Grease duct joints are held collectively through fashioned V clamps and sealed with 3M Fire Barrier 2000+. The minimal duct thickness is defined by whatever code jurisdiction which the task is found in. Below are two code references related to the expected thickness and content sort for grease ducts. Passive https://fireresistingductworkinsu46778.ampedpages.com/an-unbiased-view-of-fire-resisting-ductwork-insulation-63910099