Structural and Fatigue Analysis of a Type C tank Vessel Hull at Class Renewal Number IV

Abstract

Duringthelifetimeofavessel,structuraldefectsariseintheformofmaterialwastage(corrosion),fractures, deformations leading to the deterioration of its condition. The impact of corrosion on vessels is one of the most indispensable point of interest in terms of safety and economics. In order to decide on actions to be taken for a proper maintenance of the vessel, surveys are to be performed in compliance with sound marine practice. Namely, regarding the hull condition, these surveys include visual examination of the hull,assessmentofpossiblestructuraldefectsand,dependingonthevesselageandmaintenancecondition, thickness measurements in order to determine the structure wastage. The vessel under consideration is a type C tank inland vessel at class renewal number IV (vessel age>15 years). The scope and extent of thickness measurements at class renewal number IV are defined, together with acceptance criteria, in Bureau Veritas NR 597 requirements for thickness measurements applicable to inland vessels. Taking into account the thickness measurements report, structural and fatigue analysis is carried out in the present thesis using BV Rules and direct engineering calculations (finite element method) to provide information regarding the strength of the vessel structure and to estimate the fatigue life of structural details. Fatigue damage and fatigue life of critical structural details have been evaluated in accordance with a deterministic/simplified approach proposed by BV.