A bowed trapeze means the support span is not stiff enough for the load. Upgrade the support or add approved intermediate support before it distorts the duct.
Do not keep stacking duct on a support that is already sagging.
Check
Measure how much the strut is deflecting.
Check whether duct corners are being pinched.
Confirm rod spacing and support detail.
Unload or temporarily support before swapping strut.
Re-level after upgraded support is installed.
Steps
Measure how much the strut is deflecting.
Check whether duct corners are being pinched.
Confirm rod spacing and support detail.
Unload or temporarily support before swapping strut.
Re-level after upgraded support is installed.
Say this to your foreman
The trapeze under [duct/run] is bowing at [location]. I checked the span and duct skin. Do you want a heavier/deeper strut or center rod added before we keep loading the run?