Full Content is available to subscribers

Subscribe/Learn More  >

Effects of Free Spans on On-Bottom Stability of Offshore Pipelines: A Global Approach

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

Det Norske Veritas, Ho̸vik, Norway

Paper No. OMAE2010-20988, pp. 999-1009; 11 pages
  • 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


On-bottom stability design of pipelines normally assumes that the pipeline rests on a flat seabed without any free spans. This paper presents on-bottom stability calculations accounting for the presence of free spans. It should be noted however that the calculations presented in this paper are only meant to be indicative, and not for design purposes. The absolute static stability criterion in DNV-RP-F109 is given on a form that directly compares the hydrodynamic loads on the pipeline to the resistance provided by the pipe soil interaction. Hence, by following this line one can estimate the effect that the presence of free spans has on both the load and the resistance. It is known that hydrodynamic loads, lift and drag, are higher close to the seabed than away from it. This will obviously be beneficial from an on-bottom stability point of view. The effect that the free spans have on the pipe soil resistance is not so obvious. Often, one assumes that this resistance consists of two components, pure Coulomb friction and so-called passive resistance due to penetration. The Coulomb friction part is herein assumed to be independent on the span fraction as the total weight remains the same, whereas the soil models in DNV-RP-F109 predicts an overall reduction in passive resistance due to the presence of free spans. For the on-bottom stability calculations it turns out the approach predicts a beneficial effect for pipelines on a sandy seabed. However, under most conditions on clay, where the beneficial passive resistance is more important, the prediction is that the presence of free spans is not beneficial.

Copyright © 2010 by ASME



Interactive Graphics


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

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