Oxygen Service Dangers

[aggieengineerrmb]

Does anyone know of a reason that it would be unwise to use carbon steel for ball valve bodies when used in an oxygen service environment? The valves, of course, would be cleaned and degreased, and we are talking about industrial O2 services, not breathable O2.

We have an old (20+ year) note from someone in our files that warns that carbon steel should not be used in O2 services due to the danger of impurities in the steel causing combustion. I have looked, but can't find any information that supports this assertion.

 

[MikeHalloran]

Corrosion-doctors.org says only that carbon steel is brittle at low temperatures and thus unsuitable for LOX service.

AirProducts says that rust particle may travel with the flow and impinge on something, and the impingement may provide sufficient energy for ignition. They also remind us that, so far as oxygen is concerned, steel is fuel, so only an ignition source is missing from the fire triad.

See AirProducts SaftyGram #33, second hit on this page:

http://www.google.com/search?hl=en&lr=&q="carbon+steel"+"oxygen+service"+fire&btnG=Search

The pdf doesn't load right for me, but the view as html works okay for our purposes.







Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA

 

[aviat]

Iron is used as a fuel in chemical oxygen generators, like the ones that were on Value jet a few years ago. The following site gives information on both LOX and gas systems.

http://www.brcompliance.com/NASA Oxygen Standard I.pdf

 

[scooter911]

I looked in the "Safe use of Oxygen and Oxygen Systems" book from ASTM and it doesn't recommend it because they ignite easily and offer little weight savings. All sources of ignition must be identified and removed from the system. Try calling Joel Stoltzfus, 505-524-5731, he's with Nasa at the White Sands Facility and teaches a great course on O2 systems. Think of an Oxy-acetl torch, only works on steel because it'll burn easily in O2 environment.

Hope this helps

Scooter

 

[hacksaw]

what pressure?

 

[powerjunx]

better CHECK to HTTP//.

http://WWW.SWAGELOK.COM

 

[GL431]

I know of a case in which a carbon steel ball valve body started burning when an operator inadvertently closed the valve (95% oxygen at 50 barg, gaseous). The velocity of the flowing oxygen increased due to the smaller cross section available for flow upon the closing of the valve. That led to the conditions necessary for ignition. That would speak for not using carbon steel.

You should definitely get good literature on oxygen safety and speak to an expert like the NASA man suggested further above. There are some surprising design and safety issues associated with oxygen, which normal designers will not readily understand the first time around.