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Painting mild (A36) steel in a wastewater clarifier

Painting mild (A36) steel in a wastewater clarifier

Painting mild (A36) steel in a wastewater clarifier

(OP)
thread332-266160

I have to find a coating for a rebuild of a "Tow Bro" header that is to be immersed in a secondary wastewater treatment plant. The existing one was originally galvanized, and is now pretty much completely corroded (1/4" steel rusted through in several locations). I found a spec on the internet for use of TNEMEC N69 for a similar case.

Does anybody have recommendations? The problems are that (1) it is immersed 24/7 in sewage with some H2S, (2) microbal corrosion can occur at holidays in paint, as we can't grind every weld smooth and there will be crevises (3) the header is about 55' long, fabricated to bolt together in sections, and gets to a cross section as small as 3" x 15". The problem with (3) is that getting good coverage inside the header could be a problem.

Coal tar epoxies are also possible, but the word is that they will soon be in the classification as toxics. That could make problems down the road.

Any help greatly appreciated !

RE: Painting mild (A36) steel in a wastewater clarifier

How much life are you hoping to get out this header?

RE: Painting mild (A36) steel in a wastewater clarifier

(OP)
First, sorry about the delay. I got sidetracked, then the holidays, and also ill. Sheesh ...

We hope to give the header a 30 year life with minimal maintenance, which is to say, a thorough maintenance after 12 - 15 years.

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