... purpose, diameter from 80-1500mm. The spiral duct forming machine ZHTF-1500I is used to produce ... the round rigid air duct for ventilation purpose, diameter from 80-1500mm.Main ... spiral tubeformer, spiral duct forming machine, ventilationd duct machine, spiral tube former, spiral duct former, ventilationd duct machine, HVAC duct machine. HVAC duct spiral forming machine