Expansion Loop supports type 6

[MECA 02]

Hello,

I received a calculation note for a pipe rack project, in which we have many pipes modeled with 3 expansion loops for a length of 300 meters. I know that some lines may not require 3 expansion loops given their design conditions (T=65°C, P=10 bar). In thise calculation note, the engineer has considered only a rest support, no guide and no fixed support. Is it correct not to consider fixed and guide supports between the two expansion loops?

 

[LittleInch]

No guides at all?

That's pretty ropey.

We had something similar a little while ago and people have seen all options, including line stops at the midpoint or not.
Have a read of this one.

https://www.eng-tips.com/viewthread.cfm?qid=520656

Have you got a plan view drawing or sketch and are there three loops or two?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[RVAmeche]

Can't really say without a sketch but no guides generally means nothing to force movement into the loop where you want it. Things will slide around and your loops wont deflect the way they were supposed to.

 

[mk3223]

Is it correct not to consider fixed and guide supports between the two expansion loops?

No, it’s incorrect.

 

[1503-44]

I would place 4 full anchors on 3 loops, not guides, fully anchoring each loop. It will prohibit walking and ensure that the anchor forces are distributed amongst all anchors, not collecting forces to only one anchor, additionally restricting all growth to occur within the region of the loops, not growing into the units at each end.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[MECA 02]

I really appreciate all your responses, thank you.
Another question, please, regarding the supports on the loops— see attached. In my opinion, there are too many supports. Is it correct like this?

 

[1503-44]

Please Click the camera icon to upload images.

Yes, looks like a lot, but it's pipe size dependent.
Generally 6 to 7m spans can be made to work.

Where there is potential for future adjacent piping to be installed, vertical loops are preferred over flat turns. Or Elbow up, elbow left, elbow right, elbow right, elbow down. Such configurations provide enhanced flexibility and do not block adjacent pipe routing.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[mk3223]

It looks that this is just a preliminary piping sketch to show the support nodes along the piping routing. The next step is to have a Piping Engineer to review the piping loop routing design and perform the stress calc for the required anchor or guide at the proper locations.

 

[LittleInch]

Pipe racks tend to contain many different sized pipes so rack support separation tends to be based on the smaller sizes.

So a9 or 10m span might be too long but other pipes need 5m.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Snickster]

I agree I would put anchors or limit stops halfway between the each of the loops and ends to keep the pipe from walking. That is very flexible layout with 10 meter loops. Seems very excessive loop sizes. I would also put guides every three supports about to keep the pipe centered on support and take any horizontal wind loading.

Why 1 meter spacing in some cases. Seems way short but maybe that is just where the support beams fell.

You have serious overhanging of supports at elbows which is a no no for Saudi Aramco projects which I think this may be. I see one overhang at 4700 mm which is way too much. You need to get the supports within 1500 mm of elbows.

 

[StressGuy]

I see one overhang at 4700 mm which is way too much. You need to get the supports within 1500 mm of elbows.

Sure, but we also can't tell how close the support at node 190 is to the elbow, given we can't see where the 76985 mm dimension starts from.


Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.