5052 H32 ?

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gandrfab
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Location: Edgewater Fl

5052 H32 ?

#1

Post by gandrfab » Wed Feb 14, 2018 9:18 am

I'm replacing the cracked plastic tank on my hydraulic bender.
I cut, DA'd, welded and filled the bottom 5 pieces of 1/8" aluminum with water last night.

i come in today to check for leaks and dump the water to find what looks like the start of pitting.
It is city water. I wasn't expecting to see that this fast.

Kind of makes me question every tank I built or have seen built over the last 20+ years. :banghead:
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kmorin
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Re: 5052 H32 ?

#2

Post by kmorin » Wed Feb 14, 2018 2:36 pm

G&R,
I'm not there and the photos are kind of generic in regard surface definition - I can see some coloration or discoloration- but not much definition of pitting or corrosion.

When you strip mill scale the sander/buffer/disk/abrasive could have had lots of small trace contaminants that could lead to to discoloration. Hydrocarbons for example, if there were grease/oil/lube etc on the disc when the mill scale was stripped? that could smear and leave traces and the muni water could have mineral salts that reacted with the cleaned metal and left color indications where the hydrocarbons were smeared?

In the case of coloration versus actual corrosion; color changes are not always the initiation of corrosion- they can be from the water's reaction to the metal's surface oxides. There is oxide on aluminum in a few seconds after it is cleaned of the current layer of 'anything' - that is fresh metal will react to oxygen and form and oxide film and this film may not be uniform due to surface contaminants that are left from the previous stripping operation.

So to test.... get some acid, etch the box/tank to white metal- using an acetone pre-rinse to make sure you have all the hydrocarbons removed; then use the acid to get a uniform etch/white metal exposed surface. NExt- repeat your water fill operation and if the various discolorations happen AFTER acetone & acid ??? then the metal is reacting to the water- but I'd expect the reaction to be uniform over the entire surface?? Not spotted here and there???

It looks like the water was reacting differently to some unseen contamination left on the surfaces after the de-scaling operation- that's what I conclude from the shape and spread of the color patches- but that is what I'd expect a uniform acid wash/etch to reveal?

Next, water, especially tap water is often loaded with dissolved mineral/metal "salts" in the form of compounds that form in the ground water containing various traces of reacted metals and minerals. The water from the tap is surely not distilled! While filtering will take out the 'big chunks' of particulate; those in solution are not removed by filtration which is about all municipal water gets.

Not much definitive help - more like a 'what if' speculation? I don't think your previous tanks are at risk or in that much time you'd have begun to hear about pin hole corrosion?

interested to learn if you conduct tests to discover the cause of the discoloration?

Cheers,
Kevin Morin
Kenai, AK
kmorin

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gandrfab
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Joined: Fri Mar 28, 2008 12:33 pm
Location: Edgewater Fl

Re: 5052 H32 ?

#3

Post by gandrfab » Wed Feb 14, 2018 3:14 pm

I can't feel or see pitting, I'll assume it's just discoloration.
As far as tests go they will have to wait, the pipe bender is going back together.

Thanks, every time you post I learn something.

kmorin
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Re: 5052 H32 ?

#4

Post by kmorin » Wed Feb 14, 2018 4:55 pm

G&R,

there wasn't any Simple Green soap involved in the clean up was there? That stuff has a clear warning in the MSDS about use on aluminum since I think the green is partly to do with copper ions included for some reason in the formula? I've seen some very exotic pitting from not washing Simple Green off of marine aluminum adequately!!

Wish I had more insight but I understand the bender needs to be in service. What about just doing some testing with your tap water on a single piece of material in a plastic tray/tote/bucket?

Cheers,
Kevin Morin
Kenai, AK
kmorin

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gandrfab
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Location: Edgewater Fl

Re: 5052 H32 ?

#5

Post by gandrfab » Thu Feb 15, 2018 2:50 pm

I don't have any Simple Green. I always have lacquer thinner in the shop.
I might make some test trays, it does have my interest.
But lazy will most likely win.

One of the 1st places I worked a guy was making a drop in roof pan for a van that couldn't leak. He kept taking the box outside and filling it with water to find leak after leak after leak. Rinse repeat.

After all his effort to finally get it done my cocky younger BACK SIDE said I could do it in one shot.
He gave me a "Ya right, prove it" that job was done so I sheared 6) 6"X6"X 1/8" aluminum pieces, welded the bottom 5 pieces together filled it half way with water.
Welded most of the top on and left one small hole then shook it to cool it some.
Waited for the small hole to dry and then zapped it closed.

I smiled and showed it to him.

Another older guy (that wasn't a welder yet) asked if he could have it to show his sons and he took it home.
Now to add to that I taught him to tig weld back then and his 2 sons grew up and I taught both of them to mig and tig steel and aluminum. I haven't seen any of them in a few years.
I wonder if he still has that box with water in it.

kmorin
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Re: 5052 H32 ?

#6

Post by kmorin » Thu Feb 15, 2018 3:46 pm

G&R, why not just drop some small pieces of the same plate/sheet into a plastic (non-reactive) bucket of the same water? do some different cleaning treatments, and drop some coupons into the tap water and see?

I don't see the need to make pans/trays/tanks to do this test- just take some more of your time - what would be different than just coupons in water?

cheers,
Kevin Morin
Kenai, AK
kmorin

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gandrfab
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Re: 5052 H32 ?

#7

Post by gandrfab » Fri Feb 16, 2018 9:34 am

Solutions, This'll happen.

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gandrfab
Posts: 376
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Re: 5052 H32 ?

#8

Post by gandrfab » Thu Jul 12, 2018 12:06 pm

Sadly, I never got around to doing this simple test.

My bender reservoir is holding up great.

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