An insert for placement within a generally tubular fluid conduit having an inner conduit wall. The insert functions to provide quasi-laminar flow to a fluid, and is constructed as a generally ring shaped flow-through structure having an outer wall and an inner wall. The outer wall has a shape complimentary to the inner conduit wall such that the structure can be held by friction fit at an interface of the outer wall and conduit wall. The inner wall of the structure has projecting inwardly therefrom a plurality of uniformly spaced generally sinusoidal shaped vanes each terminating at an apex disposed between about 0.4 and 0.8 the radius dimension of the structure, and extending longitudinally preferably helically at an angle between about 17 degrees and 19 degrees in relation to a horizontal plane. Substantially identical construction as that of the insert is also incorporated within an inventive tubular fluid conduit having an inner wall with at least one integral quasi-laminar...