Summary for powder coating galvanized substrate Discussion
Powder coating galvanized substrate is discussed only indirectly in the provided thread excerpt, which appears to be a books/resources listing rather than a full Q&A. The visible text recommends several suggested galvanizing books for engineers, shops, and specifiers, including Dietrich Horstmann’s "Faults in Hot-Dip Galvanizing," available in English, French, and German. Because the excerpt does not include the actual question or any technical answers about powder coating over galvanized steel, no process guidance, compatibility advice, or troubleshooting details can be confirmed from the source. The safest takeaway is that the page points readers toward reference material on galvanizing defects and practice, but the specific powder-coating topic is not answered in the excerpt provided.
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SUGGESTED GALVANIZING BOOKS
for Engineers, Shops, Specifiers
“Hot Dip Galvanizing of Steel Structures” by Kuklik & Kudlacek (2016)
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“Handbook of Hot Dip Galvanization” by Maass & Peissker (2011)
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“Galvanized Steel Reinforcement in Concrete” by Stephen Yeomans (2004)
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“Hot Dip Galvanizing — A Guide to Process Selection & Galvanizing Practice” by M. J. Hornsby (1995)
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“Faults in Hot-Dip Galvanizing” by Dietrich Horstmann (in English, French & German)
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“User’s Guide to Hot Dip Galvanizing for Corrosion Protection in Atmospheric Service” by NACE (1997 only rarely avail.)
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Hello,
I am a senior estimator in Myrtle Beach, S.C.
We are interested in learning about possible “adverse affects”that may occur with powder coat systems on galvanized piping. After reading many of your interesting articles on this matter, we feel confident with this application on galvanized surfaces, but we are uncertain with the specifications for pretreatment material type(s).Additionally, are there any known problems with surface bonding even if a specified chemical is used as the selected method for pre-treatment? What should a contractor look for on the finished product when determining compliance with bonding? Finally, what are the primary materials used by manufacturers for protection of the galvanized material surfaces? (i.e. Oil, wax, clear coat, etc.)
We would appreciate your sharing of information on this subject.
Thanks for your interesting Web Site !
Sincerely,
Scott A. Nivens Jr.,Senior Estimator
construction service- Myrtle Beach, South Carolina, USA
2000
A. Second part first! Most galvanisers do not protect although some may use a chromate dip to provide some white rust protection. A customer could doubtless specify any protection requirements, subject to quantity!
If the piping has a “rough” thick Zn surface, phosphoric acid etch cleaner followed by a chromate-resin dry-in-place pretreat will give 2000+ hours salt spray under powder. If gassing is a problem specify anti-gassing powder. The pretreat above cannot be degassed at high temp. without adverse effects.
Alternative is to use a dedicated hexavalent chromate process after acid etch. Rinse and dry gently. Then ramp up temp for the degassing cycle before coating. Either method should give excellent performance. Although zinc phosphating can be used it is quite difficult to get a really good fine grain complete coating. My UK experience shows that the first 2 methods will pass
BS 6497 (architectural spec for HDG/powder) and zinc phos won’t. R
Roger Bridger
Walterisation (UK) Ltd – Croydon, UK