BUT... I sometimes question if they are actually building to that standard or just stamping stuff.
That’s always the problem with buying things made in China sold by a Chinese company. Really, that’s always the problem buying things made in China (and elsewhere, including the US), but at least with a US company there is hopefully somebody doing quality assurance of the items that has a little more, shall we say, legally enforceable liability and therefore lower tolerance for fraudulent parts.
The other part that worries me is that 6061 and 6351 aluminum are both allowed. 6351 is the “bad” alloy that suffers from sustained load cracking. You would hope they’re not using 6351, but there’s just no way to know. I know the DOT 3AL standard allows 6351 as well, but I also know that none of the American suppliers are using it. I have no idea what the Chinese might be using, and would be reluctant to believe just their say so.
There’s a certain amount of logic that says if the tanks pass Hydro then they are fine for our application. And that would be fine if the condition of the tanks couldn’t change on their own over time. The problem is, you can’t be certain of that because you can’t be certain of the aluminum alloy.
The tricky part to me, besides getting every random scuba shop to fill a tank it doesn’t have DOT markings, is getting these things hydroed. The ISO standard only requires a requalification every 10 years, which is nice. But a quick google didn’t show me places offering to perform that requalification test. I’m sure they exist. But that’s now an awful lot of headaches.
I realize that the OP is asking about something that has already happened, but wow: those Chinese tanks would have to be noticeably cheaper than what I could get used tanks for, and I’m certain they weren’t. Again, a quick Google shows those available on Alibaba for $85 a tank, minimum order 10 and does not include shipping, which is probably fairly substantial. You can get it down to $75 a tank if you order 100. But unless those tanks were never leaving my facility, I can’t imagine it would be very straightforward to own those tanks.
I am, however, interested to see what other details the community here can figure out.
