Overfilling and life expectancy. (LP Tanks)

[Superlyte27]

The problem with overfilling is not as much that they will fail Hydro its more that they will explode. For a tank to pass a Visual inpection you can have a crack through the threads as long as you have 8 good threads from the top out of the 15. If you over fill a tank you have a very high chance of an explosion. PSI/PCI has done test were they had a tank with a crack through all of the 15 threads and it will filled at a proper fill rate (no faster than 500psi per min) and filled to only 3000PSI and that tank did not explode. They did the same fill rate and over filled it, and the tank ruptured at 3300PSI. So yes everfilling will shorten the life of the tank but you will still get quite a few hydros, the problem is that overfilling causes cracks and the more you do it the higher chance of a tank rupture. If you want a tank that you can fill past 3000psi get a HP tank. They make tanks that have a working pressure higher than 3000psi. I would recomend only filling to 3000psi or getting new tanks with higher working pressures.

Um.... LOL, anyone ever seen thread cracks in a steel tank? You are comparing apples to oranges man. Or you are off topic.

 

[Mitchell Teeters]

Dave you are wasting your time dude.

 

[idive2]

I was under the impression that the water surrounding the tank inside the vat was at atmospheric pressure and the expanding tank
was just displacing this water ?

 

[Superlyte27]

You are correct.

 

[lucca brassi]

http://www.fillexpress.com/library/dryfills.pdf

DIR Explorers

 

[Superlyte27]

and your point???

 

[lucca brassi]

D.I.R. way

 

[Sitkadiver]

I did a google search of DOT 3AA a while back and it shed light on the fact that the DOT 3AA standard for hydro testing is 5/3 working pressure.... Thus a 3000 psi tank is hydro tested to 5000 and a 2400 psi tank is tested to 4000 psi....

I doubt you'de want to fill any cylinder to 5,000 psi, unless you want to see a fireworks display, but it seems that over filling to say 3200 or 3500 is well within reason.

Last week I fell asleep while filling some 72's and a 95. They ran up to 4,000 psi.... Here's a thread I started on VSS:

The Vintage Scuba Diving Community Forum - OOppps I did a bad thing.

I think what Luis has to say is legit. I trust his judgement.

 

[Sitkadiver]

Almost forgot, Here's the link to the DOT hydro test standards.... Scroll down to get to the table...

Cylinder Maintenance and Testing reuirements, for high and low pressure service cylinders. Code of Federal Regulations 49, Part 173.34. Department of Transportation. Cylinder and Valve requirements for maintenance.

Seems 5/3 is 66% over 100.. so if we over fill only 15 or 20 % we should be safe. Right?