Treat grease/special exhaust as red-zone work: using non-approved sealant/tape on grease duct.
High-risk starter answer - treat grease duct, hood exhaust, kitchen exhaust, lab exhaust, and special exhaust as red-zone work. Do not use random tape, mastic, or caulk on special exhaust because the approved sealing method may be listed/project-specific.
Ask any time grease/special exhaust involves access, weld, wrap, slope, clearance, penetration, contaminant, or support questions.
Watch out
Do not assume normal galvanized duct rules apply. Do not patch grease/special exhaust with normal duct tape or generic sealant.
Check
Confirm whether this is grease duct, kitchen exhaust, lab exhaust, industrial exhaust, or normal exhaust.
Check the approved drawings/spec/submittal.
Look for cleanout/access, clearance, enclosure/wrap, weld/seal, slope/drainage, and inspection requirements.
Verify the approved seal/weld/gasket method from the spec/submittal.
Steps
Confirm the system is grease, kitchen exhaust, industrial exhaust, dust, or chemical/fume exhaust.
Check approved detail for material, access, cleanouts, joints, wrap, slope, and support.
Identify hot-work or fire-watch requirements.
Focus on the actual issue: using non-approved sealant/tape on grease duct.
Photograph or mark the condition if someone else needs to approve it.
Say this to your foreman
In Grease Duct, Kitchen Exhaust & Industrial Exhaust, I'm looking at: Using non-approved sealant/tape on grease duct. What should I verify before I cut, drill, seal, cover, move, or install?