III. Structural Features

• Trunnion-Mounted Ball Design: The ball is supported by upper and lower trunnions, distributing pressure loads to prevent deformation under high pressure. This eliminates “ball blowdown” risk, ensuring stable operation even in flow surges—critical for Class 600+ high-pressure systems.
• Metal-to-Metal Sealing: Precision-lapped metal seat and ball surfaces (Ra ≤0.8μm) form a bubble-tight seal (ANSI FCI 70-2 Class V). Spring-loaded seats automatically compensate for thermal expansion and wear, maintaining tightness across temperature cycles and long-term use.
• Safety Enhancements:
  • Anti-blowout stem: Stem bottom features an inverted seal structure to prevent ejection under high pressure, meeting API 600 safety standards.
  • Anti-static device: 304 stainless steel spring connects the ball and body, dissipating static (resistance ≤10⁶Ω) to avoid sparks in flammable media like natural gas.
  • Fire-safe design: Graphite backup seals ensure basic shut-off after fire, compliant with API 607, reducing leakage risks in fire emergencies.
• Double Block and Bleed (DBB): Configurable to isolate upstream and downstream media simultaneously, with a bleed port to vent trapped pressure—enhancing maintenance safety in high-risk systems.

IV. Manufacturing Processes

• Forged Material Preparation: Use high-quality forged steel billets (A105/F316), and verify the chemical composition (such as A105 C≤0.30%, Mn≤1.00%) through spectral analysis to ensure mechanical properties.Forgings undergo ultrasonic testing to eliminate internal defects like cracks or shrinkage.
• 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 for tight sealing.
  • Body & Flange: CNC lathes machine flange sealing faces to flatness ≤0.05mm, with bolt holes drilled to ±0.1mm tolerance for pipeline alignment. Trunnions are precision-machined to ensure stable ball rotation.
• Heat Treatment: Forged components undergo annealing (650-700℃) to relieve internal stress, reducing deformation risks during operation. Metal seats may be Stellite-coated (hardness ≥55 HRC) for wear resistance.
• Assembly & Testing:
  • Seat Assembly: Spring-loaded seats are pre-tested at 1.5×rated pressure to validate compensation capability, ensuring consistent contact with the ball.
  • Performance Testing: Each valve undergoes API 598 testing: hydrostatic shell test (1.5×rated pressure, 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 actuation.