Study on Damage of Propeller Shaft Sleeve for Seawater Lubricated Rubber Bearing-2nd Report

Abstract

The previous report described corrosive wear on propeller shaft sleeves, made of bronze, in seawater-lubricated stern tube rubber bearings. Accompanying is the occurrence of craters on the sleeve surface due to the action of erosion corrosion. As a countermeasure, based on the mechanism of erosion corrosion, this second report will provide the development of a cathodic protection bearing, what prevents corrosion of the sleeve surface and reduces wear. Using anodes installed in some of the water channel grooves of rubber bearings, this method is characterized by intermittent protection at best, and protection conditions were investigated by means of fundamental testing and using bearings of 140 mm in diameter. As a result, a current density of 8 A/m 2 was found to protect the sleeve from corrosive wear. Cathodically protected bearings were also applied to bearings of 500 mm in diameter and equipped for a ferry vessel. The results are presented here in terms of bearing design, trial running, and successful reduction of wear during actual in-service use.