What's the trick to seating a stubborn Pittsburgh seam on a large rectangular fitting?
1st YearDuct AssemblyYELLOW · Check First
Start at one end. Use your hand seamers or a raw hide mallet to gently start the flange into the pocket. * Work your way down the line incrementally, tapping the male edge fully home into the pocket *before* you start flattening down the locking lip. If you hammer the lip flat prematurely at the start, the rest of the run will bind out of alignment.