Letter 37008

Passivating/Pickling  

+++++

After Tig welding stainless steel tubing, we then go through the process of pickling/ passavating the heat spots. This is done in the usual manner using acid cleaning and then scrubbing off with scourer pads. My question is that does anyone know of a quicker or easier way to remove the weld heat marks off the stainless.

John Kernan
Stainless steel manufacturing - Brisbane, Qld, Australia

The last couple of times we printed similar inquiries, we were inundated with responses that were ads for proprietary pickling pastes and electrolytic stain removal machines, John. So we suggest that you try those terms with a search engine. We will print any TECHNICAL responses we get, but we can't print ads or testimonials or patent numbers. Good luck.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

John

I am not sure where to find documentation, but I know some shops use a heated potassium permanganate solution, followed by a nitric acid dip to remove the weld scale. It is somewhat time consuming, but not labor intensive. The scale comes off faster if it is brushed immediately after welding.

Willie Alexander
- Colorado Springs CO

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