Overfilling HP steel tanks

[Hoosier]

Just out of curiosity....

What is the average life time of HP steel tank? I don't mind if I can use at most 15 years with the overfill (4K PSI) though...

 

[dumpsterDiver]

,,

 

[Leadking]

DOT spec tanks like the 3AA LPs are made with massive safety margins. The exemption process under which the HPs are made allows a manufacturer to conditionally make a lighter or higher pressure tank in return for keeping the DOT informed about failures, so the DOT can review the safety of the tank from time to time and decide whether it is safe to continue using them. So exemption tanks like the HPs may have considerbly less safety margin to abuse.

We know this is the case with the PSTs, as they historically have had problems just passing normal hydro tests even when they have not been overfilled, and PST had to come up with a modified hydro test procedure in order to get a reasonable pass rate. This does not augur well for overfilling!

Just an add on to your post, 3AA cylinders are hydo'd to 5/3 and the E series tanks are hydro'd to 3/2.

Lee
www.seapearls.com

 

[CD_in_Chitown]

Just out of curiosity....

What is the average life time of HP steel tank? I don't mind if I can use at most 15 years with the overfill (4K PSI) though...

It's measured in cycles, and I think its 100,000 but am looking for citation on how that computes to dives

 

[DEEPLOU]

I more worried about how overfilling affects to 1st stage...:huh:

Most 1st stages are not designed for 4000psi.
According to my "regulator man", such pressures will affect the HP seat in the fist stage, leading to early failure.

 

[Hoosier]

It's measured in cycles, and I think its 100,000 but am looking for citation on how that computes to dives

Hmm~~~ Asuuming it can reduce the 50% of the lifetime, it is 50,000 cycles for 15 years. It should be about 3,333 fills per year.... Another, 75% reduction of the lifetime, 25,000 cycles for 15 years = 1,666 fills per year..
Not that bad..

Most 1st stages are not designed for 4000psi.
According to my "regulator man", such pressures will affect the HP seat in the fist stage, leading to early failure.

Are you sure of this? You mean that "Most 1st stages?" Most DIN kit is rated 300bar (4500 psi), at least on ScubaPro and Apeks.



As long as the tank can get through the hydro test and compressor can feed up to 4K, it doesn't look like a big issue to me.