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What is the Longitudinal Seam and Transverse Joint in Rectangular Duct?

Harry Thompson IVOctober 23rd, 2018
                   
Longitudinal part of Rectangular Duct is the length, while the Transverse part is the width.

  • SMACNA refers to the Longitudinal as a seam and Transverse as a joint.
  • A seam is securing together two longitudinal oriented edges of duct in the direction of airflow.
  • A joint is the Transverse connection that connects the end of one duct section to another.
  • The Longitudinal Seam in Rectangular Duct is either a Pittsburgh Lock or a “Snap” Lock. Both types are formed on a machine that takes a sheet of metal and rollforms a profile on each of the flat edges — a Male Flange on one edge and a Female Pocket on the other edge.
  • The Transverse Connection options are Slip & Drive, Ductmate, or TDC/F. Of these, only Ductmate is an entirely separate component. Both Slip & Drive and TDC/F involve rollforming a profile on the edge of the metal.