TDC/TDF flange clips are spaced too far apart

Cleats/clips pull the long TDC/TDF flange spans together so the gasket compresses across the whole joint, not just at the corners. Use the shop/project detail for spacing. If the approved cleats are not available, ask the foreman before using 5/16 self-tappers through the flange as the field fallback.

Rectangular Duct & Fittings 1st Year GREEN

Stop if

Spacing those clips three feet apart is going to allow the metal flange to blow out and leak. Snap a metal clip every 8-to-10 inches along that flat span to squeeze that center gasket tight.

Watch out

Do not rely on corners alone for long flat flange spans. Do not substitute screws for cleats without foreman/shop approval. Do not use fasteners to drag a twisted joint into alignment.

Check

Check that the duct is level and aligned before adding cleats or screws.
Confirm gasket is on one flange face and is not rolled or stretched.
Seat the corners first, then work the long flange spans evenly.
Use the required cleats/clips per shop/project detail.
If cleats are unavailable, verify whether 5/16 self-tappers in the flange are approved for this job before shooting them.

Steps

Check if the flange face bows between corners.
Confirm required clip type and spacing with shop/project detail.
Add clips evenly along the flat span.
Inspect gasket compression after clips are installed.
Leak-check or listen for whistle at startup.