Abstract: Methods and systems for efficient and accurate re-starting of data transfers using volatile data transfer mechanisms, such as pipes, following an error. According to one embodiment, portions of the transferred data can be saved in a fallback file. In addition, checkpoint commands can be periodically provided, upon which much of the data in the fallback file can be overwritten. During the original transmission, the data that has passed through the mechanism can be counted, and a signature for the data that has passed can be accumulated. After certain error conditions, the data in the fallback file can be recovered and passed to the receiving process and the transmission can then be resumed at the point where it had left off. After other errors requiring a complete re-start, a second signature of the re-transmitted data can be accumulated and original and second signatures compared to determine if the data is valid.

Abstract: Crude oil tank cleaning apparatus includes a gimbal having a substantially straight passageway extending therethough. A mounting bracket sealingly and rotatably mounts the gimbal in a wall of the tank so that the gimbal has an interior side exposed to the interior of the tank and an exterior side exposed to the exterior of the tank. A straight pipe is sealingly mounted in the gimbal passageway. The pipe has an inlet end on the exterior side of the gimbal for connecting the pipe to a high pressure fluid source and an outlet end on the interior side of the gimbal such that the inlet and outlet ends define a linear flow passageway through the pipe for discharging the fluid in fluid jet into the tank. An actuator, mounted on the exterior of the tank, has a first end connected to a rotatable portion of the gimbal and a second end connected to a stationary portion of the tank or the mounting bracket for reciprocating the gimbal and pipe between selected positions.