Home /
T.O.C.
FAQs
 
Good
Books
Ref.
Libr.
Advertise
Here
Help
Wanted
Current
Q&A's
Search 🔍
the Site

Chime right in! (no registration req'd)

-----

"Powder Coating Galvanized Substrate"



2000

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, S.C. USA
^


2000

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 hi 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 [affil. link to spec at Techstreet] (architectural spec for HDG/powder) and zinc phos won't. R

Roger Bridger
Walterisation (UK) Ltd - Croydon, UK
^

none
finishing.com is made possible by ...
this text gets replaced with bannerText
spacer gets replaced with bannerImages

Q, A, or Comment on THIS thread SEARCH for Threads about ... My Topic Not Found: Start 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:

 
Jobshops
Capital
Equipment
Chemicals &
Consumables
Consult'g, Train'g
& Software


About/Contact    -    Privacy Policy    -    ©1995-2021 finishing.com, Pine Beach, New Jersey, USA