Probabilistic estimates of corrosion rate of fuel tank structures of aging bulk carriers

Abstract

This paper considers corrosion wastage of two ship hull structure members as a part of investigated fuel oil tanks of 25 aging bulk carriers. Taking into account that many factors which influence corrosion wastage of ship hull structures are of uncertain nature, the related corrosion rate (c1) is considered here as a real-valued continuous distribution, assuming that the corrosion wastage starts after 5, 6 or 7 years. In all considered cases, by using available data and applying three basic statistical tests, it is established that between two-parameter continuous distributions, normal, Weibull and logistic distributions are best fitted distributions for the mentioned corrosion rate (c1). Note that the presented statistical, numerical and graphical results concerning two mentioned ship hull structure members allow to compare and discuss the corresponding probabilistic estimates for the corrosion rate (c1). Keywords: Bulk carriers, Fuel tanks, Inner bottom plates, Side watertight girder, Corrosion rate, Depth of corrosion, Normal distribution, Weibull distribution, Logistic distribution