III. Structural Features

• Top Entry Design: The valve body has a removable top cover connected to the body via bolts. Internal components (ball, seat, stem) can be accessed and removed from the top for inspection or replacement without disassembling the entire valve or disconnecting the pipeline, significantly reducing maintenance time—ideal for systems with limited installation space or buried pipelines.
• Trunnion-Mounted Ball: The ball is fixed by upper and lower trunnions, preventing displacement caused by media pressure and reducing wear on sealing surfaces. Compared to floating ball structures, its load-bearing capacity is 40% higher, maintaining stable operation even under Class 600 high pressure, extending service life.
• Gear Operation System: Equipped with a worm gearbox with an optimized transmission ratio of 1:30, reducing manual operation force by 60% for easy opening/closing of DN150 large-diameter valves. The gearbox housing is made of cast iron with IP65 protection, dustproof and waterproof, suitable for outdoor or humid environments.
• Safety Enhancements:
  • Anti-blowout Stem: The stem features an inverted seal structure at the bottom to prevent accidental blowout under high pressure, meeting API 600 safety standards;
  • Anti-static Device: A stainless steel spring connects the ball and valve body to discharge static electricity (resistance ≤10⁶Ω), avoiding spark risks from static buildup;
  • Fire-safe Construction: The seat uses graphite backup sealing to maintain basic sealing performance after fire, complying with API 607 fire safety requirements.

IV. Manufacturing Processes

• Body Casting: WCB cast carbon steel valve bodies are produced using resin sand casting, followed by annealing (650-700℃ for 4 hours) to eliminate internal stress and reduce deformation risks. Castings have surface roughness ≤25μm, no internal shrinkage or cracks, and pass 100% penetrant testing (PT).
• Precision Machining:
  • Valve flow channels and flange faces are machined by 5-axis machining centers, with dimensional tolerance controlled within ±0.05mm. Flange sealing surfaces have flatness ≤0.05mm to ensure tight fit with pipeline flanges;
  • Balls are processed by CNC grinders, with surface roughness Ra≤0.8μm and sealing surface angle error ≤0.05° for reliable sealing;
  • Gearbox gears are manufactured using high-precision hobbing, with tooth surface hardness ≥55 HRC and meshing clearance ≤0.03mm for smooth transmission.
• Assembly & Testing:
  • Seats are pre-assembled with spring preload adjustment to automatically compensate for sealing gaps during temperature changes;
  • Valves undergo API 598 testing: shell hydrostatic test (1.5×nominal pressure for 30 minutes with no leakage); seat test (1.1×nominal pressure with bubble leakage ≤1 per minute);
  • Operation test: 100 opening/closing cycles via manual gear operation to verify smooth operation, no jamming, and accurate position indication.
• Surface Treatment: Valve bodies are sandblasted (Sa 2.5) and coated with high-temperature anti-rust paint (dry film thickness ≥100μm), passing 1000-hour salt spray testing for outdoor or high-humidity environments.