0

Full Content is available to subscribers

Subscribe/Learn More  >

Application of DNV-RP-F204 for Determining Riser VIV Safety Factors

[+] Author Affiliations
Muthu Chezhian, Kim Mo̸rk, Marit Ronæss

Det Norske Veritas, Ho̸vik, Norway

Trond Stokka Meling

Statoil, Stavanger, Norway

Paper No. OMAE2005-67021, pp. 57-63; 7 pages
doi:10.1115/OMAE2005-67021
From:
  • ASME 2005 24th International Conference on Offshore Mechanics and Arctic Engineering
  • 24th International Conference on Offshore Mechanics and Arctic Engineering: Volume 1, Parts A and B
  • Halkidiki, Greece, June 12–17, 2005
  • Conference Sponsors: Ocean, Offshore and Arctic Engineering Division
  • ISBN: 0-7918-4195-2 | eISBN: 0-7918-3759-9
  • Copyright © 2005 by ASME

abstract

Fatigue is often the governing criterion for deepwater riser design. Fatigue assessment methods based on SN curves typically use fatigue safety factors and there is a lack on consensus about the appropriate Design Fatigue Factor (DFF) for VIV that should be applied. A DFF of 20 is commonly used in project specifications to account for a larger uncertainty in prediction of fatigue damage due to VIV, i.e. fatigue life due to VIV should be at least 20 times more than the service life of the riser. Recent case studies and benchmarking assessments, have confirmed that the DFF of 20 for VIV is not always an optimal choice. Owing to the complexity of the VIV problem, often semi-empirical solutions are adopted in the riser VIV analysis. The implicit uncertainty and bias associated with the VIV analysis model, needs to be considered along with the VIV fatigue safety factor, in order to establish the adequate acceptance criterion for VIV induced fatigue. The stochastic variables governing the VIV and their associated uncertainties can vary widely from case to case and this in turn will influence the VIV safety factor. Different stochastic variables may be relevant based on the floater type, riser type, environmental modeling, analysis methodology etc. In addition to these stochastic variables, the uncertainty in the VIV specific variables, such as Strouhal number, bandwidth parameters, damping effects, lift coefficient, response models (Amplitude /Diameter ratio), etc also need to be considered in the evaluation of the VIV safety factor. In this paper, guidance is provided by means of case studies for establishing case specific VIV safety factors. By performing a set of dedicated analyses for the prevailing uncertain input parameters, the resulting uncertainty in the VIV fatigue damage is estimated. The enhanced risk based criterion presented in DNV Recommended Practice RP-F204 [7], developed as part of the Norwegian Deepwater Programme (NDP) is applied for these case studies to calculate the required VIV fatigue safety factors. This project was sponsored by NDP, whose contribution and support is gratefully acknowledged.

Copyright © 2005 by ASME

Figures

Tables

Interactive Graphics

Video

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In