Patent ID: 8459307

Claim:
A seam for ductwork having a male end portion integrally formed at a distal end of a duct wall, said seam comprising: a female end portion integrally formed at another distal end of said duct wall; and wherein said female end portion includes a first fold bent to extend inwardly and substantially perpendicular to said duct wall, a second fold bent to extend in a direction substantially parallel to said duct wall, a third fold bent back upon said second fold such that said third fold and said second fold are substantially parallel, and a fourth fold bent at an open angle from said third fold extending outwardly and defining thereby a female groove for accommodating said male portion therein, said fourth fold having a distal end, said distal end being pre-bent in a direction towards said female groove so as to provide a clearance to permit entry of said male end portion into said female groove.