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-----Powder Coated Cabinets are Rusting
September 9, 2011
We are into electrical equipment manufacturing business.
Currently we are Powder coating our CR-MS cabinets which are installed in open atmosphere in electrical grids and we are facing rusting issues frequently.
To resolve this problem should we re-visit the powder coating process or go for a better process such as ED Primer+Powder coating which may give superior corrosion resistance.Please suggest.
Buyer - India
Hi, Venkatesan
The cabinets probably have spot welds, seams, welded tabs, etc. that will tend to prevent perfect powder coating coverage. Yes, I think they should be e-primed before powder coating.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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September 9, 2011
You are powdercoating steel that goes outside.
What are you doing for corrosion protection? Powdercoating is porous, as are most paints. And any scratch will allow even more water to contact the steel.
Powdercoating alone is a weak specification for corrosion protection. You really need some electrolytic protection also perhaps.
Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK
First of three simultaneous responses -- September 9, 2011
Also, what is the pre paint process. If you are not using a Mn^Zinc phosphate, consider it for a quality finish.
- Navarre, Florida
Second of three simultaneous responses -- September 9, 2011
September 12, 2011
My BAD. I said Mn phosphate and I meant zinc phosphate. Mn would be an expensive and poor route.
Sorry.
- Navarre, Florida
Third of three simultaneous responses -- September 10, 2011
First, it seems you are relying upon the Powder as a rust preventative?
Don't!
Cold Rolled Mild Steel requires protection in any environment let alone an exterior one.
My suggestions are based on a long experience:
Choose a Zinc Alume substrate not CRS.
Ensure any Arc Welds are Si Bronze.
Ensure any weld affected areas are Zinc Rich epoxy primed.
Ensure that an adequate pre-treatment process is in place.
I envisage either a first class Zinc or Chrome Phosphate process.
Ensure that you are using premium quality TGIC containing Powder.
Ensure that adequate OH&S procedures are in place to utilise these materials.
Thermoset Powdercoat is micro-porous it is not a barrier coating!
Hope this helps,
Regards,
Bill
Trainer - Salamander Bay, Australia
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