Wrong bolt spacing or missing clamps on long flange

Long flange sides need the approved cleats, clamps, or fastener pattern so the gasket compresses evenly. Match the project/manufacturer detail instead of guessing spacing.

Rectangular Duct & Fittings 2nd Year YELLOW

Stop if

Ask when connector type, gasket, cleat/bolt schedule, pressure class, or manufacturer detail is unclear.

Watch out

Do not leave a long flange side loose or use random spacing, corners, or bolts to drag a crooked joint together.

Check

Support and align both duct sections before hardware starts.
Confirm gasket is continuous on one flange face and corners are on the joining duct.
Start corner hardware evenly, then install the approved side cleats/clamps/fasteners.
If flange cleats are unavailable, ask and verify before using 5/16 self-tappers in the flange.
Check the full flange face and backside for even contact.

Steps

Support and align both duct sections before hardware starts.
Confirm gasket is continuous on one flange face and corners are on the joining duct.
Start corner hardware evenly, then install the approved side cleats/clamps/fasteners.
If flange cleats are unavailable, ask and verify before using 5/16 self-tappers in the flange.
Check the full flange face and backside for even contact.

Say this to your foreman

In Rectangular Duct Assembly: TDC / Ductmate / Flanges, I'm looking at: Wrong bolt spacing or missing clamps on long flange. What should I verify before I cut, drill, seal, cover, move, or install?