The study objective is to analyze the values of contact approach in the flat joints of special equipment, using unified modules obtained from the experiment and existing dependencies. The task is to compare the values of contact approaches obtained as a result of calculations based on existing dependencies with the results of experiments. Research methods: experimental studies and already existing computational methods of research to determine the values of contact approach. The novelty of the work: refined dependencies are obtained, as well as the values of coefficients of already existing dependencies for calculating the values of contact approaches of extended parts of unified modules during their assembly. Research results: the obtained results of calculations and experiments are analyzed. The values of the coefficients for the existing methods of calculating contact approach are refined, and experimental dependences are obtained. Conclusions: studies have shown that for extended contact sections, the use of calculated dependencies in some conditions gives an error that cannot be neglected. When designing high-precision equipment, such calculations require accurate definition.