The topic of the final work from the course Metal Engineering 1 is to describe the areas of implementation of hollow circular tubular sections in the civil engineering, and especially to the design of splices that are very specific both in terms of frequent use and in terms of the calculation itself. The paper explains the concept of splices, the technology of their execution and their application in different fields of civil engineering. The second part is a more detailed description of the procedure for calculating the splices exposed to the longitudinal force, bending moment and torsion moment. Finally, a numerical example illustrates the practical calculation of one variant of the mounting extension.