Sewn vs. Welded HVAC Duct Construction


Flextral’s standard HVAC ducting (series DU90 and DU91) are of welded construction.  Welded seems allow our duct to be used in a bi-directional manner.  Meaning, it doesn’t matter which end is connected to the HVAC unit and which is connected to the vent.  In a sewn duct construction, the duct must be installed directionally specific.  There is a slight tab hanging off the end of the seam, which is only meant for uni-directional flow.  Bi-directional flow will cause turbulence in the air flow and result in an inefficient setup.  Additionally, welded seams are a stronger joint over sewn. 


Sewn seams do have some advantages, such that they can allow for installation of hanging grommets.  This is important if the ducting application is required to be suspended.  If your application requires this check out our DU93 series.

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