contamination are not encountered if subsequent coats are applied within
specified recoat windows and unusual atmospheric events do not occur. Such
atmospheric events as a coastal storm blowing onshore can bring unusual
chloride contamination. Concern for intercoat contamination should be
continually prevalent, and spot testing should be accomplished to verify
satisfactory conditions. Where visual examination or spot testing
indicates contamination, perform sufficient testing to verify
non-contamination, or to define extent of contamination for appropriate
treatment.
Apply each coat in a consistent wet film, at 90 degrees to previous coat.
Ensure that primer and intermediate coat "cold joints" are no less than 150
mm six inches from welds. Apply stripe coat by brush. Apply all other
coats by spray application. Use appropriate controls to prevent airborne
coating fog from drifting beyond[ [15][____] feet [three][____] meters from
the structure perimeter] [the tank berm]. Cover or protect all surfaces
that will not be coated. The cleanliness, temperature, recoat windows, and
airborne paint containment requirements may necessitate the use of
enclosures, portable shelters, or other appropriate controls.
**************************************************************************
NOTE: Maximum thickness measurements are to limit
internal stresses in each coat and in total system.
Internal stresses of epoxy and polyurethane coatings
on steel can be significant, and unless limited
through thickness, can cause premature failure as
the coating ages. Such failures as shrinkage
cracking and delamination, either from the substrate
or between coats, are common. This system is
limited to 12 mils to allow for maintenance
overcoating without creating excessive film build.
**************************************************************************
Apply coatings at the following specified thickness:
Desired Thickness Range
Minimum
Maximum
Coat
Mils DFT
Mils DFT
Mils DFT
Primer
2-5
2
6
Intermediate
3-5
3
8
Top
2-3
2
4
Total system
-----
9
12
3.7.2.1
Application of Primer
Apply primer coat, maintaining paint supply container height within 1 meter
3 feet of the paint nozzle for applying zinc primer. Maintain constant
agitation of paint pot to ensure that zinc does not settle in container.
3.7.2.2
Application of Stripe Coat
Apply a stripe coat of intermediate coat epoxy material within RECOAT
WINDOW of primer, allowing sufficient dry time to allow application of
intermediate coat within RECOAT WINDOW of primer. Apply by brush, working
material into corners, crevices, angles, and welds, and onto outside
corners and angles.
SECTION 09971
Page 29
Previous Page
