Corrosive Wear of Bronze Propeller Shaft Sleeve (Part 1; Investigation of the Sleeve Used and Fundamental Corrosive Wear Test)

Abstract

As propeller shaft diameters of ferries become larger in conjunction with higher vessel speed and equipping with CPPs (controllable pitch propellers), the life duration of a stern tube bearing under seawater lubrication has a tendency to be reduced. The wear of the propeller shaft sleeve is typically greater than that of the rubber bearings, with triangularly shaped craters appearing on the sleeve surface. In this paper, we describe the investigation of a used sleeve sample taken from an actual vessel, as well as the wear characteristics of various bronze alloys examined by conducting corrosive wear testing under sliding conditions equivalent to actual ferry service. The results indicated that corrosive wear was the main cause of sleeve wear and, based on comparisons between the amount of wear in seawater and in distilled water, the influence of corrosion on sleeve wear was found to be substantial. Also, the craters are considered to be formed by erosion corrosion. In a follow-up report, cathodic protection is applied to the sleeve as a countermeasure based on the mechanism, and the wear characteristics are reported together with the application to an actual vessel.