The tank in question that blew at 2200 psi while in hydro and VIP was also filled with O2 and dropped - that makes a major difference.
The reality is that 3AA and 3Al tanks, as well as various special permit tanks are pretty much designed to be part of an idiot proof system.
Consider the test pressure of a 3000 psi AL 80, it's 5000 psi and the burst disc assembly is required by regulation to blow at between 90% and 100% of the test pressure. That means 4500 to 5000 psi on a 3000 psi AL 80. Finally, the burst pressure of a Luxfer AL 80 (as tested in each lot of 200 tanks) is 7200 to 7800 psi.
So to get an AL 80 to burst due to an inattentive tank monkey:
1) the burst disc assembly would have to be disabled, and
2) the compressor would have to fill to a pressure of at least 7000 psi.
I have not seen a shop yet that runs a compressor to 7,000 psi.
Way back in the day I had a set of steel 50s that were doubled. They were 1800 psi tanks and the shop treated them like double AL 50s that were much more common at the time and filled them to 3000 psi. 3000 psi happens to be the test pressure for 1800 psi 3AA steel tanks, so it got my immediate attention. (This was before cave fills were common in 3AA steel tanks, so it was a "really big" over fill at the time.) The burst disc assembly was for a 2250 psi steel tank (3375 psi test pressure) so it pushed it to the limit but did not blow the disc. It did make me reconsider using a 2250 psi assembly rather than the less common and harder to find 1800 psi assembly, but to be honest I really doubt another 375 psi would have ruptured the tank as there is plenty of margin in the 3AA and 3AL engineering standards.
So while I fully agree with the need to know what you are doing and to have properly trained and attentive fill staff, the tanks are designed for real world use and the occasional real world screw up and there's no need to panic when a tank gets over filled.
The reality is that 3AA and 3Al tanks, as well as various special permit tanks are pretty much designed to be part of an idiot proof system.
Consider the test pressure of a 3000 psi AL 80, it's 5000 psi and the burst disc assembly is required by regulation to blow at between 90% and 100% of the test pressure. That means 4500 to 5000 psi on a 3000 psi AL 80. Finally, the burst pressure of a Luxfer AL 80 (as tested in each lot of 200 tanks) is 7200 to 7800 psi.
So to get an AL 80 to burst due to an inattentive tank monkey:
1) the burst disc assembly would have to be disabled, and
2) the compressor would have to fill to a pressure of at least 7000 psi.
I have not seen a shop yet that runs a compressor to 7,000 psi.
Way back in the day I had a set of steel 50s that were doubled. They were 1800 psi tanks and the shop treated them like double AL 50s that were much more common at the time and filled them to 3000 psi. 3000 psi happens to be the test pressure for 1800 psi 3AA steel tanks, so it got my immediate attention. (This was before cave fills were common in 3AA steel tanks, so it was a "really big" over fill at the time.) The burst disc assembly was for a 2250 psi steel tank (3375 psi test pressure) so it pushed it to the limit but did not blow the disc. It did make me reconsider using a 2250 psi assembly rather than the less common and harder to find 1800 psi assembly, but to be honest I really doubt another 375 psi would have ruptured the tank as there is plenty of margin in the 3AA and 3AL engineering standards.
So while I fully agree with the need to know what you are doing and to have properly trained and attentive fill staff, the tanks are designed for real world use and the occasional real world screw up and there's no need to panic when a tank gets over filled.
