Help identify tank alloy

[HKGuns]

If you are anything like me, as a new diver, you're gonna need a larger tank! Otherwise you'll get around 5 minutes out of that one!

 

[greeniguana]

Check with your LDS before you chuck the tank. I have a shop nearby that doesn't mind filling them. If nothing else you might be able to use it for filling tires.

 

[rjack321]

Which 6351 Luxfers are the good ones?

The gongs

 

[BigRed96]

I have another tank made of the same alloy that that has had the VE, Viz, and Hydro and my LDS will fill it. Probably shouldn’t have bought it but live and learn.

 

[broncobowsher]

Which 6351 Luxfers are the good ones?

Still looking for the marks that say it is the 6351. I don't see them on the neck, which is why I asked what the rest of the markings are.

You must be a good tank whisperer if you can read all the markings that are not shown.

 

[runsongas]

@broncobowsher it is by the manufacture date which is very clear on the provided photo

 

[tridacna]

Still looking for the marks that say it is the 6351. I don't see them on the neck, which is why I asked what the rest of the markings are.

You must be a good tank whisperer if you can read all the markings that are not shown.

There is no stamp for 6061 or 6351. The manufacturer stamp coupled with its birthday is all you need to hear the sad (or happy) whispers. @runsongas nailed it in post #2.

 

[Bob DBF]

You must be a good tank whisperer if you can read all the markings that are not shown.

Just do it the way a dive shop does, no AL tank before 1990. If I want to look at a tank before that I'll check the bad alloy thread.

 

[rjack321]

Still looking for the marks that say it is the 6351. I don't see them on the neck, which is why I asked what the rest of the markings are.

You must be a good tank whisperer if you can read all the markings that are not shown.

There is no 6351 vs 6061 alloy stamp

To determine the alloy and viability of the tank at all you need:
Manufacturer (Catalina never used it so that is an immediate rule out)
Cylinder size - the switchover date happened at different times for different sizes
Born date

For some tanks, the special permits or exemptions have since expired so they cannot be hydroed or VE stamped at all (WK Ali tanks for instance). This is not specific to aluminum tanks though. Norris made some HP steel exemption tanks a few years ago and they didn't renew the exemption so they are worthless now.