Extruded, seamless round duct is available in sizes up to 24-in. according to the following table:
Round duct larger than 24 in. should be fabricated from Corzan® industrial sheet and butt welded with longitudinal seams.
Square duct can also be fabricated by thermal bending Corzan sheet and butt welding with longitudinal seams. Find recommendations for butt welding in our Sheet and Lining section.
Fabricated duct should be made from Corzan sheet according to the following guidelines:
Elbows and bevels should have a minimum center-line radius of 1.5 times the duct diameter.