A movable coupling for a pipeline, which can be applied in aviation and aerospace. The coupling includes a dip pipe, a counter piece and a displaceable component. The counter piece has a passage, into which the dip pipe is inserted. The counter piece has a holder extending from the passage. The component includes a clearance that the dip pipe extends through. A portion of the displaceable component is received in the holder so the displaceable component can be displaced relative to the counter piece in a direction not parallel to the longitudinal axis of the dip pipe. When the dip pipe moves relative to the counter piece, the displaceable component is tight against the dip pipe and also against the counter piece. A tank arrangement includes a tank with a pipeline connected to the tank and including a movable coupling.