Air ventilation duct 1 material:FRP,stainless steel.Galvanized steel 2 Insulated, ... introduction of steel pipelines,ventilation pipeline,ventilating ducts ,air duct,air conditioning duct,ventilation duct,air ducting Brief introductionSteel materials of ventilation ducts now is the ... the galvanized ones,it can be used in all air conditioning and ventilation systems,and stainless ones can be used into ...