Ahhh..... so it's not actually the firebox crown, but the outer wrapper of a belpaire box, all clear now, I think.
Coming back to Bob's original description reminded Me of one of the late Tom Paisleys Burrell ploughing engines, where the crown had overheated so much whilst in steam that it had bowed down about 21/2", dragging the stays with it, the late Dan Doncaster reckoned that it was Burrells attempt to make an undroppable fusible plug. Mind You, it must have already had an undroppable plug to have done it in the first place.
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6th June 2023, 11:21 AM
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