Laboratory Testing & General Mineral Processing Engineering

Laboratory Testing & General Mineral Processing Engineering

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Help With Strange Oxidation Problem (3 replies)

M
Luftbert
1 month ago
Luftbert 1 month ago

Hi,

I am a homeowner with an odd oxidation problem - hoping somebody can help.  Will try to keep the story short, though it is a little interesting.

For some years, a 3/4" main copper water supply pipe in my basement kept developing oxidation in a certain section.  I thought it was related to a trickle of electricity from the electical system ground, but nope.  Then figured it was due to some localized one-time problem (spilled chemical on the pipe or something).  I had a 3-4 foor section of the pipe replaced.  The oxidation came back.

Things got worse, and eventually I figured that a prior homeowner genius had sealed a half-gallon milk container containing some acid (car battery my guess) BEHIND THE PLYWOOD SHEARWALL in the basement, where it was slowly leaking out, trickling down the stud, and hitting the pipe (and a large electrical wire, but the plastic insulation on that looks undamaged).  

I extracted the source (which is still sitting in a closed 5 gallon bucket outside the house).  So problem solved, right? No.  Ever since, I have noticed an accelerated level of oxidation on tools and materials in my basement.  I have lived in the house for over 25 years, and the rate of oxidation on metals is MARKEDLY accelerated (including on metal that never showed any oxidation before) and widespread - i.e., on metal there is no possible way got splashed directly with the acid.  The pipe continues to corrode apace.

My only hint of a theory is that a moderate amount of the acid soaked into the stud and sill plate as the problem was peaking, and when I ruptured the container a bit while extracting it.  And presumably its vapor has a corrosive effect in the general environs.  But in the basement, there is no smell, no perceivable air quality issue at all.  I would think only a billowing toxic clould would be able to affect metal that is remote from the source.   Am I wrong?  The exposed wood is well ventilated and should have "dried out." But presumably it remains a source of corrosive vapor that is not perceptable to my senses.  Is there anything I can due to neutralize acid that has soaked into wood members? Apply baking soda? 

Thanks

Matt

J
Jorge
1 month ago
Jorge 1 month ago

The corrosion of copper is an interesting topic. I think, you should determine the water quality in your house. For example, if the pH is lower than 7, your piping system receives acid water. If the pH is 7, there is not acid water. Other important parameter to evaluate is the dissolved oxygen because the presence of oxygen favors the corrosion of copper pipes. The presence of green deposits is copper carbonate. Other possible reason is the microbial activity. In this case, chlorination can be considered to solve the problem.

M
Luftbert
1 month ago
Luftbert 1 month ago

Thanks Jorge.  I think my story-telling may have obscured my point a bit.  The corrosion on the pipe is from a clear cause: direct spill of acidic liquid.  The mystery is that my tools and other metal objects in the basement are experiencing accelerated occidation, apparently due to just being in a room sharing the same air. Thanks.

J
Jorge
4 weeks ago
Jorge 4 weeks ago

You clarified your problem, that is good. If your tools show corrosion and oxidation, the acid liquid might have released some fumes in the basement. You are right, they can cause the oxidation of your tools. You can use a circular wire brush to remove the oxidation. Regarding the wood, I suggest to add soda ash, it is very effective to neutralize acid compounds. 

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