TinnerFlow™3rd YearDuct Assembly, Seams & JointsCheck first
Thermal movement needs somewhere to go. Replace the damaged section and add the approved expansion/flexible detail if the run is growing under heat.
Warm discharge air can make long metal runs move. If the run is locked solid, wide flat-oval seams may take the stress and split.
Check temperature, run length, fixed points, supports, and whether an expansion coupling/flex connector is required. Replace split seam sections that cannot be restored mechanically.
Use this as training guidance. Foreman direction, approved drawings, project specs, manufacturer instructions, employer safety policy, and AHJ/code requirements always control the final answer.