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.
**************************************************************************
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
expected to receive a maintenance overcoat.
**************************************************************************
Apply coatings at the following specified thickness:
Desired Thickness Range
Minimum
Maximum
Coat
Mils DFT
Mils DFT
Mils DFT
Primer
3-5
3
8
Intermediate
3-5
3
8
Top
3-5
3
8
Total system
-----
9
20
Measure coating thickness in accordance with SSPC PA 2 to confirm that
coating application is within the specified range and within the tolerances
of that standard. For non-compliant areas, increase number of test areas
to identify all non-compliant application as required by SSPC PA 2. Add
coating as required to correct underuns, and remove coating with excess
thickness to bare steel and reapply as specified in Article entitled
"Procedure for Holiday and Spot Repairs of Newly Applied Coating."
3.10.2.1
Application of Roof Joint Sealant
Apply sealant to the roof-to-shell joint, to all roof plate lap joints, and
to roof-to-rafter joints up to 15 mm 0.5 inch gap to exclude moisture from
these marginally prepared crevice areas. Allow sealant to cure according
to manufacturer's instructions prior to application of the stripe coat.
3.10.2.2
Application of Stripe Coat
Apply stripe coat of epoxy primer material prior to application of general
primer coat on CEILING and SHELL. Apply stripe coat of epoxy intermediate
coat material after application of general primer coat on FLOOR. Where
stripe coat is applied to areas of joint sealant, allow appropriate curing
time for joint sealant. Apply stripe coat by brush, working the material
into corners, crevices, pitted areas, and welds, and onto outside corners
and angles. Where roof-to-rafter joints exceed 15 mm 0.5 inch gap and roof
joint sealant was not applied, use appropriate application tools to provide
"best effort" coating of all exposed steel surfaces in the gap.
Mini-rollers or other tools may be required.
3.10.2.3
Application of Primer
Apply primer coat within RECOAT WINDOW of stripe coat.
SECTION 09973
Page 28
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