To limit the probability that the tank will be damaged during relocation operations, which could lead to the escape of liquid, which could lead to the ignition of vapour from a nearby ignition source, which could lead to harm to persons.
To limit the probability that the relocated tank will be reused, which could lead to the escape of liquid or vapour, which could lead to the ignition of vapour from a nearby ignition source, which could lead to harm to persons.