Re: Cold weather and valves.
I read one of the special quality acceptance tests a year or two ago, one trial following production was that 100% of all tubes ( it was America manufacturer possibly GE) underwent so many cycles of being cooled then immersed in boiling water and repeated some tens of times.
So called corrosion jacking where corrosion from damp storage enters a button base alongside a pin and leads to stress fractures and failure of the glass to metal seal.
I have wondered if many valves come pre stressed from production from being allowed to cool too rapidly after the base is flame welded to the envelope?
I very much doubt that there was much effort put into a gradual post production annealing process after evacuation.
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