I know it's not trivial but do organisation working with vacuum chambers ever set it up so that the atmosphere inside a pressure vessel is kept full of dehydrated oxygen/nitrogen air at positive pressure during maintenance activities?
I know they make sure that all the workers suit up to prevent oil from skin ruining any chance at a high vacuum.
Sure, it's very common to flush a system with dry nitrogen for that reason. But of course if you have to fully open a part of the system you're usually out of luck (also you usually don't have valves at every intersection etc., so some part may still be exposed to the atmosphere even if part is "kept dry").
I know they make sure that all the workers suit up to prevent oil from skin ruining any chance at a high vacuum.