Anti-corrosion treatment for the inner wall and upper inner side of industrial water tanks
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Seeking advice: What material is suitable for anti-corrosion protection of the inner wall and the inner side of the roof of industrial carbon steel water tanks? These are equipment used in on-site construction, and the construction site is located by the sea, where the humidity remains above 85% throughout the year, with frequent rainfall
Epoxy coal tar pitch, or epoxy polyamide, or chlorinated rubber – any of these should work.
If the water medium is ordinary fresh water (tap water, such as that in fire extinguishers), an epoxy zinc-rich primer + epoxy intermediate coat + epoxy topcoat can be used for both the inner wall of the tank and the inner side of its roof. Note that the coating on the inner side of the roof does not need to be very thick; 2–3 coats are sufficient, with a total thickness of less than 150 microns. Inside the tank (whether it is a dome tank or another type of structure, with domed water tanks being the most common), there is no need to take into account the marine atmospheric conditions or humidity levels. If you have the means, you can investigate the crude oil storage facilities built by CNPC and Sinopec in Dalian, as well as those in Zhenhai and Zhoushan. All of these facilities are equipped with large fire suppression tanks (each tank has a capacity of at least 20,000 cubic meters), and their interior anti-corrosion designs are roughly similar. Additionally: Epoxy coal tar pitch and chlorinated rubber are generally used as external anti-corrosion coatings. The former is mostly used for buried pipelines, while the latter is commonly applied to the outer walls of storage tanks; it is not suitable for internal tank anti-corrosion. Last edited by phil79q on 2009-3-4 20:29.]
Thank you, Floor 5. I would like to use iron red epoxy primer applied in 2 coats, without using any topcoat. Is that feasible?
You’re welcome! In my opinion, the epoxy iron red primer does not provide sufficient corrosion resistance. Primers are primarily designed to offer good adhesion – that is, a high bonding strength with steel – but their corrosion resistance is limited. That’s why topcoats with better corrosion resistance are needed. This is the principle behind the design of coating systems: each layer serves a different purpose. It’s better to apply a topcoat as well; one coat of primer followed by one coat of topcoat will do. Last edited by phil79q on 2009-3-4 21:37.]
Doing this will not yield very good results, unless 4 coats are applied to increase the coating thickness. It is best to apply two coats of epoxy iron oxide primer and two coats of epoxy polyamide topcoat, for a total thickness of around 150 microns. Let’s explain the reasons: 1. The iron red primer has a decent rust-preventing effect; its main function is to prevent the spread of rust, but its effectiveness is limited ； The 2 epoxy polyamide topcoat not only increases the coating thickness, but also boasts a dense film due to its high resin content, as well as good resistance to penetration. Combined with the other two elements and 4 layers of coating, this can significantly reduce water penetration, thereby slowing down the rate of corrosion. Personal opinion: The coating is too thin; no matter how good the paint is, the results won’t be very good. If you want to save trouble, just use 3 coats of iron red primer – that will be good enough.
Please use 1900-1 polyurethane conductive primer and 1900-1 polyurethane conductive topcoat
Two errors: 1 is a water tank, not an oil tank; antistatic coating is completely unnecessary； 2 is inside the tank, not outside; polyurethane coating is even less necessary.