III. Structural Features

• Floating Ball Design: The ball is not fixed to trunnions but “floats” within the body. When media flows, pressure pushes the ball against the downstream seat, creating a self-tightening seal. This design eliminates complex trunnion structures, reducing weight while ensuring sealing reliability under varying pressures.
• Metal-to-Metal Sealing: The ball and seat feature precision-machined, lapped metal surfaces (Ra ≤0.8μm). SS304 or Stellite-coated seats resist wear, corrosion, and high temperatures, outperforming soft seals in steam, abrasive, or chemical environments.
• Manual Operation System: Equipped with a worm gearbox (cast iron housing) with a 30:1 transmission ratio, lowering manual force required to operate large-diameter valves. The handwheel (cast iron with anti-slip coating) includes position indicators for clear open/close status.
• Safety Enhancements:
  • Anti-blowout stem: Stem bottom features an inverted seal structure, preventing ejection under high pressure (API 600 compliant).
  • Anti-static device: Stainless steel spring connects ball and body, dissipating static (resistance ≤10⁶Ω) to avoid sparks in flammable media.

IV. Manufacturing Processes

• Material Selection & Inspection: Carbon steel and SS304 raw materials undergo spectral analysis to verify chemical composition (e.g., SS304: 18-20% Cr, 8-10.5% Ni). WCB forgings are ultrasonic-tested to eliminate internal defects.
• Precision Machining:
  • Ball & Seat: CNC grinders achieve ball roundness ≤0.01mm and surface finish Ra ≤0.8μm; seats are lapped to match ball contours, ensuring uniform contact.
  • Body & Flange: CNC lathes machine flange sealing faces to flatness ≤0.05mm, with bolt holes drilled to ±0.1mm tolerance for pipeline alignment.
• Assembly & Testing:
  • Seal Assembly: Metal seats are pre-loaded with springs to compensate for thermal expansion, ensuring consistent contact with the ball.
  • Performance Testing: Each valve undergoes:
    • Hydrostatic shell test (1.5×PN40 for 30 minutes) with no leakage.
    • Gas tightness test (0.6MPa nitrogen) with leakage ≤0.1×10⁻⁶ mL/s.
    • Operation test (100+ cycles) to verify smooth gear operation and position accuracy.
• Surface Treatment: Carbon steel bodies are sandblasted (Sa 2.5) and coated with high-temperature anti-rust paint (dry film thickness ≥80μm); SS304 components are passivated to enhance corrosion resistance.