Vessel motions during pipelaying
Vessel motions during pipelaying
(OP)
I am starting my graduate research.
It should be something about subsea pipelines.
Is it common to consider Vessel motions during pipelaying?
Or are the stresses during installation considered in an unrealistic static condition?
Do you think the considering vessel motions will result in very different stresses?
Do you think this is a good topic for a PhD?!
PS. Please inform me if you have some nice ideas/topics other than the mentioned one, regarding subsea pipelines.
It should be something about subsea pipelines.
Is it common to consider Vessel motions during pipelaying?
Or are the stresses during installation considered in an unrealistic static condition?
Do you think the considering vessel motions will result in very different stresses?
Do you think this is a good topic for a PhD?!
PS. Please inform me if you have some nice ideas/topics other than the mentioned one, regarding subsea pipelines.





RE: Vessel motions during pipelaying
RE: Vessel motions during pipelaying
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The lay analysis you would do depends on the type of lay you are doing (S-lay, J-Lay, Reel Lay, Flex Lay etc). Different vessels have different responses to a given seastate. We use RAO data to simulate that response and then the affects on the lay. A large semi lay barge will be more stable than a smaller monohull. But it will still have an effect. The motions will generate hydrodynamic load on pipe which need to be assessed.
Andrew Palmers subsea pipeline book would be worth a look. Its not a topic I know much about as we have a department of analysts who do all this stuff for us.
RE: Vessel motions during pipelaying
Static analysis is performed for various configurations of pipelaying and worst case is selected to perform the dynamic analysis which will include the RAO for the barge and the hydrodynamic loading on the pipeline itself. This analysis will determin the safe sea state for pipelaying.
Narendranath R
Pipeline engineering is made easy with state of the art computer software, visit www.narendranath.itgo.com.
RE: Vessel motions during pipelaying
the oldest software package is called OFFPIPE
more recent and also 3D models can be designed now with either Orcaflex as mentionned in previous answer or competitor Deepline http://www.principia.fr/eng/logiciels/deeplines/
The way analysis proceed today particularly in deepwaters is to identify the limiting seastate for installation and each vessel will have its limitations which will be very dependant also of the type of pipe to install.
An interesting field of research for your PhD would be to develop a method that would provide a better decision making aid during installation rather than just weather forecast, superintendant experience or gut feeling, and hundreds of analysis. For instance by linking directly the actual vessel motions to the constraints effectively supported by the pipeline beeing laid.
RE: Vessel motions during pipelaying
RE: Vessel motions during pipelaying
Ive seen Robert Malahy's name on the OFFPIPE software (OFFPIPE.com). I guess he has developed the program...
RE: Vessel motions during pipelaying
Narendranath R
Pipeline engineering is made easy with state of the art computer software, visit www.narendranath.itgo.com.