Fix the gasket condition before bolting/sealing: over-tightening and crushing gasket unevenly. The gasket needs clean contact and continuity at the flange/corners.
Protect the gasket and flange face before tightening. A dirty, folded, missing, crushed, or broken gasket becomes a leak path.
Ask when connector type, gasket, cleat/bolt schedule, pressure class, or manufacturer detail is unclear.
Watch out
Do not bolt over dirty, wet, folded, missing, or displaced gasket.
Check
Clean the flange face
Check gasket continuity and corners
Make sure the gasket stayed in place while lifting
Steps
Align the duct sections square.
Check flange faces, corners, gasket, and cleats/bolts.
Fix damage or missing parts before tightening.
Tighten or cleat evenly per project/manufacturer detail.
Focus on the actual issue: over-tightening and crushing gasket unevenly.
Say this to your foreman
In Rectangular Duct Assembly: TDC / Ductmate / Flanges, I'm looking at: Over-tightening and crushing gasket unevenly. What should I verify before I cut, drill, seal, cover, move, or install?