Letter 13010

Passivation-Abrasive Blasted Stainless Steel 

Dear Sir,

I'm a first time visitor to your forum. I don't have a comment. However, I do have a question.

I have Stainless Steel 304 Diamond Tread Deck Plates that were inadvertently abrasive blasted with steel grit. Deck plates are flash rusting. Can deck plates be passivated?

I work in a marine environment aboard ship. SS 304 deck plates were temporarily removed from a machinery space and taken to a shop for cleaning. Once at the shop they were inadvertly abrasively blasted. Cleaning was interpreted as abrasive blasting (shop is heavy into painting and abrasive blasting). Deck plates are flash rusting. Painting the deck plates was considered, it was short lived though, due to potential slip hazard. I know only what I have learned in this forum about passivation.

Any spec of light on this issue is welcomed and greatly appreciated. I enjoyed the short visit to your forum and I have added it to my favorites for future visits.

Ramon Jauregui
- San Diego, CA,. USA

Yup, your guys screwed up but I guess you already know that.

Any standard passivation procedure will work for you.

Soak em in 10% nitric acid solution for half an hour at 70 degrees or higher and you should be alright.

You could also use citric acid if you have a disposal problem.

See ASTM A 976-96 for full details or search this website for passivation. There is lots of information here.

For the heavy contamination that you have I would prefer to use nitric. It seems to work a little better than citric in this particular circumstance. If you find that you still get some rusting after the passivation procedure it is because of the amount of iron that has been driven into the surface of your diamond plate by the blasting procedure. How deep it has been driven depends on the air pressure used and the state of the blasting material. Have faith and repassivate. It will clear it all given a little patience.

Good luck,

John Holroyd
- Elkhorn, WI

Ramon:

Yes, you can easily get your deck plates passivated. A local jobshop should be able to handle the job.

Dan Weaver Team Metal Finishing Toccoa, GA

Ramon:

You will find that the correct citric acid based formulas will give you faster and better removal of the rust than the nitric solutions.

Lee Kremer Stellar Solutions, Inc. McHenry, Illinois

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