Robert Swinney wrote:
Boiler trivia: It wasn't because of a tied-down safety valve, but the worst
loss of life to a U.S. maritime disaster was the boiler explosion on the
Sultana in 1865. The Sultana, a govt. contract, ex-luxury steamer carried a
vast overload of US prisoners of war, recently freed from Southern prisons.
There wasn't a lot of news coverage of it at the time, certainly no headline
coverage, because it happened the same day Lincoln was assasinated.
Reportedly the boiler blew at the site of a welded patch only a few days
old. The Sultana's boilers may have been over-pressured to accommodate the
overload of human cargo. There's a good chance the safetys may have been
maladjusted.

Bob Swinney
wrote in message

Or the water may have gotten low. On many boiler/safety valve setups,
adding water to an overheated boiler that had gotten too low would
generate steam faster than the safety valve could handle, and boiler
would blow, safety valve or no safety valve.