DNV DNV CLASSIFICATION NOTES 30.5 PDF

Introduction

General

This Classification Note gives guidance for description of important environmental conditions as well as giving guidance for arriving at environmental loads.

Environmental conditions are described in clauses / 2-4 While environmental loads are described in clauses 5-7

Environmental conditions

Environmental conditions cover natural phenomena which may contribute to structural damages, operation disturbances or navigation failures. Phenomena of general importance are:

•  Wind

• Waves

• Currents.

Phenomena which may be important in specific cases are:

• Ice

• Earthquake

• Soil conditions

• Temperature

• Fouling

• Visibility

• Tides.

The phenomena are usually described by physical variables of statistical nature. The statistical description should reveal the extreme conditions as well as the long- and shortterm variations.

The environmental design data should be representative for the geographical areas where the structure will be situated, or where the operation w!ll take place. For ships and other mobile units which operate world-wide, environmentaJ data for particularly hostile areas, such as the North Atlantic Ocean, may be considered.

Empirical, statistical data used as a basis for evaluation of operation and design must cover a sufficiently long time period.

For operations of limited duration, seasonal variations must be ta.ken into accovnt. For meteorological and oceanographical data, 3-4 years is a minimum. Earthquakes must be based on long-term historical data.

Environmental loads

Environmental loads are loads caused by environmental phenomena.

Environmental loads to be used for design are to be based on environmental data for the specific location and operation in question, and are to be determined by use of relevant methods applicable for the location/operation taking into account type of structure, size, shape and response characteristics.