In this paper a comparison between the results obtained using multi pass welding finite element (FE) simulation and the contour method was made to evaluate the accuracy in residual stresses simulated for plates with different thicknesses. The contour method has been used to measure the residual stresses in multi pass butt-welded plates. Two 316 austenitic stainless steel multi pass Metal Inert Gas (MIG) butt-welded plates of 10 mm thickness were cut using wire Electric Discharge Machining (EDM). The measurements of the cross-section were made with a coordinate measuring machine (CMM) and the points obtained were used to calculate the residual stresses by mean of static analysis of finite elements. A multi pass welding FE simulation of the two plates was made to obtain the residual stresses after time cooling. The simulated results are generally in good agreement with the experimental measurements. Other plates of 25 mm thickness and the same material were multi pass MIG butt-welded to evaluate the behavior with different thicknesses. In this case the number of passes was 11. The same method was applied to obtain the residual stresses. A comparison between different thicknesses was made. The residual stresses validation will allow the finite element simulation to be used for the later simulation of residual stresses relaxation.