The possible configurations of bent tubes are virtually unlimited.
From the manufacturing point of view, the greater the bend radius to O.D. relationship becomes, the easier it is to produce a component with minimum distortion (ovality) in the bend area. This is also true relative to wall thickness, in that the heavier wall products generally bend better.
||2 x O.D. (ref. min.)
||± .05 R
||2 x O.D. (min.)
||± 1 deg.