Abstract: A method and apparatus for cleaning the interior of the storage tanks of the type used for storing large volumes of liquids, such as crude oil, wherein hydrocarbon sludge accumulates with the passage of time, such apparatus comprising concentric hallow pipes, a spray nozzle for injecting a flushing fluid, and connecting means including a packing gland which allows the concentric pipes to be movably oriented inside a storage tank through a manway. With this construction, a flushing fluid can be sprayed into a sludge layer in the storage tank through the inner pipe and sludge/flushing fluid withdrawn through the annular region between the concentric pipes. The packing gland in the connecting means, and a second packing gland between the inner and outer pipes allows for independent movement of the pipes within the storage tank.