Question Older steel 72 Pitt Depth

[PBcatfish]

I thought I would leverage this thread again instead of starting a new one for another LP72 identification question. Who made these tanks? And how would I tell if it has a liner inside?

I can't tell what the hydro mark is. Is it a circle with something inside of it (a D maybe?), or is it an outline of a C? In any case, the rest of the marks are:

ICC 3AA 2250
K64433
USD
9C67+

They are indeed US Divers tanks: I got a pair of them that were still attached to the "aqua-lung-pac" (why did USD put everything in quotes?!?) with J-valves and the pull levers still in place.

According to @captain it seems that the hydro mark might be a C over an L which would make it a PST? Ref: 1970 US Diver's LP72 - Lined or not?

The tanks are seemingly in nice condition. They seem to be vinyl-wrapped on the outside? I don't think it's paint, but it is quite intact. I'm guessing that it's the "Tuff Koate" that @Akimbo refers to in a 1970 catalog a couple of posts later in the above link.

One thing that is different from the 1970 description is that I'm pretty certain that these are *not* galvanized under the Tuff Koate. The couple of places that the outer liner is damaged shows brown-black metal, not galvanized metal. So they're probably not the exact same tanks as were sold in 1970.

I'm more worried about whether they have the epoxy liner or not. It seems that 1967 is right on the border of internal liner or not. The inside looks like a uniform brown-orange coating. I've seen tanks that looked like that when they were consistently exposed to wet fills; but I've never seen an epoxy liner before, and I understand that they're brown, too. I've got the tanks soaking with phosphoric acid right now, so we'll see what happens.

However, if it is liner, it seems intact. If they pass hydro, I'm using them as-is, and I get to keep the original stickers this time!


Thank you very much for any help you might be able to provide. I appreciate it.

I have one of the Vinyl coated tanks from USD. Mine is shiny steel inside, with no liner. The coating makes it impossible to read some of the numbers that are stamped into the tank, so I am looking for a good way to remove the coating so that I can get a fresh hydro test, unless someone want's to buy it as-is for collector value.

At one time, I was able to identify the original manufacturer who made the tank for USD, but the name of that company has fallen out of my head since then. I'm pretty sure it wasn't PST. I think it was someone I was less familiar with. If you google around a bit, or search this forum some more, you may locate that information. It is out there somewhere. Also, USD may have used more than one supplier, so just because mine wasn't PST, doesn't necessarily mean that yours wasn't.

The first recertification date on my tank is 1977, so it would seem likely that the born on date would be 1972 or earlier. I can't actually read the original date, nor most of the other numbers/letters.

 

[Akimbo]

You can download catalogs here if it helps you sort it out:
Vintage Double Hose / VDH Worldwide Manuals and Catalogs Repository

 

[Jimchris]

I am looking for a good way to remove the coating so that I can get a fresh hydro test, unless someone want's to buy it as-is for collector value.

A surface prep disc that chucks into a drill will strip the vinyl off the stamped markings. Home improvement stores sell them. If you want to completely strip the vinyl, I used Citrastrip and a razor blade scraper on one of mine, then followed up with cold galvanizing spray, as well as top coat spraypaint. Aircraft remover would probably work as well.

 

[tmassey]

Thanks, @Akimbo for the link. I just looked at the 1967 US Divers catalog. Sure enough, the tanks are lined. It also does *not* mention that the yellow-coated tanks are galvanized, so I'm going to assume that this is something that changed between 1967 and 1970. Pity.

And it seems that they're *probably* PST-made from the CL hydro, though it could be someone else. I guess it doesn't really matter; I just like to know. Seeing as they're not marked PST, I'm likely not going to get a plus rating on the hydro; but frankly, if you don't fill these to 3000 they're not the capacity I want, and if you're willing to fill to 3000 the extra bit of stamping probably isn't interesting to you anyway...

Alrighty. I'm going to move forward with these as-is: vinyl over raw steel on the outside, epoxy liner over raw steel on the inside. I'm gonna get them hydroed, and when (if? ) they pass, I'm gonna put air (ahem, EAN32) in them and dive them.

That is, after I get a manifold for them. I *thought* I ordered one a few weeks ago, but didn't; and now the price has literally *doubled*... Ugh. Gonna snap up a couple from Piranha while I can.

ETA: I dug into the catalogs a little further. Looks like 1966 has no mention of epoxy liners, but 1967 does. So it seems that somewhere in there is the dividing line between liners and not. Missed it by that much! (in my best Maxwell Smart voice.) Also, the 1969 catalog says tanks are either galvanized or yellow coated (with no mention of "over galvanized"); 1970 adds the "over galvanized" language. 1970 keeps the same descriptions (epoxy internal liner, galvanized exterior with or without Tuff Koate); but 1971 and after describe the tanks as Molychrome steel tanks with galvanized exteriors with or without Tuff Koate, and in the case of the black tanks it describes them as having "Molychrome steel tank interior lined with exclusive jet black vinyl over a hot dipped galvanized finish". Seeing as the tank is black on the *outside*, and I don't think *anyone* galvanized the *inside* of any tank (zinc is not great stuff to inhale), I'm assuming that vinyl liner is only on the outside. So it seems the liners didn't stick around long: 1967 through 1970 or so. So now you know!

 

[Eric Sedletzky]

I have one of the Vinyl coated tanks from USD. Mine is shiny steel inside, with no liner. The coating makes it impossible to read some of the numbers that are stamped into the tank, so I am looking for a good way to remove the coating so that I can get a fresh hydro test, unless someone want's to buy it as-is for collector value.

At one time, I was able to identify the original manufacturer who made the tank for USD, but the name of that company has fallen out of my head since then. I'm pretty sure it wasn't PST. I think it was someone I was less familiar with. If you google around a bit, or search this forum some more, you may locate that information. It is out there somewhere. Also, USD may have used more than one supplier, so just because mine wasn't PST, doesn't necessarily mean that yours wasn't.

The first recertification date on my tank is 1977, so it would seem likely that the born on date would be 1972 or earlier. I can't actually read the original date, nor most of the other numbers/letters.

Use these And/or a hard wire wheel also on a 4-1/2” grinder.
Pick out the vinyl that’s still stuck in the lettering with an awl. Sand blast the tank after if you want more ‘tooth’. Use galvite cold galvanizing compound over the steel two coats, and you’re done.