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OS-C501

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Offshore Standard DNV-<strong>OS</strong>-<strong>C501</strong>, November 2013<br />

App.A Check-lists for design input – Page 211<br />

A.4 Environments<br />

The term environment designates in this standard the surroundings that impose no direct load on the structure.<br />

The environment may impose indirect loads on the structure, e.g. thermal stresses or swelling due to moisture<br />

uptake. This should be considered as a load effect, and calculated according to the relevant parts of Sec.8.<br />

However, the environment is generally considered for its effect on the degradation of material strength.<br />

Table A-5 Examples of Environments<br />

Temperature internal and external<br />

Temperature variations<br />

Temperature gradients<br />

UV radiation<br />

Moisture<br />

NATURAL Sea water<br />

Lightning<br />

Acid rain<br />

Atmospheric electrical field<br />

Animals (e.g. shark bites on tethers,<br />

elephants walking on pipes)<br />

Transported or contained fluids and<br />

chemicals<br />

Temperature internal and external<br />

Pressure internal and external<br />

Oil spill<br />

Cleaning materials<br />

FUNCTIONAL Paint solvents<br />

Accidental chemicals<br />

Fire<br />

Process gas leaks<br />

Service induced shocks<br />

Accidental high pressure steam<br />

A.5 Distribution types of basic variables<br />

From DNV Classification Notes – No. 30.6 - Table 2.1<br />

Table A-6 Standard variables and corresponding distribution types<br />

Variable name<br />

Distribution type<br />

Wind Short-term instantaneous gust speed Normal<br />

Long-term n-minute average speed<br />

Weibull<br />

Extreme speed yearly<br />

Gumbel<br />

Waves Short-term instantaneous surface elevation (deep-water) Normal<br />

Short-term heights<br />

Rayleigh<br />

Wave period<br />

Longuet-Higgins<br />

Long-term significant wave height<br />

Weibull<br />

Long-term mean zero upcrossing or peak period<br />

Lognormal<br />

Joint significant height/mean zero upcrossing or peak period 3-parameter Weibull (height) / Lognormal<br />

period conditioned on height<br />

Extreme height yearly<br />

Gumbel<br />

Current Long-term speed Weibull<br />

Extreme yearly<br />

Gumbel<br />

Forces Hydro-dynamic coefficients Lognormal<br />

Fatigue Scale parameter on S-N curve Lognormal<br />

Fatigue threshold<br />

Lognormal<br />

DET NORSKE VERITAS AS

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