The modelling of the eddy current testing of U-bend steam generator tubes is a valuable tool for interpreting measured signals due to geometric distortions that can arise during the bending process. Especially, the decentred trajectory of the probe into the bending must be taken into account to ensure the accuracy of the simulated signal. As the exact trajectory is a priori not known, we propose an efficient way to build a database of the simulated signal for all possible positions of the probe into the tube, based on an adaptation of the boundary element method that is developed at CEA LIST.