Choosing the right duct system is one of the most consequential decisions on any HVAC project. GI (Galvanized Iron) duct and PI-Duct (Pre-Insulated Duct) each have clear strengths — and understanding them will save you time, budget, and compliance headaches.
What is GI Duct?
GI duct is fabricated from galvanized steel sheet. It is the most widely used duct type in commercial and industrial HVAC systems worldwide. GI ducts are built to withstand high static pressures and are fully compliant with QCS 2014 Section 22 and SMACNA standards.
GI ducts can be rectangular, circular, or oval — and can be manufactured to virtually any custom dimension on-site or in-factory. They are typically wrapped externally with glass wool or PIR insulation after installation.
- APPLUS Fire Rated — 120-minute fire resistance
- QCS 2014 Section 22 compliant
- Civil Defense approved for Qatar
- Available in gauge 0.5mm to 1.6mm
What is PI-Duct (Pre-Insulated Duct)?
PI-Duct integrates the duct and insulation into a single pre-fabricated panel, typically using a PIR foam core with aluminium foil facings. This eliminates the need for separate external insulation, reducing installation time significantly.
PI-Duct is ideal for air conditioning systems where thermal performance and condensation control are critical — particularly in hot and humid climates.
- UL 181 Listed — MH63347
- Maximum velocity: 25 m/s
- Maximum pressure: 2000 Pa
- Thermal conductivity: λ = 0.023 W/m·K
Which Should You Choose?
| Factor | GI Duct | PI-Duct |
|---|---|---|
| Installation speed | Moderate (insulation separate) | Fast (all-in-one) |
| Pressure rating | Up to 2500 Pa | Up to 2000 Pa |
| Fire rating | Up to 120 min (APPLUS) | Class 1 |
| Thermal performance | Depends on insulation spec | Excellent (λ = 0.023) |
| Best for | High-pressure, fire-rated, custom | Standard AC, fast installations |
For most commercial projects, GI duct remains the specification standard. PI-Duct is increasingly used for fan coil unit connections, ceiling void runs, and speed-prioritised installations.
