Flange Loose Gear Cryogenic Gate Valve Bevel Gear Operated Flat Gate Valve Cast Steel Gate Valves

III. Structural Design & Features

1. Cryogenic Optimization

• Extended stem (protrusion ≥150mm) isolates cold media from operation mechanism, preventing frosting.
• Fiberglass thermal gasket between bonnet and body reduces heat transfer by 60%, minimizing cold loss.

2. Bevel Gear Drive Benefits

• 2:1 gear ratio reduces DN300 valve torque from 280N·m to 85N·m, enabling single-hand operation.
• Gearbox with lithium-based grease (-50°C to 120°C) extends maintenance cycle to 24 months.

3. Reliable Sealing

• Double-eccentric gate-seat design self-laps sealing surfaces, compensating for ≤0.3mm wear.
• V-type graphite packing + bellows dual sealing ensures zero leakage at 1.1x working pressure.

IV. Manufacturing & Quality Control

1. Cryogenic Material Treatment

• Cast steel normalized at 920°C + tempered at 650°C, impact energy ≥27J at -40°C (Charpy V-notch).
• STL6 overlay on seats aged at 500°C to eliminate stress, hardness HRC58-62.

2. Precision Machining

• Lost foam casting for body, dimension tolerance ≤±0.8mm, surface roughness Ra≤12.5μm.
• Bevel gears with ISO 8 class meshing, carburized and quenched (case depth 0.8-1.2mm).

3. Cryogenic Testing

• Cryogenic treatment: -196°C liquid nitrogen immersion for 24h to detect intergranular corrosion.
• Pressure cycling: 1,000 cycles at -46°C with no sealing degradation.