Abstract: A packaged column arrangement for an air separation plant in which a cold box is filled with an insulating material and higher and lower pressure columns are mounted within the cold box. The lower pressure column has an intermediate reboiler connected to the higher pressure column for condensing nitrogen enriched tower overhead formed within the higher pressure column in order to produce reflux for the columns. The higher and lower pressure columns are positioned within the cold box so that the higher and lower pressure columns are in a sufficiently staggered relationship that the reflux stream to the higher pressure column flows under gravitational influence. Moreover, auxiliary equipment such as vaporizer and subcooling heat exchange units can be conveniently connected to the columns when themselves may be mounted within the cold box by a simple I-beam mounting.