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 the specific operating conditions of your duct — 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. We manufacture in-house. Every construction is matched to your application, not pulled from a generic catalog.
Fabric Expansion Joint Constructions
Select by operating condition. Each construction is defined by its temperature envelope and gas-chemistry suitability — not by appearance.
The correct construction is determined by your gas temperature and chemistry first, then by movement and geometry. Start with the operating envelope below, or use the Selection Guide to map your conditions to a recommended belt.
PTFE / Fluoropolymer Fabric Joints
For wet, acidic flue gas below the acid dew point. A PTFE/ePTFE gas-tight barrier resists SO₂/SO₃, HCl and HF condensate attack.
View construction →Fiberglass Fabric Joints
The workhorse for dry, high-temperature flue gas in boilers, furnaces and air heaters. High thermal resistance with proven service life.
View construction →Silicone-Coated Fabric Joints
Flexible, abrasion- and weather-resistant construction for mid-temperature exhaust, gas turbine and HVAC ducting.
View construction →Ceramic Fiber Fabric Joints
For extreme-temperature service at furnace inlets, kilns and waste incineration ducts where fiberglass reaches its limit.
View construction →Composite / Engineered Multi-Layer Belts
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 & temperature resistance
Multi-layer construction matches barrier, insulation and seal materials to your exact gas chemistry and temperature.
Low and negative pressure capability
Designed for low-pressure and vacuum (ID fan suction) 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.
Reliability comes from the layer stack, not a single fabric. Selecting to continuous temperature alone, or omitting a fluoropolymer barrier below the acid dew point, are the two most common causes of premature failure. Select a layer to see its material options and limits.
Cover / Weather Layer
Outer protection against ambient conditions, UV, abrasion and mechanical wear.
- Materials: silicone-coated glass, PTFE-coated glass
Fluoropolymer Barrier Film
Gas-tight chemical barrier. Mandatory below the acid dew point.
- Materials: PTFE / ePTFE film
- Resists SO₂/SO₃, HCl, HF condensate
Insulation Pillow / Bolster
Reduces belt temperature and protects outer layers from peak gas heat.
- Materials: ceramic fiber, fiberglass insulation
Gas Seal Membrane
Primary containment of process gas.
- Materials: PTFE film, fluoroelastomer, coated glass
Reinforcement Fabric
Structural strength and movement capability; carries pressure and vacuum loads.
- Materials: fiberglass, aramid, 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 |
| Aramid / composite | Application-specific | Good | App-specific | High |
Applications & Duct Locations
Find your service. Each application carries specific conditions that drive material and construction choice.
Power Generation
Boiler outlet · ID/FD fan connections · air heater · ESP inlet/outlet ducts.
High temperature with frequent thermal cycling. Dry flue gas typically uses fiberglass construction; ID fan connections require vacuum-rated reinforcement.
Get a quote for this application →FGD / Flue Gas Desulfurization
Absorber inlet/outlet · GGH · bypass ducts.
Wet, acidic gas operating below the acid dew point. A PTFE/ePTFE gas-tight barrier is mandatory to resist SO₂/SO₃ condensate attack.
Get a quote for this application →Cement Plants
Kiln · preheater · raw mill · baghouse ducts.
High temperature combined with heavy abrasive particulate. Requires robust insulation pillows and abrasion-resistant cover layers.
Get a quote for this application →Steel Plants
Sinter plant · blast furnace gas · dedusting ducts.
High temperature, heavy particulate and process gases. Construction balances thermal resistance with abrasion protection.
Get a quote for this application →Waste Incineration
Flue gas ducts · acid-gas environments.
Extreme temperature with corrosive acid gases. Combines ceramic insulation with fluoropolymer barrier protection.
Get a quote for this application →Industrial Boilers
Economizer · stack · fan connections.
Moderate-to-high temperature dry gas. Fiberglass construction with movement matched to thermal growth.
Get a quote for this application →HVAC / Gas Turbine
Exhaust and inlet ducting.
Mid-temperature service with vibration and flexibility demands — typically silicone-coated construction.
Get a quote for this application →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.
Correct selection follows a fixed order: temperature, then gas chemistry and dew point, then particulate, pressure and movement, then geometry. The more accurate your inputs — particularly peak temperature and dew point — the more reliable the result.
Technical Specifications
Specifications by construction type. Select a tab to view the full operating data.
The following ranges are representative for standard constructions. Final ratings are confirmed against your specific layer stack and geometry at quotation.
| Max continuous temperature | ~260°C |
|---|---|
| Max peak / excursion temperature | ~290°C |
| Pressure rating (positive) | Low pressure |
| Vacuum capability | Yes, with reinforcement |
| Round diameters | Per drawing |
| Rectangular dimensions | Per drawing |
| Movement | Axial / lateral / angular / torsional |
| Standards | EJMA, FSA design practices |
| Max continuous temperature | ~550°C |
|---|---|
| Max peak / excursion temperature | ~600°C |
| Pressure rating (positive) | Low pressure |
| Vacuum capability | Yes, with reinforcement |
| Round diameters | Per drawing |
| Rectangular dimensions | Per drawing |
| Movement | Axial / lateral / angular / torsional |
| Standards | EJMA, FSA design practices |
| Max continuous temperature | ~300°C |
|---|---|
| Max peak / excursion temperature | ~330°C |
| Pressure rating (positive) | Low pressure |
| Vacuum capability | Yes, with reinforcement |
| Round diameters | Per drawing |
| Rectangular dimensions | Per drawing |
| Movement | Axial / lateral / angular / torsional |
| Standards | EJMA, FSA design practices |
| Max continuous temperature | ~1000°C+ |
|---|---|
| Max peak / excursion temperature | ~1100°C |
| Pressure rating (positive) | Low pressure |
| Vacuum capability | Limited / by design |
| Round diameters | Per drawing |
| Rectangular dimensions | Per drawing |
| Movement | Axial / lateral / angular / torsional |
| Standards | EJMA, FSA design practices |
| Max continuous temperature | Application-specific |
|---|---|
| Max peak / excursion temperature | Application-specific |
| Pressure rating (positive) | Engineered to condition |
| Vacuum capability | Engineered to condition |
| Round diameters | Per drawing |
| Rectangular dimensions | Per drawing |
| Movement | Axial / lateral / angular / torsional |
| Standards | EJMA, FSA design practices |
Construction Comparison
Compare the five constructions across the parameters that drive selection.
Use this table to narrow your shortlist. Where conditions are borderline — particularly near the acid dew point or peak-temperature limits — confirm with the Selection Guide or our engineering team before specifying.
| Construction | Max Cont. Temp | Max Peak Temp | Chemical Resistance | Below Dew Point | Abrasion | Flexibility | Relative Cost | Typical Applications |
|---|---|---|---|---|---|---|---|---|
| PTFE / Fluoropolymer | ~260°C | ~290°C | Excellent | Yes | Moderate | Moderate | High | Wet acidic flue gas, FGD |
| Fiberglass | ~550°C | ~600°C | Moderate | No | Moderate | Moderate | Low | Dry high-temp flue gas |
| Silicone | ~300°C | ~330°C | Moderate | Limited | Good | High | Moderate | HVAC, gas turbine, vibration |
| Ceramic Fiber | ~1000°C+ | ~1100°C | Moderate | No | Moderate | Moderate | High | Extreme-heat service |
| Composite | App-specific | App-specific | Good | App-specific | High | Engineered | Engineered | When standards fall short |
Engineering Support
We work as a design partner — from movement analysis to outage-grade replacement.
Our engineering team supports your project from specification through installation. We analyze thermal growth and movement, design the layer stack for your gas chemistry, and work from your drawings or an existing sample to match replacement units precisely.
- 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
- Installation guidance and field support
Project Case Studies
Proven constructions in demanding service.
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 SO₂/SO₃ service.
Result: In service with no leakage; replacement fabricated within the outage window.
Discuss a similar application →Challenge: High temperature with heavy abrasive particulate wearing through prior joints.
Solution: Fiberglass construction with reinforced insulation pillow and abrasion-resistant cover.
Result: Extended service life under continuous abrasive load.
Discuss a similar application →Challenge: Negative pressure at fan suction causing belt collapse.
Solution: Vacuum-rated reinforcement with movement matched to thermal growth.
Result: Stable operation under sustained negative pressure.
Discuss a similar application →Resources & Downloads
Technical documentation for specification, design and installation.
Datasheets and the selection guide are available immediately. The full product catalog is available on request.
Frequently Asked Questions
Technical answers on selection, reliability and procurement.
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.
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.
From mid-temperature silicone constructions (~300°C) through fiberglass (~550°C) to ceramic fiber (1000°C+), depending on the layer stack. Always specify to peak temperature, not continuous.
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.
It is the temperature at which acidic vapors (e.g., SO₃) condense as corrosive liquid. Below it, condensate attacks the belt — making a PTFE/ePTFE gas-tight barrier mandatory.
Fiberglass for dry, high-temperature flue gas; PTFE/fluoropolymer for wet, acidic gas below the dew point. Many constructions combine both across different layers.
Yes, with anti-collapse reinforcement designed for the negative pressure at ID fan suction.
Service life depends on correct construction for the conditions. A correctly specified joint typically delivers multi-year service; mis-specification is the primary cause of short life.
Yes — we fabricate from your existing drawing or a physical sample, including for outage replacements.
We manufacture in-house with our own QA, material traceability and engineering team — not a trading intermediary.
Request a Quote
Send your operating conditions and a drawing or sample. We typically respond within 24–48 hours.
The more complete your operating data — temperature, gas composition, dew point, movement and dimensions — the faster and more precise our response. Flag outage or emergency requirements and we’ll fast-track your request.
- Manufacturer, not a trader
- ISO 9001 Certified
- EJMA Member
- Material traceability
- Drawing confidentiality assured
- Quotes typically within 24–48 hours
- Emergency outage fast-track available