At what temperature is Nitrogen transported? Is it better to transport at room temperature or colder temps?

Answer 1

Nitrogen and other gasses like Helium can be transported at room temperature in pressure bottles, or at cryogenic temperatures as liquids. The cryogenic solution is less weight (this is why it is used in rockets, for oxygen), but more care must be taken with the cryogenic vessels. Room temperature pressure bottles can be stored without maintenence for years, but they can still be hazardous if broken.

Answer 2

The volume is a WHOLE lot less when it's liquid.

So it's transported in liquid form.

No reason to make it any/much colder than that.

So look up the highest temperature at which nitrogen can be a liquid unpressurized, and the transport temperature will be around that.