This article is focused on the stress analyses of the welded structure of the device designed to the scales calibrating with maximum loading capacity up to ten tons. The article includes basic knowledges of the theory of elasticity and stress analysis and numerical method called Finite Element Method that were used for the task solution. Cores of the work were stress analyses of selected parts of the designed structure of the device. For stress analyses the ADINA numerical software was used. Results of analyses of the primary design device showed that strength in same locations did not respond to the required maximal load. The structure in critical locations was modified and subsequently reanalyses confirmed the sufficient strength with prescribed safety factor.