Hi,

I am currently analysing Cargo offloading Piping for FPSO.

Which is runing around 250m with 55°C as temp I need to determine loops in this run.

What are the criterias I should take into considerations.

Thanks & Regards
Nilesh

Are you serious ?

FPSO piping has been known to fail in weeks due to fatigue.

Get some experienced, professional help.

MoverZ,

I posted this quetions for experienced help only..

Please send some link if you want to share...

For Fatigue senario I have nice design of around 7 loops in the run giving low bending stresses due to accelerations and hence very little to none fatigue damage.

Basicaly I want to remove some of the loops in the run so need help in that.

Kind Regards
Nilesh

If you know about fatigue and have sized some loops, what is difficult about optimising the loops ?

So far as loops, which I presume are in piping along the ship's axis are concerned, I would have expected fatigue due to sagging and hogging to be more of a problem than accelerations.

Hi Moverz,
Have you ever considered roll suppurts to deal with hog and sag on lines of the main FPSO pipe rack?
You think it's possible to have no expansion loops on the main header, but these rolling supports or may be PTFE supports (Flare header for instance) and then have branched flexible enough to handle hog/sag displacements?
Thanks

Anything is possible. Roller type supports need maintenace which may be an issue due to access.

Would your branches have to be so flexible that controlling their position might not be feasible.

The Hog/Sag induced axial movements will be around +-150 mm assuming I have no expansion loops on the flare header. I'm going to design the lines for maximum design temperature to be the solar radiation (I don't consider fire temperature)so I don't have too much expansion displacement.
The thing I'm worried about is I don't want to invent sth new in such an old industry, therefore I'm looking for any existing design based on this thinking.
Anyway, as you advised the maintenance could be an issue, but I'm thinking the roller would act better for this case as they have to move all the time due to hog/sag motions. this might reduce required maintenance.
Let me know how you think.
PS. Please let me know how I can find a copy of the conference paper for FPSO fatigue assessment held in 2009.
Best

Hi All,

please let me know how to enter the displacement due to hogging and sagging, because if we give restraint we cant key in the displacement value so how possible to enter hog and sagging displacements

Enter the displacements, without the restraints. (A displacement is a boundary condition - i.e. a restraint.)

Dear Richard,

thank you, is it advisable to give the hogging and sagging values in the C NODE. so for the same node I have restraint as well as the displacements.

If you want to entire displacments on more node number
you can develop the micro as explained in the attached paper.
Its very usefull.

Regards,

akula

Dear Kumar,

Thank you. I will follow it




Thanks & Regards

Baskar