The objective of this study is to perform physical tests on T-joint welded tubes to determine the axial static load behavior and compared them with the analytical and numerical calculations. Three experiments are performed and it is examined that typical collapse modes develop in the section of tube and associated Von-Mises stresses (distortion energy) are compared with the analytical method and numerical simulations. The comparisons with the experimental results are satisfactory. The validated numerical model is used to study the Von-Mises stresses with variation in the leg lengths of weld (2 mm, 3 mm leg lengths). The strength of fillet welded connections is investigated for different leg lengths. The ultimate strength of weld metal is determined by considering the forces acting on the welds. The effect of different leg lengths on the strength of welds is investigated by numerical methods and compared with analytical calculations which show that they are in agreement. The increasing in weld leg length is caused of increasing in weld strength and decreasing in stress progress in weld that cause the increasing in life and strength of the weld which is also in agreement with Iman Hadipour [4].