Tank explosion kills one - Cozumel

[blanik]

for what i've heard (according to the personnel of my dive center), a visual inspection is done to find traces of rust inside a tank, if rust is detected the tank can be sandblasted (or some similar procedure) to remove all trace of rust, it must then pass a hydro to insure it's still good, an hydro would be the only "go-no go" test that is valid to kill a tank, the vis is only for rust or presence of contaminants

 

[boulderjohn]

for what i've heard (according to the personnel of my dive center), a visual inspection is done to find traces of rust inside a tank, if rust is detected the tank can be sandblasted (or some similar procedure) to remove all trace of rust, it must then pass a hydro to insure it's still good, an hydro would be the only "go-no go" test that is valid to kill a tank, the vis is only for rust or presence of contaminants

You have been misinformed.

 

[NAM001]

First of all hydro is a test and a vis is an inspection.

The hydro tests the physical ability of the tank to hold pressure and measure the stretch and recovery of the tank material. The vis is an inspection to see if there are inperfections inside and outside of the tank that could invalidate the hydro. such as cracks in the metel, rust spots that have eaten its way into the metel making the walls thinner. Physical gouges in the sides inside and out, tank warpage, broken valve dip tubes, and much more. They are only vaguely related to each other. The ability to stretch and recover changes with repeated filling and emptying. It takes many cycles to weaken the meterial so it is TESTED each 5 years in the USA. Because you can get a fill from a compressor that has a problem, or the tank has been dropped ect you do a visual INSPECTION of tanks in the USA at intervals not to exceed 1 yr. Loosly put Hydro and 5 yr vis is a federal reglation and anual vis is an industry requirement. Hydro is a go or no go test as you put it. The vis is not. Got a bad thread , fix it...... got rust n your tank , clean/fix it. A hydro is not a requirement after fixing a problem with the vis inspection. I think you have confusion of what hydro, vis, o2 cleaning ect. are. Its hard to believe that a qualified shop would say this. If the shop is saying this,,, You are out and out being lied to.

for what i've heard (according to the personnel of my dive center), a visual inspection is done to find traces of rust inside a tank, if rust is detected the tank can be sandblasted (or some similar procedure) to remove all trace of rust, it must then pass a hydro to insure it's still good, an hydro would be the only "go-no go" test that is valid to kill a tank, the vis is only for rust or presence of contaminants

 

[halocline]

If this was a Kidde AL tank from the 70s, it was a 6351 alloy tank, and there's the likely problem. While these tanks can be legally inspected and filled, even in the U.S., the 'industry standard' (whatever that is) is to take 6351 alloy tanks out of service. Given the extreme consequences of a rupture, it's a good idea. New scuba tanks are simply not that expensive.

In a way, I was relieved to read that this terrible accident likely involved a 6351 tank, because it does provide a reasonable explanation and does NOT indicate a problem with 6061 tanks, which are the only ones I've ever seen in Cozumel.

 

[nadwidny]

for what i've heard (according to the personnel of my dive center),

15th rule of scuba-If you heard it from a dive shop then it's wrong.

 

[Pearlman]

A tank that goes from 3000PSI->2000PSI every day will have a longer life than a tank that goes from 3000PSI to 100PSI every day.


flots

Curious - Why is that?

P



Sent from MiPad

 

[DandyDon]

Curious - Why is that?

The tank that goes from 3000PSI->2000PSI every day will does have as much metal movement, contraction and expansion as the tank that goes from 3000PSI to 100PSI every day.

 

[Johnoly]

Curious - Why is that?

Metal fatigue > metal stretching

Grab a paper clip out of your desk drawer.
Bend an end of it so it's almost straight
Bend it back 180 degrees to it's original position
Repeat and count the number of times til it breaks.

Go to the other end of the same paper clip
Only bend it towards straight at about 30 degrees
Bend it back to it's original position.
Repeat and count the number of times til it breaks.

It's similar physics with scuba tanks as they expand and contract with fills. On your scuba tanks there will usually be listed and REE number. This is what they use to measure the expansion.

 

[billt4sf]

And if you're Joe or Jane Diver, maybe give some thought next time to hanging around the fill station while the process is ongoing. There are safer places to be should something go wrong.

- Ken

Joe diver here. What should I look for that tells me I should avoid that tank / operator when I'm in some far-off place?

- Bill

 

[Dahodevil]

Exactly my thoughts.
I had a pair of these Luxfer tanks and soon as I found out about the issues I gave them to my LDS to cut the tops off and use them in the display cabinet. They still looked new.