Failed O2 cylinder valve

[lowviz]

Don't sweat it. It is like everything else, the more you learn the less you come to rely on 'what just seems to be right'.

The real-world runs on immutable physical rules. I'll go with them every time, even if they grind my gears...

 

[tech_diver]

I've seen HP valve seats that were scorched by an oxygen burn. It was always pretty obvious (blackened, melty.)

Not sure what's up with this scenario.

 

[JahJahwarrior]

Fascinating thread! I had no clue about the bluesteel extra hole and I'm not sure I'm a fan.

Here is my theory of what happened here: The cheap plastic valve knob that Bluesteel uses stripped, and when you were closing the valve, it was spinning around the valve stem without actually spinning it.

Alternate theory: Something gunked up the threads of the valve seat, making it feel like it was closed when it was still open.

The hole in the retaining cap area has nothing to do with this. You can screw the valve seat all the way in, and pressurize the tank without the retaining cap in place and it won't let any gas out of the valve opening, which is the space that matters for your fill whip.

 

[rjack321]

The hole is supposed to be there to depressurize the tank if someone were to unscrew the valve with residual pressure in there. Contrary to popular belief that isn't that hard to do and even just 200psi behind a valve flying off into your face can absolutely kill you.

Your bonnet nut is toast. The threads on that are not the seal. The copper crush washer in the bottom was the seal. When that corroded or the nut loosened you had HP o2 jetting up via the thread annular space. Brass has a pretty high O2 tolerance but looks like that escaping gas melted or eroded the brass threads.

 

[davehicks]

Well I guess there was nothing wierd about the valve after all. Thanks to all for looking at this and informing me that the two holes are by design in the blue steel valve. On reflection it makes good sense for these as pressure relief on disassembly.

I bought a few service kits and new seats for the valve and put it back together. I filled the tank today with no problems at all. The bonnet nut was just fine.

The valve had failed for the classic reason of degraded a oring, and was easily fixed.

 

[Couv]

The valve had failed for the classic reason of degraded a oring, and was easily fixed.

What prevented the valve from being shut off? An o-ring might allow an open valve to leak, but something either failed in the knob, stem or seat to prevent the valve from closing-or am I missing something?

 

[davehicks]

The oring, washer, and copper crush gasket were all degraded. The seat had deep groves in it too. Between those factors the valve would not seal. That's all I can figure...

 

[Couv]

Thanks @davehicks ,

This thread serves as important reminder to service tank valves a little more often than I've been doing.