Wipe surface with rag saturated with Naphtha, and check for surface
tackiness, loss of gloss, or other indications that solvent has softened
surface. If softening is found on 95% of test sites, this is indication
that coating has not fully cured, and GLOSS REMOVAL is not required if TACK
COAT is applied within three hours and full coat is applied within the TACK
COAT RECOAT WINDOW. Test surfaces at rate of three tests for the first 100
square meters 1000 square feet plus one test for each additional 100 square
meters 1000 square feet or part thereof.
TACK COAT - Where indicated, apply coat of intermediate coat epoxy, at 25
to 50 microns 1 to 2 mils WFT, then apply next specified full coat within
TACK COAT RECOAT WINDOW. Thin TACK COAT material approximately 25% by
volume, using appropriate epoxy thinner.
GLOSS REMOVAL - Where indicated, remove all gloss by hand sanding, in a
linear fashion, with 150-200 grit wet/dry sandpaper, followed by a solvent
wiping with a clean rag soaked with denatured alcohol to remove dust. Do
not use rotary sanders or grinders.
3.9.2
Application of Coating System and Roof Joint Sealant
Apply coatings in accordance with SSPC PA 1 and as specified herein. Apply
sealant and coatings to surfaces that meet all stated surface preparation
requirements.
After application of primer coat and prior to application of each
subsequent coat, perform testing prescribed in article entitled
"Pre-Application Testing For Surface Contamination," as necessary, to
ensure minimal intercoat contamination. This testing may be reduced to one
half of the prescribed rate for bare steel if the testing indicates no
contamination when sampling is evenly distributed over surfaces being
tested. If contamination is found between coats, revert to the specified
testing rate. Generally, oil and grease contamination and soluble salts
contamination are not encountered if subsequent coats are applied within
specified recoat windows and the quality of air entering tank is
controlled. 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 tank perimeter] [the tank berm]. The cleanliness, temperature,
recoat windows, and airborne paint containment requirements may necessitate
the use of portable shelters or other appropriate controls.
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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 not
SECTION 09972
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