When do you use a bellows seal valve?
Use a bellows seal valve when your application meets one or more of the following criteria:
- Strict emission requirements under TA-Luft, VDI 2440 or ISO 15848
- Media is toxic, flammable or environmentally hazardous
- Maintenance is costly or impractical due to location or process continuity
- Operating temperature exceeds 180 °C or drops below 0 °C (cryogenic)
- Steam systems where condensate formation or leakage is not permitted
For non-critical applications with clean media, a standard globe valve is often the more cost-effective choice.
How does the metal bellows work?
The metal bellows is hermetically welded to the valve stem. When the valve is operated, the bellows compensates for the vertical stem movement without allowing any contact between the medium and the surrounding environment. There is no packing to wear out, no gland to re-tighten and no emission point requiring periodic inspection.
The flow path follows the globe valve principle: as the valve opens, the disc moves upward and gradually increases the annular flow opening. This makes the bellows seal valve equally suitable as a control valve — flow can be dosed precisely without pressure surges.
Bellows seal valve or globe valve: which do you choose?
| Criterion |
Bellows seal valve |
Globe valve |
| Emissions |
+ Complies with TA-Luft |
- Packing can deteriorate |
| Maintenance |
+ No packing replacement |
- Periodic adjustment required |
| Purchase price |
- Higher |
+ Lower |
| Flow control |
+ Gradual, precise |
+ Gradual |
| Temperature range |
+ Cryogenic to >400 °C |
+ Standard to 300 °C |
| Toxic media |
+ Yes |
- Limited |
Versions, materials and standards
Select your bellows seal valve based on pressure, temperature, medium and required certification.
Materials:
- Cast iron (EN-GJL-250): water, steam to PN16
- Carbon steel (WCB / P250GH): steam, condensate, oil to PN40
- Stainless steel (CF8M / 1.4408): chemical, food, cryogenic
- Hastelloy / Duplex: aggressive acids, chlorine, ammonia
Connections: flanged (EN 1092, ASME B16.5 RF/RTJ), butt weld (BW), threaded end (NPT/BSP)
Standards and certifications: EN 13480, ASME B31.1/B31.3, material certificates EN10204-3.1, TA-Luft, Classification societies (DNV, Lloyd's, Bureau Veritas)
Pressure ratings: PN10 to PN250 | ASME Class 150 to Class 600+
Note when selecting: a higher pressure class does not automatically require a heavier bellows — bellows wall thickness and number of convolutions determine service life under cyclic loading.
Applications by industry
Steam and condensate
Bellows seal valves are used in steam lines and condensate return systems where packing emissions compromise process safety or hygiene. Combine with a steam trap for fully controlled steam management.
Thermal oil
In thermal oil installations up to 350 °C, stem leakage creates a fire hazard. The welded bellows eliminates this risk without additional safety measures.
Chemical industry
For chlorine, ammonia, sulphuric acid and other aggressive media, the stainless steel or Hastelloy bellows seal valve meets TA-Luft emission requirements. ARI Armaturen supplies certified versions for these applications.
Food & beverage and pharma
In hygienic processes, the bellows seal valve is used for steam-in-place (SIP) and clean-in-place (CIP) applications, where the sealed design also prevents external contamination.
Cryogenic installations
For liquid nitrogen, LNG and other cryogenic media down to -196 °C, the bellows seal valve is preferred for its temperature-resistant bellows and the absence of packing that becomes brittle at low temperatures. Spirax Sarco supplies specialised versions for this temperature range.
Actuating a bellows seal valve
Bellows seal valves fitted with an ISO 5210 top flange are directly compatible with pneumatic and electric actuators. Handwheel versions are not standard-ready for automation — an ISO top flange version is required, or the valve must be replaced entirely.
Actuator selection:
- Pneumatic: high switching frequency, fail-safe execution available
- Electric: suitable where compressed air is unavailable, precise positioning
- Manual: handwheel or extended stem for remote operation without automation
When requesting a quote, provide the ISO top flange specification and required torque — these determine actuator selection. The bellows seal valve can also be combined with safety valves for protected process stations.
Expert advice on bellows seal valves
Select the right bellows seal valve based on medium, pressure, temperature and required certifications, or request a quote directly from our valve specialists.
Request a quote
Frequently asked questions
What pressure and temperature ratings are available for bellows seal valves?
Standard versions are available up to PN250 and ASME Class 600. Maximum temperature depends on material: carbon steel to approximately 400 °C, stainless steel to 550 °C. Cryogenic versions are rated down to -196 °C. Contact us for specifications outside these ranges.
Which certifications are available for bellows seal valves?
Ebora supplies bellows seal valves with material certificates to EN10204-3.1, TA-Luft certification (VDI 2440), classification society approvals (DNV, Bureau Veritas, Lloyd's) and PED compliance (2014/68/EU). Please state the required certification when placing your enquiry.
What is the difference between a PN and ASME rated version?
PN-rated versions follow European EN/DIN standards for flange connections and pressure classes. ASME-rated versions are intended for installations governed by US codes (ASME B31.1 or B31.3), such as petrochemical and offshore projects. When in doubt, the applicable installation standard determines which version you need.
