Big John wrote in message . ..
Fred

One more.

Scuba tanks have to be pressure tested every few years. This is done
in a tank of water in case they fail.

So under water testing is a common thing (except for KC-135's BG)

Big John


IIUC Scuba tanks are routinely filled while submerged in water for
cooling purposes. In the examples I gave the vessels were pressure
tested while FILLED with water so that there was no compressed air
inside.

In the scuba example the water ouside the pressure vessel provides
(some I suppose) protection from the explosion should it fail.

In the earlier examples, filling the pressure vessel with water
prevents an explosion should the vessel fail.

Just to be clear.

--

FF