Abstract: A pipeline (12) for the transportation of a process fluid comprises an autonomous shut-off valve system comprises a shut-off valve (1) including a fluid powered valve actuator (2) moveable between a closed and an open position by means of pressure generated by the process fluid, a pressure tapping (3) in the pipeline upstream of the shut-off valve, a fluid connection to the pressure tapping arranged to deliver process fluid to power opening of the said shut-off valve, at least one pressure sensor (16) arranged in a hydraulic line extending from the pressure tapping, at least one control valve (8A, 8B, 8C) operable to permit or prevent flow of pressurised fluid to the shut-off valve actuator; and a controller (15) arranged to open and close the control valve. The control valve is commanded to open and close when pressure thresholds are reached, the pressure thresholds being detected by the pressure sensor and the control valve being commanded to close by the controller.