Research and Development


Technical Paper

Estimation of plate thickness deduction of oil tanker for domestic area - Indonesia waterways

Tahun 2018
The requirement of plate thickness of classification society is taking into account the net thickness, corrosion allowance and additional extra margin as owner request. Corrosion allowance is an additional constant value that is related to the environmental condition which shall be added in the formulae to calculate the requirement plate thickness and profile of the ship construction in accordance with the classification society rules. It is known that major Classification Societies rules are based on the North Atlantic Ocean enviromental condition. However, if the ships are operated in local domestic area, i.e. Indonesia waterways, the rules requirements become very conservative. These condition make the ship design be coming over design. This study aims to develop time-dependent corrosion allowance formulation. The statistical analysis of thickness diminution carried out using measurement records that are documented from 23 Oil Tankers during her voyages in Indonesian waterways. The age of target ships was ranging from 5 to 23 years. The thickness measurements were located in the deck plate, bottom plate, inner bottom plate and side shell plate which are located on ballast tank, fresh water tank, void tank, fuel oil tank, slop tank and cargo tank. It is found that the Weibull distribution could be used for estimation the time dependent plate thickness deduction. In general, for design life of 25 years the greatest deduction of plate thickness is in deck area of 2.4 mm, followed by bottom plate of 1.8 mm, 1.6 mm side plate and the smallest is in inner bottom plate which is 1.1 mm. Generally, the results show that the thickness diminutions in Indonesian waterways are smaller than IACS CSR requirements, but greater than Sone’s results.

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