A pipe separator for the separation of fluids, for example the separation of oil, gas and water in connection with the extraction and production of oil and gas from formations beneath the sea bed. The pipe separator includes a pipe-shaped separator body (1) with an inlet and outlet that principally corresponds to a transport pipe (4, 7) to which the pipe separator is connected. The pipe separator further includes a pipe bend or loop (2) arranged in the pipe separator or in connection with its outlet to form a downstream fluid seal in relation to the pipe separator body (1), which is designed to maintain a fluid level in the pipe separator, but which also allows the pipe separator (1) and the loop (2) to be pigged.