Failed O2 cylinder valve

[davehicks]

I was recently trans-filling a small 14cf O2 cylinder. As I shut it down and depressurized the whip to remove I found it would not depressurize. I had both tanks full closed and when I vented the whip gas kept flowing. I realized that the cylinder valve being filled would not seal. I had to let the tank fully empty from the whip bleeder before I could disconnect.

I just removed the valve and took it apart to find what you see below. The threads of the valve itself seem to have split or burst. So this is why the tank would not seal.

The tank is a 14cf 2000psi tank and has not ever been over filled to my knowledge. The tank and probably the valve too date from 2007. The valve is a Bluesteel/OMS brand.

Any idea what might have happened here?

 

[lowviz]

#1 Do NOT lose, give away, loan, or trash that part. It is a museum piece!

Now for Monday morning quarterbacking. You may have had adiabatic heating of some foreign material on the thread if the valve was opened too quickly. That little spark under the pressure of pure oxygen started an 'oxygen lance'.


ALWAYS open a pure oxygen cylinder like you are defusing a bomb.

-my .02

 

[Couv]

Those threads are where the bonnet screws into. Are the threads on the bonnet damaged?

 

[davehicks]

Those threads look to be where the bonnet screws into. Are the threads on the bonnet damaged?

No the bonnet threads look just fine. No discoloration or erosion. I looked more closely at the whole thing and found a HOLE in the valve stem on the threads. Not sure where that came from...

I am thinking that the oring on the valve stem was not Viton, or if it was it is eroded. I found black rubber bits on the seat stem and the oring is flat as a pancake.

 

[OTF]

I want to say oxygen fire as well but I'm not an expert and other people here are.

In any case that's fascinating and lucky, could have gone much worse!

What does the other side of that thread look like?

 

[Jeremy Williams]

That’s kinda interesting... where is the valve seat? Was it damaged?

 

[Bob DBF]

I'd be thanking the gods of SCUBA for protecting me. I wonder if that valve had ever been rebuilt?

 

[davehicks]

That’s kinda interesting... where is the valve seat? Was it damaged?

Everything else looks ok. Here are some close up of the valve parts and the oring. I cleaned of the parts before taking the pictures.

 

[Jeremy Williams]

The thing is... that unless the valve body developed an extra hole in it somewhere... that brass colored valve seat is the only component on the top side of the valve that needs to seal to close the valve... you should inspect the face of the valve seat to see if it’s damaged (the round side that’s facing down). There are lots more parts at play when the valve is open, but when it’s closed, the only two parts that are “working” are the neck oring and the valve seat. Those two things are keeping the air in the tank... So if you were able to close the valve (i.e. screw in the valve seat) and the valve was still leaking... What does it look like right at the bottom of where you removed the valve seat?

 

[OTF]

Given the weirdness of those two holes i'm wondering if there's more serious erosion inside the body of the valve. Would be interesting to cut in half. Reminds me of the weird s*** that happens with lightning damage.