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Home-passivating stainless steel

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Home-passivating stainless steel

Postby sugarcreek » Mon Jan 21, 2013 10:19 am

Last summer I welded in a full length 1/2" stainless coupling into my keggle HLT. I built a dimpling tool and rather waiting for a stainless coupling for the collar used a galvanized coupling. This has led to rusting around the coupling that was pulled through the dimple. Bottom line is that I need to passivate the stainless to get rid of the rust. I dont think a nitric acid bath is an option at home. I've read some about the use of citric acid and the Google machine led me here:

http://www.citrisurf.com/

Anyone have any experience with this or pointers on how to permanently get rid of this rust??
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Re: Home-passivating stainless steel

Postby manu de hanoi » Mon Jan 21, 2013 11:33 am

sugarcreek wrote:Last summer I welded in a full length 1/2" stainless coupling into my keggle HLT. I built a dimpling tool and rather waiting for a stainless coupling for the collar used a galvanized coupling. This has led to rusting around the coupling that was pulled through the dimple. Bottom line is that I need to passivate the stainless to get rid of the rust. I dont think a nitric acid bath is an option at home. I've read some about the use of citric acid and the Google machine led me here:

http://www.citrisurf.com/

Anyone have any experience with this or pointers on how to permanently get rid of this rust??

you have a TIG or stick welder ?
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Re: Home-passivating stainless steel

Postby sugarcreek » Mon Jan 21, 2013 11:40 am

My mistake! I soldered the coupling using Stay-brite 8 silver (6%) solder and a mapp torch (or whatever they are now). Looking to buy a small inverter TIG unit if any one is selling.
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Re: Home-passivating stainless steel

Postby jake_leg » Mon Jan 21, 2013 11:48 am

I remember Aaron Schnell
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Re: Home-passivating stainless steel

Postby manu de hanoi » Mon Jan 21, 2013 11:51 am

ok, I have a trick if you have a welder. But without it, I dont recommend citric passivation (it's somewhere in the astm standards). I tried without success. if you have 304 grade SS (not 201) perhaps diluted sulfuric acid would give you something
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Re: Home-passivating stainless steel

Postby brantoken » Tue Jan 22, 2013 10:44 am

citric acid does work but it is slow , add some rock salt to it to speed it up.
It is cheap and it works.
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Re: Home-passivating stainless steel

Postby jake_leg » Tue Jan 22, 2013 2:01 pm

brantoken wrote:citric acid does work but it is slow , add some rock salt to it to speed it up.
It is cheap and it works.


Citric + heat is recommended. It takes 4 minutes. See the link I posted.
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