Is it a brand new tank, or did you get it used?
It seems if there is silicone on the outside of the seams, that it may have been repaired. Normally doesn't come from the factory like that. At least not an aquarium I have seen before.
Does it seem like the silicone is done well, do you see air bubbles or gaps anywhere in it? Theres really only 1 way to find out. Maybe you could move the tank and stand outside and fill it up over the weekend and let it sit and see.