whats happening with a not checked tank

[h90]

A few month ago I was diving somewhere very outside in Thailand. The instructor had his own equipment for his customer because the shop does not take care enough (so he told me). Seeing the aluminium tanks, I saw half a sticker telling next inspection 1995!!!!!!!!!!! What is happening when a tank age, does it start to leak? Does it get a rocket? or explode?
(last month they made new color in all the rooms, with the BCDs, Regulators hanging on the wall (full of color)----you can imagine how the take care of everything??)

 

[divenutny]

I would not expect an old tank to explode or start to leak. I have steel tanks that were made in 1957, aluminum tanks made in 1988. I would be concerned with the lack of maintenance. If no one looked at these tanks, then you have no clue if an issue is about to happen. There could be corrosion or cracks near the neck. However, I would not assume that is the case.

They should have the tanks checked or stop using them. Should something go wrong, even if it was not a maintenance issue, they could wind up in big trouble. Even in Thailand.

 

[h90]

I would not expect an old tank to explode or start to leak. I have steel tanks that were made in 1957, aluminum tanks made in 1988. I would be concerned with the lack of maintenance. If no one looked at these tanks, then you have no clue if an issue is about to happen. There could be corrosion or cracks near the neck. However, I would not assume that is the case.

They should have the tanks checked or stop using them. Should something go wrong, even if it was not a maintenance issue, they could wind up in big trouble. Even in Thailand.

well the problem is that company has no manager, no technican and the only instructor told in written form and verbal to everone arround that he don't agree with the maintenance......

what happens if they get a crack near the neck? Will it get a large crack and the air goes out slow or does the valve fly away like a bullet and the cylinder turns into a rocket???

I only know my father was in a technical school when an oxygen cylinder went away like a rocket through the roof (somewhen 1950-1960).

What is happening when a scuba cylinder brakes???

 

[Stu S.]

It depends upon the quality of air going into it. The insides could be perfect, or covered with ugly stuff. I had an aluminum tank that looked like new inside after 34 years of use and no maintenance, just testing. "Tank maintenance" is just inspection or cleaning the insides, and not structural repairs, but you guys know that.

Usually a crack will result in a leak during filling, and a full failure is extremely rare. Cracks and failures are a low probability with aluminim tanks, so this one was probably OK.

"Probably OK" is not an acceptable condition in the U.S.

 

[oxyhacker]

If it's a 6351 "bad alloy" tank, or an old steel tank with serious internal corrosion, which if last inspected in 1995 it could very easily be, it might "banana peel", ripping open on the side and possibly into several pieces which will be violently hurled outward with enough force to kill or do serious harm to anyone they hit.

Even if the tank stays in one piece the force of the outrushing air will send it flying, once again, with enough force to kill anyone it its way and or do as much property damage as if a small explosive charge had been set off.

If it's a later tank, and all goes according to plan, cracks should be self limiting, so the tank will begin to leak long before it will tear apart.

The good news is that statistically a bad tank is far more likely to explode when it is being filled than used, so if you suspect a tank has not seen good maintenance, find something else to do while it is being filled.

 

[h90]

what I didn't mention: it is this one with the sticker, but I am sure all their tanks (maybe 20-30 piece) haven't been checked that long. Some might be newer. But the point is they simply don't check them.

 

[Scared Silly]

Many resorts do not put inspection stickers on their cylinders but they do inspect them. I have asked several times at different places how often they do a visual inspection.

 

[deepblueme]

It's not just the cracking that will lead to a problem.
I had a customer bring in a pony that he used once a year for for 10-14 dives salt water with a total of 35 dives on it and the tank had pits some the size in depth of half the tank thickness.
Some how salt water had gotten in the tank (most likely forced in under pressure during a wet fill).
The salt mixing under pressure with the Alm. made a gummy paste that was acidic and was eating in to the tank.

Same thing will happen with the valve reacting to the tank and pitting the neck where the o-ring seals. Can't count how many tanks I've seen "foaming" at the valve/tank seal and been told "it's ok".

 

[h90]

Many resorts do not put inspection stickers on their cylinders but they do inspect them. I have asked several times at different places how often they do a visual inspection.

that would be a good explanation....

 

[JahJahwarrior]

I don't mean to josh you for your english skills, but that phrase, "does it get a rocket?" makes me giggle every time I read this thread...


The idea of one day UPS delivering a rocket for my tank......I guess that's one way to remind someone to get their tank vip'd, right? "I have here a rocket for your Luxfer tank over there, your LDS sent it." "Oh, that's right, I have to get these vip'd next month! Thank you!"