Wear Condition Evolution of Cylinder Liner-Piston Ring on the Two-Stroke Marine Diesel Engine Through Long-Term Monitoring and Analysis of Cylinder Oil

Abstract

In recent years, stringent policies on low-sulfur fuel oil (LSFO) usage in the shipping industry have raised concerns regarding the reliability of two-stroke marine engines. This study conducts a longitudinal investigation of the main engine on a wood-pulp carrier fuelled with LSFO, aiming to underlying causes of cylinder wear and develop solutions. Throughout an operation period of roughly 2500 h, drain oil was sampled with the following characteristics evaluated: viscosity, basicity, moisture contents, ferrography and compound containment, as well as the concentration of trace elements, seeking to monitor the wear and lubrication status of a two-stroke marine engine. The comparative analysis of representative lubricant samples revealed that the severity of cylinder wear intensifies with engine operation when using LSFO, transitioning from rubbing wear to fatigue, cutting and sliding wear, with the corrosion-induced wear being prevalent even during the early stage of the engine lifecycle. Meanwhile, intermittent replacement of high alkalinity cylinder oil has been proven an effective solution for improving cleanliness, mitigating cylinder wear and lubricant degradation. Viscosity and basicity with high sensitivity can serve as control parameters to determine the necessity of oil replacement. To prevent the generation of severe corrosive wear, intervals for oil replacement are advised to exceed no more than 500 h.