Hydrogen pressure vessel 1

[nhtien]

Hi to all,

I'm about to design a pressure vessel (VIII-1) which his service have a low concentration (3%) of hydrogen. Material selected is 316L for the design pressure of 500 psig (-20F to 140F). Is there any restriction for design and fabrication?
-reinf. pad not recommended?
-full penetration weld only?
-pwht required?
-xrays required?
-threaded connections?
-flanged connections?
any things else missing?

thanks in advance.

 

[metengr]

nhtien;
Please consult with an experienced pressure vessel design engineer. Your questions indicate you are in over your head in terms of pressure vessel design.

 

[chaulklate]

metengr is right, you should get a consult on this other than this forum banter. It may not be just the concentration, but more a factor of partial pressure. But to reinforce your current direction:

1. if you can get away without using repads, that's great, although it might be difficult at that pressure, unless you beef up the shell thickness and/or specify one piece integral nozzles such as LWN, HB, etc
2. yes to full penetration for butt welds
3. do NOT pwht austenitic stainless steel (you can, but it is usally advised against, but that's a whole other topic)
4. 100% xrays above and beyond RT-1
5. no to threaded connections (hydrogen has a tendency to bypas threaded connections)
6. yes to flanged connections (see 1 above)