zinc primers for interior water tanks 1

[darthsoilsguy2]

thread332-327161

I want to reboot an old thread that was closed, but the issue doesn't appear to be resolved yet (or at least not to me). Ignore the "Lead" part of the old thread, it is not a human health issue. There is on-going debate about whether or not the zinc primer contributes to premature coatings failure. Coating manufacturers are debating the use of zinc-rich primers for immersion in water storage tanks. It appears this is spearheaded by Tnemec on the Pro-Zinc side and Carboline against Zinc. Sherwin-Williams and Induron appear to be siding with Tnemec on this by offering a zinc-rich primer, but they don't appear to be as vocal in support of it so this might just be a neutral position just to sell paint.

Tnemec brags about how they were first with using Zinc primers inside water tanks in 1997. Carboline talks about the zinc primed tanks to be "ticking time bombs" and refuses to offer it for internal use.

I figure a good 3-coat system is good for 15-20 years. another 10 years from now and this debate should be settled, but i'm wondering if there are failures rolling in now....

Is anybody finding the blistering that carboline warns against in tanks less than 10 years from recoating? and were zinc primers confirmed?
I'm sure this issue must be heavily debated inside the coatings community more than i'm finding on the internet... are there other groups weighing in?
Is there any independent research out there with something to say about this?
How are specifiers approaching this?

Thanks for contributing
DSG

 

[gr2vessels]

DSG,
Recently I have seen a 24 years old, offshore CS storage vessel for potable water. Some areas of external coating had to be repaired, but the inside white paint was as new (except a small damage from a a tool dropped from the top opening - repair on a 4" x 4" area). The 75-80% zinc solids content for the primer worked miracles, so the tank is back in operation for another 20 more years. I hope this tells you something....The secret is the substrate preparation and minimum 75% zinc solids content.
Cheers,
gr2vessels