Straight Pipe Pressure Balanced Expansion Joint

Straight Pipe Pressure Balanced Expansion Joints are specifically designed for long-distance straight pipelines to address the issue that standard axial expansion joints cannot counteract the thrust generated by internal pipeline pressure. Consisting of a working bellows, a balancing bellows, an intermediate balancing cylinder, and pressure-bearing tie rods, these joints rely on structural mechanical balance to counteract the thrust generated by the internal pressure of the medium. They do not require heavy-duty fixed supports and only need simple guide supports. They primarily absorb axial thermal expansion and contraction of the pipeline, preventing damage to pipes, pumps, and valves caused by internal pressure thrust. They are commonly used in long-distance steam and process straight pipe runs.

Product Structure

Working bellows: Absorbs axial thermal displacement of the pipeline

Balancing bellows and balancing cylinder: Offset internal pressure thrust to achieve pressure balance

Pressure-bearing tie rods and nuts: Bear the balancing load to ensure structural stability

End Connections / Flanges: Available in both welded and flanged connection types

Transportation Locking Device: Provided as factory protection; removed after installation

Product Advantages

1. Features a built-in pressure-balancing structure that offsets internal pressure thrust, reducing support fabrication and installation costs

2. Suitable for long straight pipe runs; provides large axial compensation and stable operation

3. Isolates internal pressure thrust to protect equipment such as pumps, valves, and heat exchangers

4. High rigidity; resistant to fatigue and vibration; withstands high temperatures and pressures; resistant to instability and deformation

5. Simple installation; eliminates the need for heavy-duty fixed supports; simplifies piping design; shortens construction time

Applicable Conditions

Long-distance straight process piping, high-temperature and high-pressure steam pipelines, petrochemical and oil/gas transmission pipelines, power plant pipelines, and long-distance HVAC networks. Suitable for: Straight pipe sections with large spans, where heavy-duty fixed supports cannot be installed, and where end-of-line equipment requires protection

Not suitable for: Elbows, non-standard pipe sections, and pipelines requiring significant lateral or angular compensation

Technical Specifications

Material: 304, 316L, 321, duplex steel, Hastelloy, etc. (customizable) Nominal Diameter: DN50–DN6000 Pressure Rating: PN0.25–PN40; ultra-high pressure available upon request Temperature Range: –196°C to 480°C Connection Type: Welded pipe ends / flanged connection Compensation Capacity: Compensates for axial displacement only; does not compensate for lateral or angular displacement

Selection & Installation Guidelines

1. Designed solely for axial compensation and pressure balancing; must not be installed at elbow bends to prevent failure

2. The pressure-bearing tie rod and balancing cylinder are critical load-bearing components; cutting, striking, or removal is strictly prohibited

3. Be sure to remove the shipping lock bolts before commissioning; otherwise, normal compensation will not be possible

4. Install guide supports along the pipeline to ensure the expansion joint expands and contracts in a straight line, preventing misalignment and instability

5. When selecting a model, provide the pipe diameter, pressure, temperature, and axial compensation amount to ensure compatibility with the operating conditions

Bulk Supply Capability

We possess a reliable capacity for large-scale supply, specifically catering to orders for metal bellows expansion joints and spring supports/hangers required for major projects in the petrochemical, refining, and power generation sectors.

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

1. Standard Products: We can handle large-volume orders, with a stable monthly output that ensures continuous supply.

2. Customized Project Products: Even for large orders comprising a diverse mix of specifications, we ensure full material traceability for every individual unit, conduct non-destructive testing (NDT) by batch, and manage components through unique, individual part numbering.

3. Flexible Phased Delivery: For long-term projects—such as refinery expansions—we can align production and shipments with the construction progress on-site, ensuring that deliveries match the installation schedule. Furthermore, by leveraging our location within a mature industrial cluster, we can 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: We apply uniform production processes, Welding Procedure Specifications (WPS), and inspection standards across the entire batch. We provide comprehensive documentation for the full order, including batch test records, Material Test Certificates (MTC), and inspection reports.