Metal finishing Q&As since 1989
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Chemical percentage and process of stainless steel,carbon steel, monel, Inconel,hastelloy, alloy steel in tube product
April 27, 2010
dear sir,
I am working in tube manufacturing company.I make various material tubes,we use HCl,nitric acid & HF mixure in stainless steel 304,
304l, 310, 316, 316l, 316TI, 321, 347, 317l, monel-200 & other monel grades, Inconel-800, 825, 600; alloy steel, carbon steel, mild steel, Hastelloy, etc. in pickling & passivation process, but we do not satisfy outside & inside surface & also pitting problems, so please sir guide actual pickling procedure & its related percentage of acid. please sir respond positively.
thanking you sir
company employee - Baroda, Gujrat, India
April , 2010
Hi, Subhashchandra. I'm sorry, but I don't think your question is yet fully formed. You mention at least 18 different materials of construction, 2 different processes that you want to perform on each, 3 different acids you are using, and that you have not escaped problems either with the inside surfaces nor the outside surfaces :-)
People cannot realistically respond: there is no one exact mix of HCl, HNO3 and HF that will allow you to pickle and passivate a material with no problems and with no regard for its composition :-)
Please name your most common material of construction, and the acid concentration, time and temperature that you use, and exactly what problems you have with with that specific acid combination on that specific alloy, and I'm reasonably confident that someone can start you on the road towards continuous improvement. Good luck!
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted's reply is kind. With such a wide diversity of metals, you should hire a very qualified consultant. If you are currently trying to process all of these materials in 1 or 2 main treatment tanks, I would be shocked if you did not have significant problems or are dumping the tank frequently.
James Watts- Navarre, Florida
April 29, 2010
May 11, 2010
please sir give me answer
dear sir,
what means pickling & passivation process ? why do pickle & passivation?
acid percentages in both process?
steel - Baroda, Gujrat, India
May 11, 2010
Subhashchandra,
Pickling generally means the removal of scale, tough oxides, and discolorations due to welding, heat treating, etc. Usually it involves a nitric acid or nitric/HF bath.
Passivation in the case of stainless steel and some nonferrous alloys, refers to the removal of surface iron to prevent rust corrosion.
Please refer to ASTM standards A380 and A967.
Ray Kremer
Stellar Solutions, Inc.
McHenry, Illinois
May 12, 2010
Dear Subhashchandra Patel,
Better you call any of the plating chemical supplier in your area, and share all your problems and requirement.
He may give better answer and advise to you.
- Salem, Tamil Nadu, India
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