PSI - Issue 59

Igor Stadnyk et al. / Procedia Structural Integrity 59 (2024) 679–686 Igor Stadnyk et al./ Structural Integrity Procedia 00 (2023) 000 – 000

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deviation of the body thickness  a = 0.2 mm, the permissible value of corrosion destruction Х max = 2 mm (thickness of protective coating), then the resource of vaporizing device on the determining part (body) at the given probability of failure-free operation will be in the ratio given in Table. 1.

Table 1. Dependence of the service life of the corrosion-protected body of the evaporator of the sugar plant on the probability of failure-free operation Probability of failure-free operation 0.9 0.99 0.999 Quantile 1.282 2.326 3.090 Resource T, years 1.701 1.476 1.319

The given technique can be combined with the developed computer program "CORRODERE", which enables to obtain statistically reliable data in laboratory conditions for predicting the reliability and durability of the equipment and to outline the main ways of its anti-corrosion protection. Corrosion-mechanical wear is usually long-term, which creates prerequisites for the formation of chemisorption film, especially with high concentration of the extract in starch-containing medium. The nature of the fermentation dynamics (Oliynychuk et al., 2016) and the indicators of fermentation of starch-containing raw materials with the inhibitor do not affect the rate of maturation of maturing of the brew with sequential and parallel filling of fermenters at temperatures up to 60 0 С and slow down the corrosive effect. This fact is reflected on the fatigue curves (Fig. 4).

Fig. 4. Fatigue curves: 1 – air; 2 – starch-containing environment; 3 – starch-containing medium + 2 g/l extract.

This is especially noticeable on the basis of 5·10 7 cycles of circulation circuits, where the fatigue boundary conditions are 7 times lower than the fatigue boundary in air (curves 1 and 2). When high-level stress occurs (> 220...240 MPa), where there is a greater influence of mechanical factors, the difference in resistance to corrosion and wear in air and in the environment is noticeably smaller. The introduction of the inhibitor into the environment affects the resistance of the device surface to corrosion and mechanical wear (curve 3). However, this effect is much smaller than its effect on general corrosion in the absence of cyclic stresses. The corrosion inhibition coefficient at the inhibitor concentration of 0.8 g/l is 7.2, while on the basis of 5·10 7 – it reaches only 2.6. The presence of the inhibitor in the medium changes the nature of the corrosion-mechanical wear of the device surface. In the process of long-term research, the chemisorption film, which can change into the phase one, provides significantly higher protection indicators. 5. Conclusions The combination of inhibitors and inhibited protective systems with other types of aggressive media is of great practical importance. Such protection can be used to increase the durability of the transportation systems of food processing plants.