Static field route #18925

What do I do when welded grease duct is bowing or binding when it heats up?

Grease Duct, Kitchen Exhaust & Industrial Exhaust🟥 STOP / VERIFYV189 answer-gap expansion

📖 Verified core answer

Hot welded duct can move. If supports are locking it rigid with no movement path, stop and get an approved support/expansion detail before hangers, welds, or structure get damaged.

Open in Field Rescue Open category

Field verification checklist

Confirm where the duct is bowing, binding, rubbing, or cracking hangers/supports.
Check if the run has rigid clamps at multiple points with no movement path.
Look at hangers, shaft penetrations, wrap, cleanouts, and nearby combustibles/structure.
Verify the support/expansion detail in the approved drawings and submittals.
Stop startup/cover if movement is damaging supports or rated/fire-wrap conditions.

Ask foreman

The welded grease duct is bowing/binding at [location] when hot. I checked supports and movement path. Do you want sliding supports, expansion detail, or engineer/detailer direction before we lock this run in?

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 just tighten hangers harder on a hot grease duct that is trying to move.

Why this matters

Thermal movement can damage supports, welds, fire wrap, penetrations, and nearby structure if not allowed for correctly.

Verification basis

Approved drawings/specs, project coordination drawings, manufacturer instructions/submittals, shop standards, foreman/detailer direction, employer policy, and AHJ/code requirements.