Visual and optical method for corrosion depth assessment of escalator metal structures

Introduction. Supporting metal structure is the basis of escalator: drive units, track systems, guard devices, and other components that ensure the escalator operation are mounted on it. One of the most common types of corrosion damage on escalator metal structures is uniform corrosion over the entire surface. This process is characterized by progressive penetration of corrosion from the material outer layers to its internal structure, resulting in a decreased effective cross-section and reduced strength characteristics. As operating loads remain relatively constant, this leads to increased strain.
The implications of this study refer to reduced labor and financial costs of comprehensive inspections of escalator metal structures through introducing remote control methods that provide continuous monitoring of their condition and allow for the automation of calculation procedures, thereby increasing their efficiency without compromising the quality of technical condition assessments.
Materials and methods. Data from a comprehensive survey of escalators of St. Petersburg Metro State Unitary Enterprise have been used, the study being completed by STEK LLC expert organization and specialists from Land Transport and Technological Complexes Department of St. Petersburg State Transport University of Emperor Alexander I (PSUTS). Analysis of design documentation, statistical methods and mathematical modeling has been used in the study.
Results. The functional principle of the proposed visual-optical diagnostics method is to be used as an integral part of a comprehensive corrosion monitoring system aimed at continuous assessment of the operational condition of escalator load-bearing metal structures and early identification of potential failures associated with the development of corrosion damage.
Conclusion. The proposed method provides a comprehensive quantitative assessment of corrosion damage based on three parameters: penetration depth, local (focal) defects, and changes in the mechanical properties of the metal. Expanding the range of characteristics leads to at least a 30% increase in informative value of the results, which allows for a 1.5-fold improvement in the accuracy of predicting the residual life of metal structures.

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