GALVANIZED SHEET STEEL:
Shall be of Lock-forming quality; ASTM A653/ A653 M
G90 coating designation; Phosphatized finish for surfaces of ducts exposed to view.
ASTM A480 I/ A480 M
Type 304 (316L for fume hood & lab exhaust duct) Sheet form with No. 2B finish for surfaces of ducts exposed to view.
ASTM B209, Alloy 3003, Temper H 14
Sheet form with standard, one-side bright finish for ducts exposed to view, and
Mill finish for concealed ducts.
PLASTIC COATED STEEL:
Plastic heat fused to Galvanized Steel; ASTM A653/ A653 M
4x1 reversed 4 mils of P.V.S. coating on the inside surface and 1 mil epoxy back coat on the outside.
ASTM A 366/A 366M
Cold rolled sheets: commercial quality with oiled, exposed matte finish.