A method of calculating plastic deformation during bending a rotating circular beam is presented. Rotating blank loading is examined in the two cases: plastic deformation occurs over the thickness of the blank and plastic deformation is absent in the blank. When the pipe being bent rotates, the symmetry with respect to the force plane is broken. The nature of bending deformation of a rotating blank differs from that of a fixed one. Since the beam axis is not a plane but a space curve, there is a lateral displacement and deviation of the deflection from the force plane.