Why is flat-oval duct deforming on a flat Unistrut support?
3rd YearYELLOW · Check FirstFlat-Oval Supports
Short answer
Flat-oval needs support that respects its shape. A flat bar can distort the flat span if the duct is wide/heavy.
Field answer
Flat-oval duct has broad flat faces. If the support does not cradle it correctly, the bottom panel can sag and the internal air shape changes.
Check the duct profile, weight, support spacing, and approved support detail. Recovery may be shaped saddles, wider bearing, isolation pads, internal support, or a revised hanger layout.
What to check first
- Inspect bottom panel sag and side radius distortion.
- Check if the support bears on one narrow line.
- Verify flat-oval support detail and spacing.
- Temporarily support before modifying hangers.
- Confirm airflow path is not deformed after correction.
Do not do this
Do not support wide flat-oval duct like a small round branch if it is deforming.
Why it matters
Poor support can distort the duct, create pressure loss, rub hangers, and damage joints.
Ask foreman
The flat-oval duct at [location] is sagging across the trapeze bar. I checked the support contact and shape. Do you want a shaped saddle/wider cradle or internal support detail?
Related Field Rescue route
Final direction belongs to the foreman, approved drawings/specs, manufacturer instructions, pressure/material schedule, employer policy, and AHJ/code requirements.