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Matco Associates Inc. Specialists in Materials Engineering, Corrosion and Failure Analysis

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The Failure Analysis Forum: corrosion on grid blasted stainless steel

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    Dear Miss/Sir;

    One of my best customers has a problem related to stainless steels that I have to resolve. I do not know if you can help me, but I try it, in order to get the maximun information and to solve the problem correctly.
    The fact is that a stainless steel system (with pipes, tank, and lost of pieces of stainless steel) has been corroded in less than 3 mounths. The problem is related to the grid-blasting operation that our customer had performed on the system once the equipment was build up and installed (in-situ).
    We know that, in order to get the maximun corrosion resistance of the stainless steel, we have not to grid blasting the surface, but our costumer did it. After this, they did not clean it properly and the did not passivate it.
    We did a study of the system and get next conclusions: corrosion only on surcafe, less than 0,1mm of penetration; lost of contamination with Al, Si…even Cl. We did not discover contamination of Fe-particles.
    Next step is clean it and repair it and here is the question because we are not specialised in such matter: we know that we hace to grind it (or polish in order to extract surface corrosion (pits) and contamination) and even the roughness created with the grid blasting (strong roughness). We suppose that we have to clean it with water pressure jet system and the passivate with something, but, do you know or have any idea of how exactly ? Types, Trademarks of the material used, times and so on of the different steps ?
    Thanks a lot for your information and all that could help me in order to solve the problem.
    Yours
    J. Delgado;
    • CommentAuthorasotoe
    • CommentTimeApr 29th 2009
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    • CommentAuthorasotoe
    • CommentTimeApr 29th 2009
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    Dear Jorge,

    1. To clean with warm water and brush.
    2. Passivate with HCl in paste (welding consumables store).
    3. wait for 5 minutes.
    4. Rinse with cold water.
    5. Ready.

    Alejandro Soto
    • CommentAuthoreoakes
    • CommentTimeOct 22nd 2009
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    Why would they blast it and not put a protective coating on it?

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