Metal finishing Q&As since 1989

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Chromate Conversion coating on Zinc Plated Fasteners

Dear Sir,

We use pipe fittings in the trim of the valves. These fittings are zinc plated to 45 micron thickness.

These fittings are exposed to petrochemical plant environment.

I would like to know whether chromate conversion method would increase the life and by what amount?

Is Zinc plating with chromate conversion suitable for Fasteners?

Kiran Rane
Firetech - India
2005

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Dear Mr Kiran;

45 microns of zinc plating is too much for any fastener. Looks like you are trying to duplicate Hot dip galvanising. To answer your question, all zinc plating has chromate conversion by default. Olive drab chromate conversion will last the longest in a petrochemical atmosphere; however you should look at using Zinc-nickel Alloy plating which will be the best choice for your application.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2005