This paper presents an original method for aligning 3D shapes modeled as NURBS based B-rep models, exploiting partial symmetries of the shape. Aligning 3D shapes is an important pre-processing step in 3D shape retrieval and indexation: a reliable alignment of the shapes is necessary. Given a 3D model, three canonical planes define the normalized pose. We characterize the first canonical plane by an efficient computation of the dominant partial symmetry, using an efficient face matching approach. An algorithm based on minimizing the projection area determines the two relative remaining planes. To evaluate the robustness and the effectiveness of the alignment, this technique is applied to 3D shape retrieval within a repository of NURBS based B-Rep models.