The problems of determining the corrosive wear of steel structures are considered. The results of applying ultrasonic method to determine the remaining profile of the structure are described. The main advantages and disadvantages of ultrasonic thickness meters comparing to mechanical devices are given. Low reliability of the method based on evaluating the thickness of the corrosion oxides is substantiated. The problems of determining the original section of the elements are outlined. The algorithm for determining the corrosive wear is developed. An example of its application on a real object is shown.