In message , Nick Leverton
writes
Melting of fusible plugs (thus releasing boiler pressure steam into the
firebox) has occurred a couple of times in preservation, but the RAIB
don't seem to have reports on them for some reason.
Fusible plugs are to put the fire out and shouldn't cause a blow back.
I've only seen one example of where the plugs melted, and put the fire
out efficiently is what they did, without a blow back. It was an 82xxx
on a Bristol TM to Bath Green Park train, and the incident happened at
Mangotsfield where the rising gradient from Bristol suddenly becomes a
falling one towards Warmley, causing the boiler water to slosh to the
front of the boiler and uncover the plugs.
--
Clive