The function of the frame is to support and protect the tank shell, and to facilitate the stowage, security, and transport by standard ISO container handling equipment. The overall dimensions and corner castings are in accordance with container specifications. The frame is designed to cope with the stresses of a fully loaded tank when handled in accordance with the relevant ISO standard.
Although tank containers are of fairly uniform external appearance, the shell construction materials and fittings vary. Tanks are classified according to the specification of the tank shell and fittings, which determine the category of product that may be loaded.