The tanks may be equipped with suction booms if, a) the boom is fitted with an internal or external stop-valve fixed directly to the shell, or directly to a bend that is welded to the shell; b) the stop-valve mentioned in a) is so arranged that carriage with the valve in an open position is prevented; and c) the boom is contstructed in such a way that the tanki will not leak as a result of accidental impact on the boom.