Dive Cylinder Explodes - Sydney

[rjack321]

@rjack321

Not to be facetious but, why someone is surprised when a crack appears after hydro amazes me.

Hydro stretches the tank, so much the the tank never returns to its pre hydro dimensions. So if there is a defect the hydro us just going to make it worse.

All Aluminum tanks IMO should be eddy current inspected ( with steel it gets more complicated, it can be done though)

Visual can't be used to confirm and eddy current detection at eddy current is able to find defects that the eye can't

The visual plus Eddy current tester is a piece of crap and is best used as a door stop.

Clearly the people who devise the testing procedures and frequency of scuba tanks are fools ad don't understand the science.

6351 tanks are perfectly safe if subjected to a proper inspection method. After all you all fly in aircraft that are inspected for cracks, and indeed fly with cracks that are within an allowable limit.

I think the reason for the "surprise" is that the hydro test itself could make a crack where none existed before. People are conditioned to think of a tank which passes hydro as safe and that's not necessarily the case. And having a hydro crack a tank is definitely not SLC since the test itself is quite short.

I have no idea how you define "perfectly" safe. NOTHING is perfectly safe. The risk from 6351 cylinders is rather low statistically speaking, but its not zero. Still poor consolation to the family of an employee who was killed by a "rare" explosion.

 

[Kodad]

Any word on the victim?

 

[NAM001]

There s so much talk about whether these tanks are good or bad. Most of the tanks are good except those made in a vary narrow window time. Because of that the odds are in your favor of noting happening. The bad part is that those that do VIP's are very poor at what they do and the chances of a bad tank being ok"d to use is very high. personally Im all in favor of total removal of those tanks in the effected window from service. That however will only work is all tanks can get looked at for birth date.

I dont recall but is Australia one that hydros every year or every 2 years.

 

[clownfishsydney]

Latest news (from an impecable source) is that the tank was out of test and in very poor condition. Authorities are wondering why it was being filled.

The victim is now conscious I understand, but as I posted previously, has lost one leg above the knee and damage to the other and possible a skull fracture.

PS Read all the posts before asking questions and many things have already been posted, even the question asked above this.

 

[NAM001]

You can't fix negligence either. I bought a 40 cu ft cylinder less than a year ago that I was to use for technical diving as a 100% O2 bottle. The owner of the shop put O2 in it without O2 cleaning it apparently and not conducting a VIP either. I discover this because I'm decided to have this cylinder O2 re-cleaned at another shop and that shop owner notified me of the issues and told me I was lucky it didn't ignite.

I think the other shop is over reacting and you may not want to use them. on the other hand if they are that fearful then when they say its clean it probably is. Reality is that you can clean it your self with dimple green, clean water and a blow dryer. its not rocket science. Your tank valve is not a major project to clean either. Lots of services are sold form fear.

 

[wetb4igetinthewater]

I think the other shop is over reacting and you may not want to use them. on the other hand if they are that fearful then when they say its clean it probably is. Reality is that you can clean it your self with dimple green, clean water and a blow dryer. its not rocket science. Your tank valve is not a major project to clean either. Lots of services are sold form fear.

Well, I had to get it tumbled to get the issues ironed out. The current shop did speak to XS Scuba about it, and said those problems happen on occasion, but that VIPs find it and a tumble takes care of it. This is why you VIP a tank and O2 clean the parts before you put in pure oxygen into it.

 

[NAM001]

Well, I had to get it tumbled to get the issues ironed out. The current shop did speak to XS Scuba about it, and said those problems happen on occasion, but that VIPs find it and a tumble takes care of it. This is why you VIP a tank and O2 clean the parts before you put in pure oxygen into it.

O2 cleaning is to rid the tank of hydrocarbons. If you don't have them in there to begin with there is nothing to clean. Granted you get them from every fill from a system that does not explode when under the same pressure. You also purge the tank of hydro carbons as you breath the gas. IMO O2 cleaning is a general procedure that covers all O2 systems. A one solution fits all. piping right angle bends expansions and restrictions. most of which you do not have in a scuba tank and valve to the degree you have in a real O2 system. Also as long as you control your fill rate you don't have any problem. Yes a sparkley cleaning may be what saves you when you do an O2 fill 0-3000psi in 30 seconds on a tank with a oil puddle in it. I respect the hazards of such systems. That respect comes from knowledge and not fear.

 

[NAM001]

They're not that big. Clearwater Marine Aquarium where I used to volunteer has a fill station with a containment box. I bet pricing would come down if it became a government requirement and therefore the things would be sold at a much higher volume. Certainly rules have been enacted (often) for things that have killed fewer people.

I'm sure diveshops would complain at first. But in the end, everyone would be safer for it. The funny thing about that is that the diveshop owners and employees who would be most likely to complain would be the ones who saw the most benefit.

The only place I can think of off the top of my head where it might be a problem is on LOBs. I suspect space is at a premium on boats.

Nothing gets cheaper when there is a government mandate. I can imagine filling 20 or more tanks at a time with these. I like the bunker as a tank room and control the fill form another space.

 

[NAM001]

Poking around the web's attic, I came across this at Aluminum Tank Controversy Continues: Undercurrent 08/2000

The leading manufacturer, Luxfer, has just issued a new policy statement requiring that every Luxfer 6351-T6 aluminum scuba cylinder be visually inspected at least every 2.5 years and that the cylinder neck be(using electromagnetic waves to detect cracks in tank threads that might not be visible to the naked eye) or equivalent non-destructive testing equipment. These requirements are in addition to DOTmandated VIP and hydro tests. For cylinders in heavy use (for example, those filled five or more times a week), Luxfer recommends visual inspection every four months.

This was dated August of 2000, 16 years ago.

Thanks for quoting that. I have posted that many times but did not know it was just for luxfer tanks. When I Last had my PSI class whe word was vis is good up to a year. No one disagrees on that. that one year was based on tanks being filled twice a week. For tanks being filled 3-6 times vis should be done at 6 months. and if more often quarterly or monthly. twice a week is a vis every 100 fills.

 

[Peter69_56]

Just a question on the side, since filling tanks has its risks, could they put the tank being filled in a protection enclosure?

I remember that they now fill truck tires in a sort of cage because they had explosion in the past. Maybe it could be applied to scuba tanks?

Yes filling them in a water tank helps if they fail. Testing is done in a chamber but the tanks are pressurised with water and if they fail its water that releases and not a big deal compared to air test. While filling if done in a water tank it reduces the impact, but most dive shops chose to fill in the shop on the ground, thus exposing the whole shop to a bomb.