A double wall round or oval duct system assembly having an outer duct connector, an inner duct connector and a closure ring is provided. The inner duct connector of the duct assembly has an adhesive applied on the transverse flange face of its transverse flange thus allowing a sealing connection between the inner and outer duct connectors upon compression with the closure ring. The double wall round or oval duct system assembly will improve the efficiency and will reduce or eliminate air leakage upon connection of two round or oval duct segments. A method of installing the assembly system is also provided.