Rectangular Bellows Expansion Joint

Rectangular bellows expansion joints, also known as rectangular metal bellows compensators, are specifically designed for use with rectangular and square flue and duct systems. They rely on the elastic deformation of the rectangular bellows to absorb axial, lateral, and angular displacements caused by thermal expansion and contraction of the ductwork, while also reducing vibration and noise and compensating for installation deviations and foundation settlement. They are commonly used in low-pressure, large-cross-section duct systems such as boiler flue gas, hot air, and dust collection ducts.

Since 2012, Yangzhou Tianshun has specialized in the manufacturing of rectangular metal bellows expansion joints (rectangular expansion compensators). Leveraging 14 years of industry expertise, a 35,000-square-meter modern production facility, and a professional workforce of over 100 technical staff, we provide both standard and fully customized rectangular bellows solutions to clients in more than 45 countries worldwide.

All our rectangular expansion joints are designed and manufactured in accordance with international standards, including EJMA, EN 14917, GOST, and ASME. We provide a Material Test Certificate (MTC) for every component, ensuring full material traceability. Prior to shipment, every unit undergoes 100% non-destructive testing (NDT) as well as hydrostatic or pneumatic leak testing. We also offer bespoke, non-standard designs based on your specific drawings, cross-sectional dimensions, and displacement parameters.

Our products serve a wide range of sectors, including oil refining, petrochemicals, power generation, metallurgy, boiler flue gas systems, dust removal/desulfurization/denitrification processes, and hot-air ducting systems. Available configurations include single-bellows, multi-bellows, hinged, universal-hinged, and internally-sleeved (liner-equipped) rectangular expansion joints. We utilize high-performance alloys—such as 321, 316L, 316H, Inconel 625, and Hastelloy—that offer superior resistance to high temperatures, erosion, and corrosion.

We provide comprehensive support for EPC projects, ranging from preliminary budget estimates during the bidding phase to final supply for secured contracts, as well as the provision of spare parts for the maintenance of environmental flue gas systems. For EPC projects in the CIS region and the Middle East, we can supply fatigue analysis reports, WPS/PQR welding documentation, and a complete technical dossier to assist clients in meeting the certification requirements of their respective countries and regions.

Product Structure

Rectangular Bellows Body: The core elastic component, available in structures such as the rounded-corner CE type and right-angle type

Rectangular Flanges: Connect to square ducts via bolted joints

Deflector Sleeve (Optional): Prevents direct impact of flue gas and dust on the bellows, extending service life

Limit Rod (Optional): Limits the maximum compensation range to prevent excessive stretching or compression of the bellows

Shipping Restraints: Provided for factory protection; removed after installation is complete

Product Advantages

1. Suitable for square/rectangular ducts; available in large-cross-section custom designs; capable of absorbing multi-directional displacement (axial, lateral, and angular) simultaneously

2. Reduces vibration and noise, isolating the transmission of vibrations from fans and boiler equipment to the ductwork

3. Excellent sealing performance and high-temperature resistance; withstands dust-laden and corrosive flue gas media

4. Compensates for installation misalignment and foundation settlement, reducing on-site construction complexity

5. Diverse structural configurations; rounded-corner designs offer superior fatigue resistance

Applicable Operating Conditions

Boiler flue ducts, hot air ducts, dust removal and exhaust ducts, as well as rectangular duct systems in power plants, metallurgy, cement, and chemical industries.

Suitable for: Square/rectangular large-cross-section ducts, low-pressure high-temperature flue gas, dust-laden gases, and vibration damping at fan inlets and outlets

Not suitable for: High-pressure circular process pipelines (circular bellows expansion joints are preferred)

Technical Specifications

Material: 304, 316L, 321, Corten steel, nickel-based alloys, etc. (customizable) Cross-sectional Dimensions: Customizable based on duct length and width (A × B) Pressure Rating: PN0.01–PN2.5 (primarily low pressure) Temperature Range: –20°C to 800°C Connection Method: Rectangular flange connection / welding Compensation Capacity: Axial displacement, lateral displacement, angular displacement

Selection & Installation Guidelines

1. For selection, the duct cross-sectional dimensions (length and width), pressure, temperature, medium, and compensation amounts in all three directions must be provided

2. Rounded-corner designs offer better fatigue resistance than right-angle designs; installation of a flow guide sleeve is recommended in dust-erosion conditions

3. Limit rods are used solely to restrict maximum displacement and must not bear the thrust from internal pipe pressure

4. Remove the shipping lock bolts after installation to ensure the bellows can expand and contract freely

5. Ducts must be equipped with appropriately spaced fixed supports and guide supports to prevent the bellows from twisting or becoming unstable

Factory Scale and Production Capacity

Our partner production facility spans 35,000 square meters and employs over 100 skilled technical and production personnel, backed by 14 years of experience in manufacturing piping components. The workshop is fully equipped for forming, welding, heat treatment, non-destructive testing (NDT), and hydrostatic/pneumatic pressure testing. We specialize in custom-engineered large-cross-section rectangular expansion joints, which can be tailored to specific dimensions, corrugation heights, and the number of corrugations; we are also capable of producing rectangular expansion joints using high-alloy materials and heavy-gauge plates. Leveraging a well-established local industrial cluster, we can scale production beyond our internal capacity—while maintaining strict quality control and oversight—by coordinating with external partner facilities. This ensures that neither product quality nor delivery timelines are compromised. We offer both standard product lines and customized solutions for projects involving flue gas, denitrification/desulfurization systems, and hot-air piping, with flexible production scheduling available for large-scale orders.

Bulk Supply Capability

We possess a robust capacity for large-scale supply, specifically for orders involving rectangular corrugated expansion joints and spring supports/hangers used in large-scale flue gas duct projects for power plants, smelting facilities, and desulfurization/denitrification systems.

Supported by a stable and qualified supply chain, we maintain consistent stock of standard stainless steel plates, specialized alloys (such as 321/316L and Inconel 625), and standard components. For high-volume project orders, we prioritize production scheduling and offer flexible shift management to shorten overall delivery lead times.

1. Standard Products: We can handle large-volume orders, ensuring steady output and continuous supply.

2. Customized Project Products: For large-scale orders involving a mix of cross-sections, corrugation profiles, and materials, we provide full material traceability for each unit, batch-based non-destructive testing (NDT), and individual component identification.

3. Flexible Phased Delivery: For long-term projects—such as power plant construction or environmental facility expansions—we offer phased production and staggered shipments aligned with the on-site construction schedule and installation progress. Leveraging a mature local industrial cluster, we can also scale up production beyond our internal capacity; we establish the production standards and oversee external partner facilities to ensure that product quality and delivery timelines remain uncompromised.

4. Consistent Quality Control for Bulk Orders: Every order is executed according to unified production processes, Welding Procedure Specifications (WPS), and inspection standards. We provide comprehensive documentation for the entire batch, including test records, Material Test Certificates (MTC), and inspection reports.

FAQ:

Q1: Can project-specific fabrication drawings and calculation reports for rectangular expansion joints be provided during the tender/inquiry stage? 

A1: During the tender/budgeting stage, we can provide standard data sheets and general reference diagrams. Project-specific fabrication drawings and formal calculation reports will be issued upon order confirmation. If the client requires a pre-award review of supplier drawings, this documentation service can be quoted separately as an optional value-added item.

Q2: Which international standards are followed for rectangular bellows expansion joints and pipe supports/hangers? 

A2: Rectangular metal bellows expansion joints are designed in accordance with standards such as EJMA, EN 14917, GOST, and the ASME series. Pipe supports and hangers comply with standards including MSS SP-58, MSS SP-127, ASME B31.1/B31.3, EN 13480-3, GOST 22130-2018, and GB/T 17116.

Q3: What high-alloy materials are available for high-temperature flue gas or corrosive desulfurization (FGD) environments? 

A3: We offer special alloys—such as SS321, 316H, Inconel 625, and Hastelloy—suitable for high-temperature flue gas and sulfur-containing, erosive/corrosive environments. A full Material Test Certificate (MTC) is provided for every heat/batch of material.

Q4: What export packaging options are available? How are large-cross-section rectangular expansion joints packaged and protected? 

A4: We provide standard plywood export crates, as well as heavy-duty, moisture-proof, and anti-rust packaging designed for long-haul ocean freight. For large-cross-section or ultra-heavy rectangular expansion joints that cannot fit into enclosed crates, we utilize heavy-duty steel cradles secured with specialized positioning fixtures. Critical components—such as the bellows and flange faces—receive extra protection, and the units are prepared for transport via break-bulk or flat-rack/open-top containers.

Q5: What technical documentation can be provided? 

A5: We have successfully secured formal projects and are capable of preparing a complete set of WPS (Welding Procedure Specification), PQR (Procedure Qualification Record), and ITP (Inspection and Test Plan) documentation. We also provide the full range of technical supporting data required for EAC/COC certification.

Q6: What is the product warranty period? 

A6: The warranty period is 24 months from the date the goods arrive at the port of destination, covering defects in manufacturing. This warranty does not cover damage resulting from improper transportation, incorrect installation, or operation under abnormal conditions.