Galvanised iron common plate duct mainly consists of angle yards, flange clamps, and flanges connected with the duct as a whole, galvanised common plate flange duct, also known as flangeless duct, mainly in the duct iron plated with a layer of zinc, the iron to play a protective role. Zinc plating by passivation treatment, dyeing or coating light protection agent, can significantly improve its protective and decorative. Its production form is faster, more convenient and less air leakage rate than the traditional rectangular duct processing. Its advantage is to save materials, reduce project investment; small air leakage, reduce energy consumption, save operating costs, quite popular with construction companies. Usually used in fresh air system, air conditioning system, smoke exhaust system, etc..