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FRP Duct that carries
what steel cannot
Wet acidic exhaust destroys galvanised and coated steel ductwork from the inside. GRP ducting has no coating to fail. We build rectangular and circular ducts, fume extraction runs and stack liners, with nozzles and access openings moulded in.
Rectangular and Circular
Fume Duct
Stack Liner
Vinyl ester + C-veil
Made in Vietnam
Product Range
Three forms, one material
Ducting is rarely a catalogue item. Cross-section, routing and support points are set by the building, so almost every job is designed and built to the specific installation.
Round and rectangular sections, joined by bolted flange or laminated butt and strap.
Illustrative images, not project photographs.
TYPE 01
Rectangular Duct
The usual choice inside buildings, where a rectangular section fits the available ceiling space better than a round one. Flat panels carry less load than a cylinder, so stiffener design does the work.
- Hand lay-up, panel and stiffener construction
- Flanged sections for site assembly
- Access doors and instrument ports moulded in
- Cleanroom and process exhaust
TYPE 02
Circular Duct
Structurally the most efficient section, and the preferred choice for longer runs and higher negative pressure. Filament wound in the same way as pipe.
- Filament wound, uniform wall thickness
- Long runs with fewer joints
- Elbows, tees and reducers to match
- Scrubber inlet and outlet ducting
TYPE 03
Stack Liner
A GRP liner inside an existing steel or concrete stack. The structure stays, the corroding surface is replaced. Often the cheaper answer to a failing stack.
- Retrofit into existing stack structure
- Wet acidic and condensing service
- Sectional build for site assembly
- Post-FGD and scrubber discharge
Design
Specification
| Item | Detail |
|---|---|
| Section | Rectangular, circular, and transition pieces between the two |
| Size range | Circular DN100 to DN3000. Rectangular sized to the installation, no fixed limit |
| Resin | Vinyl ester for wet acidic exhaust. Isophthalic for general ventilation. Fire-retardant grade to ASTM E84 Class I where required |
| Liner | C-veil for acid service. Synthetic veil for general service |
| Reinforcement | External ribs and stiffeners, spacing set by the negative pressure case |
| Jointing | Bolted flange joint, or laminated butt and strap overlay. Both are standard for round and rectangular sections |
| Integral fittings | Access doors, damper frames, drain points, instrument ports, support lugs |
| Standards | ASTM D2996 (wound sections), ASTM E84 (fire-retardant grade), client specification |
Sizes above are our normal working range. If your scope falls outside it, send the specification and we will confirm whether we can build it.
Negative pressure decides the design
An exhaust duct spends its life under suction. Internal pressure is easy to design for, because it pushes the wall into tension where the laminate is strongest. Suction does the opposite, and a duct that fails does so by buckling inward, not by bursting.
- Fan static pressure the design case, including the blocked-filter condition
- Stiffener spacing the main variable, set from the buckling calculation rather than from wall thickness alone
- Rectangular panels flat spans need more support than a curved section of the same area
- Support points hanger positions come from the same calculation, not chosen on site
This is why we ask for flow rate, fan pressure and the routing before quoting. Duct that is priced on area alone is priced without knowing what holds it up.
Delivered Projects
Ducting we have built
Select any item to open the project detail page.
SEMICONDUCTOR
Samsung GRP Rectangular Exhaust Duct
Cleanroom exhaust ducting, with stiffener design set by the negative pressure case.
SEMICONDUCTOR
Amkor New Factory Scrubber and Duct Array
Scrubbers and connecting ductwork supplied together as an array for a new facility.
CHEMICAL
Maruei Kako GRP Fume Exhaust Duct
Acid fume extraction in continuous wet corrosive service, built to Japanese client requirements.
Send the flow rate and the fan curve
Gas composition, operating temperature, flow rate, fan static pressure and the routing are enough for us to size the section and the stiffeners. A layout sketch is fine, drawings are not required.
Need help? Contact us
