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.
3.8.3.2
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 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.
3.8.4
Abrasive Blasting
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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.
The specified 2-3 mil surface profile is the
preferred depth for preparing for the primer. On
steel that was previously prepared to a deeper depth
and coated, a depth of 4 mils can be tolerated with
an additional mil of primer thickness.
To validate contractor claims of pre-existing
profile greater than allowed, test an appropriate
number of representative spots with abrasive that
removes paint but does not affect profile, such as
bicarbonate of soda, or other soft abrasive, or
waterblasting, etc.
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Abrasive blast steel surfaces to white metal in accordance with SSPC SP 5.
SECTION 09972
Page 23
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