Static field route #19653

What do I do when TDC/TDF flange clips are spaced too far apart?

Rectangular Duct Assembly: TDC / Ductmate / Flanges✅ FIELD REFERENCEField answer expansion

📖 Verified core answer

Large flat flange spans can bow away from the gasket. Add the required clips per shop standard/project detail so the center span seals, not just the corners.

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Field verification checklist

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.

Ask foreman

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.

Text to foreman

Route options

A Correct prep/setup only if the fix is within your assignment and the approved method is clear.

B Hold and document if it affects safety, structural support, rated assemblies, airflow, access, tools, material condition, or another trade.

C Bring the journeyman/foreman the location, what you checked, and what decision you need before the crew loses time.

Do not do this

Do not rely on corner bolts alone for long flat flange spans.

Why this matters

Center-span flange leaks are common when clips are missing or spaced too far apart.

Final verification

Use this as field training guidance. Final direction still comes from the foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, pressure/material schedule, and AHJ/code requirements.

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