Overpressurizing / Overfilling steel tanks

[joewr]

Someone says, "I am not aware of a single "metal X, Y or Z" tank exploding; or he says, "When ______ explodes, it just cracks, I think."

This is not data. Data is collected by scientists and engineers who do pressure testing and create wonderful graphs that show P and T and failure incidents or rates. This data is then used to create the standards.

Standards are set with various limits in mind. For some products, such as turbine blades for passenger jets the standards for failure are set such that the blades are replaced long before any failure will occur. That is a 100% safety factor.

The standards that I am most familiar with are those used for equipment in the Petroleum industry. And I can guarantee that no P,T limitations took the form I have seen here. So, until you guys put up data that was taken in a proper manner, you are just expressing opinions...not facts. And if someone gets hot under the collar if asked to show such data when he is esposing exceeding pressure limits, it just means he does not have the data. He may have faith and reasoning, but he does not have data.

And I am not taking sides here.


Joewr...

 

[Iguana Don]

Originally posted by joewr
Someone says, "I am not aware of a single "metal X, Y or Z" tank exploding; or he says, "When ______ explodes, it just cracks, I think."

This is not data. Data is collected by scientists and engineers who do pressure testing and create wonderful graphs that show P and T and failure incidents or rates. This data is then used to create the standards

Sorry Joewr, gotta disagree with you on this.

Data - Facts or information to be used as a basis for deciding something.-----Oxford American Dictionary

I have had this thrown in my face before that only scientists & engineers can collect data......H@#$e S@#t.

Data does not have to be collected just in some geeks laboratory, contrary to popular belief, it CAN be collected in REAL WORLD experiences and I have much more faith in real world.

Went to my local hydro shop which I use on a regular basis and have developed a good rapport with. We discussed the differences in the two failures. As was mentioned earlier, when a steel tank fails it slits, usually about 2-3 inches long and about 1/4 inch wide. When an aluminum tank fails, it spreads wide open (similar to a flasher and his trenchcoat), spreading shards and reeking havoc and destruction to everything around.

Yes I do put more faith in that 1/32" of copper burst disc than I do 1/2" of aluminum.

This message was NOT brought to you by engineers......Who gave us The Tacoma Narrows Bridge or by scientists who gave us Synthetic Anthrax.

ID

 

[Bob3]

It's only a matter of time before the DOT gets wind of the every day overfilling practices & starts setting up check points to load up their coffers with money from fines.
It may take FL a bit longer because they're sort of third world in some aspects, but as soon as they start smelling bucks...

trivia note: The "+" rating on bottles came about during wartime when the govt. needed to carry more compressed gases without bothering to manufacture more bottles. Cargo space was at a premium too, so they just overfilled 'em by 10%.

Got a friend that blows scuba tanks up for fun, got a couple on video tape. Those suckers can FLY.

 

[large_diver]

LOL -- what a hobby -- scuba tank demolition!

 

[roakey]

Originally posted by MrMrEZG

well if they are properly maintained then they wouldn't get overfilled.

You're using your conclusion as a premise to your argument.

Originally posted by MrMrEZG

and as for as ALs go you seem to be telling us that a 1/32" thick copper disc (aka burst disc) can withstand more of a load than 1/2" thick aluminum and that is why it is more dangerous to overfill ALs.

The way that AL and steel handles stress is completely different. That's why we overfill steels and don't overfill ALs.

Originally posted by MrMrEZG

you say that realism can go a long way, well how real are the markings on a tank that say to fill to xxxxpsi?

As real as other limits set by lawyers. Like million dollar settlements for hot coffee being spilled in your lap. The limits are set so some abused, ignored cylinder won't blow. Are their some idiots out there that will try and overfill some abused, ignored cylinder? Yes. You can't fix stupid. Are there responsible folks who take care of their equipment so it can safely take over pressurization? Yes. Those are the folks we're talking about here.

Originally posted by MrMrEZG

Greg Trahan
PSI #12115

Roger Oakey
PSI #10058

I sincerely hope my number impresses folks as little as your number did me.

 

[roakey]

Originally posted by joewr
This is not data. Data is collected by scientists and engineers...

I've never had a scientist or an engineer tell me that if I release a weight belt above my foot it will fall and hurt my foot (I guess I'd need a doctor to tell me that, wouldn't I?). So next time I'm thinking of letting go of my weight belt above my foot I can assume that'll hang in mid-air, correct?

Roak

 

[joewr]

Originally posted by Mr....G

Greg Trahan
PSI #12115

Originally posted by roakey
.

Roger Oakey
PSI #10058

I sincerely hope my number impresses folks as little as your number did me.

Huh?


Joewr...

CDL #H0252286
SCC #41000134446
VISA #__________

 

[joewr]

Roak,

Everytime you put on a piece of dive gear you are letting a scientist or engineer give you advice. That is, unless, you invented and made your own polymers for BC's, wet/dry suits, etc. Of course, you may have invented all the electrical appliances you use, along with anything that uses an internal combustion engine. And I suppose you invented and set the standards for the materials that are used on the roads you drive upon, the house you live in, the building you work in, etc.

Just who do you think invented the Al and steel that you use in tanks? Some instructor from a dive organization? Look around yourself someday and see all the materials that you depend on to make life a little better. Most were invented by scientists and engineers. Polymers, going to the moon, scuba diving, you name it: scientists and engineers helped to make it possible.

Next time you dive, take off all the gear that has a synthetic component on it or an electronic component in it. Then go diving...it will not be a very deep or very long dive.

Joewr...geez...I repeat, geez...

 

[roakey]

Originally posted by Bob3
trivia note: The "+" rating on bottles came about during wartime when the govt. needed to carry more compressed gases without bothering to manufacture more bottles. Cargo space was at a premium too, so they just overfilled 'em by 10%.

Welcome to our side of the argument, Bob3, even if you don’t realize you crossed over!

Let me rephrase what you just said:

“In wartime it was decided that the working pressure stamped on cylinders was conservative and the cylinders could be over-pressurized safely. This practice was deemed so safe, in fact, that it was continued BEYOND the completion of the war (read: emergency conditions) and is still in use today.”

Now, for the million-dollar question:

1) Did some bureaucrat saying “It’s safe to overfill cylinders 10%” make it safe?

Or:

2) Was it already safe to overfill by 10% and some bureaucrat simply acknowledged this fact?

As previously stated Faber tests their LP cylinders to 4.5k psi for 10k cycles. Assuming some caver does 4 dives a weekend, we’re talking 1/5 as many cycles at 1k psi less over 10 years. Yes, it’s safe, it’s just that PST’s and Faber’s Lawyers won’t let them say so since they have to make their specifications based on the lowest common denominator, which is the idiot that has a neglected, corroded cylinder sitting on its side in the garage.

The over filling camp is simply not waiting for some bureaucrat to get their head out of a dark place before doing something that’s safe. This process, as you pointed out and appear to agree with, has been done before (unless you’re willing to defend the position that ABSOLUTELY NO ONE was overfilling cylinders in wartime before the 10% + rating was approved).

Originally posted by Bob3

It may take FL a bit longer because they're sort of third world in some aspects,

Try getting a Nitrox fill at 10 random shops in FL cave country and then try doing the same in California and come back and tell me who’s a third world country. Florida cave country is years ahead of the rest of us in ALL aspects of technical diving.

Roak

 

[roakey]

Originally posted by joewr


Huh?

I'm rarely impressed by people flashing credentials, I'm more impressed with well reasoned arguments. MrMrEZG’s posting of his PSI number is a classic example the invalid argument methodology of “Appeal to Authority” This more commonly takes the form of “Well, the head of the association of toad collectors says that…”

I was simply pointing out that I’m a PSI inspector too, and that should have absolutely zero to do with people’s acceptance or rejection of my arguments.

Now, your posting of your Visa number would have certainly impressed me, please go ahead!

Roak