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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

Subhashchandra Patel
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!


Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

April 29, 2010

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

May 11, 2010

please sir give me answer

dear sir,
what means pickling & passivation process ? why do pickle & passivation?
acid percentages in both process?

Subhashchandra Patel
steel - Baroda, Gujrat, India

May 11, 2010

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
Ray Kremer
Stellar Solutions, Inc.
supporting advertiser
McHenry, Illinois
stellar solutions banner

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.

Kannan Boopathi
- Salem, Tamil Nadu, India

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