Ventilation duct,air ducting 1 low resistance,high density, 2 good feature of compression strength. 3 ... stainless The introduction of ventilation duct, insulated duct,flexible duct,air conditioning duct.\ Brief introduction Steel materials of ventilation ducts ... to civil fense project,hotels,marketings,and industrial buildings for air vcntilations and discharging fume. The internal of steel piplines ...