Hello rajarajan

The only pressure the tank will see is the hydrostatic pressure from the liquid. You are probably aware if the One-Foot formula in API 650. It looks like this:

td = 2.6D(H-1)G/Sd + CA.

The H in that formula determines the pressure acting in the tank at each shell course. As there is no internal pressure, there is not tendency for the tank to lift, thus no bolting is required.