0

Full Content is available to subscribers

Subscribe/Learn More  >

Effects of Free Spans on Lateral Stability of Offshore Pipelines: A Local Approach

[+] Author Affiliations
Knut Vedeld, Håvar Sollund, Olav Aamlid

Det Norske Veritas AS, Ho̸vik, Norway

Paper No. OMAE2010-21086, pp. 1051-1059; 9 pages
doi:10.1115/OMAE2010-21086
From:
  • ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering
  • 29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 5, Parts A and B
  • Shanghai, China, June 6–11, 2010
  • Conference Sponsors: Ocean, Offshore and Arctic Engineering Division
  • ISBN: 978-0-7918-4913-2 | eISBN: 978-0-7918-3873-0
  • Copyright © 2010 by ASME

abstract

Current industry practice on determination of necessary weight for lateral stability of offshore pipelines makes many important assumptions on the boundary conditions and initial configurations of a subsea pipeline. The pipe is assumed to be on a flat seabed, the distance between local constraints of the pipeline is assumed to be so large that the boundary conditions at the ends have no influence on the maximum lateral displacement, and the contact between seabed and pipeline is assumed to be uniform. Pipelines are in reality placed on rough seabed, and the contact between pipeline and seabed may be very non-uniform. Therefore it is necessary to investigate the effects of free spans and their influence on lateral stability. Pipelines in free spans experience much lower hydrodynamic loads, including lift, drag and inertia, but at the same time a reduced overall resistance. The local influence of the free span is governed by span gap, span length, soil properties, pipe geometry, effective axial force and pipe submerged weight. Local studies of lateral stability on span shoulders have been performed using a simplified approach according to the absolute stability criterion and penetration models according to DNV-RP-F109, and the influence with respect to design according to the absolute static stability criterion is shown. It is demonstrated in this paper that local displacements on free span shoulders may occur even if the pipe satisfies the absolute stability criterion. However, the overall effects of free spans [2] are fairly minor on the global pipeline behaviour, even for pipes with a high ratio of spans to contact points. Therefore, the displacements demonstrated in this paper are likely to be local to smaller areas on span shoulders.

Copyright © 2010 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