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Chemical Formula of Passivation chemical
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We use SS 304 & 316L wire mesh,of various Microns & protective SS guard of 0.8 mm thick sheet, in the manufacture of Pleated filters.After Tig welding of the guard,the welded portion has to be cleaned by some chemical,say Passivation & hence the request for formula.
Rangarajan srinivasanMfg of SS Pleated Filters - Chennai, Tamil Nadu, India
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If you have to remove the weld discoloration chemically (and without electricity) you will have to use hazardous chemicals like HNO3/ HF blends. You could electropolish if that is possible.
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 Lee Kremer Stellar Solutions, Inc.  McHenry, Illinois |
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You can get an electrowand which will remove the discoloration and passivate the welded area instantaneously.
This method is fast and safe and with the finishing solutions machine acid is contained safely in a tank and dispensed by the machine as required.
Steve Clarkpolishing & plating - Belfast, Maine, U.S.A.
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Yes, removing blackish scale and discolouration is a problem. But, now there good pickling & passivation jelly in India available which can solve this problem without wire brushing or grinding.
It's really effective and you do not require that wire brushing or grinding. Just by applying on Stainless Steel dirty weld seam area, keep there for around 15 minutes and wash with water. That's all. I hope you should also try some jelly for solving your problem.
- Mumbai ( Bombay ), India