This paper deals with the development of a fast numerical semi-analytical model dedicated to the simulation of the non-destructive testing of ferromagnetic tubes by using the magnetic flux leakage method(MFL). Taking into account the characteristic of the ferromagnetic material, the B-H curve, the numerical model is based on the generalized boundary element method which implies the evaluation of two magnetic fictitious scalar densities. Integral equations are discretized via the Galerkin's method and the particularity of this paper lies in the implementation of high order basis functions for the interpolation of the scalar unknowns. Simulated data provided by the numerical model are compared to FE data in order to show the validity of the numerical approach.