PIGGYBACKED PIPELINE ON-BOTTOM STABILITY ANALYSIS

[judeotuks]

Hello,

I am thinking of the best approach on carrying out on-bottom stability of a 4-inch gas lift line being piggybacked by a 12-inch main pipeline:

-Analyzing just the stability of the 12-inch main line (ignoring the piggybacked line) or

- calculating the equv. WT of both lines , then using it for the on-bottom stability analysis.

Please which is the best or correct approach? Is there any important consideration when analyzing stability for piggybacked pipelines?

 

[BigInch]

Both lines, taking into consideration any gaps between the two. Any potential for extra turbulence and higher drag must be accounted for. Remember to consider marine growth's thickness and substantial addition to drag factor.

you must get smarter than the software you're using.

 

[judeotuks]

I would also have to consider the ORIENTATION of the piggybacked line coupled with the equivalent diameter (the sum of the large diameter pipeline, small diameter pipeline and gap between the pipelines)in determining the hydrodynamic forces due to waves and currents

 

[BigInch]

Don't count on the orientation as it comes to final rest on the bottom to be anything but the worse possible you can have.

you must get smarter than the software you're using.

 

[judeotuks]

Oh yeah that makes sense..Thank you very much

 

[BigInch]

It's hard to control axial rotation, especially if the pipeline is not straight.

you must get smarter than the software you're using.