Does This Tank Need To Be Cleaned?

[guruboy]

I'll show them the pictures and see if I can't get a refund.

I actually saw it being tumbled on the rollers, horizontally. Curious- does the tumbling process usually involve rolling it at an angle to help clean the bottom?

 

[tbone1004]

no because you have to get the top crown as well. The tank is however supposed to be filled quite a bit and you should see a ring around the bottom from tumbling, this looks like they didn't tumble long enough. if the walls looked like the bottom, it would have had to be in the tumbler over night

 

[guruboy]

Did not stay to watch the entire tumbling process. was just dropping off some other tanks for hydro. walls were not as bad as the bottom.

maybe they didnt put enough stuff in? or maybe just not long enough as you said.

 

[DEdiveguy1]

from the pictures it appears that they didn't use enough media and, like tbone1004 suggests, they probably didn't let it tumble long enough. I know cylinder techs who have had to tumble some steel cylinders for 1-2 days to remove severe rust. good luck!

 

[Jack Hammer]

Odd, OP said it was tumbled then hydro tested. That would account for the tank looking that way, but would be the back words way of doing it. Have you asked the shop to retumble it?

 

[tbone1004]

sometimes you have to tumble if the walls are rusted so bad it won't pass the VIP that they have to do before hydro. The walls look normal for something post hydro, but I have never seen the bottom of a tank look like that after tumbling or after hydro

 

[guruboy]

The tank was tumbled first, then hydro tested.

I had it tumbled because the bottom looked a little too dirty to me. The walls weren't as clean as they were now, but not terrible.

I showed the shop the pictures and they agreed it should be cleaner and refunded me.

I guess this tank is still clean enough to pass the hydro VIP?

 

[rcontrera]

Of course, it will take a trained inspector to be sure, but the center of the bottom looks to be pretty rusted to me. One note on shot blasting, the high speed of the shot actually "beats" the rust and breaks it off instead of cutting it like grit would do. One bad part of that is that it can sometimes embed tiny micro grains into the sides or bottom of the tank and the will get released after a good pressure "stretch" leaving a layer of dust inside. I am a big fan of PROPER tumbling and finishing up with a brush system to polish. Good luck!

 

[halocline]

The right brush will do the job just fine. Luis H posted about a really good one some time back; you might try searching for his posts. One issue with tumbling and most hydro shops is that they are used to tumbling non-breathing-air tanks, so what they're trying to do is just get rid of the crap that might clog a filter on a welding regulator or something like that. Scuba tanks get tumbled for longer to get them cleaner. And if the initial rust was mostly on the bottom, tumbling is not as good as a good brush to begin with. Even with lots of media, the walls get most of the abrasion.

 

[2airishuman]

We have hydro shop here that does internal shot blasting of tanks. They get less than 20 bucks to do it and it does a better job than tumbling. This may be worth looking around for.

That would be All Safe in Wyoming, MN. I just dropped off two tanks at my LDS that will end up there.

They will shot blast, hydro, and VIP your tanks if you bring them in person or ship them. It's expensive to ship tanks, but they will do the job right the first time.

All Safe | Cylinder Certification Services