How about weld the shapes then fillet selected nodes:
Or maybe I'm misunderstanding... if you're trying to fit the image around a tube shape with bitmaps, to make it seem like the decal is on the tube, you can convert them into one then play with the bitmap Shear Effect.
Thanks. Yes, I understand hot to weld & use the fillet method. I was thinking more along a magic mathematical equation so as to get an accurate curve (diameter of the tube etc.). Overthinking I'm sure but...