No cost, no registration, no passwords -- just aloha, fun & authoritative answers
(as an eBay Partner & Amazon Affiliate we earn from qualifying purchases)

Where the
world gathers for metal finishing
Q&As since 1989

-----

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.

Venkatesan Narayanan
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
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.

James Watts
- 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.

James Watts
- 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

William Doherty
Trainer - Salamander Bay, Australia

(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories: