Static field route #14855

How do I use drift pins and C-clamps on TDC/Ductmate alignment

Rectangular Duct Assembly: TDC / Ductmate / Flanges🚨 STOP / VERIFYField tool note — alignment aids, not force tools

📖 Verified core answer

Use drift pins and C-clamps as alignment helpers only. Get the duct supported, level, and close first. Then use drift pins to line up corner holes and C-clamps/locking clamps to hold flange faces while you start corners, cleats, or approved fasteners.

Open in Field Rescue Open category

Field verification checklist

Is the duct supported and level before pinning or clamping?
Are the holes close enough for a drift pin without prying the flange?
Is the C-clamp sitting where it will not crush the duct, gasket, or corner?
Are corners started before final tightening?
Are cleats/clips or approved fallback screws installed along the long spans?

Ask foreman

The TDC/Ductmate joint is close but needs help holding alignment. Do you want drift pins at the corners and C-clamps on the flange while I start the corners/cleats?

Text to foreman

Route options

AStop and verify the approved detail, listing, engineered note, code/AHJ requirement, or foreman direction for this exact location.

BHold the condition clean and safe; do not cut, drill, seal, cover, weld, reroute, or improvise around it.

CBring the foreman/superintendent/inspector the location, what you checked, and the decision needed before work continues.

Do not do this

Do not use a drift pin to pry a twisted flange into place. Do not reef down a C-clamp until the gasket crushes or the flange bends. Do not use alignment tools to hide a wrong-size or unsupported piece.

Why this matters

Drift pins and C-clamps save time when the joint is close, but they can damage the flange, crush the gasket, or hide a crooked run if they are used as force tools.