What do the terms (a) “cross-broken duct” and (b) beaded duct mean? I WAG the latter term could mean a bead of caulk OR a bead from a weld? (FYI: Some duct seams are caulked and some are welded for commercial applications).
Any help would be appreciated…
Getting my ducts in a row…! 
Cross broken means a flat single piece pressed corner to corner in an X to reinforce.
Beaded means an edge turned over itself-doubling its thickness .
That’s close…
Both cross breaking and beading do the same thing, and that’s to add rigidity to the ductwork. (which is not the same as reinforcing, which employs different methods)
The “return” ductwork in your system is under ‘negative’ pressure—meaning that the ductwork wants to implode or suck in. The “supply” ductwork is under ‘positive’ pressure and want to explode or blow out.
When the blower is off, the system is under no pressure. However…when the blower starts up the return and supply ducts are immediately drawn into negative and positive pressures [respectively]. This sudden pressure change will cause the ductwork to “pop”—in HVAC jargon they [can] “oil can.” (think of the old oil cans you’d press the bottom of to force oil out)
By cross breaking or beading the duct you add rigidity to the duct and the chance of oil canning (some HVAC guys call it “tin canning.”) is reduced.
Oil canning has no effect on a unit’s performance. It’s simply an irritating noise associated with a sudden change in ductwork pressure. (at fan start up) Cross breaking/beading simply eliminates the possibility of that noise.
But cross breaking and beading are still the same thing. A fab shop that has a “beader” will run the metal through the beader while flat and before the duct is “broken” or bent. If they don’t own a beading machine they will use their “press break” or “hand break” and put a slight crease or “break” in the duct, before it is “broken” or bent. The two are easy to identify; cross breaking is a slight crease in every straight joint of duct, and is always shaped like an “X”.
A beaded duct has a “bead” or half circle or radius “groove” pressed into the duct. Beading is faster in the fabricating process compared to cross breaking. Any shop that has a beader will always produce beaded duct.
A beader however, is a few thousand dollars and not every shop has one. Those shops that don’t have a beader cross break. So…any given shop will either make cross broken duct, or beaded duct but not both.
ETA: bending over the end of a duct to double it’s thickness is called “hemming” the duct.
Welded duct is used most often in grease ducts. (like kitchen exhausts)
Small shops are more likely to not have a roll beader and therefore cross break. Small shops are often residential, although some small commercial shops cross break. Commercial buildings often need lots of duct, and so a high volume fab shop is often used. And…almost all high volume fab shops have roll beaders. (and other high volume machines, some of which can cost $500K)
The long and short of all that is that you may see cross broken or beaded duct in either residential or commercial buildings, but you are more likely to see beaded duct in commercial buildings and cross broken duct in homes. [generally]