My motto is: "When in doubt, keep it." or something like that..... I'm also a huge packrat (but not a hoarder, there is a difference)
You'll find a use somewhere. I'm sure that oxygen valve isn't cheap, and those fittings appear to be all stainless, which also aren't cheap.
"Stop giving me credit for those stupid quotes! For that last time it wasn't me! STFU NOOB!" <-- Benjamin Franklin