Rectangular Expansion Joints
Rectangular expansion joints are custom-designed metal expansion joints developed primarily for low-pressure applications such as ducts, exhaust, and ventilation systems. They are capable of absorbing axial, lateral, and angular movements while accommodating large rectangular cross-sections.
Overview
Rectangular expansion joints are specially engineered to compensate for thermal expansion, vibration, and mechanical movement in rectangular ducting systems. Unlike circular joints, they are primarily used in low-pressure environments such as exhaust, ventilation, and flue gas systems.
Movement Capability
- Absorbs axial movement
- Absorbs lateral movement
- Absorbs angular movement
- Can be designed for combined axial and lateral displacement
Design & Construction
- Single or multi-convolution rectangular bellows
- Available as single-bellows or twin-bellows configurations
- Twin-bellows design recommended for large lateral movements
- Corner configurations: single mitre, double mitre, or rounded corners
- Supplied as complete units or sectional assemblies for transport and on-site reassembly
Customization Options
- No practical size limitation – sectional delivery available
- Frames and bellows tailored to customer-specific dimensions
- Designed as fully customized solutions for rectangular ducting systems
Materials
- Austenitic stainless steels (300 series)
- Duplex stainless steels
- Aluminium
- Titanium
- High-nickel alloys: Inconel, Incoloy, Hastelloy, Monel
High-Temperature Insulation Option
For applications with extremely high internal temperatures (up to approximately 1000 °C) and low external surface temperature requirements (e.g. 90 °C), rectangular expansion joints can be equipped with special internal flow liners.
- Flow liner material example: EN 1.4845
- Designed with expansion gaps to prevent liner buckling
- Void between liner and bellows filled with high-temperature insulation bolster
- Reduces external surface temperature for personnel safety and system protection
Applications
- Rectangular ducting systems
- Exhaust gas systems
- Ventilation systems
- Flue gas and air handling systems
- Industrial process ducts
Key Advantages
- Absorbs multi-directional movement
- Ideal for large rectangular cross-sections
- Highly customizable design
- Suitable for extreme temperature gradients
- Reliable solution for low-pressure ducting applications