Exploding scuba tank kills two tourists (sep 24, 2010)

[taucherguy]

Thanks for the pic. Looks darn scary. I agree on the kinetic energy killing the person hit by it. I was not sure about it exploding or the valve hitting somebody and in this case a couple of people. Very sad and frightening story.

 

[DevonDiver]

what causes a scuba tank to explode?

A flaw in the cylinder and/or valve, leading to a rupture and catastrophic loss of pressure. A 3000psi cylinder contains an enormous amount of kinetic energy.

An average scuba tank, filled to 3000psi, contains approximately 1.3 million foot-pounds of kinetic energy potential. This is enough to lift a 100-ton locomotive off its tracks and into the air.
The explosive power of a scuba tank is equivalent to a hand grenade.

Link: Scuba Tank Safety (what happened when a tank exploded in a car)

 

[Scott L]

It could be the effect of galvanic corrosion between the brass valve and the ali/steel cylinder. I have seen examples where this corrosion has reduced the cylinder threads to insufficient size to securely hold the valve in place.

Outside of the EU and the States, does the remainder of the world inspect cylinders?

 

[dannobee]

Since information is rather sparse on this, and we're just throwing out hypotheses, The difference in thread between the U.S. 3/4" NPT valves and the metric 25mm is minimal. For some stupid reason, you can screw the wrong valve into a cylinder but it doesn't have enough contact on the threads to hold it in place at high pressure.

It could also be that it was one of the old alloy tanks that are prone to cracks in the neck. Observers might conclude that the "valve came out of the cylinder."

 

[DevonDiver]

Outside of the EU and the States, does the remainder of the world inspect cylinders?

It may not be as effectively regulated by governments, but every country that I've worked or dived in has had a requirement to inspect tanks.

However, that does rely on proper dive shop management. I took over running a dive school in Thailand. My first task was to get all the regulators and cylinders tested/serviced because I could find no record of that work being done.

Out of 60 tanks, 5 failed inspection. The worst 2 failed because of cylinder valve thread corrosion. All of those tanks were written off and destroyed. Until I took over that dive center, the previous manager and staff had been giving those tanks to students every day....

 

[mike_s]

It may not be as effectively regulated by governments, but every country that I've worked or dived in has had a requirement to inspect tanks.

Not sure if you've worked in the US, but it has no government requirement for tank inspection other than at Hydro time.

yearly "visual inspections" is a self created by the dive industry and not law.

 

[rigdiver]

Not sure if you've worked in the US, but it has no government requirement for tank inspection other than at Hydro time.

yearly "visual inspections" is a self created by the dive industry and not law.

That's not quite what I heard at the last PSI class I took. Seems some of this is now in the CFR and is "Law."

 

[Thalassamania]

Question!

Would that not work more like a reliefvalve and make the valve pop off and the tank fly around? And most likely killing due to the heavy impact? I am just trying to understand this. Aluminum would deform and steel would be like shrapnel to my knowledge.

I've seen the result of tanks letting loose, they can go right through a reinforced cinder block wall!

That's not quite what I heard at the last PSI class I took. Seems some of this is now in the CFR and is "Law."

I find that encouraging, can you supply a CFR reference?

 

[alibi 2]

I know here we have the DOT regulations we all have to follow on our tanks, ie the yearly visual and 5yr hydro...but what are the regulations in some of these other countries?

 

[mike_s]

That's not quite what I heard at the last PSI class I took. Seems some of this is now in the CFR and is "Law."

surely he provided you a link or reference to which CFR that is ?

(that is required for the RECREATIONAL dive industry?


It's required by OHSA for COMMERCIAL DIVERS, but not recreational divers. OHSA has no authority over recreational.


If you read them, you'll just find that basically that Section 29 Code 1910.421(g) requires: (for COMMERCIAL DIVERS, under OHSA).

Equipment inspection. The breathing gas supply system including reserve breathing gas supplies, masks, helmets, thermal protection, and bell handling mechanism (when appropriate) shall be inspected prior to each dive.​

Also inspection is required for COMMERCIAL DIVING cylinders. (not recreational)

Section 29 CFR 1910.101(a)

"Inspection of compressed gas cylinders." Each employer shall determine that compressed gas cylinders under his control are in a safe condition to the extent that this can be determined by visual inspection. Visual and other inspections shall be conducted as prescribed in the Hazardous Materials Regulations of the Department of Transportation (49 CFR parts 171-179 and 14 CFR part 103). Where those regulations are not applicable, visual and other inspections shall be conducted in accordance with Compressed Gas Association Pamphlets C-6-1968 and C-8-1962, which is incorporated by reference as specified in Sec. 1910.6. ​

Let me note again that these are for COMMERCIAL DIVING regulations. Not required for recreational cylinders you own.

I know here we have the DOT regulations we all have to follow on our tanks, ie the yearly visual and 5yr hydro...but what are the regulations in some of these other countries?

Can you give the DOT regulation that requires a "yearly visual"? (there is none). Hydro is required. but not a yearly visual.