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

 

Resource Guide Extreme Temperatures

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

Elcometer, Inc.
Elcometer 266
DC Holiday Detector

Easily Finds Pinholes, Flaws & Thin Spots; Safer, More Reliable Testing; Voltage-Adjustable Keypad; Dual-Safety Switch On Handle.


Fischer Technology Inc.
MP0R with rotating display screen

View your coating thickness readings from any angle with rotating display screen. New graphic display with easy menu navigation. Click for Video
Call 800-243-8417


KTA-Tator, Inc. - Corporate Office
KTA-Tator
Coatings Inspection

Any structure, any height, any place - A qualified coatings inspector is always available. Call 800-245-6379.


U.S. Zinc
Historic Reliability. Innovative Performance.

Our products are essential ingredients in many materials used around the globe every day. Historic reliability. Innovative performance. U.S. Zinc - Helping the world work™


Termarust Technologies
Termarust (HR CSA) Chemically Stops
Active Corrosion

Hydro Utility Penstock Overcoated in 1997. Was power washed and overcoated with major cost saving. No environmental impact with Termarust's low LC50 of 41,007 ppm.


International Paint LLC

International Paint Engineered Coatings

Learn about our solutions for:
  • Structural Steel
  • Piping & Equipment
  • Storage Tanks
  • Pressure Vessels
  • Secondary Containment


    Trelawny Surface Preparation Technology
    Surface Preparation Equipment

    Manufacturer of needle scalers, grinders, scarifiers and scabblers. Pneumatic tools for Marine and Construction. US distributor CS Unitec: 800-700-5919


    Polygon
    POLYGON - Temporary Humidity Control

    We specialize in innovative climate control solutions for industrial painting, utilizing alternative energy sources and combining desiccants with heating or cooling.


    Global Werbeagentur GmbH (obo: Vincentz Network Hannover - European Coatings Show)
    European Coatings Show

    For the first time over 1,000 exhibitors from all over the world! Plan your visit online now!

  •  
     
     
    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