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Use of Liquid ammonia in Flux bath

We are Hot Dip Galvanizer located in Jeddah , Saudi Arabia. The dry Hot Dip Galvanizing method is used in our plant.

How does one keep a track of the Nickel Ammonium Chloride flux bath concentration?. What is the function of peroidic addition of liquid ammonia ⇦ this on eBay or Amazon [affil links] to the bath ?

FRANCIS RODRIGUES
- Jeddah , Saudi Arabia
2005

A technical point, no help- I am not a galvanizer. By liquid ammonia, do you mean ammonium hydroxide solution? Liquid ammonia is only a liquid at about 40 below zero.

James Watts
- Navarre, Florida
2005

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2005

Galvanizing flux solution is normally ZINC ammonium chloride. Normally triple or quad salt. There is some use of nickel chloride in flux solution to reduce steel reactivity, but there are known health hazards. A 26 deg. Be' solution (lighter than water 0.9 g/ml)of ammonium hydroxide (also called aqua ammonia; e.g. 400 volumes of ammonia dissolved in one volume of water). In the "old days" we used ANHYDROUS ammonia to neutralize "spent" acid. It would NOT be normal to use anhyrous ammonia (anhydrous means without water). in a flux solution. Aqua ammonia is the best agent to raise the pH of a flux solution (but only if it needs it). Hydrochloric acid is used to lower the pH of the flux solution. The proper pH of a flux solution is 4.2.
Regards,

Dr. Thomas H. Cook
Galvanizing Consultant - Hot Springs, South Dakota, USA

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Further point... Presumably you mean zinc ammonium chloride. Can't think of any possible reason for adding a nickel salt to the flux.

Surely, if you're adding ammonia to the flux, it's for some known reason? What do the people who are adding it tell you when you ask them about it?

Sounds like a very expensive alternative to a decent water rinse after pickling, to neutralise carried-over hydrochloric acid.

Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.
2005

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DEAR SIR MADAM
I AM M.J.HEYDARY PRODUCTION MANAGER OF A GALVANIZING COMPANY.THIS IS VERY IMPORTANT FOR ME TO KNOW ABOUT USING NICKEL CHLORIDE IN FLUXING SOLUTION. DID YOU TEST THIS METHOD? AND HOW MANY IT CAN REDUCE THE REACTIVITY OF IRON?
I AM LOOKING FORWARD TO YOUR VERY KIND REPLY.

YOURS TRULY
M.J.HEYDARY

MOHAMMAD JAVAD HEYDARY
PRODUCTION MANAGER - IRAN
2007