Product Overview
The Large Round Flange Edge Welded Bellows is the heavy-duty flagship of our standard product line, designed for large-scale industrial vacuum systems where substantial structural loads, high pressure differentials, and extreme temperatures converge. With large-diameter flanges and a reinforced multi-convolution diaphragm stack, this bellows handles up to 20 bar positive pressure and operating temperatures to 400°C — making it suitable for vacuum smelting, aerospace thermal test chambers, and nuclear industry service.
Despite its scale, this bellows is built with the same micro-plasma edge welding precision as our smallest UHV models. Each diaphragm is individually welded under controlled atmosphere, and the completed assembly undergoes helium mass spectrometer leak testing. For the largest standard sizes in our catalog (up to 1,200mm OD), see the large-diameter range in our AT-Series Specification Catalog.
Key Benefits
- Maximum structural strength — large-diameter flanges with reinforced bolt patterns distribute loads across multiple fasteners, handling positive pressures up to 20 bar in sizes that smaller bellows cannot achieve
- Reinforced diaphragm design with thicker walls (up to 0.5mm) and optimized convolution geometry withstands high external collapse pressure under full vacuum while maintaining flexibility
- Superior thermal capability — SS316L rated to 400°C; Inconel 718 upgrade available to 700°C for the most extreme environments (see Material Selection Guide)
- 1 million+ cycle fatigue life — edge welded construction eliminates the premature fatigue failure modes common to formed bellows of comparable size
- Designed for harsh industrial environments — corrosion-resistant SS316L with optional passivation or electropolishing for chemical and marine atmosphere service
Technical Specifications
- Flange Type: Large Round Flange (ISO-K, ISO-F, ANSI, JIS; custom drilling patterns on request)
- Material: SS316L Stainless Steel — AM350 and Inconel 718 available
- Vacuum Level: 10⁻⁸ mbar (standard); UHV 10⁻¹⁰ mbar with copper gasket option
- Operating Pressure: Up to 20 bar positive pressure (external collapse rated for full vacuum)
- Operating Temperature: -196°C to +400°C (SS316L); up to 700°C (Inconel 718)
- Axial Stroke: ±15–20mm
- Angular Deflection: ±4°
- Cycle Life: 1,000,000+ cycles at rated stroke
- Surface Finish: Standard / Passivated / Electropolished
Typical Applications
- Large vacuum coating production lines — architectural glass coating, roll-to-roll web coating, display panel manufacturing
- Industrial vacuum smelting furnaces — vacuum arc remelting (VAR), vacuum induction melting (VIM), electron beam melting
- Aerospace test equipment — large thermal vacuum chambers for satellite qualification, engine altitude test cells
- Nuclear industry vacuum systems — tritium extraction plants, fuel rod inspection stations, hot cell vacuum services
- Large-scale research installations — fusion reactor vacuum vessel connections, space simulation chambers, neutrino detector vacuum systems
