PHYSICAL AND STATISTICAL METHOD OF ESTIMATING THE DURABILITY OF METAL VENTILATION AND CHIMNEY PIPES

The article deals with a complex and urgent engineering problem - ensuring the durability and operational reliability of metal ventilation and chimney pipes operating under aggressive environmental conditions. The main attention is focused on the development of a physical and statistical method for assessing the technical condition and predicting the service life of structures, taking into account the stochastic nature of degradation processes. The paper notes that classical approaches do not allow taking into account the random variability of material parameters and external loads, which limits the accuracy of predictions and complicates maintenance planning. The proposed method is based on the use of mathematical models that combine elements of reliability theory, statistical analysis, and physicochemical modeling of changes in material properties. The durability assessment is carried out by analyzing the physical and mechanical characteristics of structures, their changes over time under the influence of the environment and loads, as well as taking into account technological and geometric factors. A significant role in the proposed system is played by parametric models that allow describing the probability of failure-free operation of structures at any time of operation. The article discusses the principle of constructing the reliability function, defines the key indicators - average service life, gamma percentage life, reliability index, and safety level. Methods for linearizing property functions that do not have an analytical expression using central-difference approximations are presented. Approaches to the construction of approximating distribution functions using models from the Johnson and Pearson families are also proposed. Particular attention is paid to the system of planned preventive maintenance, which is a basic tool for managing the aging of structures. The authors substantiate the need to implement such systems based on the results of technical condition monitoring and predictive models. Several options for engineering intervention are considered: elimination of the impact of the negative environment, slowing down aging, one-time restoration, and periodic repairs. The approach to standardization of service life and reliability levels in accordance with European standards is generalized. It is shown that effective management of structural life is possible only if the residual life is accurately predicted and physical and statistical models are integrated. The results of the study are valuable for engineers, designers, operators, and technical supervision authorities. The proposed physical and statistical approach reduces the risk of accidents, minimizes losses, increases safety, and extends the service life of critical infrastructure facilities operating in difficult operating conditions