Assessing the possibility of changing the monitoring frequency of the residual thicknesses of the navigation locks gates elements

Abstract

One of the main methods for monitoring the technical condition of the navigation locks gates is to determine the amount of corrosion wear of their elements using ultrasonic thickness measurement. This diagnostic operation is performed at least once every five years. In accordance with the methodology, the control requires the removal of the protective coating in the measurement area. At the same time, there is no possibility of a full restoration of the coating. The specified frequency of measurements is adopted based on the peculiarities of the maintenance of locks and the durability of protective coatings, the service life of which does not exceed 5 years. It is noted that recently, the cases of measurements with a satisfactory technical condition of the protective coating on the elements of the structures, which are being examined, have been more frequent. This circumstance indicates an increase in the service life of protective coatings and, consequently, the possibility of revising the established frequency of measurements of the residual thickness of the gates elements. In this regard, the purpose of the study is to assess the possibility of changing the timing of ultrasonic thickness measurement during primary and periodic measurements of the residual thicknesses of the gate elements, taking into account the state of the protective coating. To achieve this goal, the collection and analysis of the range of protective coatings used in the anticorrosion protection of the main and emergency repair gates of navigation locks, their service life, as well as permissible deviations in thickness for the supplied rolled metal, are carried out. It has been established that epoxy-based protective coatings are most often used as primer and top coats. The thickness of the applied coatings has increased by 2–3 times and averages 200–350 µm. Damage to coatings in the period from 5 to 10 years of operation averages about 6 % of the total surface area. In the course of the study, it has been also found that the permissible minus limit values for deviations in the thickness of the supplied rolled products can range from 0.8 to 4.2 mm, depending on the thickness of the sheet and the accuracy of its manufacture. The presence of such deviations has a particularly negative effect on the resource of small thicknesses. Additionally, the maximum average value of the corrosion rate of metal structure elements in operation is determined. The totality of the information obtained makes it possible to develop recommendations for changing the timing of the residual thicknesses measurement, ensuring the safe operation of the considered elements of mechanical equipment.