The Titans announced the moves Wednesday.
Backup center Chris Spencer, who hurt his ankle in the preseason opener, has been on crutches. So the 6-foot-3, 310-pound Vallos gives the Titans help at a position where left guard Andy Levitre was snapping the ball Monday. Vallos has played 59 games in six seasons with Philadelphia, Jacksonville, Cleveland Seattle with 15 last season for Denver.
The 6-5, 250-pound Adams has been on practice squads in Tampa Bay, Detroit, Cincinnati and the Giants. He was in camp last season in Cleveland and was signed out of LSU by Jacksonville.
The Titans waived linebacker David Gilbert and offensive lineman Viondy Merisma.