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Steel tubing and CR plating

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Tubing:
We Zinc plate /yellow 2"x1" x 36" long tubing. We are having blisters in the tubing seam welding area full length, also on the tubing radius. Any suggestions?

Also after we apply the brightener, we due not get a constant yellow coloration, we see several different colorings on the finish.

Any ideas on both issues?

Hector Ernesto Contreras
Metal Fab, Powder Paint & Plating - Nogales, Arizona
2006

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Looks like you need a lot of help in plating; better to try getting good experienced help though experienced personnel or a consultant at your site to look into the process.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2006

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2006

First it would be most likely that you have a pre plate problem. I would look very closely at the cleaning and pickle process. After cleaning and pickling the part should be clean at all areas with no water breaks and no smuts (especially at the weld). Also, you should check the weld is being made properly - not burned, no burnt flux, no burnt pits, etc.
In answer to your problem with yellow chromate after brightener additions, I will assume that you are running a chloride zinc bath and that this is typical when total organics are high and/or the brightener is not properly mixed or proportioned with other additives.

I think the previous respondent is correct that you need to hire a consultant to develop correct process parameters and procedures and see that they are instituted.

Gene Packman
process supplier - Great Neck, New York