Accidental Tank Overfill - Should I be worried

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mmcdanie

Contributor
Messages
180
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Location
Southern Calif.
# of dives
100 - 199
My LDS just overfilled my HP80 (rated 3442psi) to about 4400 psi. I pointed out the issue when I went to get the tank from them. They took the tank off the compressor, said that it was at that pressure for about an hour, and brought the pressue down to 3300psi for me. Since I did not know the ramifications I ask them what they thought. They stated that a one time issue like this would not be a problem but repeated overfills would not be good for the tank, sounded right to me. They compted me the cost of the fill. Can trust this reasoning or should I be more concerned?
Thanks ahead of time.
 
They are rated for 10,000 cycles at hydro test pressure before failure. There is it's first hydro test! The burst disc should fail long before the tank explodes.

Heck I wouldn't have let them drain it past 4,200 psi which is what my regs are rated for. Anything below 3,500 psi is a short fill in my book.
 
During hydrostatic testing, your tank will be pressurised to 5/3 of its working pressure, which would be around 5700 psi. So filling the tank to 4400 psi once isn't likely to cause any damage, unless the tank is already old enough that you'd have doubts about it passing a hydro. Doing it repeatedly certainly would shorten the tank's life, but I'd go with what your LDS said. I'd also rib them gently about checking rated pressures on tanks next time you go for a fill, but that's possibly just me...

If you have concerns, you could always get the tank hydro-tested: they will check that (a) the amount it deforms when over-pressurised is within acceptable limits and (b) it returns to acceptably close to its previous size when depressurised - that'll tell you whether your tank is developing metal fatigue. But unless it's an old tank or hasn't been inspected/hydroed for a long time, I wouldn't worry about it.
 
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And yet, overfills of HP tanks are almost unheard of!!!!
 
The tank will be fine, i routinely used to fill my HP tanks to 3800 when they were cooling in a tank of water. The biggest issue that you will run into first will be the burst disc rupturing, however most burst discs rupture very close to what the hydrostatic pressure is.

One thing to note the HP steel tanks are not hydro tested to 5/3 their working pressure, they are tested at a pressure of 5250, the DOT has specific rules for the testing of the HP steel tanks.
 
That's a good fill, I regularly have LP's filled to 3800-4000 psi.
They are rated at 2640(2400 + 10%).
I find it to be very handy that some thoughtful guy at the plant where they made them,
stamped my turn pressure right there on the shoulder.
Just in case I forget when to turn around and go back.
I personally would dive them, & request the same in the future.
 
And yet, overfills of HP tanks are almost unheard of!!!!


Prolly because the compressor is working its hardest at those pressures.

Much easier to fill a LP tank to 3000 then it is to fill a HP tank to 4000......this is why everyone loves LP tanks im sure haha
 
One thing to note the HP steel tanks are not hydro tested to 5/3 their working pressure, they are tested at a pressure of 5250, the DOT has specific rules for the testing of the HP steel tanks.

Yay! Learned a new thing. All my tanks are aluminum, what with all this lovely tropical water I paddle about in - had no idea procedures for HP steels were different.
 
On the aggressor last year all my tanks were filled to 3,500 (aluminum 80s) Damn, I loved it.
 
https://www.shearwater.com/products/peregrine/

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