In a tank container, a support member 20, which is inserted between a reinforcing ring 11 of the tank 10 and a lower cross-strut 17 of the container framework is composed of two sheet-metal elements 21, 22 which are bent towards each other and which may be fitted in the spandrel space formed between reinforcing ring 11 and cross-strut 17 and welded to each other in such a way as to result in a central rigid rectangular tube having softer surface elements arranged on the two outer sides for preventing peak stresses.