Stop and verify the duct piece and shop detail. Typical slip-and-drive uses slips/S on one pair of sides and drives on the other, but transitions and fittings can make the pattern look different.
Confirm piece mark, size, airflow, and connector sides
Seat the S and drive cleanly
Check corners, support, gaps, and sharp edges
Ask foreman
In Rectangular Duct Assembly: S-and-Drive, I’m looking at: What do I do when the short-side/long-side connector pattern looks wrong? What should I verify before I cut, drill, seal, cover, move, or install?
Do not
Do not use force, screws, tape, or mastic to hide a bad mechanical fit.
