Former WBO champion Briggs, 43, is aiming to move a step closer to a shot at nemesis Wladimir Klitschko later in the year and is massively favoured for another knockout in Panama.
New Yorker Briggs has stopped a record number of his opponents in the very first round, five of which have come in his last six outings since a self-imposed exile from the sport between 2010 and 2014.
At the weigh-in, ring legend Roberto Duran stepped in as the outspoken Briggs gave Petranyi a dressing down in his usual fashion.
The bout will take place at the Hotel Sortis in Panama City.