The industry demand for ice-classed tankers is rapidly increasing as a result of the growing exports of oil from Russia. There has been a trend toward allowing for alternative designs using direct calculation approaches. However, no complete procedure is available. This paper presents a procedure for designing ice-strengthened structures of tankers using direct calculation approaches. It addresses the main issues, including ice load definition, material modeling, structural modeling and acceptance criteria. The paper summarizes a recent joint ABS-SHI project that will become the basis of the future, refined design practice.
Due to the increasing Russian oil exports from the Port of Primorsk and Sakhalin, the number of new tankers being ordered with ice strengthening is steadily growing. Russia is the second largest crude oil exporter after Saudi Arabia, and as the country's port and pipeline infrastructure is expanded, it may export around 1.5 million barrels per day in 2010, compared to just over 500,000 barrels per day in 2002. In addition, because traffic in the Baltic Sea is also growing, the environmental suitability of tankers traveling in the coastal waters of Finland, Sweden and other Baltic nations is an issue of public concern. Considering these factors and the recent harsh ice conditions in the Baltic Sea and Gulf of Finland, tanker owners are intending to build vessels to ice classes. The Ice Class fleet is expected to grow by9% in 2004, 12% in 2005 and 33% in 2006, according to Clarkson Research. The vessels traveling in the North Baltic are required to be in compliance with the Finnish-Swedish Ice Class Rules (FMA, 2002), abbreviated as FSICR below. The majority of the new ice strengthened tankers are built to the FSICR, which have been widely adopted by all major classification societies, such as the American Bureau of Shipping (ABS, 2005a).
