Dear Friends,
I'm analyzing a 52" heavy walled (45mm thk.) gas export line with the design pressure of 100 bars.
Although I've tried so much to reduce the system weight applied on pipe supports, I'm not satisfied yet as I can't find the reason for such high loads in hydrotest (WW+HP) load case. I get the load arround 600,000N (HYD)/400,000(SUS) on some of the supports arround expansion loops. Specially I have one such a big load on a turnnion which is going to mount a 13m, 30" vertical riser of the system (connecting to the 52" horizontal line) which realy makes me worried.
I've checked for possible lift-offs and rectified all load unbalancies.
Please let me know your ideas...

I'm assuming that your model is correct and not over-stressed.

You pipe will be 1416 kg/m run, contents(water) 1190 kg/m run, total 2606 kg/m run.

That is 25565N per metre run of pipe, so your 600,000N would represent a supported length of 23.5m approx. That is a reasonable span. What's the problem with that ?

Just add some supports if the load is too high.

Why not load your model and can be checked by specialist?

At risk of repeating myself, there is nothing exceptional about the load quoted. It's a very big, very heavy pipe. If you don't want very big loads that go with it, then add very many supports.

Tank you moverZ for your reply,
I think it can't be a good solution to add too much supports having very little spacing between them compared to the pipe reasonable support which you mentioned it as 23m. However I have support spacing of 8 meters as the pipe is on a pipe rack. I don't have this big load there but on the supports near a 3D expansion loop.
I estimated the system load full of water something arround the one you calculated but the problem is I don't have 23 meters between supports. It is arround 15 meters.
for the other part of the system (The riser I described above) the load itself may be reasonable to some extent but I don't dare handling it via a turnnion!!!

Without a diagram I cannot see where you might need a trunnion, but surely there must be other ways to design a support structure for this large pipe and thus avoid a trunnion ?

Dear MoverZ,
Thank you for your reply,
Actually the file is in my company which I don't have access to at the moment. I'll try to get it uploaded soonest.
Best

The loads are big if we consider supporting equipment and structural members. Increasing support numbers, if possible, sometimes might be the best solution for pipe attachment as well as the supporting structural members.

I suggest you have a talk with structural engineer to design the supporting members to check the member sizes, their transport and lifting. Sometimes you may be surprised by the complain of structural engineer to design structural member for the purpose instead of selecting a standard member for the lower loads. Same thing for the design of column and their bases. So increasing number of supports, lowering loads on the supports, supporting structural members, columns might solve many problems in once.

Pipe rack standards spans are normally 6 metres, this may be used for the suppoting distances. I would suggest you find structural drawings to see the available possible support locations in case someone else has already planned. Otherwise you need to talk to the structural engineer about the pipe rack in mind and possible member sizes with the selected span lengths. This will solve your problems quickly, otherwise you may end up repeating your calculation during manufacture which will be problem.

I trust this answer your question.