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9 comments
Commentator
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Neutralizing corrosive compounds

07/08/2008 6:29 PM

I have a light edge corrosion issue with a steel sheet (ASTM A792 - 55% Al, Zn Alloy coated by the Hot-Dip process) that I have had evaluated (EDS) and it was determined that the corrosion appears to be connected with an environmental source of excess sulfur bearing compounds.

While the cause of the sulfur compounds is important, I am more concerned with a treatment to neutralize the current corrosion as well as any additional corrosion.

Application: Roll-formed sheet-metal panel used on the outside of a metal structure.

Preferred treatment: Spray on

Any ideas? I am the Quality Control Manager for a major metal building fabricator and engineering company. I'm not a chemist, therefore I'm not sure how to combat this issue. This is not a common problem, however, no less important.

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Pathfinder Tags: compounds Corrosion neutralizing sulfer
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#1

Re: Neutralizing corrosive compounds

07/10/2008 4:37 AM

You say "light edge corrosion" If the sheet was cut after galvanising then you will have exposed steel which will corrode.. A problem with coating is that of edges paint always riuns away and so you get a thinner coating and corrosion at the edges. Same probably happens with galvanising - edges should be rounded.

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#4
In reply to #1

Re: Neutralizing corrosive compounds

07/10/2008 8:59 AM

Yes, it is sheared.

And like I mentioned earlier (ether this post or another) this is not a common reaction.

We literally have 10's of thousands of panels in this application in the field and this is isolated to a small area or region of the country.

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#2

Re: Neutralizing corrosive compounds

07/10/2008 4:48 AM

i think you can use some contain acid neutralize ability rust preventives, usually add some alkilane additives just like high TBN petrolium calcium.it reacts with acidiod.

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Commentator
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#5
In reply to #2

Re: Neutralizing corrosive compounds

07/10/2008 9:01 AM

Any specific recommendations?

A spray on inhibitor is preferred.

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#3

Re: Neutralizing corrosive compounds

07/10/2008 7:31 AM

I'd be interested to know a bit more about the observed results of this corrosion. The basics of the situation should fit into this (below) scenario somewhere, but how sulfur (sulfur gases perhaps?) figures into it is what is unclear:

Factors Associated Mainly with the Metal

  • Effective electrode potential of a metal in a solution
  • Overvoltage of hydrogen on the metal
  • Chemical and physical homogeneity of the metal surface
  • Inherent ability to form an insoluble protective film

Factors Which Vary Mainly with the Environment

  • Hydrogen-ion concentration (pH) in the solution
  • Influence of oxygen in solution adjacent to the metal
  • Specific nature and concentration of other ions in solution
  • Rate of flow of the solution in contact with the metal
  • Ability of environment to form a protective deposit on the metal
  • Temperature
  • Cyclic stress (corrosion fatigue)
  • Contact between dissimilar metals or other materials as affecting localized corrosion.
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#6

Re: Neutralizing corrosive compounds

07/10/2008 9:11 AM

Call me! We have a customer ASP services who we solved this problem for. www.arcmelt.com

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Commentator
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#8
In reply to #6

Re: Neutralizing corrosive compounds

07/10/2008 11:52 AM

Thank you!

Please e-mail me for contact.

CAM

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Guru

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#7

Re: Neutralizing corrosive compounds

07/10/2008 9:36 AM

Hello CAMILLIONTWO1!

Iron, your steel sheet start to rust because the environment, air, humidity, direct contact with it is acidic. To neutralize, use DiMethylEthanolAmine as is or in solution to passivate your steel by coating (spraying on a thin coat), deeping in a bath (you know the form, if allow it) or just rub ir with a rag containing the liquid. Please, don't drink it and use safety cloths, gloves, and goggles. It works for me to eliminate rust problems but you have to try to prove it. All the best, Gil.

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#9
In reply to #7

Re: Neutralizing corrosive compounds

07/10/2008 11:52 AM

Thank you!

I sent e-mail

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Users who posted comments:

adamchen (1); Anonymous Poster (1); Camilliontwo1 (4); EnviroMan (1); Gil Becker (1); NiCrMoNoMore (1)

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