A.F.A.I.K., it is never acceptable to remove tournament chips from a tournament regardless of whether it is announced or not. the reason, of course, is because the person removing the chips could be doing it so they can return to another tournament with those chips and replace the chips to their stack thus increasing their chip count unfairly.

at most tournaments, it is announced or at least expressed in the house rules that chips are to remain in your hand or in a rack when moving from table to table and anybody caught putting chips in a pocket will be immediately disqualified.