Local heating and high temperatures connected with the welding processes cause temporary thermal stresses and permanent plastic strains, which can reduce the strength of the welded cross.section. Different analytical methods, experimental methods and empirical formulae were developed to determinate the stresses created during the welding works [1-5]. This paper deals with the analysis of some of these methods and presents Modified empirical formulae, which were developed by the author during research activities about the determination and distribution of welding stresses in the web and the flanges of welded I-cross-sections.