Introduction and Technical Structure
Rectangular ducts are among the main components of air distribution networks in tall buildings, commercial centers, and industries where there is limited space for duct passage in suspended ceilings. Kian Fan Industrial Production Group, utilizing modern machinery and plasma cutting technology, performs the production process of these ducts in a fully mechanized manner with high precision. The duct bodies are made of galvanized, aluminum, or stainless steel sheets, which are selected based on the type of application and environmental conditions.
The production process includes 3D modeling, precise plasma cutting, and sheet bending. The edges of the sheet along the duct length and fittings are connected using the Pittsburgh Seam technique, which is one of the strongest connection methods in duct fabrication. The maximum length of each duct section is 1250 mm, which facilitates handling and installation. One of the prominent features of this product is the presence of transverse beads on the duct surface, which are created at specified intervals on the sheet. These beads significantly increase the duct's strength and prevent deformation against positive and negative pressures. If necessary, the duct's strength can be further increased for higher pressures by adding reinforcing rods (Angle Iron).

Advantages of Machine Production
Machine production of rectangular ducts at Kian Fan offers numerous advantages that guarantee the final quality of the project. The first advantage is high-quality sealing compliant with international duct fabrication standards. The Pittsburgh seam created by the machine has high integrity and impermeability. The second advantage is proper sealing between connections and reduced system leakage, which directly impacts energy efficiency and reduces operating costs.
High strength due to the presence of transverse beads is the third advantage, causing the ducts to resist vibration and impact. Finally, the significant reduction in fabrication and delivery time increases project progress speed, making installation fast and easy. High precision in cutting and bending ensures that pieces fit together precisely like a puzzle at the workshop site.

TDC Flange Connection System
The connection of pieces in the rectangular ductwork system at Kian Fan is performed using TDC (Transverse Duct Connector) flanges. This modern and fast connection method is a suitable alternative to traditional flanging methods. The TDC flange connection consists of several profiles, corners, and cleats. The duct surface is placed inside the profiles in a sliding manner and is secured using spot welding or riveting connections.
To create complete sealing, an EPDM sealing tape is placed between the flanges, which prevents air leakage. The flanges are secured to each other using bolt and nut connections at the corners, and special cleats are used along the connection seam, which drastically increases assembly speed. This connection system not only has high strength but also provides a smooth internal surface for airflow.

Specialized Applications
Kian Fan's rectangular ducts have applications in diverse projects. In office and commercial buildings with low suspended ceiling heights, rectangular ducts are an ideal choice due to occupying less space compared to round ducts. In factories and industries, these ducts are used for transporting large volumes of air and particles. Also, in central HVAC systems of hospitals and hotels, rectangular ducts with TDC connections are considered a standard choice due to excellent sealing and noise reduction.

Conclusion
The rectangular duct of Kian Fan Industrial Production Group, relying on precise machine production, modern TDC connections, and high-quality materials, is a stable, resistant, and optimized solution for air distribution networks. Choosing this product guarantees quality, execution speed, and high efficiency in HVAC systems.