until surfaces are free of oil and grease.
WATER BREAK TEST - Spray atomized mist of distilled water onto surface, and
observe for water beading. If water "wets" surface rather than beading up,
surface can be considered free of oil or grease contamination. Beading of
water (water forms droplets) is evidence of oil or grease contamination.
BLACK LIGHT TEST - Inspect surfaces for oil and grease contamination using
the light specified in the Article entitled "Black Light." Use light no
more than 381 mm 15 inches from surface unless testing indicates that the
specific oil or grease found in tank fluoresce at a greater distance. Use
light in tank that is completely sealed from light infiltration, under a
hood, or at night. Any fluorescing on steel surfaces is indication of
petroleum oil/grease contamination. Use either WATER BREAK TEST or CLOTH
RUB TEST to confirm both contaminated and non-contaminated areas detected
by BLACK LIGHT TEST. The BLACK LIGHT TEST may not be used during
inspection of prepared surfaces for oil and grease contamination unless
proven to fluoresce the oil and/or grease found in the specific tank and
documented during testing prior to abrasive blasting. Generally, only
petroleum oil/grease will fluoresce, however, some may not fluoresce
sufficiently to be recognized and other methods, such as the WATER BREAK
TEST or CLOTH RUB TEST, must be used to confirm findings of the BLACK LIGHT
TEST.
CLOTH RUB TEST - Rub a clean, white, lint free, cotton cloth onto surface
and observe for discoloration. To confirm oil or grease contamination in
lightly stained areas, a non-staining solvent may be used to aid in oil or
grease extraction. Any visible discoloration is evidence of oil or grease
contamination.
3.9.3.2
Pre-Preparation Testing for Soluble Salts Contamination
Test surfaces for soluble salts, and wash as required, prior to abrasive
blasting. Soluble salt testing is also required in Article entitled
"Pre-Application Testing for Soluble Salts Contamination" as a final
acceptance test of prepared surfaces after abrasive blasting, and
successful completion of this phase does not negate that requirement. This
phase is recommended since pre-preparation testing and washing are
generally more advantageous than attempting to remove soluble salt
contamination after abrasive blasting. Effective removal of soluble salts
will require removal of any barrier to the steel surface, including rust.
This procedure may necessitate combinations of wet abrasive blasting, high
pressure water rinsing, and cleaning using a solution of water washing and
soluble salts remover. The soluble salts remover shall be acidic,
biodegradable, nontoxic, noncorrosive, and after application, will not
interfere with primer adhesion. Delays between testing and preparation, or
testing and coating application, may allow for the formation of new
contamination. Use potable water, or potable water modified with a soluble
salt remover, for all washing or wet abrasive blasting. Test methods and
equipment used in this phase are selected at the Contractor's discretion.
3.9.4
Abrasive Blasting
**************************************************************************
NOTE: The issue of maximum profile on new
structures is an important one. Once a profile is
established, it is nearly impossible to reduce it,
therefore, the initial profile will dictate the
profile for the life of the structure.
SECTION 09970
Page 24
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