High-Temperature Steam Flanged Forged Steel Lift Check Valve

III. Structural Design & Technical Features

1. Lift Check Mechanism
   • Disc moves along vertical guide rods coaxial with the flow path, sealing specific pressure ≥18MPa for bidirectional bubble-tight performance.
   • Guide groove precision ≤0.03mm ensures smooth reset, preventing jamming in fluctuating conditions.
2. High-Temperature Optimization
   • Extended bonnet design (prolongation ≥50mm) reduces heat loss, keeping stem temperature ≤60℃ at 425℃ to prevent packing aging.
   • Valve disc spring made of 60Si2Mn alloy steel (quenched & tempered), tension loss ≤5% at 400℃ for low-pressure sealing reliability.
3. Forging Process Advantages
   • Body formed by 3000-ton die forging, eliminating casting porosity, grain size refined to Grade 7, fatigue resistance 40% higher than cast valves.
   • Surface sandblasted + epoxy primer (dry film thickness ≥100μm), atmospheric corrosion resistance ≥8 years.

IV. Manufacturing Processes & Quality Control

1. Precision Machining
   • Seat sealing surface CNC ground to flatness ≤0.01mm, red lead test contact rate ≥90%.
   • Stem straightness ≤0.02mm/m, coaxiality with packing ≤0.05mm for bias-free operation.
2. Heat Treatment
   • Forged blanks normalized at 920℃ + tempered at 650℃ to eliminate stress, hardness controlled at HB170-210.
   • STL alloy overlay aged at 550℃ to avoid welding stress cracks, hardness uniformity deviation ≤±3HRC.
3. Comprehensive Testing
   • Hydrostatic test: 1.5x pressure (30min hold), 1.1x sealing pressure—zero leakage (API 598).
   • High-temperature aging: 1000h continuous operation in 425℃ steam, seal wear ≤0.05mm.
   • Material traceability: Spectral analysis per heat (C/Si/Mn deviation ≤0.03%), provided with MTR.