PaintSquare.com
      | Connect Follow us on Twitter Like us on Facebook
About | Subscribe | Advertise
  

 

Download our free e-book! Quality Control

Problem Solving Forum

| More

November 11 - November 15, 2013

I have galvanized steel in direct contact with powder-coated aluminum in an outdoor exposure. The galvanized steel is corroding. What is the best way to remedy the situation?



More items for Quality Control


Selected Answers

From Robert Cameron of Belzona Houston on November 22, 2013:
There are two-part epoxies available that are tolerant to surface contaminants. I would remove loose contaminants with hand tools and even refer to SSPC-SP 11, Power Tool Cleaning to Bare Metal, if possible on the galvanized section (no need to knock off the galvanized layer if it is tightly adhered). Then mask the powder-coated area, and apply two coats of this two-part, surface- tolerant epoxy.

From Karen Fischer of Amstar of Western New York, Inc. on November 19, 2013:
Though there isn't much information here as to what kind of structure this might be and how the two materials are connected (fixed or movable), my first inclination would be to isolate the two dissimilar metals with a neutral, non-reactive material of some kind to eliminate the direct contact between these two metals. Clearly, the galvanized metal is reacting with the powder-coated material. I don't know what kind of structure this is, but some type of rubber or plastic spacer may be enough to stop this reaction. Painting of the galvanized metal may not provide sufficient isolation, especially if the connection is movable. Repair and re-galvanizing the corroded area can then be accomplished.

From Carl Thompson of Hill Brothers on November 11, 2013:
I would tape the powder-coated aluminum where it meets the steel. Aluminum is amphoteric and can be attacked by either acid or alkali. Treat the galvanized steel with a 20% solution of phosphoric acid. Wait 15 minutes, then wipe the rust and corrosion away. If some corrosion remains, repeat the process. When cleaned, neutralize the galvanized steel with a very dilute solution of ammonia. You should see a white residue on the surface . This is an oxide of phosphoric and should help keep further corrosion away. Any holes developed from corrosion should be filled with a metallic, 2-part epoxy putty. If painting is desired, brush away any loose white powder with a stiff copper brush and proceed. To prevent any galvanic reaction between the aluminum and the stainless steel, painting the galvanized metal would be preferred.

Please sign in to submit your answer this question    

Tagged categories: Aluminum; Corrosion; Galvanized steel


Current PSF Question | Submit a PSF Question | Full PSF Archive

KTA-Tator, Inc. - Corporate Office
KTA-Tator EH&S Services

• Ambient & Worker Exposure Air Monitoring
• Safety & Health Program Development
• Lead Paint Assessments
& Specifications
• Health Hazard & Jobsite Safety Assessments
Call 1-800-245-6379


Elcometer, Inc.
New Elcometer 456 Coating Thickness Gauge

Best In Class Just Got Better. Technologically Intelligent And Robust. Marvelous Design And Durability. An Earth-Shattering Revolution In Coating Inspection.


SSPC: The Society for Protective Coatings
http://www.sspc.org/

Join SSPC and Enhance
Your Career !


Termarust Technologies
Termarust (HR CSA) Chemically Stops
Active Corrosion

Truss bridge treated with Termarust's (HR CSA) in 1995. This highway & rail truss bridge is still stable and there still is no active corrosion.


Fischer Technology Inc.
Measure TSA Coatings on Stainless Steel

The PHASCOPE® PMP10 from FISCHER precisely measures thermally sprayed aluminum (TSA) on stainless steel.


U.S. Zinc
Service. Better With U.S.

From custom-blend zinc dust products to technical support, logistics and environmental compliance, we are there for you.


Bullard

The Next Generation
of Blasting

• Lightest
• Coolest
• Most Comfortable
• Most Dependable


Clemco Industries Corp.
Global engineering-trusted solutions

For more than 70 years, Clemco has provided the highest quality blast equipment with a total commitment to comfort and safety.


Axxiom Manufacturing
Schmidt Improves
Portable Blasters

Schmidt's VBS System reduces blowdown intensity, prevents exhaust from damaging floor while using no screens or filters. Reduces sound; Increasing safety.
Call 1-800-231-2085


Binks/DeVilbiss
Built for Tough Jobs

From Epoxies to Urethanes to other high solid coatings, the new Binks Airless 75 delivers a great finish using an ergonomic design. Visit binks.com for more information.

 
 
 
Technology Publishing

The Technology Publishing Network

The Journal of Protective Coatings & Linings (JPCL) PaintSquare
Durability + Design Paint BidTracker

 
EXPLORE:      JPCL   |   PaintSquare News   |   Interact   |   Buying Guides   |   Webinars   |   Resources   |   Classifieds
REGISTER AND SUBSCRIBE:      Free PaintSquare Registration   |   Subscribe to JPCL   |   Subscribe to PaintSquare News
MORE:      About PaintSquare.com   |   Privacy policy   |   Terms & conditions   |   Site Map   |   Search   |   Contact Us
 

© Copyright 2000-2015, Technology Publishing / PaintSquare, All rights reserved
2100 Wharton Street, Suite 310, Pittsburgh PA 15203-1951; Tel 1-412-431-8300; Fax 1-412-431-5428; E-mail webmaster@paintsquare.com