Spiral Manufacturing Co., Inc. manufactures high-pressure underground duct systems engineered for durable, efficient HVAC air distribution and corrosive industrial environments. Its UL-listed Polyvinyl Steel (PVS) coated duct combines the structural strength of galvanized steel with the corrosion resistance of a fused polyvinyl coating, making it ideal for underground installations and chemical fume exhaust applications. The company offers a complete range of spiral pipe, fittings, elbows, reducers, tees, taps, and custom components designed for long service life and dependable performance. Built to meet SMACNA and UL standards, Spiral Manufacturing’s underground duct solutions provide reliable, code-compliant performance for commercial and industrial projects.