Abstract: Method and apparatus for cleaning a storage or transport tank by spraying a cleaning agent against the interior wall using at least one spray nozzle, said nozzle making a rotating movement in a plane, while said plane is simultaneously revolved around an axis which makes an angle with the axis of rotation of the nozzle, the point of impingement of a jet cleaning agent delivered by the nozzle describing a track over the interior wall of the container, said track passing a plurality of times a closed circumferential line on the wall of the tank, which line is chosen as a reference, wherein the nozzle or each nozzle is so controlled that passages of the impingement track that is being described substantially occur in the greatest as yet unintersected portion of said circumferential line, which portion is located between earlier points of intersection of the impingement track and said circumferential line namely, at distances from said earlier points of intersection which substantially bear a ratio of 1:(1/2.