Features: 1) Spiral tube former for producing spiral round ventilation ducts, with diameter ranging from 80 to 1,600mm. 2) Spiral oval tube former for producing spiral oval ventilation ducts. 3) Spiral paper core / tube forming machine. 4) Spiral corrugated steel pipe making machine for producing post-tensions pipes / tubes used in road and bridge construction. 5) Spiral flexible hose making machine for producing flexible hose. 6) Annular corrugated flexible pipe / hose machine. 7) Spiral steel tube welding machine producing spiral steel tube from 60mm to 3,000mm. 8) Straight steel tube welding machine producing straight steel tube from 10mm to 610mm. spiral tube formerair duct work ventilation duct work