May 11, 2015

Long-Lasting Tank Interior Coating Systems – Part II

by Tony Ippoliti

Got a new tank project upcoming? Want the interior coating of the tank to last a long time? Want it to last a long time without much maintenance, too? You’re able to do this if you’re aware of the AWWA D102 Standard and the Inside Coating Systems within it.

Inside Coating Systems (ICS) are defined in Section 4.4.1 as “coating systems for the inside surfaces of steel water tanks” and refer to the “general type” of coatings but do not “limit acceptable materials to an exact formulation.” As stated in Part I of this series, manufacturers may use the same resin type but are not required to have identical formulas.  This allows for resin, pigment, and solvent improvements to be made in coatings intended for the interior tank surfaces. Formulators are allowed enhancements, specifiers are allowed choice, and tank Owners gets a competitive price from multiple suppliers. Everyone wins.

Coatings made with epoxy resins have been used for a long time to protect the interior surfaces of water tanks. These coatings resist water penetration and adhere tenaciously. Inside Coating System No.1 and No.2, representing a two- or three-coat epoxy system, provide 8.0 – 12.0 mils of minimum epoxy protection. Epoxies are also well suited to protect synergistically with water tanks having cathodic protection systems.

Coatings

Another coating type, used by industry for many years prior to its introduction to the water tank market, are defined as elastomers. These coatings are, and remain, flexible and may be made of components that combine to form polyurea’s, as one example. Polyurea’s cure, and build film thickness, extremely quickly: a perfect combination when your tank needs to go back-in-service today.

Polyurea’s are represented in AWWA D102 as Inside Coating System No.4. At the required minimum 25.0 mils thickness, it may represent the longest-lasting interior coating system currently available.

Want to know more about Long-Lasting Tank Interior Coating Systems?

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