Ice force predictions using the ISO 19906 Arctic offshore structures standard and three national standards have been compared for structures offshore Sakhalin. A multi-leg structure with leg diameters 18 and 24 m subjected to several design ice conditions, level ice 1.2 m, rafted ice 3.5 m and a first year ridge keel 21 m deep was evaluated. ISO 19906 is the most complete and transparent standard in providing guidance. It incorporates guidance on ice strength from the Russian standard, and ice thickness and geometry effects from the Canadian standard. Further guidance is still needed for multi-leg structures.
Late in 2010 an international standard, ISO 19906 Arctic offshore structures (ISO, 2010), was published. It reflects a consensus of the international ice engineering community, and covers a range of topics pertinent to the design of offshore structures in Arctic and cold regions areas (Spring et al, 2011). ISO 19906 comprises a Normative part, which contains the provisions a designer must follow in order to be compliant with the ISO standard. It also contains an Annex A of informative text and commentary to assist the designer in complying with the requirement of the Normative text, e.g. methodologies, equations, descriptions and references. It should be noted that ISO 19906 only covers Arctic and cold region aspects of offshore structure design. There are three national standards which were reviewed in preparation of ISO 19906, and provided guidance for Arctic offshore structures; Canada's CAN/CSA S471-04 General requirements, design criteria, the environment, and loads (2008), the United States' API (American Petroleum Institute) RP 2N Recommended Practice for Planning, Designing, and Constructing Structures and Pipelines for Arctic Conditions (1995) and the Russian Federation's SNiP 2.06.04-82* Loads and Effects on Hydrotechnical Structures (from waves, ice and vessels) (1995).