also the word 'padded' may be used when an inert gas like nitrogen is used to fill the empty space in a drum or tank to aid in preservation. You ought to have added more context, such as the original phrase or paragraph or list so that if there is mention of nitrogen, we could be more certain of the assistance we are trying to give you.

Drums where gas or moisture has been allowed to enter, causing them to appear swollen (like tins or cartons of food that have gone bad).