316L bellows expansion joint, good anti-rust property for water and general chemical pipelines.
Desc: This stainless steel welded metal bellows expansion joint is designed to absorb thermal expansion, contraction, vibration and minor misalignment of industrial pipelines. It can accommodate axial, lateral and angular displacement effectively. Available materials include 304, 316L, 321 and 254SMO. Manufactured in accordance with EJMA and GB/T12777 standards. We support custom diameter, wave number, wall thickness and pressure rating from PN6 up to PN160. Flange or butt-weld ends are optional. Material test certificate 3.1, hydraulic test and RT inspection reports can be provided upon request. Widely used in water, steam, oil and general chemical piping systems.
1. Overview
Metal bellows are thin-walled corrugated elastic metal components, acting as the flexible core of metal expansion joints. With continuous corrugated profiles, they absorb axial, lateral, angular and combined displacements under working pressure while maintaining tight sealing.
They are designed to compensate thermal expansion and contraction of pipelines, isolate vibration, reduce noise, accommodate installation misalignment, and provide hermetic sealing for pressure or vacuum systems. They can be applied as pipeline compensators, mechanical seal components, instrument sensing elements and flexible connectors for high-temperature and corrosive media.
Common industries include petrochemical, power generation, LPG, natural gas, metallurgy, shipbuilding, aerospace, refrigeration and semiconductor.
2. Main Types by Production Process
Formed Bellows (Hydroformed / Mechanically Formed)
Manufactured from seamless metal tubing via hydraulic bulging or rolling. U-shaped, Ω-shaped and S-shaped convolutions are available. The bellows body has no weld seam, bringing low leakage risk, stable pressure resistance and reliable fatigue performance. U-shaped formed bellows are the standard choice for most piping expansion joints.
Welded Diaphragm Bellows
Fabricated by stacking thin metal diaphragms and alternately welding inner and outer edges. They feature thinner wall thickness, superior flexibility and larger single-unit displacement. They are widely adopted in precision instruments, vacuum feedthroughs, bellows valves and high-precision sealing applications, with a higher price compared with formed bellows.
3. Material Performance Reference
| Material | Continuous Service Temperature | Key Features | Typical Application |
|---|---|---|---|
| 304 Stainless Steel | ≤550℃ | General corrosion resistance, cost-effective | Steam, water, air and common gas pipelines |
| 316L Stainless Steel | ≤550℃ | Good chloride resistance, anti-pitting corrosion | Chemical media, coastal conditions, LPG service |
| 321 Stainless Steel | ≤600℃ | Stabilized alloy, excellent high-temperature property | High-temperature flue gas, heat exchange systems |
| Inconel 625 | ≤980℃ | Superior high-temperature and corrosion resistance | Hot exhaust streams, severe chemical processes |
| Monel 400 | ≤480℃ | Excellent resistance to seawater and alkaline fluids | Seawater, brine and marine piping |
