Grease duct joints are held with each other by the use of formed V clamps and sealed with 3M Fire Barrier 2000+. Fire resistant board for sealing company penetrations in walls or flooring For the duration of this kind of fire, the temperature inside the duct is usually around 800°C https://fireresistingductworkinsu23445.tusblogos.com/37170855/everything-about-fire-resisting-ductwork-insulation