aka:
First your said you needed insulation for a "for a nitro tank".
Then you came back and defined the above as a "liq'd nitrogen" tank. That is a Crogenic application around -350 oF and calling for special insulation under partial vacuum.
Now, you return once again to change the rules of the game by saying that you are dealing with "a holding tank for nitrogen (gas)". Can you please decide just exactly what it is you are trying to do, the capacity, temperatures, pressures, location, and a detailed explanation of the process? Otherwise, you've started a confusion rather than a help session. Gaseous nitrogen is not normally stored at cryogenic temperatures. Liquid nitrogen is. It makes a BIG difference.