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Hydrochloric Acid Concentration in Pickling before Galvanizing?
Q. Dear all,
Please I want to know the concentration percentage for the Hydrochloric acid used in the Pickling tank.
NB: The galvanized metal doesn't need to be hardly cleaned.
Please advice about the best concentration percentage.
Project Research Department - Egypt
February 11, 2009
publicly reply to Riad ElEzbawy
? Hi, Riad. Sorry but I don't understand your situation. Strong hydrochloric acid (say 35 percent) is used in pickling in a steel mill; a lower concentration (say 10 to 25 percent is used in acid activation) before plating or galvanizing ... but it sounds like you want to clean galvanized (zinc coated) metal, and even very mild hydrochloric acid will very quickly remove the zinc.
So I don't quite understand "pickling" a galvanized surface.
Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
publicly reply to Ted Mooney
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A. Hydrochloric acid is often used for cleaning steel prior to galvanizing, and at typical strengths of 3-15%. Its common to start a new tank at a high strength (say 15%) then as the tank ages the acid concentration reduces as it converts iron oxides to iron chloride. ![]() Geoff Crowley Crithwood Ltd. Westfield, Scotland, UK ![]() publicly reply to Geoff Crowley Q. Dear Mr. Geoff Crowley - Lisbon, Portugal October 31, 2011 publicly reply to Luis Xavier A. Hi Luis. Courtesy of Barlow R. Campano, Chemical Engineer HIDADA Galvanizing Plants 1 & 2 Jeddah, Saudi Arabia, we have a good article on that subject in our on-line library. Good luck. A. Sir: Galvanizing Consultant - Hot Springs, South Dakota, USA publicly reply to Dr. Thomas H. Cook Q. Dear Mr. Ted, - Cairo, Egypt publicly reply to Riad ElEzbawy |
Q. Dr. Cook,
You talked about the iron content increasing over the life of the bath. At what percentage is it too high?
- Statesville, North Carolina, USA
March 13, 2009
publicly reply to Tim Williams
A. Sir:
I just looked at a graph that I made 30 years ago. With 0% zinc and 10% "free" HCl at 72 F, the maximum solubility of iron(+2) is 12%. When zinc is present in the acid then the iron(+2) solubility is lower.
Regards,
Galvanizing Consultant - Hot Springs, South Dakota, USA
March 21, 2009
publicly reply to Dr. Thomas H. Cook

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