The rectangular duct end looks upside down or rotated

Stop and verify orientation before connecting. Check piece mark, airflow, branch direction, access doors, dampers, and downstream fit.

Stop before the duct gets damaged. A duct end that is out of square, rotated, or oil-canning is usually telling you the piece or alignment is wrong.

Stop if

• Ask when rotating the piece changes access, branch direction, offset, damper, or ceiling clearance.

Watch out

• Do not force the duct until it buckles or locks in wrong.

Check

• Verify orientation
• Check squareness and cross-break direction
• Confirm the piece belongs in that spot

Steps

• Find the piece mark/tag.
• Compare openings and branches to the drawing.
• Check how the next fitting connects.
• Dry-fit if safe.
• Ask before rotating or modifying.

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