Tank explosion kills one - Cozumel

[flots am]

I would still like to get hold of some real data on tank failure frequency. I suspect it is a very rare event but like this one- so lethal when it happens- that we could easily give it more weighting than it is due. You are probably right. Bad air is probably a much bigger risk.

Does anyone keep or publish statistics on these events?

Fortunately, tank failures aren't random, they're caused by various flaws and abuses.

If the tank gets proper maintenance, inspection and usage, a failure is (almost?) unheard of. I don't believe I've ever heard of an aluminum cylinder that had a proper hydro, VIP and Eddy Current Test, and that wasn't mishandled or overfilled, exploding.

Instead of summary statistics, what would be useful is knowing which fill stations require and enforce the expected standards for SCUBA cylinder maintenance and filling, and who doesn't.

flots

 

[WB2GLP]

I spent a day in October of 2010 working on their equipment with Willy Torres, one of the instructors at SCC. I questioned him about their visual tank inspection process since none of the tanks had the typical stickers seen in the US. He explained that tanks were inspected regularly based on tank number and logged in a database. Tanks that were just inspected were hit with a small pink sticker with a date code dispensed from a pricing gun similar to what you would see at a supermarket. Since SCC is the only shop filling their tanks, there was no need for big stickers. I'm not sure if they're still doing the pink sticker thing today.

I did notice the older tanks mixed within their fleet of tanks. They were noticeably different in neck profile from the luxfer tanks.

 

[kombiguy]

A bad tank can explode at any pressure. I've been present when one let go at an estimated 1000 psi.

That was exactly my point. A burst disk is no guarantee that a tank cannot or will not explode.

---------- Post added September 3rd, 2014 at 02:09 PM ----------

I think you misunderstand the general concept. While you're correct that a burst disc is set to blow at a SLIGHTLY higher pressure than the working pressure of the tank, the working pressure of a tank is not also the pressure at which it will rupture/fail. Tanks are hydroed at 5/3 their stamped/working pressure. An aluminum tank would be hydrostatically tested at 5000psi. So the order of march would be working pressure, burst disc pressure, hydro test pressure, tank failure pressure.

The whole idea behind a burst disc is that it blows BEFORE the tank explodes, not the other way around. But in some areas, burst discs may not be replaced regulaly and have corroded shut, and they've been deliberately disabled, or discs of significantrly higher pressure are instaklkled to allow for higher over-fills without triggering the burst disc.

No one knows the history of this particular tank. It may have been repeatedly over-filled which can induce metal fatigue. It may have been out of hydro. It may have had undetected or known-but-ignored hairline fractures. But simply put, tanks that are properly inspected and meet certain standards will not rupture at pressures less than that of a burst disc.

- Ken

I understand the procedure completely. And your post agrees with my point. A tank filled to 3000 psi can explode even though its burst disk remains intact. The burst disk does not, in all cases, prevent a tank from exploding.

 

[flots am]

I understand the procedure completely. And your post agrees with my point. A tank filled to 3000 psi can explode even though its burst disk remains intact. The burst disk does not, in all cases, prevent a tank from exploding.

A burst disk will prevent a properly inspected tank from exploding.

If the tank is already failing (neck crack, etc), then there's certainly the possibility the tank will go before the burst disk, however this is something that the inspection would have found, so it's really an issue with maintenance, not random explosions.

flots.

 

[NAM001]

The more and more that comes out in this thread about hydro ect makes me ask. What are the Hydro and Vis requirements for coz? I ask because as i understand it you go to australia and hydro is an anual. I doubt than the majority of divers have a clue what the regulations are and just accept a rental tank as being fit for use when they leave the USA.

 

[Peter69_56]

The more and more that comes out in this thread about hydro ect makes me ask. What are the Hydro and Vis requirements for coz? I ask because as i understand it you go to australia and hydro is an anual. I doubt than the majority of diers have a clue what the regulations are and just accept a rental tank as being fit for use when they leave the USA.

Yes you are correct. Australian standards are hydro and inspection annually.

 

[NAM001]

I cant think of a time that i checked a tank for hydro and vis. I co to coz and have dove with sand dollar severall times on the santa rosa wall. Never did i look at the tank markings. i have checked the gas in the tank bot not the tank. I imagine that we majoritivly all do that when we are out of the states or on a charter. Makes me wonder if after this is over SB doesnt create a forum to educate divers of out of country regulations. We always hear of things like you have to have a signal buoy, or no gloves and the like, but i have never thought about the lack, or noninforcement of things like hydros or vis of tanks. Rhis makes me look at the many diving related incidents in the past in the gulf or carribean. I guess we are pretty lucky when in the US we only have to sweat whether you have to have a flag or not.

Ands speeking of Australia. When is the last time they have been in the spot light from a similar incident????? It seems that they have a pretty good record in that regard.

 

[Peter69_56]

I think the last was 1997 http://www.southerntasdivers.com.au/WHS_cylinder_warning.pdf

 

[diver257a]

I think the last was 1997 http://www.southerntasdivers.com.au/WHS_cylinder_warning.pdf

There was a cylinder explosion in a NSW dive store during 2009 - please refer https://www.adas.org.au/index.php?option=com_content&view=article&id=358&Itemid=116, Scuba tank explodes, man airlifted | Port Macquarie News and Scuba Tanks as Lethal Weapons: Undercurrent 02/2011

 

[pinshootr]

When we dove there last Dec 14' I saw several tanks out of Hydro.