Alistair Heaton wrote:
(big snips)

> Al is very soft so its tolerance to abuse is very poor compared to steel.
> eg if you a cylinder is dragged on concret by accident steel you will just
> take the paint off, Al you will remove material off the cyclinder and find it
> very hard to get it through the next test if your brave enough to fill it again
> if it was bad.

Hi Alistair,

As I said:

> Oz is dominated by ally cylinders
> although in my case the main tanks are steels, only the pony is ally.
> Last I heard we didn't consider allys much of a problem.

Now we probably have a huge number of allys which are hire tanks, used
by beginner divers and all those who come to Oz to dive. They just
keep on keeping on.

These tanks would be CONSIDERABLY more abused than ally tanks owned by someone.

Mind, O2 tanks might be another question, as you say. But then there
are not a few local (read Pacific) liveaboards that I've been on with
ally O2 tanks.

Cheers,

Christian