Hydro's and old tanks...

[cummings66]

My concern reading the thread is whether or not that hydro date is gone? If you obscure any markings on a cylinder you have condemned it. That's why some shops X out a serial number or hydro date, etc. Anything that gets rid of previous data is bad.

However, that doesn't mean you couldn't get a shop to fill it because most of them don't know the rules anyhow. Plus, it's a rule not a law. So, for what it's worth it's not kosher to do it, it might or might not effect fills depending on shop and that depends on the shops viewpoint of old cylinders.

[Kyzzle]

After looking at it again... The old hydro wasnt stamped out or scratched out or anything. It is still there. Me being a newb looked at the new hydro stamp and saw that they scratched the paint off so they could put the new stamp on... having never had hydro's done before I automaticaly assumed that's how it was done... And we all know what happens when you Ass-u-me...

[cummings66]

That's better then, yes they sometimes scratch the paint off, sometimes not. If not sometimes it's not deep enough and over time it can flake leading to a hydro date that's not acceptable which is why they scratch.

[JahJahwarrior]

That's one of the more helpful links I've found, really helps explain how to read tank markings.

USD tanks, NavyHMC basically explained very well. That's a 6351 alloy (compared to the 6061 alloy which is safe), and I wouldn't bother hydroing it. A lot of people will fill 6351 tanks, but I personally am scared of them. I've seen pictures of what an explosion will do, and I value my life. It's an argument people will have until they are blue in the face, but I personally choose not to fill 6351 alloy tanks, even if they are eddy current tested.

The 95 cylinder is great, hopefully your second 80 turns otu to be post 89 as well!

[navyhmc]

In all honesty, I'm not too worried about my own tank, it's passed the hydro, VIP and eddy. From what I've read, my tank has been treated fairly gently and never dropped, left in an overly hot car, or subjected to tens of thousands of fills. I also have a lot of faith in the guy that tested it. I watched him do a few visual thread checks on tanks and he spotted cracks with a naked eye that I could barely see magnified. But still, it's unfortunate that it's lifeexpectancy is now measured in months.

[JahJahwarrior]

Originally Posted by navyhmc

In all honesty, I'm not too worried about my own tank, it's passed the hydro, VIP and eddy. From what I've read, my tank has been treated fairly gently and never dropped, left in an overly hot car, or subjected to tens of thousands of fills. I also have a lot of faith in the guy that tested it. I watched him do a few visual thread checks on tanks and he spotted cracks with a naked eye that I could barely see magnified. But still, it's unfortunate that it's lifeexpectancy is now measured in months.

SLC is, as best as I understand it, caused entirely by sustained load and has little to do with being dropped, being left in hot or cold cars, or being filled tens of thousands of times. That's what scares me.

[navyhmc]

Originally Posted by JahJahwarrior

SLC is, as best as I understand it, caused entirely by sustained load and has little to do with being dropped, being left in hot or cold cars, or being filled tens of thousands of times. That's what scares me.

True to a point, I can't find the article, but something like 90% of the tanks that had SLC-not necessarily failures, but failed a vip, fell in the well used category. That and I don't keep a full tank on hand during the off season-500-700 psi to store.

[acamato]

I did a quick search for SP-6498 (DOT Special Permit 6498) and came up with this:

Sources - A Brief Scuba Cylinder History
Luxfer and Walter Kidde continued production under the DOT SP6498, E6498 or SP7042. E7042 until the DOT formalized the aluminum cylinder category 3AL in July 1982

TO tell who hydro'ed your cylinder: Look at the 4 characters between the month & year of hydro. Usually a letter and 3 numbers. Look up the "approval" on this website:
PHMSA - Cylinders - Authorized DOT Cylinder Retesters: Domestic

You can also use this website to, save some $$ and, find a local retester. The LDS will usually sends them out.

[Kyzzle]

Thanks Acamato for the info, good stuff!

I also went and picked up my other tank today from my Lds, which past hydro (and got a couple dives in), and after checking the "born on date"... it was made in 1991! So I feel good having two tanks with acceptable years on both my al80's... it's just the al62 that is really old, but has past hydro and eddy current... My LDS assured my that even tho it is old, if it past hydro and eddy, they don't see why I shouldn't use it. So we'll see...

Another question outa curiosity... When you all get your tanks hydro'd from your LDS, does the air fill get included with your cost of hydro, or is that extra? With my first tank I took in, it was a free air fill with the hydro, and this time they charged me extra for air... I didn't really catch it till after I left and was adding it up so I couldn't question it...

Anyways thanks to all for the help and info, much appreciated!

[acamato]

My LDS does not charge for air when they hydro or VIP. It is built into the price.