A method and apparatus capable of forming a dual tube conduit having a predetermined outer tube dimension, a predetermined inner tube dimension, and a predetermined gap between the tubes. A dual tube workpiece may be initially bent in one or more zones to a desired nonlinear configuration, the inner and outer tubes are hydroform expanded simultaneously to obtain the selected inner tube dimension, and the outer tube is then hydroform expanded to the desired outer tube dimension and to the desired gap therebetween, while the inner tube is held constant.