Assuming that your focus is on overcoated TSA, then try:

TA Sumon, et al, Failure Of Aluminium Metal Spray/Organic Duplex Coating Systems On Structural Steel, Corrosion Engineering, Science And Technology, Vol 48, (7), 2013, pp 552 - 557.

Often taken as the seminal work on why such duplex coatings are not in favour.

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

Also perhaps worth noting, the findings also apply other situations than marine environments where there is a risk exposure of duplex coatings to chlorides. For example, steel structures on highway networks where road de-icing salts are used in winter. I think the work done in the reference paper arose (at least in part) because of that problem on the UK motorways network. It prompted a significant change to the standard highways paint specifications.

Cheers

GGG

Is there a similar issue in splash/ tidal zones with duplex coatings over hot-dip galvanizing, rather than over aluminium metal sprays?

Thank you SJones for your feedback and GGG for your remark. LittleWheels is asking exactly what I need. Hot dip galvanizing overcoated in splash zone. Is there a reference paper as well?

Why didn't you ask for exactly what you wanted?

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

Why didn't you assume that my focus was on overcoated HDG?
Why didn't you share your knowledge for both options?
This is not a forum for psychoanalysis.
If you want to help, I appreciate it, if you don't want, at least don't let others understand it through pointless questions.

The point being: I wasted my time over your inability to formulate a question. Now, do you want to be a little more precise about exactly what items of the structure in the splashzone you are addressing? You know from ISO 12944-9 that overcoating HDG is an allowable option, so it must have some favour with someone somewhere in the world. If you research the AGA website Here you will find articles expounding the virtue of using HDG duplex systems in the splashzone, but you won't find it as a recommended option in oil & gas specifications in spite of ISO 12944-9. Sometimes, it gets allowed for small tertiary structural items and appurtenances, but, clearly, it's not going to be applicable to large primary and secondary structural items.

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

I also assumed the question related to thermal sprayed systems, often structural members in marine/offshore applications are too large to galvanize so it somewhat unusual. I have encountered galvanizing in the renewables sector but usually without painting and above the splash zone. Perhaps you could share with us what component is of interest?

If you go the route of ISO12944-9 do make sure the has the relevant performance test data from an independent test house. Take particular note of what that says about the surface preparation before painting.

Cheers

GG

ISO 12944-9 Table 3 does not include minimum requirements for overcoated HDG in splash/tidal zone.
ISO 12944-5 mentions the possibility of premature failure of overcoated HDG in immersed conditions (splash/tidal zone is a more aggressive environment than immersion)
AGA is just promoting its product, have they ever examined exactly the case of overcoated HDG in splash/tidal zone and what were the characteristics of the overcoating? Based on what industry standard?
Component is the steel structure of fenders.
I may not have the ability of formulating a question in english language but I am not and will never be rude, arrogant and phlegmatic.
I appreciate your help.

Haven't we been here previously:

https://www.eng-tips.com/viewthread.cfm?qid=473424

Cheers

GG

Exactly! But I decided to repost. Manufacturer of fenders have in their standard product range painted steel structures not overcoated HDG. I need to know the performance of duplex coating system over HDG in order to face the owner. He needs a guarantee for 15 years and I cannot find an industry standard to be based on.
And like you have said, even if tests are performed for the actual conditions, they may fail.
Never mind don't waste your time any more. I really appreciate your help up to now.

Well surely you have enough to go and discuss with the owner? You can refer to the ISO standards and maybe NORSOK M501 if you have a copy. You can refer to what the suppliers do and you can refer to these discussions to find references but have drawn a blank. Then ask the owner if they know of something and if they insist you proceed then formally say it is their risk.

CHeers

GG

Thank you very much GGedge! Indeed!
Mr. SJones as well.

OK - I'm a bit lost as to the objective. Are you saying that the standard offering is a normal coating system, and that you don't believe that you will get 15 years out of it, so you are looking to try and justify a HDG duplex system? 1000 microns of properly applied and qualified glass flake should get a 15 year durability. A 15 year guarantee is not going to happen whatever is put on. Does the owner know the difference between durability and guarantee?

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

The owner requires HDG+A7.13 for splash/tidal zone.
The engineering consultant has update to HDG+CX to reflect the latest edition of ISO.
I am on the contractor's side and I try to convince both that overcoated HDG is not applicable for splash/tidal zone.