Best Coating for Steel in Tidal Zone 1

[cod]

Regardless of cost considerations, what is the absolutely best protective coating for a trussed steel structure in the tidal/splash zone?

This horizontal structure is a beam that will be partially immersed a low tide and 3/4 immersed at normal high tides and sacrificial anodes will be applied which of course will not be effective above mean water. The structure will be all welded construction and have four large corner members with vertical and horizontal members plus braces which make for many, many corners and crevices.

We have used glass flake epoxy in the past and lately one of our clients preferred the "Humidur ML" of Acotec, NV coating instead. Years ago, the US Corps of Engineers performed good practical tests for coatings and the glass flake proved the best but to my knowledge that study has not been extended to present coatings that may be better.

Any new ideas would be most welcome.

C. Daniell

 

[SJones]

How will you judge whether one coating is better than another? One can only really go by actual long term experience or by performance testing. Since it would appear that the former is not available then the latter option seems appropriate. Try reviewing Norsok M-501 and NACE TM0404.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[mshimko]

Is the cost of the surface preparation, environmental controls, and QA during surface preparation and application also not a consideration?

I ask as regardless of the type of coating applied, not taking the proper (and sometimes expensive) steps during surface preparation & application will greatly affect the service life of the coating.