Round Duct Back Flange

The round reverse flange AD-FN is designed for bolted connection of round air ducts with the same diameter. It is used in ventilation and air conditioning systems where a reliable, detachable, and airtight joint is required.
For AD-VKK straight-seam ducts and AD-SPN spiral ducts, reverse flanges are manufactured with a slightly reduced (“minus”) diameter to ensure precise fitting with duct fittings. For shaped components, the flanges are produced in nominal diameter.
The standard flange thickness is 1.5 mm, providing sufficient rigidity, dimensional stability, and long service life. The flange is made of galvanized steel and is suitable for general and industrial ventilation systems.