The article draws attention to the problems of maintaining fuel injection pumps of marine diesel engines in the conditions of the use of residual fuels in which the quality is steadily deteriorating. The analysis of tribological processes occurring in hydraulic precision pairs of fuel injection pumps, such as a barrel-plunger, is presented. Problems occurring regarding the operation of injection pumps and the possibilities of their avoidance on board are discussed. The means of condition monitoring, including the application of thermography methods, are characterized. The authors have done research concerning diagnosing injection systems of high and medium power engines by using acoustic emission (AE) signals. The experiment results obtained with the use of acoustic emission and wavelet analysis confirmed the dependency of the frequency components contained in the acoustic emission signal on the condition state of the injector pumps’ tribological pair.

The quality or reliability of diagnostics is understood as obtaining the most likely diagnosis, and finding possible causes leading to incorrect operation of the system. In real engine running conditions it is often very difficult. Dependable methods providing the most reliable diagnoses have not been developed yet. It becomes more and more important to identify the limit state in condition monitoring—the state that should not be exceeded because continued operation of such a machine is not advisable for technical, economic, or operational safety reasons. The authors have implemented a method using acoustic emission signal analysis for the identification of the injection pump limit state in a working engine. The use of the cross gain function allows one to reliably diagnose limit conditions related to the wear of the precision pair in injection pumps of running engines, working as energy transmission systems on ships and in land-based power stations. The paper draws the results for two different marine diesel engines: two-stroke (by MAN B&W type 7S80MC-C) and four-stroke (by Wartsila type SW 380). The experiment results obtained indicate that the use of the cross gain function allows us to determine the limit condition for a various type of injection pump.

Acoustic emission (AE) is one of the methods of non-destructive evaluation (NDE), and functions by means of detecting elastic waves caused by dynamic movements in AE sources, such as cracking in various material structures. In the case of offshore wind turbines, the most vulnerable components are their blades. Therefore, the authors proposed a method using AE to diagnose wind turbine blades. In the identification of their condition during monitoring, it was noted that the changes characterising blade damage involve non-linear phenomena; hence, wave phenomena do not occur in the principal components of the amplitudes or their harmonics. When the authors used the inverse transformation in the signal analysis process, which essentially leads to finding a signal measure, it allowed them to distinguish the wave spectrum of an undamaged system from one in which the material structure of the blade was damaged. The characteristic frequencies of individual phenomena interacting with the blade of a working turbine provide the basis for the introduction of filters (or narrowband sensors) that will increase the quality of the diagnosis itself. Considering the above, the use of the coherence function was proposed as an important measure of a diagnostic signal, reflecting a given condition of the blade.

This article presents the influence of various ship’s operational conditions occurring during manoeuvres related to entering and leaving the ports and mooring operations. Frequent starts and stops of the ship’s propulsion unit are then required, which affect the variability of the energetic loads of the ship’s power plant, causing accelerated, non-design wear of the ship’s main propulsion engine. The effects of cold start-ups of the main ship engine are the subject of this study. Conditions of the engine inlet valve damage process are discussed. The physics of the degradation process leading to air inlet valve damage was considered. Laboratory tests of structure continuity and their results are discussed, and the valve material defects were excluded as the cause of the damage. The causes of repeated damage to the inlet air valves were identified. The effectiveness of the performed corrective measures was confirmed by a documented control test of the engine start-up. The article is a utilitarian premise for the requirements of the Classification Society.

In this article, there are presented problems of tribological wear occurring in slow speed diesel engines elements such as piston – piston rings – cylinder liner assembly and fuel injection pumps caused by use of poor quality fuels. There are defined specific quality standards for bunkered marine residual and distillate fuels with accordance to ISO Standard 8217:2010 and recommended by engine maker’s fuel quality at engine inlet. Moreover, there are characterized common contaminants in this fuels with special attention to the most harmful the residual fuel catalytic particles so-called Cat-Fines, specified the maximum limits and described their influence on engine’s tribological pairs. Furthermore, this paper considers the operational precautions and treatment of poor quality fuels with elaboration of specific procedures to prevent and reduce the influence of Cat-fines to tribological wear in engine elements containing issues of fuel oil storage and distribution on board, fuel oil treatment, usage of poor quality fuels and condition monitoring of engine elements.

The paper discusses the problem of maintenance of the marine steam turbogenerator sets used in power systems on VLCC type oil tankers. The analysis of operation, monitoring and applied diagnostic methods of a selected turbogenerator working in the AT series waste energy system produced by Mitsubishi is presented. The analysis focuses on the applied maintenance method and its credibility and effectiveness in terms of technical assessment. The results of the performed maintenance actions and applied operational procedures making use of technical diagnostics and supported by a wider range of measurement capabilities of external service are presented and evaluated. The range of the study includes the readiness, reliability and safety of the use of turbogenerators being the result of the maintenance performed in accordance with the applied strategy of operation.