How to calculate the pipe thermal bowing in LNG project? 1

[Alex Matveeff]

How to calculate the temperatures on the top and the bottom of the pipe for LNG?
How to decide which slope of the pipe is critical, when we should not consider the thermal bowing effect?
Is there any literature about this?

 

[LittleInch]

Please don't tell me Start-prof can do it?

You need to be introducing part liquid, part vapour.

So long as you blow cold vapour down it first to cool it down before introducing liquid it won't happen.

Steam condensate lines have a similar issue if you blow hot steam on top of cold condensate

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

 

[MJCronin]

Here is some more info on this phenom...

https://www.eng-tips.com/viewthread.cfm?qid=348516

https://whatispiping.com/what-is-th...on occurs,the piping or supporting structure.

Piping analysis software (such as CAESAR-II or AUTOPIPE) can be used to evaluate this situation

https://whatispiping.com/piping-thermal-bowing-consideration-in-caesar-ii

https://broadtechengineering.com/piping-engineering/

MJCronin
Sr. Process Engineer

 

[Alex Matveeff]

MJCronin,
Thank you for your answer. I am the author of one of the articles you mentioned. Unfortunately, my question is a more complex. I want to find the real engineering practice for determining of temperatures Ttop and Tbottom. Maybe there's some recommended practice, articles, books that can explain it for LNG? All the information that I've found already over literature and internet doesn't answer this question

For example we have a horizontal pipe with the ambient temperature. And the liquid gas with a temperature Tgas flow inside very quickly.
At the first moment of time Ttop=ambient, Tbottom=ambient-x1. Thermal gradient is Ttop-Tbottom=x1
After some time pass we will have Ttop=ambient-xt(t), Tbottom=ambient-xb(t). Thermal gradient is Ttop-Tbottom=xb(t)-xt(t)
After a long time time we will have Ttop=Tgas, Tbottom=Tgas. Thermal gradient is zero
The question is how to determine the xb(t)-xt(t). Thermal gradient will be zero before gas flow in. And it will be zero when the pipe cross section will be cooled uniformly.
At the certain moment of time Tmax, the thermal gradient will be maximum xb(Tmax)-xt(Tmax).
So my question is the literature or common practice how to deal with it. I understand, that we can perform the thermal transient analysis in ANSYS or similar software. But maybe there is a more simple way to do it?

And the other question is about pipe slope. How does it influence on the thermal gradient value?
If the slope lower than 0.0001 we consider the thermal bowing. What if the slope is 0.01?

Is there a people who has the experience or know the right books, articles?



I'm the PASS/START-PROF Pipe Stress Analysis Software Developer