Carbon steel air ducts are ventilation duct systems made primarily of carbon steel with a carbon mass fraction below 2.11%, widely used in building air conditioning, industrial ventilation, smoke exhaust, and dust removal. Their excellent mechanical properties, economy, and adaptability make them an important component in ventilation systems.

 

Carbon steel air ducts are typically made of cold-rolled or hot-rolled steel sheets. Material selection depends on specific system requirements: when the thickness is no more than 1.2 mm, hot-dip galvanized steel sheets are preferred to enhance corrosion resistance; when the thickness is no less than 1.5 mm, cold-rolled steel sheets can be used. In special applications, such as smoke exhaust ducts passing through equipment management areas or enclosed spaces, 2 mm thick steel sheets are required to meet higher fire resistance and structural strength requirements.

 

The manufacturing of carbon steel air ducts involves several critical process steps. In the blanking and forming stage, precise line drawing and cutting must be performed according to construction drawings, with strict line position verification. When using angle steel flange connections, a 6 to 9 mm flange allowance should be reserved at the pipe end. For sheet thickness exceeding 1.5 mm, electric welding or argon arc welding can be used for splicing. During welding, spot welding should first be used for fixation, followed by intermittent skip welding with a spacing of 100 to 150 mm and a weld length of 30 to 50 mm. Post-welding slag removal and anti-corrosion treatment are mandatory to ensure long-term durability.

 

To prevent deformation and vibration noise during operation, ducts must be reinforced according to their width. For widths between 630 and 1250 mm, rolled bead reinforcement is used; for widths between 1600 and 3000 mm, 40×4 angle steel should be used for reinforcement along the airflow direction, with a spacing of 800 to 1000 mm. Intermittent welding is used between the angle steel reinforcement frame and the duct, with a uniform weld length of 20 mm and evenly distributed spacing.

 

During installation, the form of supports and hangers must meet design requirements, and the angle steel flange specifications, bolt, and rivet spacing must strictly follow specifications. Duct welds should be full and uniform to ensure airtightness. Spiral ducts with double-sided internal and external welded joints feature low air leakage rates and a smooth circular shape, making them particularly suitable for low-pressure or negative-pressure flue gas and dust gas conveying systems, effectively improving system efficiency and reliability.

 

Carbon steel air ducts are mainly used in air conditioning supply, fresh air, return air systems, as well as ventilation and smoke exhaust, pressurized air supply, and industrial dust removal pipelines. They are especially widely used in long-distance flue gas conveying systems in steel plants, power plants, etc., where their high strength and good durability can meet the harsh requirements of complex industrial environments. Additionally, in occasions requiring thermal insulation and noise reduction, such as hotels, hospitals, and office buildings, composite duct structures can also provide effective solutions.

 

In summary, through reasonable material selection, rigorous process control, and standardized installation and maintenance, carbon steel air ducts have become an economical and efficient choice in the ventilation field.