While installing a bleed air system bolted flange face duct end, you use a new crush-type gasket, align the flange, and insert the bottom bolts first to form a cradle. Then, you install the remaining bolts and tighten all the nuts. After installation is complete you perform an operational check that reveals a leak. From the above information what important procedure did you overlook?
Flange bolts were not torqued in the proper sequence