Rectangular Expansion Joint
Non-circular fabricated bellows for low-pressure ducting and flue-gas runs — takes thermal movement where rectangular cross-sections, large dimensions and abrasive or particle-laden media rule out conventional round joints.
Technical Data
| Bellow Material | Carbon Steel St37.2 standard (opt. Stainless Steel AISI 304 / 316 / 321) |
|---|---|
| Connection Type | Weld-Neck, Flanged, or without additional connection parts |
| Media | Fluids, gases, abrasive media and solids |
| Nominal Sizes | DN25 to DN3000 |
| Max. Temperature | 550 °C |
| Max. Pressure | PN40 |
Selection Guide
Welded directly into the duct wall — the standard build.
Best forFlue-gas ductsBolting frames for demountable duct sections.
Best forMaintenance sectionsInternal baffle shields the convolutions from abrasive flow.
Best forAsh & particle ductsDatasheet & Drawings
Rectangular duct joint specifications on one page, plus the technical drawing. Every unit is drawn to your duct size — the approval drawing follows with the quotation.
EN 10204 3.1 material certificates are supplied with your shipment.
Also in This Range
Frequently Asked Questions
What is a rectangular expansion joint?
A rectangular expansion joint is a metal bellows shaped to a square or rectangular cross-section that absorbs the thermal movement of fabricated ductwork while keeping the gas path sealed. It is the ductwork counterpart to a round-pipe expansion joint.
Why do rectangular joints use rounded or mitred corners?
The corners of a rectangular bellows carry the highest stress. Rounded corners distribute that stress and give the longest fatigue life under thermal cycling; mitred (welded) corners suit lower-movement, lower-temperature duty and simpler fabrication.
What movement can a rectangular expansion joint absorb?
It accommodates axial, lateral and angular movement together, calculated separately for the wide and narrow faces of the duct so each side is sized for its actual resultant movement.
Should I choose a metal or fabric rectangular joint?
Metal rectangular joints suit higher temperatures, pressures and erosive gas; fabric joints suit low-pressure ducts needing very large movement at near-zero reaction force. TOTFLEX supplies both and advises per duct.
What sizes and materials are available?
Units are made to order from small fan connections to large boiler and stack ducts, in carbon steel, stainless (304 / 316 / 321) or heat-resistant alloys chosen for the gas chemistry and temperature — a design envelope to around 550 °C, verified per duty.
Does TOTFLEX provide drawings and certificates?
Yes. An approval drawing is issued before fabrication, and units ship with EN 10204 3.1 material certificates, weld/NDT and dimensional reports, and PED/SEP declarations where applicable.
Engineered to order. Delivered worldwide.
Send your duty conditions — size, pressure, temperature, medium and connections — and our engineers return a drawing, material selection and lead time.
Request a quote