April 21, 2009

A Look Inside the AWWA D102-06 Standard

by Tony Ippoliti

The American Water Works Association publishes the D102-06 standard “Coating Steel Water Storage Tanks“.¬† Specifiers use it to dictate the kind of paint coating system they want applied to their water tank. Within the D102-06 standard, there are currently 6 coating systems for exterior steel tanksurfaces (Outside Coating Systems – OCS) and 5 coating systems for interior surfaces (Inside Coating Systems – ICS).

One of the interior systems can present you with several benefits if you decide to use it:¬† ICS No. 4. It consists of a 100% solids polyurethane and/or polyurea type coating. A 100% solids coating is one that has no solvent … so 100% of what’s “in the can” is the coating, not the coating and solvent. Having a coating without solvent often allows a project to be painted more quickly because the painting contractors – and you – know that the film thickness applied is the film thickness you’ll get when the coating cures.

And 100% solids polyurea coatings, for example, cure FAST. Depending upon the particular manufacturer you choose, it could be 30 seconds to 3 minutes!¬† No more “waiting for paint to dry”!

What’s more, these coatings are applied at a minimum dry film thickness (DFT) of 25 mils … generally closer to 40 mils. To compare this amount with other AWWA ICS, the 3-coat epoxy system (ICS No. 2) requires only a minimum of 12.0 mils, since these films are thicker and they last longer. Plus, they remain flexible and abrasion resistant if you live in a northern state where winter may cause ice to form in the tank interior.

These coatings can also be used to repair bolted tank and concrete tank interiors.

Comments (2)

  1. August 23rd, 2011 at 4:45 am

    For potable water tanks, when doing repairs, what interla coating do you recoemmned for above ground steel water tanks to repair corroded and rusted linings and stell members? How long odes it take to cure? What is the quickest cure time that can be obtained and still meet requirements?

  2. September 14th, 2011 at 11:12 am

    Garold,
    Depending on the percentage of corrosion that is present in your tank it may be more economical to completely remove the existing coating and apply a new interior coating system. The industry has typically indicated that corrosion in excess of 30% of the service are will cost more to spot repair than complete removal and reapplying a new coating. With that being said the following is my recommendation for repairs:

    Surface Preparation: SSPC-SP11 “Power Tool Cleaning to Bare Metal” or spot blast per SSPC-SP10 “Near White Metal Blast Cleaning” follwing by feathering the edges via mechanical abrasion.

    Repair Material: 1 Coat – Sherwin-Williams SherPlate PW Epoxy @ 8.0 -12.0 mils DFT (This product can be brush applied in very small quantities or can be purchased in a side X side cartridge for touch up and repair)

    Note: if the corrosion is taking place on edges or angles – I would recommend that after surface preparation that a stripe of this material be applied to provide adequate film build for a brush application.

    The product will be cured in 24 hours for return-to-service in potable water @ 77F. The fast return-to-service time that I have seen on any product approved per ANSI/NSF Standard 61 is 16 hours.

    Regards,
    Kevin Morris

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