Optimal Fault Detection of River Ship Hulls

Abstract

The issue of determining the reliability of the hulls of inland and river-sea-going vessels after a known number of years of operation under given condition is considered. It is accepted that fault detection of a ship’s hull is a survey, measurement and evaluation of defects in each element of the ship’s hull in order to establish the methods and scope of repairs that ensure its reliable operation until the next regular survey under specified operating conditions. It is shown that the volume of residual thicknesses can be significantly reduced using the statistical data on wear rates presented in the Rules of the Russian River Register. At the same time, the reduction in the scope of measuring the parameters of defects retains the probability of detecting all defects of the hull elements to the level of 0.95, and the probability of failure-free operation of the hull until the next survey, after the elimination of the identified defects will be at least 0.95. A form of table for processing the values of the residual thicknesses of all elements in the inspection report and instructions for filling it out are given. Explanations for using the results of measurements and calculations at determining the technical condition of certain elements in the group and the ship’s hull as a whole are given. The last column of the table indicates the method of eliminating the defect of an element and groups of elements, and in the conclusion of the inspection report, the method of repair and its scope for the entire hull of the ship providing a suitable assessment of the condition after repair are indicated. The main advantage of this paper, in difference from the previous studies of the authors in this area, is that user-friendly (the designer of the defect report tables) nomograms, which allow you to reduce the number of measurements of the residual thicknesses of hull structure elements in the online mode, have been created. The performed study, allowing you to reduce the number of measurements while guaranteeing the reliable operation of the ship’s hull, will let the shipowner to reduce the cost of repair work by reducing the number of days of ship standing on the slipway (in the dock). In addition, the ship repair company will be able to free up its production facilities for the purpose of their subsequent loading with other ship repair or shipbuilding orders, which will increase the efficiency of their activities.

Forecasting the volume of defect detection works on a river fleet vessel hull

“…В результате выполненных расчетов с применением новой Инструкции доказано, что число измерений остаточных толщин элементов путем проведения предварительного этапа дефектации корпуса можно существенно сократить. В работах [1]- [3] доказано, что использование вероятностного подхода, предусмотренного новой Инструкцией, гарантирует 95 %-ю достоверность прогнозирования уровня общей и местной прочности.…”

“…адм. С. О. Макарова разработана новая «Инструкция по дефектации корпусов судов внутреннего и смешанного река -море плавания, поднадзорных РКО» 1 (далее -Инструкция) [1], основанная на вероятностном подходе, которая позволяет существенно сократить число замеров корпусных конструкций (при гарантированном обеспечении надежности эксплуатации), что может быть выгодно для судовладельца, но неэффективно для судоремонтного завода и исполнителя дефектации. Разработанная Инструкция предполагает проведение так называемого предварительного этапа дефектации, позволяющего заблаговременно, до осуществления процедуры измерения корпусных конструкций, рассчитать прогнозные остаточные толщины и разработать оптимальную схему замеров корпусных конструкций.…”