The article discusses the issue of the practical implementation of various methods for calculating the quantitative values of the operating cycles of the tank of the marine terminal. The analysis of the above methods is carried out for direct and indirect calculation of the cyclicality of the sea terminal reservoir. On the basis of the performed study of various methodologies for calculating fatigue damages of structures of one type or another, as reflected in the methodological documents, a comparison and critical analysis of the results of these calculations was carried out. The contradictory and ambiguous nature of the calculation results is shown on the examples of structural steel of the tank wall of the marine terminal. The regularities of the cyclic loading of the reservoirs of the sea terminals have been determined and a method has been developed for the quantitative assessment of the parameters of the cyclic operation of the reservoirs under various modes of operation of the terminals. It is shown that the actual cyclical operation of the marine terminal reservoir, taken into account on the basis of objective data from the dispatch control and management system, differs significantly from the values obtained by any analytical methods that assess the cargo flows passing through this reservoir. The paper presents a methodology for calculating the actual and permissible number of operating cycles for a defect in the geometry of the tank wall. The proposed technique is based on formalizing real irregular loading through equivalent circuits of regular cyclicity. The scheme for determining the variants of loading blocks is presented, which allows to objectively calculate for any reservoir the number of schematization classes and the number of loading blocks. On the basis of the proposed methodology and the "rainflow method" it is possible to schematize the actual values of irregular loading and present these data in the form of schematized cycles for different filling levels corresponding to the loading units.
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