperature copper is suitable for steam and petroleum products with nominal pressure PN≤17.0Mpa, working temperature is below ≤570℃. 

The common grade Nos for high temperature copper are ZGCr5Mo, 1Cr5M0, ZG20CrMoV, ZG15Gr1Mo1V, 12CrMoV, WC6, WC9,etc. 

8. Low temperature steel: 

Low temperature steel material is suitable for mediums such as ethylene, propylene, liquid natural gas, liquid nitrogen and other mediums with nominal pressure PN≤6.4Mpa, working temperature ≥—196℃. 

The common grade Nos for low temperature steel material are ZG1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Ti, ZG0Cr18Ni9. 

9. stainless acid-resistant steel: 

Stainless acid-resistant steel material is suitable for mediums nitric acid, acetic acid and other mediums with nominal pressure PN≤6.4Mpa, working temperature ≤200℃. 

The common grade Nos for stainless acid-resistant steel are ZG0Cr18Ni9Ti, ZG0Cr18Ni10(Nitric acid resistant), ZG0Cr18Ni12Mo2Ti , ZG1Cr18Ni12Mo2Ti(acid and urea resistant). 

Different valve material used for different working temperature: 

1.Material No: C5

Chemical component: chromium 5%, molybdenum 0.5%. 

Standard: ASTM A217

Medium: C5 material is suitable for mildly corrosive or aggressive mediums and non aggressive mediums. 

Working temperature: -30℃∽649℃.

2. Material No: C12

Chemical component: chromium 9%, molybdenum 1%. 

Standard: ASTM A217

Medium: C12 material is suitable for mildly corrosive or aggressive mediums and non aggressive mediums. 

Working temperature: -30℃∽649℃.

3. Material No: CA6NM(4)

Chemical component: chromium steel 12%, . 

Standard: ASTM A487

Medium: CA6NM(4) material is suitable for corrosive mediums. 

Working temperature: -30℃∽482℃.

4. Material No: CF8

Chemical component: stainless steel 304. 

Standard: ASTM A351

Medium: CF8 material is suitable for corrosive or super low temperature medium or high temperature non corrosive mediums. 

Working temperature: -268℃∽649℃.

If the working temperature is over 425℃, the carbon content of the 304 stainless steel should be 0.04% or above. 

5. Material No: CF3

Chemical component: stainless steel 304L . 

Standard: ASTM A351

Medium: CF3 material is suitable for corrosive and non corrosive mediums. 

Working temperature: +425℃.

6. Material No: CF3M

Chemical component: stainless steel 316L. 

Standard: ASTM A351

Medium: CF3M material is suitable for corrosive and non corrosive mediums. 

Working temperature: +454℃.

7. Material No: CW6M

Chemical component: Hastroy nickel alloy C. 

Standard: ASTM A494

Medium: CW6M material has good corrosion resistance in strong oxidizing environment, and good properties at high temperatures, high corrosion resistance to formic, phosphoric, sulfurous and sulfuric acids. 

Working temperature: +649℃.

8. Material No: CY40

Chemical component: Inco Nickel Alloy. 

Standard: ASTM A494

Medium: CY40 material has good performance in high temperature mediums, good corrosion resistance for highly corrosive fluid mediums. 

9. Material No: LCB

Chemical component: low temperature carbon steel.  

Standard: ASTM A352

Medium: LCB material is suitable for low temperature medium ( to -46℃），is not suitable for medium with temperature over 340℃。 

10.Material No: WCB

Chemical component: carbon steel. 

Standard: ASTM A216

Medium: WCB material is suitable for non corrosive mediums like water, oils, and gas. 

Working temperature: -30℃∽425℃.

11.Material No: WC6

Chemical component: chromium 1.25%, molybdenum 0.5%.

Standard: ASTM A217

Medium: WC6 material is suitable for non corrosive mediums like water, oils, and gas. 

Working temperature: -30℃∽593℃.

12.Material No: WC9

Chemical component: chromium 2.25

Standard: ASTM A217

Medium: WC9 material is suitable for non corrosive mediums like water, oils, and gas. 

Working temperature: -30℃∽593℃.

13.Material No: CA15(4)

Chemical component: chromium 12%

Standard: ASTM A217

Medium: CA15(4) material is suitable for corrosive mediums.

Working temperature: to +704℃.

14. Material No: CF8M 3

Chemical component: stainless steel 16. 

Standard: ASTM A351

Medium: CF8M 3 material is suitable for corrosive or super low temperature medium or high temperature non corrosive mediums. 

Working temperature: -268℃∽649℃.

If the working temperature is over 425℃, the carbon content of the 304 stainless steel should be 0.04% or above. 

15. Material No: CF8C

Chemical component: stainless steel 347. 

Standard: ASTM A351

Medium: CF8C material is suitable for corrosive and high temperature mediums. 

Working temperature: -268℃∽649℃.

If the working temperature is over 540℃, the carbon content of the 304 stainless steel should be 0.04% or above. 

16. Material No: CN7M

Chemical component: Alloy steel.  

Standard: ASTM A351

Medium: CN7M material has very good resistance to hot sulfuric acid corrosion. 

Working temperature: +425℃.

17. Material No: M35-1

Chemical component: Monel. 

Standard: ASTM A494

Medium: M35-1 material has good resistance to all common organic acids and salt water corrosion, also high resistance to corrosion by most alkaline solutions. 

Working temperature: +400℃.

18. Material No: N7M

Chemical component: Haste Nickel Alloy B. 

Standard: ASTM A494

Medium: N7M material is especially suitable for handling hydrofluoric acid of various concentrations and temperatures, and has good resistance to sulfuric acid and phosphoric acid corrosion.  

Working temperature: +649℃.

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