## 3 Results and Discussion  
According to the proposed energy approach, complete equilibrium fracture diagrams of the material were constructed in the coordinates \"true stress\" (\(S_{i}\))--\"true strain\" (e), which determine the stress-strain state in the local volume, taking into account the change in the cross-sectional area of the region of elastic and plastic deformations. The area enclosed by the diagram corresponds to the specific fracture energy of the material, which is invariant to loading conditions and most fully evaluates the behavior of the material under the influence of a hydrogen environment. In [19], it is shown that when the material fractures in hydrogen, the fracture stresses change little in the hydrogen environment, meaning that evaluating the load-bearing capacity of the structure under the influence of hydrogen using the force-based approach is incorrect. However, the specific fracture energy decreases by 70-90%. Therefore, it is advisable to assess the load-bearing capacity of structural elements under the influence of mechanical loading and a hydrogen environment using the energy approach. The use of the energy approach involves recording the stress-strain field during sample testing in laboratory conditions in the local volume where the maximum stresses occur, as well as similarly measuring and determining the flow distribution in deformations directly on the structural element under operational conditions using the ODCM method, which enhances the reliability of the obtained results. For pipeline systems transporting hydrogen-containing media, low-alloy ART class steels such as X52, X70, X100, as well as ferritic-peariltic steels such as 20, 6 GS, and others, are used. In this study, tests were conducted on samples made of 17G1C steel. Using the developed methodology, the load-bearing capacity of structural elements can be similarly assessed for other grades of steel. The specific energy of the destruction of 17G1C steel for two cases was calculated as the area under the true diagrams for \"\(S\)-\(e\)\" in air (1) and destroyed in water (2) (Figure 2), as well as pre-deformed and flooded (Figure 3). Figure 3: True diagram of pre-deformed samples of 17G1C steel in air (o) and in hydrogen (\(\bullet\)). Figure 2: True failure diagram of tubular samples made of 17G1C steel in air (o) and in hydrogen (\(\bullet\)). The area under the true diagram was calculated using the following equation:  
\[S=\frac{1}{2}\sum_{i=0}^{i\times-1}\left(x_{i+1}-x_{i}\right)\left(y_{i+1}-y_{i} \right), \tag{9}\]  
where \(i^{*}\) is the value corresponding to destruction. As a result of the tensile studies of tubular samples in their initial (undeformed) state and flooded at a temperature of 400 \({}^{\circ}\)C for different times, the specific fracture energy \(W_{c}\) was determined based on the constructed true fracture diagrams of 17G1C steel (Figure 2). Figure 3 shows the test results for 17G1C steel samples pre-deformed by 60% of the true fracture strain in air (o) and in gaseous hydrogen (\(\bullet\)). It was established that the specific energy of destruction in water 17G1C steel without preliminary strain is 20% lower than that in air. At the same time, the fracture strain is reduced by 35%, and the true stresses in hydrogen are 5% higher than in air, which indicates the embrittlement of 17G1C steel in hydrogen (Figure 2). Preliminary plastic deformation of the samples affects the specific energy of destruction by 60%, namely, it reduces it by 5 times (Figure 3). The ultimate strain after the previous elastic-plastic strain in the hydrogen environment decreases by 5.5 times compared to air. This is explained by the fact that in the process of elastic-plastic strain, atomic hydrogen is diffused into the formed cavities, where its molalization occurs. As a result, the movement of dislocations is blocked, and the metal embrittles. This indicates a decrease in the volume of metal that deforms elastically-plastically. At the same time, the value of the true fracture stress \(S_{i}\) increases by 5.5%.