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The article reflects one of the ways to maintain the proper technical condition of drinking water supply facilities to improve their reliability and water quality. The chosen problem is investigated by theoretical substantiation of the advantages of spraying protective coatings on damaged areas of structures and equipment formed by surface defects. The study focuses on surface damage at the micro level. The tank is the final object in the field of water supply, namely water treatment, the pipeline is the object directly through which water is transported to the consumer. Therefore, maintainance of the proper technical condition of these facilities is necessary and significant. After all, these technical facilities are the causes of secondary water pollution. The creation of a high-quality coating on the damaged areas of these objects requires the solution of a number of problems, one of which is the justification of the size of the protective particles and their relationship with the geometric parameters of the defects. As a result of this study, we state the necessity to assess the proportionality of the protective particle and the defect at the micro level. That is, the influence of the scale factor is revealed and the deformation properties of the protective particle and defect edges are taken into account, namely, the ratio of the initial size of the protective particle and the already deformed protective particle to fill the volume of the cavity of the proportional defect is obtained and it is established that the initial diameter of the protective particle should be chosen in the range of 1.0...1.1 from opening the edges of the defect for optimal filling of its cavity. Considering the deformation properties of the protective particle and the assessment of the height of its filling of a commensurate defect at the micro level, a significant effect on the surface roughness, in particular steel pipelines, a decrease in the minimum surface roughness of pipelines has been found.

This study aims to investigate the sedimentation and the consolidation of the packed bed/cake formed due to the monodispersed and bidispersed particles under different flow conditions. Mutual interactions between the bidispersed particles and the liquid are considered by using a polydispersed drag model. The attractive force is considered by using the JKR model. Sensitivity of the void fraction of a sedimented packed bed/cake due to particle-particle interaction parameters is studied. Furthermore, the effect of the fluid flow is analyzed by performing the simulations in two stages. In the first stage, packed bed/cake is formed by the sedimentation of the particles in the absence of the fluid forces and in the second stage flow through the packed bed/cake is simulated by using the CFD coupled with the discrete element method. Based on the simulations, correlations between the sedimented and the consolidated void fractions are developed.