The project elaborated in terms of engineering studies concern with project of a manufactural process of separator weldment and of an economical analysis of a production calculated for one item of a weldment and one item of a casting. During elaboration this project there were used all obtainable norms and technical bibliography. In literery studies there are summarized important knowledges related to welding constructions, welding technology, heat treatment and checking fusion splices. There was choosed box construction for this separator weldment. That is designed of two types of material. First of materials S355J2G3, EN 10025 is used for structural parts and the second material S235JR, EN 10025 is used for stiffering pars. The propriety checking of this construction and used materials was performed by Finite Element Method. After calculating costs of production of both variants we can say, that the costs of production of one piece seperator weldment are considerably lower, than costs of production of one piece of casting.