I have numbers, but I don't know how to produce an approximate pressure rating from them:
Wall thickness: 0.065" or 1.65mm
ID: ~.5"
Allowable stress: 16.7kpsi
I'm considering incorporating fittings of this size into an up-to-20X hybrid, but I'd like to make sure I'm not pushing the safety factor. I used a fitting with these measurements to 1,000psi in a pneumatic without incident, but that doesn't really say anything.
Schedule 10 SS Pressure Rating
This puts your allowable internal pressure at 3.66 kpsi (using the distortion energy derivation for yielding. The thin wall approximation, which isn't totally invalid here, gives 3.34 kpsi) . The safety factor is, of course, already included in the "allowable stress" - even the weaker SS alloys tend to have yield strengths in the mid 30KSI range (in annealed state).
Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
Thanks very much. Looking at a max pressure of about 2.2kpsi for a 20x mix, it seems I'd be perfectly justified using sch 10 SS parts. 
Of course I never thought to do this before. Idiot.

Of course I never thought to do this before. Idiot.