In theory. In practice, helium will interact with, for example, iron alloys (steel), ending up with de-electonized protons migrating through the bulk metal, and at the other end snatching up some of the fermi-gas and going their merry way.
The same way, in vacuum systems, getting rid out of the stupid hydrogen magically appearing out of nice stainless steel enclosures that have been ultrasonic cleaned and baked under vacuum is a real problem. I have seen suggestions of burning the whole chambers under vacuum at 650C to get the protons out, and even that isn't really the end of things.