Do not bridge a wide saddle gap with a pile of mastic only.
Check
Check if the saddle sits tight before screws.
Look for daylight or wide gap at the heel/toe.
Confirm saddle is made for the main duct diameter.
Dress the flange before sealant.
Recheck branch angle and airflow after reset.
Steps
Check if the saddle sits tight before screws.
Look for daylight or wide gap at the heel/toe.
Confirm saddle is made for the main duct diameter.
Dress the flange before sealant.
Recheck branch angle and airflow after reset.
Say this to your foreman
The saddle tap at [location] has a wide heel gap because it does not match the barrel. I checked the fit before sealing. Do you want the flange dressed or the correct saddle swapped in?