I have it on good authority that the helium escape valve will now be crafted from alloyed steel with sufficient nickel and/or manganese and nitrogen to maintain an austenitic microstructure at all temperatures, ranging from the cryogenic to the melting point. Of course austenitic steel can't be hardened as the microstructure does not change across temperature variations, but this will in fact help ensure a better seal and have the additional benefit of enhanced selective permeation of helium atoms by neutralizing band gap differences vs. diatomic oxygen molecules.
And will take an extra month to manufacture in an ISO14644-1 Class 1 clean room.
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