Custom engineered non-metallic ducting compensators
Fabric Expansion Joints – Custom Non-Metallic Ducting Compensators
Engineered multi-layer belts that absorb thermal movement, vibration, and misalignment in corrosive, high-temperature flue gas and process ducting – built to your duct geometry and gas chemistry.
We design and fabricate each belt to your continuous and peak gas temperature, gas composition, acid dew point, particulate loading, and movement vectors, so the joint survives years of thermal cycling and chemical exposure without leakage or premature failure.
Fabric Expansion Joint Constructions
Select by operating condition. Each construction is defined by its temperature envelope and gas-chemistry suitability – not by appearance.
PTFE / Fluoropolymer Fabric Joints
Up to ~260°C | Corrosive wet flue gas, FGD
For wet, acidic flue gas below the acid dew point. A PTFE/ePTFE gas-tight barrier resists SO2, SO3, HCl and HF condensate attack.
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Fiberglass Fabric Joints
Up to ~550°C | Dry high-temperature flue gas
The workhorse for dry, high-temperature flue gas in boilers, furnaces and air heaters. High thermal resistance with proven service life.
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Silicone-Coated Fabric Joints
Up to ~300°C | Mid-temp, flexible, vibration
Flexible, abrasion- and weather-resistant construction for mid-temperature exhaust, gas turbine and HVAC ducting.
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Ceramic Fiber Fabric Joints
Up to ~1000°C+ | Extreme high temperature
For furnace inlets, kilns and waste incineration ducts where fiberglass reaches its limit.
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Composite / Engineered Multi-Layer Belts
Application-matched | Engineered to condition
Fully engineered layer stacks built to a specific gas chemistry, dew point and movement profile when standard constructions are insufficient.
Get the right construction →Why Fabric Expansion Joints
Engineered for the conditions where metallic bellows are unsuitable.
Large multi-axis movement
Absorb significant axial, lateral and angular movement in large ducts where rigid or metallic solutions cannot flex.
Near-zero spring force
Impose negligible reaction load on connected ducting, fans and structures, protecting equipment and supports.
Engineered corrosion resistance
Multi-layer construction matches barrier, insulation and seal materials to exact gas chemistry and temperature.
Low and negative pressure capability
Designed for low-pressure and vacuum service, including anti-collapse reinforcement where required.
Field-replaceable without welding
Flanged and clamped designs allow replacement during outage windows without hot work on the duct.
Lightweight, large-section coverage
Span large rectangular and round openings at a fraction of the weight of metallic alternatives.
Inside the Belt – Multi-Layer Construction
A fabric expansion joint is an engineered layer stack. Each layer is selected for a specific function and matched to your gas conditions.
Cover / Weather Layer
Outer protection against ambient exposure, UV, abrasion and mechanical wear. Typical materials include silicone-coated glass and PTFE-coated glass.
Fluoropolymer Barrier Film
Gas-tight chemical barrier. Mandatory below the acid dew point. PTFE/ePTFE film resists SO2, SO3, HCl and HF condensate.
Insulation Pillow / Bolster
Reduces belt temperature and protects outer layers from peak gas heat. Common materials include ceramic fiber and fiberglass insulation.
Gas Seal Membrane
Primary containment of process gas. Materials include PTFE film, fluoroelastomer and coated glass.
Reinforcement Fabric
Structural strength and movement capability. Carries pressure and vacuum loads using fiberglass, aramid or composite weave.
| Material | Max Continuous Temp | Chemical Resistance | Below Dew Point | Abrasion |
|---|---|---|---|---|
| PTFE / ePTFE | ~260°C | Excellent | Yes | Moderate |
| Fiberglass | ~550°C | Moderate | No | Moderate |
| Silicone-coated glass | ~300°C | Moderate | Limited | Good |
| Ceramic fiber | 1000°C+ | Moderate | No | Moderate |
Applications & Duct Locations
Find your service. Each application carries specific conditions that drive material and construction choice.
High temperature with frequent thermal cycling. Dry flue gas typically uses fiberglass construction; ID fan connections require vacuum-rated reinforcement.
Get a construction recommendation →Wet, acidic gas operating below the acid dew point. A PTFE/ePTFE gas-tight barrier is mandatory to resist acidic condensate attack.
Get a construction recommendation →High temperature combined with heavy abrasive particulate. Requires robust insulation pillows and abrasion-resistant cover layers.
Get a construction recommendation →High temperature, heavy particulate and process gases. Construction balances thermal resistance with abrasion protection.
Get a construction recommendation →Extreme temperature with corrosive acid gases. Combines ceramic insulation with fluoropolymer barrier protection.
Get a construction recommendation →Moderate-to-high temperature dry gas. Fiberglass construction with movement matched to thermal growth.
Get a construction recommendation →Mid-temperature service with vibration and flexibility demands – typically silicone-coated construction.
Get a construction recommendation →Fabric Expansion Joint Selection Guide
Define your operating conditions. We map them to a recommended belt construction – and you can submit those exact inputs as your RFQ.
Technical Specifications
Specifications by construction type. Select a tab to view the full operating data.
| Maximum continuous temperature | ~260°C |
|---|---|
| Pressure / vacuum | Low positive and negative pressure with reinforcement |
| Typical service | FGD, wet acidic flue gas, below dew point service |
| Maximum continuous temperature | ~550°C |
|---|---|
| Pressure / vacuum | Low positive and negative pressure with anti-collapse design |
| Typical service | Boilers, furnaces, dry high-temperature flue gas |
| Maximum continuous temperature | ~300°C |
|---|---|
| Pressure / vacuum | Low pressure duct and vibration service |
| Typical service | HVAC, gas turbine exhaust, mid-temperature ducts |
| Maximum continuous temperature | 1000°C+ |
|---|---|
| Pressure / vacuum | Application-specific frame and reinforcement |
| Typical service | Kilns, incineration, furnace inlet ducts |
| Maximum continuous temperature | Application-specific |
|---|---|
| Pressure / vacuum | Designed to operating load case |
| Typical service | Borderline chemistry, dew point, abrasion or movement conditions |
Construction Comparison
Compare the five constructions across the parameters that drive selection.
| Construction | Max continuous | Peak temp | Chemical resistance | Below dew point | Abrasion | Typical use |
|---|---|---|---|---|---|---|
| PTFE / Fluoropolymer | ~260°C | Moderate | Excellent | Best | Moderate | Wet acidic gas, FGD |
| Fiberglass | ~550°C | High | Moderate | Limited | Moderate | Dry high-temp flue gas |
| Silicone | ~300°C | Moderate | Moderate | Limited | Good | Vibration, HVAC, gas turbine |
| Ceramic fiber | 1000°C+ | Highest | Moderate | Limited | Moderate | Kilns, incineration, furnace ducts |
| Composite engineered | Application-specific | Application-specific | Engineered | Engineered | Engineered | Borderline or severe service |
Not sure which? Use the Selection Guide → or Talk to an Engineer →
Engineering Support
We work as a design partner – from movement analysis to outage-grade replacement.
- Movement and thermal-growth analysis
- Custom multi-layer construction design for your gas chemistry
- CAD / drawing support and dimension verification
- Replacement from existing drawing or physical sample
- Quick-turn and emergency outage support
Project Case Studies
Proven constructions in demanding service.
FGD Absorber Inlet – Power Plant
Challenge: Existing joint failing from acid condensate attack below the dew point.
Solution: Multi-layer construction with PTFE/ePTFE gas-tight barrier matched to wet acidic service.
No leakage after outage replacement
Cement Kiln Duct
Challenge: High temperature plus heavy abrasive particulate wearing through prior joints.
Solution: Fiberglass construction with reinforced insulation pillow and abrasion-resistant cover.
Extended service life under continuous abrasive load
Boiler ID Fan Connection – Power Plant
Challenge: Negative pressure at fan suction causing belt collapse.
Solution: Vacuum-rated reinforcement with movement matched to thermal growth.
Stable operation under sustained negative pressure
Resources & Downloads
Technical documentation for specification, design and installation.
Frequently Asked Questions
Technical answers on selection, reliability and procurement.
What is a fabric expansion joint?
A non-metallic, multi-layer textile/composite assembly that absorbs thermal movement, vibration and misalignment in low-pressure, large-section ducting where metallic bellows are impractical.
How do I select the correct material?
Work in order: continuous and peak temperature, then gas chemistry and acid dew point, then particulate, pressure and movement. Temperature sets the base material; dew point and chemistry determine whether a fluoropolymer barrier is required.
What temperature can fabric expansion joints withstand?
From mid-temperature silicone constructions around 300°C through fiberglass around 550°C to ceramic fiber at 1000°C+, depending on the layer stack. Always specify to peak temperature, not continuous.
Why do fabric expansion joints fail prematurely?
The most common causes are specifying to continuous temperature while ignoring peak excursions, and omitting a fluoropolymer barrier in gas that operates below the acid dew point. Other causes include under-specified movement, abrasion, and vacuum collapse.
Can fabric expansion joints handle vacuum?
Yes, with anti-collapse reinforcement designed for the negative pressure at ID fan suction.
Are you a manufacturer or a trader?
We manufacture in-house with our own QA, material traceability and engineering team – not a trading intermediary.