Do piercing rings on normally covered parts of the body ever set off metal detectors?

Drendon, of course the body scanners can detect your piercings, even under your clothing.

Of course there will be people that would be all like: yes it happened to me ones... bla bla bla.

In general It wont happen, If a piercing would set off a metal detector, then so would braces. That never happened to me and I travel quite regularly.

They can detect metal prosthetics inside someone's body so... yes.