Piston ring material in a two-stroke engine which sustains wear due to catalyst fines

Abstract

This research paper discusses preventive protection of the marine engine against abrasive effects of the catalyst fines in fuel. The relevant facts were gathered while analysing the performance of the slow-speed Wärtsilä RTA engine on an Aframax tanker. The analysis comprised fuel properties, regular and extraordinary examinations of the engine, including the control and replacement of piston rings and the measurement of the liner wear rate. The research particularly focused on the top compression ring as it withstands highest loads and fastest wear. On the other side, the research involved a chemical analysis of the piston rings with the purpose of establishing their chemical properties, structure, coating thickness and micro-hardness. In addition to a number of preventive measures that can be taken on board before injecting the fuel into the combustion chamber, the selection of a piston ring’s material quality affects its wear rate to a large extent. The wear rate also depends on the catalyst fines in fuel. In practice, the piston ring of GGV type proved to be resistant to abrasive wear and its chemical properties were established through laboratory material testing.