insulated tanks are manufactured as a sendwich construction, where the middle space is filled with PU foam with different thickness. It can be 50mm and it can be also 200mm. These tanks are manufactured for storage of media with higher temperatures, as an example storage of glukose in the foodstuff industry or for storage of hot water in a underground tank in a solar collector system.
It is important that PU foam is a very good isolator and therefore it can save costs with energy consumption.