Zhengda Valve

One-Stop Supplier for Rubber Joints, Bellows, and Waterproof Casings

Metal Bellows Expansion Joint

The Metal Bellows Expansion Joint, also known as a Stainless Steel Compensator or Metal Flexible Connector, is designed to absorb axial, lateral, and angular movements in piping systems caused by thermal expansion, vibrations, or installation deviations. Constructed with multi-layer stainless steel bellows and optional external protective covers, it offers superior pressure resistance, temperature tolerance, and long service life.

It is commonly used in HVAC systems, power plants, petrochemical pipelines, exhaust systems, and high-temperature applications that require reliable flexibility and leak-free performance.

Key Features

•High-Grade Stainless Steel Bellows – Made from SS304/316L for durability and corrosion resistance.

•Excellent Movement Absorption – Capable of absorbing axial, lateral, and angular displacements.

•Wide Temperature Range – Operates from -100°C to +600°C depending on the structure.

•Customizable Ends – Available with flange, threaded, or welded ends to suit installation needs.

•Pressure-Rated Design – Handles high working pressures in steam and oil pipelines.

•Also Known As – Corrugated Metal Expansion Joint, Steel Compensator, Bellows Coupling.

Technical Specifications

Dimensions & Sizes

✅ Bellows Expansion Joint Specification Table (DN32–DN1000)

Nominal Diameter (DN)	Recommended Waves	Pressure Rating (MPa)	Effective Area (cm²)	Max OD (mm)	Length (mm)	Flange DZ/F (mm)	End DF/J (mm)
DN32	8	0.25 / 0.6 / 1.0 / 1.6 / 2.5	225	250	160	250	264
DN40	8	Same as above	244	259	164	259	269
DN50	8	Same as above	259	276	172	276	282
DN65	6	Same as above	270	294	215	294	300
DN80	6	Same as above	284	338	240	338	344
DN100	6	Same as above	304	317	235	317	323
DN125	6	Same as above	334	314	282	314	316
DN150	5	Same as above	364	389	282	389	338
DN200	4	Same as above	442	384	280	384	348
DN250	4	Same as above	507	379	315	379	415
DN300	4	Same as above	562	427	366	427	466
DN350	4	Same as above	622	452	397	452	497
DN400	4	Same as above	700	478	412	478	512
DN450	3	Same as above	760	498	503	498	503
DN500	3	Same as above	835	523	431	523	531
DN600	3	Same as above	980	548	478	548	578
DN700	3	Same as above	1110	590	490	590	590
DN800	3	Same as above	1265	602	502	602	602
DN900	3	Same as above	1186	689	689	689	689
DN1000	3	Same as above	1286	692	692	692	692

Technical Parameters

✅ Technical Parameters – Metal Bellows Expansion Joint

Parameter	Unit	Typical Value / Range
Nominal Diameter	mm (DN)	DN32 – DN1000
Design Pressure	MPa	0.25 / 0.6 / 1.0 / 1.6 / 2.5 (customizable up to 6.4 MPa)
Working Temperature	°C	-40°C ~ +550°C (depending on materials)
Applicable Media	–	Water, Steam, Oil, Gas, Air, Chemical Fluids, etc.
Material – Bellows	–	Stainless Steel SS304 / SS316L / 321
Material – Flange	–	Carbon Steel / Stainless Steel / Galvanized Steel
Connection Type	–	Fixed Flange, Loose Flange, Welded End
Movement Type	–	Axial, Lateral, Angular, Universal
Axial Compensation	mm	Typically 20–50 mm (varies by model and size)
Lateral Compensation	mm	Up to 30 mm (customizable)
Angular Deflection	degrees	Up to ±15°
Design Standard	–	GB/T 12777, EJ/T 1021, EN 14917, ASME B31.3

Rubber Materials

Material	Properties	Application Purpose

SS304

Good corrosion resistance, widely used

General pipeline systems, HVAC, clean water

SS316L

Excellent corrosion and acid resistance

Chemical, food, and pharmaceutical industries

SS321

Good high-temperature resistance

Heat exchangers, boilers

Carbon Steel

High strength, economical

Low-pressure or uncritical applications

Galvanized Steel

Rust prevention for outdoor use

General construction piping

Installation Guide

✅ Maintenance Guide

• Inspect the joint regularly for deformation, leaks, or corrosion
• Check flange bolts for loosening and tighten if necessary
• Replace the joint if you find fatigue cracks or serious wear
• Clean dust or corrosive residue from the surface regularly
• Avoid long-term exposure to extreme heat or vibration
• Follow the manufacturer’s service life and replacement guidelines

Maintenance Guide

1. Pre-Installation Inspection

•Check for any shipping damage or visible deformation on the bellows.

•Verify that the product type, size, pressure rating, and flange specifications match the design requirements.

•Ensure all accessories such as tie rods, limit rods, and gaskets are included and undamaged.

2. Installation Environment

•Avoid installation in areas exposed to excessive vibration, corrosive chemicals, or UV radiation.

•For outdoor applications, use protective covers or shields to extend product life.

•Make sure the pipeline system is properly aligned and supported before installing the expansion joint.

3. Installation Instructions

•Install the expansion joint in the neutral (uncompressed and untwisted) position.

•Do not stretch, compress, or offset the bellows prior to or during installation.

•Use proper gaskets and align flanges correctly before tightening bolts.

•Tighten bolts crosswise and gradually to ensure uniform sealing pressure.

4. Precautions

•Do not use the expansion joint to correct severe pipeline misalignment.

•Never weld near the bellows while installed. Remove it first if necessary.

•Do not paint or coat the bellows surface, which may affect its flexibility and heat dissipation.

•Avoid torsional stress—do not twist the joint during installation or use.

5. Operating Conditions

•Ensure that operating pressure and temperature remain within the specified limits.

•Limit movements (axial, lateral, angular) to design specifications.

•Periodically check for vibration, noise, or unusual displacement during operation.

6. Routine Maintenance

•Perform regular visual inspections for cracks, leaks, or deformation.

•Inspect the integrity of flange bolts and tie rods.

•Replace any worn or damaged components immediately to prevent system failure.

What kind of documents are included with the shipment?

We provide a full set of export documents, including packing list, commercial invoice, product test report, and material certificate. Custom clearance documents are also available upon request.

What sizes and materials are available for metal bellows expansion joints?

Our metal bellows are available in sizes from DN25 to DN1200, and made from stainless steel 304, 316L, or carbon steel with various end connections. We offer custom configurations to meet high-pressure, high-temperature, or corrosive media requirements.

Can you produce customized rubber joints according to our drawing?

Yes. We support OEM and ODM services. Just send us your drawing or specifications, and our technical team will provide a matching solution with fast production.

Why Choose Zhengda Valve & Pipeline Co., Ltd.?

•18+ Years of Experience: Trusted manufacturer of rubber expansion joints and pipeline solutions since 2005.

•Certified Quality: ISO certified factory with strict quality control and full material traceability.

•Custom Solutions: OEM & ODM supported with fast turnaround and technical support.

•Competitive Pricing: Factory-direct pricing ensures cost-effective solutions for global buyers.

•Reliable Service: Fast response, on-time delivery, and long-term partnership mindset.

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