Pipe designing/routing for cryogenic fluids and gaseous oxygen

[Aldhissla]

Hi there,

I'm just new in my job and the area of business are very different to my old one. In general I do know how to design pipes and route them, but since now I never handled that kind of liquids / gases and I try to figure out where the differences are for designing pipes between "normal" fluids / gases and cryogenic / explosiv ones are.
The pipes I'm talking about is for example going from a seperator to a flare stack.

Particular I'm looking for advice about:
[ul]
[li]max. allowable velocity in pipes[/li]
[li]is there a minimum straight lengths for a pipe I have to have (without having trouble with micro particles getting in the elbow)[/li]
[li]max. allowable velocity in pipes (fluid/gaseous)oxygen[/li]
[/ul]

Hope I made myself clear enough, if not please say so and I'm happy to be more precise!
Any advice will help and thanks for that in advance!

Looking forward to read some :0)

 

[LittleInch]

This looks like a good start

https://www.eiga.eu/index.php?eID=dumpFile&t=f&f=2464&token=445f73d8905379110b9c1795d62fd76aac05ac3d

try googling oxygen system piping design

Max velocity is always a touchy subject and there are many such posts on this forum and the usual response is "it depends".

Oxygen for sure is a tricky fluid, but I don't know if there is really much difference in thepiping design.

no one wants the pipe to leak for any substance.

It's often more about material selection and stress analysis / expansion and contraction.

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

 

[shussain786]

Hi,

Not a full answer below but hopefully a part of it.
Gaseous oxygen velocity in piping is limited to 60m/s for non-impingement which decreases with increasing pressure. 30m/s for impingement scenario.
Although I don't know any reason for other gases to surpass that velocity, my company use that same restriction (oxygen) for other gases. See BCGA CP4 (which references eiga IGC Doc 13/12/E) may give you more helpful information.

Sadik

 

[jari001]

With cryogenic fluids you have to worry about when two phase flow starts to become an issue for the end user. Even with vacuum jacketed piping, heat gets in and you have phase change of some percent of the liquid depending on how long the lines are. Enough pressure drop from flow can also cause two phase flow issues.

One area for oxygen service that's also a bit tricky is deciding how to clean the pipes for oxygen service.

 

[EdStainless]

With oxygen everything is temperature and pressure dependent. The critical velocity is rarely in the piping, it is in the valves. I have seen the aftermath of the wrong seat material in a control valve. It burned up a couple of tons of steel before they got it shut off.
Most pure oxygen systems are built of SS for both cleanliness and protection from ignition.
There are a lot of good NASA references from the 1960's with good basic information in them also.
Start with these guys

https://www.cganet.com/

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy

 

[Aldhissla]

Thanks a lot for all the answers!

@littleInch: od course I did google at first, but it wasn't that satisfying ;0)

@shussain786: thanks to you too. It is a good start!

@jari001: indeed! It's the same if you see that someone designs a flashbox and don't think about that part of the fluid get's gaseous and needs far more space in the flashbox ...

@EdStainless: Indeed again! Seen this problem in professional life as well ... And thanks to you to! I think I have now a good point where I can start off :0)