An air transport duct, and sections of such duct, capable of connection to a support by support members and attachment members formed from two mating members. Each section has two terminal open ends and a flange disposed around each open end for connection to a flange of an adjacent section. Each flange includes two relatively transverse receiving channels adjacent to a corner of the flange, and an insertable corner member positioned into the channels. The corner member is attached to the flange by a load-bearing connection, and can support a predetermined portion of a weight of the duct by connection of the corner member to a first mating member connectable to a second mating member secured to a corresponding support member. A method of connecting a duct to a support by forming a load-bearing connection between a corner member and a flange.