Grease duct joints are held together through formed V clamps and sealed with 3M Fire Barrier 2000+. The minimum duct thickness is defined by what ever code jurisdiction which the undertaking is found in. Under are two code references associated with the essential thickness and substance kind for grease ducts. https://shanejbqes.goabroadblog.com/36016498/not-known-facts-about-fire-resisting-ductwork-insulation