OK I don't know if this will help you, my co-worker said the easiest way to do this is "You draw a poly line & a circle perpendicular to it & extrude along a path (the poly line)"
Draw a polyline the length of the pipe and fillet it with the radius you need.
Make sure your UCSFOLLOW is set to 0 then align your UCS with one side of the polyline (he used UCS > 3 and picked two points on the PLINE to align it was one side.
Then rotate your UCS around the Z axis 90 degrees and the Y axis 90 degrees so you UCS is now perpendicular to the PLINE. Draw a circle the diameter of the pipe with the center being the end of the PLINE, then EXTRUDE the Circle along a PATH, the PATH being the PLINE.
And WAHLAH (I'll follow with pics) (I'm working in ACAD 2000
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