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 valve 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.
"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. 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.

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