Inside of steel tanks black?

[manni-yunk]

I've seen this during PP Blending when the O2 ignites. The tank contains the blast, so the filler never even knows it happened. He fills as normal, and later can't figure out why his O2 content is so goobered. But he didn't pull the valve and look inside the tank.

Is this even possible??????

 

[moose_grunt]

Thanks for all the input. Unfortunately, neither whipping nor rolling it on the floor for a couple of hours with glass beads and simple green changed anything. So I guess it's off to the LDS to pay $20/tank for a proper tumble if I want a nice new gray interior


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[Superlyte27]

Yes it's possible. What do you think caused the ignition to begin with? Either oxygen inputed too fast or contaminates in a non-oxygen clean tank. I contend that those contaminants, whatever they were, caused the flash and provided the carbon for the soot

 

[Jax]

Thanks for all the input. Unfortunately, neither whipping nor rolling it on the floor for a couple of hours with glass beads and simple green changed anything. So I guess it's off to the LDS to pay $20/tank for a proper tumble if I want a nice new gray interior

So, what do you think the LDS will do that you didn't?

 

[Eric Sedletzky]

It's possible it was phosphoric acid that caused the black. Using rust mort or similar will do that is if there's so much rust scale that there is no clean metal anywhere. Phosphoric acid will turn rust into a very hard black coating by stripping out and killing any active rust and turning it into iron. They recommend brushing or rolling it on then letting it dry. The iron forms a hard scale and works also as a primer, but I don't think it would be safe to breathe air that was held in the same vessel as what had phosphoric acid in it that wasn't 100% rinsed out even if it dried. It still can have a sticky surface to it. Not only that but if the inside was that badly rusted to be turned black then it should have been bead/sand blasted spotless clean to "white" steel by the place that does the hydro. Blasting needs to be done before a hydro, and whenever a tank gets blasted it means an automatic hydro even if one was done recently.
It's also possible it was coated with another product called POR-15. It's basically a black color phosphoric acid paint that kills rust and then dries to a very hard ceramic like coating that does not breath which closes off oxygen to the metal and prevents any further oxidation.... No air, no water, no rust. But it is a paint. It was developed by the Navy as a quick easy to apply fix on out of control rust on ships until they could come in for maintenance at a later time. It's designed to be used on the outside of things not inside tanks. If it's POR-15 then I wouldn't breath it either, and I certainly wouldn't be bleeding any straight 02 into it for PP fills! with any possible aromatic hydrocarbons hovering inside.

If it was my tank I would have it blasted to clean steel.

 

[Max Speed]

You shouldn't have looked in there... ;-)

 

[Couv]

Iron Phosphate General Fact Sheet

 

[manni-yunk]

Yes it's possible. What do you think caused the ignition to begin with? Either oxygen inputed too fast or contaminates in a non-oxygen clean tank. I contend that those contaminants, whatever they were, caused the flash and provided the carbon for the soot

What ignition? There is no evidence of an ignition?

Lets look at the FACTS:

1) He bought tanks and was told that they were cleaned with something that turned them black
2) There is a well known substance that does this....

But you conclude that this isnt true - but that there was an ignition and a blast that caused the discoloration. I was unaware that the tank could/would hold back the ignition and any blast - so that you for teaching me that - but in this situation it seems to me that you are jumping to the conclusion that it happened here even though he was told the cause of the discoloration.

I dont know....

 

[Superlyte27]

Dude... I didn't say this was the case for HIS tanks. I said it was the case I had seen in the past. Try to keep in mind that my post was very early in the thread. It was just info. We didn't know if it was soot. He hadn't tried to tumble it yet. Remember that not every post is directly related to the actual occurrence from the OP. Sometimes it's just helpful info for maybe 1 of the thousands of people that read this.

No, I don't think this was ignition.

My second response was simply defense to the possibility that it could happen. Not saying it did happen in this case.

 

[pinshootr]

some older(we see it a lot in 72's) steel tanks had coatings added inside to protect from rust,as long as its not peeling its okay to use.