A tubular conduit (1) comprising: a tubular portion (2) made from a flexible material. Thereis an external helical formation (7) extending around the exterior of, and parallel to theaxis of, the tubular portion (2) and defining a first region of the tubular portion (2). Theexternal helical formation (7) is for supporting the tubular portion (2). There is also aninternal helical formation (10), protruding inwardly of the interior of the tubular portion (2)and extending parallel to the axis of the tubular portion (2) and defining a second regionof the tubular portion (2). The internal helical formation (10) is for imparting helical flow onfluid passing through the tubular portion (2). The first region does not extend throughoutthe second region.
