Alloy 20 gate valve is an industrial valve made of Alloy 20 (UNS N08020/CN7M) as the core material. Its technical characteristics and application scope are as follows:
1. Definition and basic characteristics
Material definition
Alloy 20 is a nickel-chromium-molybdenum austenitic stainless steel, containing 32.5-35% nickel, 19-21% chromium, 2-3% molybdenum, and added with copper, niobium and other elements. It has excellent corrosion resistance and high temperature stability.
Valve type
The gate valve adopts a wedge-shaped gate structure, which realizes the opening and closing control of the pipeline through vertical movement, and is suitable for working conditions that require complete cutoff of the medium.
2. Structural features
Valve body design
Cast or forged valve body, flange or butt welding connection, support DN15-DN400 caliber and 150-2500 pound pressure.
The internal flow channel is usually full-bore design to reduce fluid resistance loss.
Sealing structure
The composite design of soft seal and metal seal can withstand high temperature of ≤425℃ and maintain sealing reliability in corrosive media.
3. Material composition and strengthening mechanism
| composition | content | function |
|---|---|---|
| Ni | 32.5-35% | Enhanced resistance to reducing acid corrosion |
| Cr | 19-21% | Improve the stability of anti-oxidation and passivation film |
| Mo | 2-3% | Inhibits chloride pitting and crevice corrosion |
| Nb | 8×C%-1.0% | Carbide stabilization to prevent intergranular corrosion |
4. Typical application areas
Chemical industry
Used in sulfuric acid (concentration ≤ 80%), phosphoric acid, mixed acid and organic acid delivery systems.
Energy equipment
Adapt to high-temperature oil pipelines and heat exchange systems in refineries, with a temperature limit of 425°C.
Special media
Excellent performance in oil and gas field mining environments containing chlorides and hydrogen sulfide.
5. Performance advantages
Corrosion resistance
The pitting resistance index (PREN) ≥ 35, significantly better than 304/316 stainless steel, suitable for corrosive environments with a wide pH value.
Mechanical properties
Yield strength ≥ 275MPa, elongation ≥ 30%, with high strength and good processability.
Compatibility
Meets international standards such as ASTM, BS, JIS, and can be matched with a variety of pipeline systems.
6. Usage restrictions
Contraindications to media
Not suitable for concentrated hydrochloric acid (concentration ≥ 50%), wet chlorine and high-temperature fluoride environments.
Maintenance Requirements
After long-term operation, the wear of the valve stem seal packing needs to be checked to prevent medium leakage.
This type of valve has become an efficient fluid control solution in highly corrosive industrial scenarios through optimized material combination and structural design.