Bellows Seal Flanged Globe Valves High Pressure Cast Steel Globe Valve

III. Structural Design & Technical Features

1. Dual Sealing Assurance
   • Bellows welded between stem and bonnet form a metal diaphragm seal, external leakage ≤1×10⁻⁹mbar·L/s.
   • Packing uses V-type PTFE+graphite as a secondary seal against bellows failure.
2. Hydrodynamic Optimization
   • Streamlined flow path reduces pressure drop by 15% vs. traditional globe valves (DN50 Cv=15).
   • Plunger-type disc design eliminates friction during closure, extending seal life.
3. Bellows Reliability Design
   • Multi-layer bellows disperse stress, enhancing fatigue resistance by 300%.
   • Internal guide sleeve prevents stem offset, ensuring coaxial bellows movement.

IV. Manufacturing Processes & Quality Control

1. Bellows Fabrication
   • Hydraulic forming with wall thickness tolerance ≤±0.03mm, corrugation height error ≤±0.1mm.
   • TIG automatic welding with 100% helium mass spectrometry leak test, leakage ≤1×10⁻⁹Pa·m³/s.
2. Body Machining Precision
   • Seat sealing surface CNC lapped to flatness ≤0.005mm, roughness Ra≤0.4μm.
   • Stem straightness ≤0.01mm/m, coaxiality with bellows ≤0.05mm.
3. 3D Quality Inspection
   • Hydrostatic test: 1.5x working pressure for shell (30min hold), 1.1x for sealing (zero leakage).
   • Bellows fatigue test: 10,000 cycles without failure (ASME BPVC Section VIII Div.1).
   • Material spectral analysis: Element deviation ≤0.03% per heat.