Painting In-Service Water Tanks

A common practice in water tank repair andMCU coatings are suitable for damp surfaces
maintenance used to involve draining the tank's contentbecause, like all urethane coatings, it contains
before any coating job can be conducted, becausefoundational isocyanate groups of atoms that are
the presence of moisture condensation oftenreactive to hydrogen-based compounds. In water tank
interfered with the coating that subsequently led tocoating applications, this reactive hydrogen compound
tank coating failure.is found in water condensation.
But draining water tanks can be a costly exerciseIn some tank coating systems, the inclusion of a primer
because facilities may not often have a secondaryor intermediate coat mixture of micaceous iron oxide
storage container sufficient to hold content when the(MIO) and aluminum pigments increases the chances
primary tank is down for painting maintenance.of a successful application, because MIO-aluminum
Furthermore, the amount of time needed for the paintoverlaps to form a shield that bars moisture and
job offers some risk to the facility, particularly whencorrosive elements to damage the surface.
the water tank serves as fire protection or when itTo remove out-gassing that may occur from large
holds crucial drinking water.amount of surface moisture during MCU tank coating
And yet painting jobs for these water tanks are alsoapplication, a simple scraping of pinhole-sized surface
important to keep them in good condition and fordamages can be done. MCU coatings ideally cure at
protection and repair of corrosion, abrasion and otherabove 35 degrees Fahrenheit temperature. A slower
damages incurred through the years.curing reaction is expected at lowered temperatures
MCU Coating for In-Service Paintingalthough application is still possible to as low as 20
Until recently, water tank exterior painting was indeeddegrees Fahrenheit.
a problem, but with the technological breakthrough thatWater Tank In-Service Painting
produced moisture-cured urethane (MCU) coating,The single-component MCU coatings eliminate the
painting water tanks in-service has addressed theneed for tank draining during application. For
problem effectively.refurbishing or repairing water tank exteriors, MCU
MCU tank coating products are quick-drying and easyprovides enduring protection and aesthetic
to apply. They are more flexible and longer-lasting thanreinstatement to tanks.
standard tank coatings because of their tolerance toApplying MCU tank coating require surface preparation
more varied application conditions, abrasion-resistance,to remove chalking, rust and any loose coatings. An
and imperviousness to wind-blown dust, soil specksMCU primer is then applied following manufacturer's
and other damage-causing impacts.thickness specifications. A MIO-aluminum coat is then
Such is the effectiveness of MCU tank coatingapplied on rusted or damaged areas, topped off with
systems in in-service water tank painting jobs that theanother MCU coating for color restoration.
American Water Works Association (AWWA)MCU coatings are used by contractors because their
formally recognized the benefits of using MCU throughsingle-component system provides ease of application,
the AWWA D102-03 Industry Standard as OCSallowing contractors to complete the job faster with
(Outside Coating System) 2.tolerable maintenance down-time.
How MCU Coatings Work