Thermal Storage Tank?

In a chilled water TES tank. Where do you put the polyurethane spray on foam insulation? Is it inside the tank or outside? Because in our design, we specified it to be inside the tank, or on the surface of the inner walls. But there are no supplier who can comply with that in the Philippines, specially having the insulation submerged in chilled water. Can anyone help me?? Any insulation contractor or manufacturer on that field? Ty!