Metal Bellows

Metal Bellows Manufacturer for Thermal Expansion & Industrial Piping Systems

Metal bellows expansion joints absorb movement, reduce vibration, and handle heat expansion in pipe systems. They protect high-pressure and high-temperature pipelines from stress damage.

We manufacture single-ply and multi-ply metal bellows using stainless steel and high-nickel alloys. All designs meet EJMA standards and ASME B31.3 piping requirements.

Product Range

Single-Ply Bellows

Design: Single thick metal layer for high movement capacity at lower cost.
Wall Thickness: 0.2 mm to 1.5 mm
Best For: Engine exhaust systems, low-pressure HVAC ducts, and ventilation lines.

Multi-Ply (Multi-Layer) Bellows

Design: Multiple thin metal layers welded together for high pressure and long fatigue life.
Wall Thickness: 2 to 5 layers (0.15 mm to 0.6 mm per layer)
Best For: High-pressure steam lines, power plant pumps, and chemical pipelines.

Flanged Metal Expansion Joints

Connections: Fixed, loose (lap joint), or recessed flanges matching ASME B16.5, EN 1092-1, or JIS standards.
Best For: Pump inlets and outlets, valve connections, and heat exchangers.

Welded End Metal Expansion Joints

Connections: Beveled pipe ends (Schedule 10 to Schedule 80) for direct welding into pipelines.
Best For: Underground heating pipes, district energy networks, and leak-free chemical lines.

Tied & Universal Bellows

Design: Fitted with tie rods, hinges, or gimbals to hold pressure force while allowing lateral or angular movement.
Best For: Complex pipe routes where main pipe anchors cannot be installed.

Materials

Material Grade	Common Name	Key Feature	Best Application
AISI 304 / 304L	1.4301 / 1.4307	Good basic corrosion resistance, low cost	Water pipes, low-pressure steam, HVAC
AISI 316L	1.4404	Contains molybdenum, resists pitting	Chemical plants, marine, food processing
AISI 321	1.4541	Titanium added, resists high-heat decay	High-temp exhaust (-200 to 800 degrees C)
Inconel 625	UNS N06625	High strength, resists stress corrosion cracking	Offshore oil and gas, hot acid systems
Hastelloy C-276	UNS N10276	Resists strong oxidizers and chlorine gas	Flue gas cleaning, aggressive chemical tanks

Operating Parameters

Parameter	Specification
Pipe Size Range	DN15 to DN3600 (1/2 inch to 144 inches)
Pressure Ratings	PN2.5, PN6, PN10, PN16, PN25, PN40, PN63, PN100 (Class 150 / 300 / 600)
Vacuum Capability	Up to 1 x 10^-8 mbar.l/s leak rate
Forming Method	Hydraulic forming or mechanical roll forming
Inner Liners (Optional)	SS304, SS316L, or PTFE sleeve for high flow or abrasive fluids
Outer Covers (Optional)	Carbon steel or stainless steel shroud to prevent external damage

Industry Applications

Power Plants: Steam turbine lines, boiler feed pipes, and gas turbine exhausts.

Chemical Plants: Oil pipelines, flare lines, and heat exchanger inlets.

HVAC Systems: Chiller pipe connections, cooling towers, and steam main headers.

District Energy: Underground heating networks requiring long life without maintenance.

Shipbuilding: Engine exhaust pipes, ballast water lines, and LNG fuel piping.

Custom Manufacturing Capabilities

Design & Analysis: We run EJMA stress and fatigue calculations based on your pressure, temperature, and movement requirements.

Tube Rolling & Welding: Automatic TIG welding machines form full-penetration longitudinal seams without weak spots.

Convolution Forming: Hydraulic presses form the convolutions evenly without thinning the metal wall beyond tolerance limits.

Assembly Welding: CNC machining cuts the flanges, and skilled welders join the ends to the bellows body.

Testing & Inspection: Every unit undergoes pressure testing, weld checks, and dimensional verification.

Quality Control & Testing Standards

Every bellows assembly is tested before packing:

100% Pressure Test

We perform hydrostatic pressure tests (at 1.5 times working pressure) or pneumatic leak tests (at 1.1 times working pressure).

Weld Inspection

Radiographic Testing (RT) or Liquid Penetrant Testing (PT) checks all main seam welds per ASME Section VIII rules.

Helium Leak Test

Available for vacuum lines and dangerous gases (leak rate down to 1 x 10^-9 std cm^3/s).

Material Traceability

EN 10204 3.1 Material Test Reports (MTR) are provided for all pressure-retaining parts.

Certifications

ISO 9001:2015 Quality Management System

PED 2014/68/EU Module H for Pressure Equipment

ASME U-Stamp compliance available upon request

Packaging & Shipping Protection

Shipping Bars Installed

Yellow steel travel bars lock the bellows length during transit to prevent stretching or bending. (Note: Remove these bars after installation).

Flange Face Covers

Plastic caps or wooden covers protect all flange faces and weld ends.

Export Crates

ISPM-15 heat-treated wooden boxes with waterproof foil lining shield goods from sea humidity.

Shipping Documents

Material test reports (MTR 3.1), pressure test certificates, and inspection sheets are placed inside every box and sent via email.

Our Factory

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FAQ

Q: What is the difference between single-ply and multi-ply metal bellows?

A: Single-ply bellows use one thick metal layer. They are ideal for lower pressure and cost-sensitive applications. Multi-ply bellows use multiple thin metal layers. They handle higher working pressures while staying flexible, offering a much longer fatigue life under cyclic movement.

Q: Why are shipping bars attached to the expansion joint?

A: Shipping bars hold the expansion joint at its correct length during shipping and installation. This stops the bellows from stretching or sagging. You must remove these bars after installation and before system pressure testing or startup.

Q: How do I choose the correct material for corrosive fluids?

A: Standard SS304 or SS316L works well for clean water, steam, and mild chemicals up to 400 degrees Celsius. If your fluid contains chlorides, ocean salt, or strong acids, choose Inconel 625 or Hastelloy C-276 to prevent stress corrosion cracking.

Q: When should I request an internal flow liner?

A: You need an internal liner when fluid speed exceeds 3 meters per second for liquids or 15 meters per second for gases. Liners smooth the fluid flow, stop convolution vibration, cut pressure loss, and protect the bellows from inner wear.

Q: Can you manufacture custom bellows to fit existing pipe dimensions?

A: Yes. We build custom replacement bellows matching your exact face-to-face length, bolt hole layout, and size. You can send us your original drawing, brand model, or physical measurements to start the quote process.

Q: What test certificates come with the shipment?

A: Each shipment includes an EN 10204 3.1 Material Test Report (MTR), a Factory Pressure Test Certificate, and a Final Inspection Report. X-ray (RT), dye penetrant (PT), or helium leak test reports are included when requested in your order.

We're well-known as one of the most experienced metal bellows suppliers in China. With abundant experience, we warmly welcome you to buy high quality metal bellows in stock here and get quotation from our factory. For price consultation, contact us.

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