The current stage of civil engineering is characterized by special attention to the safety of structures with a long service life. Such objects were designed several decades ago and their safe operation was ensured by significant safety margins. Now this approach to safety has been replaced by the concept of acceptable risk. It forms the basis of a risk based inspection (RBI) maintenance strategy. The transition from preventive maintenance strategies to a technical condition maintenance is substantiated. Complex indicators of technical condition, suitable for RBI- maintenance, are considered. The methodology of the resource safety index (RSI) is proposed. The latter is used as an indicator of risk. Special models of fatigue resistance is required for its control. The purpose of this paper is to build fatigue models for critical structural elements that are serviced according to the RBI concept. Instead of the traditional S-N curve, the lifetime general equation (first model) be used, where by the arguments are the main influence factors. Along with this, a modified ε - N equation is proposed for deformation criteria. The novelty of this equation is that it uses the rate of S-N- curve (slope) obtained in the first model with high cycle fatigue. The second model, combining the results of fatigue tests, is the equation for the dispersion of durability. The third model is the accumulated damage function under overloads. The efficiency of the RSI method is demonstrated by the example of the reliability assessment of the high strength bolts. Thanks to RSI method forecasting, during RBI-maintenance, parts can be used 3-5 times longer than with traditional methods.

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The influence of changing the technological modes of rolling on the dynamic load of the coilers of rolling mills has been established. The functional equation of motion for strip winding has been determined, the solution of which makes it possible to establish the dependence of the elastic force moment on the strip winding time. The moment of elastic forces is used when calculating the dynamic factor, which characterizes the dynamic loads on the nodes of technological equipment. Investigated the change in the coefficient of dynamism at different thicknesses of the wound strip.

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As a lubrication of the spindle drive unit of the rolling stand It is proposed to switch to the oil-air lubrication system. The advantages of "oil-air" lubrication systems are indicated. The effect of iron-containing impurities on the performance of the lubrication system has been established. The methods of recognition theory for determining the boundary value of iron-containing additives in the working fluid of the lubrication system are analyzed. It has been established that for these purposes the “minimal risk” method is optimal, which, unlike the Bayesian method, is less labor-intensive. An example of the practical application of using the "minimal risk" method to determine the permissible content of iron chips in the working fluid of the "oil-air" lubrication system is given.