Specification
Bellows Seal Flanged High Pressure Cast Steel Globe Valve
I. Product Overview
NWV bellows seal flanged globe valves are engineered for toxic, flammable, and high-purity media, featuring dual sealing from bellows and packing to eliminate external leakage. Constructed from WCB cast steel, 304/316 stainless steel, and CF8/CF8M, they cover DN15-DN150 (1/2″-6″) with PN16-PN40 (1.6MPa-4.0MPa), suitable for -29℃~425℃. The valve regulates flow via stem movement, offering linear flow characteristics for precise control in chemical, pharmaceutical, and power industries with strict leakage requirements.
II. Core Technical Parameters
Specifications & Pressure-Temperature Range
Nominal Diameter: DN15/20/25/32/40/50/65/80/100/125/150 (1/2″-6″)
Pressure Class: PN16/PN25/PN40 (1.6MPa/2.5MPa/4.0MPa)
Temperature Range: -29℃~200℃ (NBR bellows), -40℃~425℃ (stainless steel bellows)
Materials & Sealing System
Body Bonnet: WCB cast steel (A216 WCB), 304/316 stainless steel (A351 CF8/CF8M)
Bellows: 316L stainless steel (wall thickness 0.25-0.5mm), 2-4 layers, fatigue life ≥10,000 cycles
Seat Seal: PTFE (standard), PPS (high-temp), hard alloy (abrasion-resistant)
Connection: Flanged (ASME B16.5, GB/T 9113), RF/FF face
Actuation & Operation
Actuation: Manual (with gearbox option), electric (IQ series actuator), pneumatic (double-acting cylinder)
Flow Characteristic: Linear, turndown ratio 100:1
Protection Grade: IP67 (electric actuator), Ex d IIB T4 (explosion-proof option)
Product Overview
III. Structural Design & Technical Features
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.
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.
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
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.
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.
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.
