Double-walled tank for low-temperature liquids

A double-walled tank for low-temperature liquids, such as liquid gas, comprising an inner tank forming a primary safety casing and an outer tank enclosing said inner tank and forming a secondary safety casing, said outer tank being constructed of reinforced concrete, a ceiling extending across the upper end of said outer rank and forming a closure for the upper end of the double-walled tank, a layer of thermal insulation located between said inner and outer tanks, a vapor-tight layer covering the inside surface of said outer tank, wherein the improvement comprises that said outer tank comprises a generally horizontally arranged base and an upwardly extending side wall extending between said base and said ceiling, said vapor-tight layer being in direct surface contact with the entire inside surface of said outer tank including said side walls and said base, and said layer of thermal insulation comprising a liquid-tight first layer of polyurethane foam disposed in surface contact with and completely covering the inside surfaces of said vapor-tight layer and forming in combination with said vapor-tight layer a continuous and complete covering on the inside surfaces of said side wall and said base of said outer tank and said first layer of polyurethane foam being joint free throughout its extent in contact with said vapor-tight layer.