An increasing number of platforms are reaching their design life. For various reasons these platforms will require an assessment of their structural integrity. As examples one may experience operational changes of the platform that may lead to increased loads or there may be damages that reduce the structural capacity. Consequently, the design premises may have changed significantly and may result in increased uncertainty about the safety of the structure. In such cases the assessment process is focused towards reassuring that the structure has adequate safety.

When performing these assessments the engineer is faced with tasks where little guidance is found in design standards and the analyses that are required are often based on advanced techniques and methodology that seldom is used in design of new structures. The cost of doing advanced analysis is relatively low compared to replacement of an existing structure, but relatively high compared to moderate additions of e.g. steel in the design of a new structure. Design standards are based on theories, methods and experience for structures in a given design life (e.g. fatigue design and corrosion protection design). When this design life is extended, sound methods for ensuring that the structures are still sufficient safe is needed. Such methods will normally be "condition based design", where inspection, maintenance and repairs are included in the assessment in integrated way.

This paper discuss the overall assessment process for life extension and outline procedures connected to how to deal with the specific aspects that engineers meet when performing assessment for structural life extension.

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