Models for guided wave inspection are developed at CEA-LIST in the CIVA software platform. They are based on a numerical approach combining a modal description in regular parts of wave guides (plates, pipes, or guides of arbitrary crosssection like rails) and a Finite Element (FE) computation, in the vicinity of flaws or guide irregularities. It enables the simulation of the interaction of guided waves with complex defects such as a flaw of arbitrary shape, corrosion, delamination or cracks. This approach is applied here to various industrial configurations. Modes are computed thanks to the Semi-Analytical Finite Element (SAFE) method in each uniform portion of the waveguide, whereas a FE computation is performed in each region surrounding a defect or a local variation of waveguide shape. Several scattering matrices can then be associated in series in the frequency domain. This offers the possibility to deal with several defects in series. Finally, a mode matching technique has been recently used to get the scattering matrix of a complete pipe elbow. The different models are set in the frequency domain so an inverse Fourier transform is finally applied to determine the temporal signal measured by the sensor. A numerical study involving all these models is presented on a SHM system for pipe inspections in order to detect defects located after an elbow. Parametric studies are proposed in order to illustrate the simulation capabilities of this set of numerical tools.