DNV-RP-F204 - Riser Fatigue Analysis

[atedionyahoo]

Ref: DNV-RP-F204 (July 2005), Sec. 3.4.1 – it is quoted as follows:

Quote
The effect of the Design Fatigue Factor (DFF) should be taken into account by reducing the allowable stress range by a factor (DFF)^-0.33
Unquote


I am confused whether to apply the above for all the cases (i.e. detail fatigue analysis required) or only for the cases which detail fatigue analysis is omitted.

Could somebody please shed light.

 

[G5Ufo]

It would be better only to apply the DFF on the omitted detail fatigue analysis.
Too bad that I don't have a copy of this document to grasp the meaning of the quote, but the principal of doing analysis in being conservative unless you have the strong background to explain when you're trying to out from the conservatism

 

[atedionyahoo]

Thanks G5Ufo,

The subject doc is available in dnv site (i.e. exchange.dnv.com/publishing/Codes/ToC_edition.asp).

Yes, I have considered the coefficient DFF^-0.33 for the omitted fatigue analysis case only.