Profile: Tangent Air, Inc. manufactures round & oval spiral duct and fittings. We offer single wall, double wall, spiral & longitudinal seam duct and matching fittings. Our products are available in galvanized, stainless steel, aluminum, paintgrip, polyvinyl coated and carbon steel. Our galvanized spiral duct and fittings are offered in both high & low pressure Smacna gauges.