III. Features Description

• Fully Welded Body Integrity: The body uses welded joints instead of bolts, eliminating potential leakage points common in flanged valves. Spherical or cylindrical welded designs (1~2 seams) ensure uniform stress distribution, critical for underground pipelines where leakage is hard to detect.
• Trunnion-Mounted Stability: The ball is fixed by upper and lower trunnions, transferring fluid pressure to trunnion bearings instead of the seat. This avoids ball displacement under high pressure, preventing seat wear and ensuring consistent sealing—vital for gas transmission.
• Forged Material Reliability: Forged bodies eliminate casting defects like shrinkage cavities or cracks, ensuring structural strength in high-pressure environments. The uniform material density resists fatigue, extending service life to 30 years.
• Gear Operation Convenience: The gear drive reduces operating torque by 50% compared to direct manual operation, allowing one person to control large-diameter (up to DN1500) valves. Its self-locking design prevents accidental rotation from pipeline vibration.
• Safety & Maintenance Features: Integrates cavity pressure self-relief (avoids overpressure damage), fire-safe design (API 607), and anti-blowout stem (prevents ejection under extreme pressure). Emergency sealant injection ports enable on-site leak repair, reducing downtime.

IV. Manufacturing Processes

• Forging & Welding: A105/F316 materials are forged to form dense blanks, then welded into spherical or cylindrical bodies using TIG welding. Ultrasonic testing verifies weld integrity, ensuring no hidden cracks.
• Precision Machining: Ball and seat surfaces are CNC-machined to Ra ≤0.8μm for tight sealing. Trunnions are press-fitted and welded to the body, with bearing surfaces ground for smooth rotation.
• Seat Assembly: PTFE seats are pre-loaded with springs to compensate for wear, ensuring consistent contact with the ball. Gear components are calibrated to 0.1~0.2mm meshing clearance for smooth torque transmission.
• Testing:
  • Hydrostatic Test: Body tested at 1.5×rated pressure (e.g., 6.4MPa for PN40) for 30 minutes; seat tested at 1.1×rated pressure to confirm no leakage.
  • Fire-Safe Test: Exposed to 750℃ fire, then tested for post-fire sealing to meet API 607.
  • Operation Test: 100+ open/close cycles verify gear smoothness and trunnion stability under pressure.