During the last decade there has been an increase in the use of high-tensile steel in ship hulls. Initially, high-tensile steel was used in the deck and bottom structure, but lately it has also been used in side-structure and transverse elements. This has given more optimised ships, in terms of both reduced steel weight/investment costs and increased earning potential by increased deadweight. The reduction in the scantlings due to high-tensile steel has in some cases given higher repair costs due to an increased number of fatigue cracks and steel replacement due to corrosion. A Net Present Value (NPV) assessment of the total cost benefit is therefore performed for a life span of 20 years with extensive, partial or moderate use of high-tensile stieel versus mild steel. The analysis studies important factors to reduce life-cycle costs of ship hull structures, and aims to increase the awareness of the implications of using high-tensile steel in shiphulls. A VLCC complying with the DnV Rules for fatigue and corrosion protection is used as a case study. The cost benefits are evaluated and consider investment costs, including steel weight, material price, coating systems, and production costs for different grades of high-tensile steel application, and operating costs including maintenance strategies, corrosion margins, fatigue, repair costs, ect. Since most of the cost items are uncertain estimates of the future, a probabilistic method is applied.
Economics of high-tensile steels in ship hulls
Wirtschaftlichkeit von hochfesten Staehlen in Schiffskoerpern
Marine Structures ; 7 , 1 ; 31-50
1994
20 Seiten, 8 Bilder, 7 Tabellen, 11 Quellen
Article (Journal)
English
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