Hydrogen fuel line.

[Carlloss]

Hi all,

Was wondering if any of members have past experience with use of aluminium material on hydrogen fuel lines. Basically, I’ve been asked to provide a design for PCV which should regulate pressure from 300bar to 1bar (4350psi to 14.5psi) to feed fuel cells. Additionally PCV should not weight more than 300g. To meet weight requirement aluminium grade Al-Li 2099 was specified (material can be changed as long as it’s ok for working conditions) .

At this moment I have concerns in relation to a) PCV connection and b) material suitability

(a) Initially ¼” NPT was proposed but I am concern about the possibility of threads being striped if inappropriate assembly technic will be use or due to load. After installation fittings should not be really removed from valve but it will be beyond my control, therefore would prefer to rather be safe than sorry
(b) So far I used aluminium only on non-pressure components therefore I am approaching this material carefully, worked mainly with UNS S31600

Would appreciate if you could through your concerns, suggestion or recommendations with this matter. Thank you.


Karol

 

[davefitz]

Refer to the NASA design document NSS 1740.16 ( discontinued in 2005 , but available online) for metallurgical recommendations re: hydrogen service. Aluminum is acceptable per NSS 1740.16.

"In this bright future, you can't forget your past..." Bob Marley

 

[btrueblood]

I'd find a more reliable connection than 1/4" NPT.

 

[EdStainless]

I would use an Allen style fitting or similar (flare with backup and jam nut).
We have actually supplied SS high pressure hydraulic line for HP hydrogen use.
They have used 0.250" x 0.018" wall in AMS 5561. (this size will handle 5ksi hyd service)
And this stuff has great damage tolerance (dents and dings don't bother it).

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[Carlloss]

Thank you all for your inputs. All literature I can find says more or less, that threaded connection should be avoided if possible, but what if you can not avoid it?
Will look into flare option defiantly and check NASA publication. Thanks.

Karol