Hi, can i use the nitrogen gas for drying the internal of 55 gallon steel drum?
why not? N2 is mostly stable.. just don't arc a current in it and you should be fine;
N2 makes up %70 of what you're breathing right now. If it's not regular N2 (pure nitrogen gas), then investigate further. Most or many nitrates are volatile and can be extremely toxic.
.. that was a partial joke about the arcing of current: in a closed system, arcing a current in air rearranges nitrogen and oxygen into nitrogen dioxide (NO2) over time- which is poisonous & dissolves in water to become nitric acid.... but that's T.M.I.. You should be fine to 'air dry'a drum so long as it Is just N2 gas and you're drying water. If you start to see an orangey-brown gas/cloudiness, then be worried - that would mean that something's reacting with it, like maybe a previous chemical that occupied the drum.
Again, if it's just water and "regular" nitrogen gas you should be fine.