III. Structural Features

• Metal-to-Metal Sealing: The disc and seat feature precision-machined, lapped surfaces (Ra ≤0.8μm) for tight contact. A bi-directional sealing design ensures bubble-tight shutoff in both flow directions, critical for high-temperature applications where thermal expansion could compromise soft-seated valves.
• High-Temp Disc & Stem: The disc (310s/CF8c) and stem (17-4 PH stainless steel, heat-treated to 35-40 HRC) resist warping and deformation under extreme heat. The stem’s anti-blowout design (API 600-compliant) prevents dislodgement during pressure surges.
• Thermal Compensation: A flexible graphite packing system and expansion bellows (blue component in the image) absorb axial/radial thermal expansion, maintaining stem seal integrity and reducing friction—key for valves cycling between ambient and high temperatures.
• Lever-Gear Actuation: The yellow lever-gear assembly provides mechanical advantage, reducing manual operation force by 40% for large-diameter (40-inch) valves. The gearbox housing (cast aluminum) offers IP66 protection against dust and water ingress.

IV. Manufacturing Processes

• Material Selection & Heat Treatment:
  • 310s/CF8c components undergo solution annealing (1050-1100°C for 30 minutes) to enhance grain structure and thermal stability.
  • 304/316 parts are passivated to boost corrosion resistance, ensuring longevity in chemically aggressive media.
• Precision Machining:
  • The valve body and disc are CNC-machined from solid forgings, with flow paths optimized via computational fluid dynamics (CFD) to minimize pressure drop (≤10% of inlet pressure at full flow).
  • Sealing surfaces are lapped to Ra ≤0.8μm, ensuring uniform contact and leak-free operation.
• Assembly & Testing:
  • The stem-disc connection is laser-welded (penetration depth ≥2mm) to prevent loosening under thermal cycling.
  • Hydrostatic tests: Shell tested at 1.5×Class 300 (7.5MPa) for 60 minutes; seat tested at 1.1×Class 300 (5.5MPa) with zero visible leakage.
  • High-temperature validation: Cycled from ambient to 1200°C (310s model) 50 times, with post-test leakage remaining within Class IV limits.
• Surface Finishing:
  • Bodies and discs are sandblasted (Sa 2.5) to remove scale, then coated with high-temp ceramic paint (dry film thickness ≥150μm) for added oxidation resistance in 1000°C+ environments.