Longitudinal Seam Circular Ducts (Rolled Ducts)

Longitudinal seam circular ducts are reliable metal conduits designed for constructing high-performance supply and extract ventilation networks. Due to the absence of an external spiral seam, they feature a smooth exterior surface, making them the preferred choice for spaces with exposed ceilings where the visual aesthetics of engineering utilities are paramount. The circular cross-section minimizes airflow resistance, resulting in lower system pressure drops, reduced operational noise, and optimized fan power consumption.

These ducting components are manufactured using cold-rolled sheet metal on specialized plate bending rolls, with the edges subsequently joined along a precise longitudinal lock seam or weld. This technology ensures strict quality control over the duct geometry, enabling the production of elements across a comprehensive range of diameters while maintaining the uniform density and structural reliability of the ventilation network.

Key Advantages of Longitudinal Ducts

• Architectural Aesthetics & Clean Internal Walls: The smooth exterior surface delivers a clean, minimalist look in modern interiors, while the absence of internal ridges prevents heavy dust and grease accumulation, simplifying routine duct cleaning and maintenance.
• Extensive Range of Available Sizes: The rolling manufacturing method allows for the production of both small and large-diameter pipes (up to 1250 mm and greater), making them ideal for high-capacity main distribution lines.
• Material Versatility: Production is fully adaptable to various metals, including galvanized steel, stainless steel, aluminum, and pre-coated sheets, allowing perfect alignment with specific project requirements and environmental conditions.
• Stable Shell Rigidity: The precisely calibrated cylindrical shape provides excellent structural resistance to pressure differentials, mitigating the risk of wall buckling or deflection under high volumetric loads.

Technical Specifications & Installation

The standard length of a single longitudinal duct section is 1250 mm, which is optimized for standard sheet metal dimensions, ensuring efficient transportation and straightforward on-site adjustments.

The wall thickness is selected based on the design diameter of the mainline and the operating pressure parameters in the ventilation network.

Assembly & Jointing Guidelines

• For small and medium diameters, sections are joined using male sleeve couplings (nipple connectors). Large-diameter mainlines are integrated using bolt-on flanged connections.
• To achieve the target airtightness class (Class B or Class C according to international standards), all assembly joints must be treated with duct sealant and reinforced with self-adhesive aluminum tape.
• Ductwork suspension to the building's structural elements should be carried out using heavy-duty steel duct clamps lined with vibration-dampening rubber profiles to eliminate structure-borne noise transmission.

Available Material Options

Longitudinal ventilation pipes are manufactured from various metal types tailored to the operational environment and the aggressiveness of the transported air stream:

• Galvanized Steel (Z275 Zinc Coating): The standard industry solution for conventional commercial and residential ventilation, offering robust corrosion protection in environments with normal humidity.
• Polyester / RAL Powder Coating: Galvanized steel sheet with an additional protective and decorative polymer layer in various colors, combining enhanced corrosion resistance with a finished look for exposed architectural designs.
• Stainless Steel (AISI 304 / 316L Grades): Specialized heavy-duty execution for facilities with strict sanitary-hygienic standards (food processing plants, medical facilities, laboratories) or for exhausting chemically aggressive fumes.
• Aluminum: A lightweight option for ventilation networks where structural weight constraints are critical or where spark-resistant properties are required.