ASTM A182 F51 stop valve is a special stop valve with a duplex stainless steel forged valve body, designed for high corrosion and high pressure conditions. Its core characteristics and uses are as follows:
1. Core material characteristics (ASTM A182 F51)
Chemical composition advantages
Ultra-low carbon (C≤0.03%) + high chromium (Cr 21-23%) + molybdenum (Mo 2.5-3.5%) + nitrogen (N 0.08-0.20%), significantly improving corrosion resistance.
Duplex structure: The ratio of austenite to ferrite is ≈1:1 at room temperature, with high strength and toughness.
Performance
Corrosion resistance: Anti-chloride pitting, stress corrosion, crevice corrosion (PREN≥29), suitable for sulfide/seawater media.
Mechanical properties: tensile strength ≥620MPa, yield strength ≥450MPa, hardness HB ≥290.
Temperature resistance: -29℃~300℃ (up to 350℃ in the short term).
2. Valve structure features Forged valve body
Adopts integral forging (not casting) to eliminate pore defects and has a pressure bearing capacity of PN40~PN420 (Class 2500).
Streamlined flow channel design, flow resistance coefficient ≤0.8, reduces pressure drop.
Seal and connection
Valve seat seal: metal hard seal (such as F51 surfacing Stellite alloy) or soft seal (PTFE).
Connection method: flange type (RF/RTJ surface) or butt welding end (WN type), pressure self-tightening seal is commonly used in high pressure conditions.
Welding process
ER2209 welding wire is used for valve body-pipe welding, and solid solution treatment (quenching at 1020-1100℃) is performed after welding to ensure that the corrosion resistance of the weld is equivalent to that of the parent material.
3. Typical application scenarios
| Industry | Specific working conditions | Advantages |
|---|---|---|
| Marine Engineering | Seawater cooling system, ship ballast water pipeline | Chloride ion corrosion resistance(Cl⁻≤50000ppm) |
| Energy Industry | Oil and gas transportation of sulfur-containing media (H₂S/CO₂), geothermal fluid control | Sulfide stress corrosion resistance |
| Chemical Process | Dilute sulfuric acid (≤20%), phosphoric acid, acetic acid medium pipeline | Acid resistance is better than 316L steel |
| Environmental protection equipment | Sewage treatment, desulfurization equipment key cutoff point | Dual effect of particle erosion resistance and corrosion resistance |
