Sheet metal HVAC ductwork is generally classified under HTS Chapter 73 as articles of iron or steel, or Chapter 76 for aluminum ductwork. Certain steel ductwork from specific countries may fall within the scope of antidumping or countervailing duty orders, and Section 232 tariffs on steel and aluminum inputs add a further cost layer. Classification and remedy scope should be confirmed for each specific product and origin.

The forming method itself does not change HTS classification — the determinative factors are the base metal, the article's shape and function, and whether it is a finished article or a semi-finished intermediate. However, roll-formed profiles that resemble extrusions may raise questions about whether they fall under extrusion-specific trade-remedy orders, making a scope analysis advisable.