An in-line separator is provided for separating fluid phases of different density from a fluid stream. The in- line separator comprises a conduit having an inlet section (2) for receiving the fluid stream, an outlet section (12) for separately transporting the fluid phases, and a swirl section (4) for inducing a swirling motion to the fluid stream as the stream flows from the inlet section (2) to the outlet section (12) , the swirl section having an interior space (19a) . At least a portion of said interior space forms a passageway (19a) for passage of tools from the inlet section (2) to the outlet section (12) .