How long do steel tanks last?

[Graeme Tolton]

Funny enough, I went to work today and looked at all the cylinders hanging around... Found one born in 1942 with that symbol. Do you know where I can find more info on this? It is quite fascinating, the life that these cylinders live.

 

[KY_BOB]

The life time of 3 or 4 divers. Really, steel tanks have pretty much an unlimited lifetime if you don't abuse them. And for what it's worth same goes for AL tanks, the advertised useful life is something like 10,000 cycles....now if some uninformed dive shop refuses to fill them, that is another issue.

Listen to this man. He is wise beyond his years. Of course he dives gear older than himself too

 

[herman]

It's 3 years younger than I am, I will have you know.

And it really is.

 

[dannobee]

I think Pete (Gilldiver) summed it up with the 3AA vs exemption tanks. The PST tanks that everyone worries about failing hydros are exemption tanks. Industrial cylinders are, almost exclusively 3AA tanks.

If you lift up a faber 3AA-3180 tank (3498 with a +), then compare it with a similar exemption tank, you know which one has more steel in it, irrespective of the different alloy. There must be something to it in the long run, because 3AA tanks rarely fail hydro-even if grossly overfilled.

Now, that said, I too have seen industrial tanks roll through the shop with early hydros, (1911 being the earliest that I've personally seen), then a boatload of retests around the crown. Most industrial tanks are rehydroed every 10 years. Not only do they have the "+", but they also have a five pointed star, indicating retesting every 10 years instead of every 5.

 

[justadyver]

I have 7 steel tanks.The 2 oldest have hydro dates of 64 and 66. I still use the tanks.

 

[TSandM]

We just got a pair of 72s from the 1970s hydroed, and they passed yet again.

 

[elan]

100 HP tanks as an example.......
Let's say I buy a new one and take good care of it (rinse after every dive),
how long will it be before it will fail hydro or dive shops will refuse to fill it due to its age?

Thanks......

This winter I bought 2 LP72s from 60 ies one passed hydro, the other one has 2 more years on it still run strong

 

[tregrrr]

Sorry, away for a couple days...

Is this something you would only run into in Europe? Did some of these cylinders make their way back to N.A. after the war?

Gill nailed that one for me:

They are quite common in the US. The bottles I have seen were all either made for, or imported by, Linde. The bottle mark above is from one of the O2 bottles I had in my garage last summer. I see at least one per year and I am not looking for them.

Up in Canada, they may not be common as that market was controlled by BOC or Airliquid.

I can't remember who my cutting gas supplier was, but it was the old man in their shop who answered my curiosity about that symbol with that trivia. I have seen dozens of them, and according to the old guy the Linde tanks are heavier than the norm, so we may see them for a long time to come...

 

[Gilldiver]

There is a lot of history behind Linde. In 1917, Linde US became part of the Union Carbide holding company. I think is was a dodge by the German Linde company to keep from having its US operation confiscated if/when the USA entered WWI. Linde Germany is still around and just bought BOC.

Union Carbide eventually spun off the Linde name as Praxair in the late 1990's. So, it may be more common to see the windowpane on tanks with Union Carbide or Praxair collars. But there are so many tanks running around for so long that they are just about everywhere. My own gas supplier is AirGas and I see at least one window every year.

 

[captain]

There is a lot of history behind Linde. In 1917, Linde US became part of the Union Carbide holding company. I think is was a dodge by the German Linde company to keep from having its US operation confiscated if/when the USA entered WWI. Linde Germany is still around and just bought BOC.

Union Carbide eventually spun off the Linde name as Praxair in the late 1990's. So, it may be more common to see the windowpane on tanks with Union Carbide or Praxair collars. But there are so many tanks running around for so long that they are just about everywhere. My own gas supplier is AirGas and I see at least one window every year.

I worked for Union Carbide at one of the Pravair units. AirGas was the distributor for gases actually produced by us.