On Tue, 1 Sep 2009 02:20:42 -0700 (PDT), Owain
wrote:

On 1 Sep, 00:03, Java Jive wrote:
Another was to get an old can, not one that contained anything highly
flammable, something like olive oil would do. *Put a centimetre or two
of water in the tin, and boil it until steam is coming out of the top.
Then turn off the gas, and quickly, using oven gloves, replace the lid
making sure it's tight. *Stand back and wait. *After a while, the can
crumples.

That one's atmospheric pressure.

Same thing can happen to hot water cylinders :-)

It can! I saw the results in an office kitchen when the plumbed-in hot
water boiler (substitute for a kettle) had been emptied of hot water to
make many cups of coffee and tea in the space of a few minutes. The cold
tap was turned on to refill it. The lid was an airtight fit -- Bang! --
one crumpled boiler! The tea lady who had been innocently using it was
almost as damaged, mentally, as the boiler. She recovered but the boiler
didn't.

--
Peter Duncanson
(in uk.tech.digital-tv)