>might stretching a cracked tank
>cause it to fail sooner than almost anything else could?

Yes but the trick is trying to determin WHEN. You know that eventially the
load release cycles will likely cause a failure of the material.I am sure they
could conduct tests that would test how extensive the crack is & how quickly it
will propagate but come on, we are talking about a $115 tank that is made of a
substandard alloy.Retire the tank and be done with it.

>
>I am still trying to understand why vip+
>failure has a relation to the tank failure.

The test can detect the problem early in the failure cycle & aviod
problems.Take a piece of aluminium wire, bend it back and forth till it breaks.
Now lightly score the wire & bend it back & forth till it breaks. Will that
light crack in the wire cause it to break right away if you load the material?
No but it will fail much quicker than the unscored piece

>We bring up an unhydroed tank which explodes,
>and say all this would be fixed
>if the unhydroed tank had been vip+ed.

That would depend on HOW the tank failed. Did it fail at the waist, did the
bottom blow off or did it start at the neck?


>
>Has anyone yet shown any relation at al between vip+ and tank failure?
>

To tell the truth I do not know what tests where done or not done by Luxfer
before they started this program. Your idea of testing tanks that fail the vip+
to failure has much merrit. It could only help us understand better what
variables may also contribute to failure.
I know a man who was filling one of these suspect tanks.It start to crack &
leak. The tank was IN HYRO & it was not being overfilled(As I recall he noticed
it a around 2000psi). >I asked before how
many tanks exploded,
>and apparently the answer was less than the fingers on your hand.
I can not answer that. I know we never heard of this type of failure 10 years
ago & now it is a factor.
Bob what advantage is it to Luxfer to start this program if there is not a
real problem with these tanks?
>
>We know that all tanks will fail. we do not take them all out of
>service.
>
>We hydro them.

The hydro will not test for the cracks Apples & oranges! Are you really
willing to take these chances with a $110 piece of gear?