In this study the effects of Fluid-structure Interaction during hydraulic transients, more precisely water hammer events, in fluid transport systems are investigated. For this purpose, a numerical model was developed to simulate the effects of Fluid-structure Interaction in a system composed of a reservoir with upstream constant level, a straight pipe and a valve coupled downstream, which can be rigidly fixed or free to move. The transfer of energy from the fluid to the structure associated with pressure waves and their effects, that is, the efforts and displacements generated, is taken into account. The Method of Characteristics is used for solving the hyperbolic partial differential equations system, associated with finite differences and linear interpolations procedures. Three coupling mechanisms are modeled: Friction, Poisson, and junction coupling. The proposed numerical procedure is validated by simulation of a benchmark problem and compared to analytical solutions found in the literature. The results indicated that the model is able to reproduce the main effects Fluid-structure Interaction during hydraulic transients in a pipe conveying fluids. List of symbols A - cross-sectional area, m2 c - classical wave speed, celerity, m/s c?? - FSI wave speed, celerity, m/s D - inner diameter of pipe, m E - Young modulus of pipe wall, Pa e - pipe wall thickness, m FSI - Fluid-Structure Interaction G - shear modulus of pipe wall material, Pa H - pressure head, m K - fluid bulk modulus, Pa L - length, m MOC - Method of Characteristics P - pressure, Pa R - inner radius of pipe, m T - period, s t - time, s u - pipe displacement, m u?? - pipe velocity, m/s V - cross-sectional fluid velocity, m/s x - axial coordinate, m g - constant, m/s ???? - Poisson ratio