Underground spaces such as parking garages, tunnels, and civil defense projects have poor ventilation and require high levels of enclosure, placing far higher demands on the strength, sealing, and corrosion resistance of ducts compared to ordinary buildings. Spiral ducts have become the preferred solution for underground ventilation systems due to their four core advantages.
I. Four core advantages
| Advantages | Value of underground space |
| High circumferential stiffness | It can withstand soil pressure, vehicle piston wind, and exhaust negative pressure without deformation or collapse. |
| Spiral reinforcement | It does not bend when suspended over long distances, reducing the number of intermediate hangers. |
| Factory prefabricated, reliable connection | Flange/socket connection with an air leakage rate of ≤1% avoids difficulties in controlling on-site welding quality. |
| Corrosion resistant | Z275 galvanized steel or 304 stainless steel can be used to cope with damp underground environments and those with weak acids or alkalis. |
II. Why are rectangular ducts and ordinary welded pipes unsuitable?
• Rectangular ducts: Stress concentration at corners, prone to bulging and cracking under high pressure; large on-site fabrication volume, poor sealing.
• Ordinary welded round pipes: No spiral reinforcement, prone to bending over long distances; numerous welds, high risk of leakage.
• Spiral ducts: One-piece spiral molding, no longitudinal welds; built-in reinforcing ribs, good rigidity; factory prefabricated, only on-site connection required.
III. Special requirements for ducts in underground spaces (and the response of spiral ducts)
| Requirements | How can spiral ducts meet the requirements? |
| Pressure resistance ≥2000Pa (piston wind, smoke exhaust) | High circumferential stiffness; 1.2-1.5mm thick plates can be used. |
| Fireproof (non-combustible, Class A) | Galvanized steel or stainless steel, naturally non-flammable |
| Moisture-resistant/weakly corrosive | Z275 galvanized coating or 304 stainless steel, with a service life of over 15 years. |
| Fast installation | Each section is 2-3 meters long, with flange/socket connections, 3-5 times faster than on-site welding. |
| Easy to maintain | The inner wall is smooth, does not easily accumulate dust, and can be washed. |
IV. Typical application case data
An underground parking garage ventilation system (using BYFO spiral ducts):
• Specifications: Φ600-1200mm, 1.2mm thick galvanized sheet (Z275)
• Connection method: Socket + sealing tape
• Test pressure: 2200Pa, deformation <0.5%
• Installation efficiency: 120 meters can be installed per day by a 2-person team
• 3 years of operation: No complaints regarding air leakage or corrosion
V. What can BYFO provide?
• Heavy-duty spiral duct machine: Processing thickness 1.5mm, diameter up to 1600mm
• Fixed-length flying cut: Smooth duct opening, error ±1mm
• Material options: Galvanized sheet (Z180~Z275), stainless steel 304/316, aluminum sheet
• Remote technical support: Installation video + online engineer guidance, worry-free for overseas customers
VI. Conclusion
For underground space ventilation, reliability is paramount. Spiral ducts, with their high strength, excellent sealing, corrosion resistance, and quick installation, have become the preferred choice for engineers worldwide in underground projects.
Need selection based on your pipe diameter and pressure?
Contact BYFO with your specifications, and we will provide a solution within 24 hours.
Email: byfo@byfomachine.com
Whatsapp: (0086)18255536645
