radial_srf_2022Feb10a.gh (22.4 KB)
The pipe and ring geometry are internalized so you can do this:
I just realized though… that you want the edges flat like the ring? I didn’t do that… yet. 
P.S. Now the edge of the lofted surface is tangent with the ring, as indicated by the vectors (below). Increasing the count from 12 to 18 or more makes it smoother?
radial_srf_2022Feb10b.gh (24.7 KB)
Again, geometry is internalized, no need for Rhino file.
By the way, if you’re willing to play with vector amplitudes (manually or by algorithm), you can use BzSpan instead of BiArc, as shown here:
P.P.S. I managed to align the seams automatically by projecting the pipe axis to the ring plane, so the manual ‘Seam’ slider is gone.
radial_srf_2022Feb10c.gh (27.8 KB)