Static field route #19090

What do I do when TDC or Ductmate flanges are twisted and the corner bolts will not line up?

Rectangular Duct Assembly: TDC / Ductmate / Flanges✅ STANDARD FIELD CORRECTIONV191 answer-gap expansion

📖 Verified core answer

A twisted flange usually means the line is hung out of square. Loosen nearby hangers, square the faces with controlled alignment, bolt it cleanly, then re-level the run.

Open in Field Rescue Open category

Field verification checklist

Check whether the previous joint is level, square, and plumb before forcing the new joint.
Loosen nearby hangers slightly to remove twist from the line.
Use clamps/alignment tools to bring faces together evenly.
Start all corners before fully tightening.
Re-check gasket compression and hanger level after the joint is made.

Ask foreman

The TDC/Ductmate corners at [location] will not line up because the line is twisted. I checked the previous hangers. Do you want me to loosen and re-square the last few joints before bolting this one?

Text to foreman

Route options

AMake the field correction only if it is within your assignment and the approved method.

BHold and document the condition if the fix affects airflow, access, life safety, pressure class, rated assemblies, equipment, or another trade.

CBring the foreman/detailer the location, what you checked, and what decision you need before cover, startup, or rework.

Do not do this

Do not beat a drift pin through twisted corner holes and permanently stress the flange or hangers.

Why this matters

Forced twisted flanges leak, tear corner holes, stress hangers, and make the next joint even worse.

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, and AHJ/code requirements.

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