Confirm that air supply for abrasive blasting is free of oil and moisture
when tested in accordance with ASTM D 4285. Test air quality at each
startup, but in no case less often than every five operating hours.
3.6.2
Surface Standard
Inspect surfaces to be coated, and select plate with similar properties and
surface characteristics for use as a surface standard. Blast clean one or
more 300 mm 1 foot square steel panels as specified in Article entitled
"Surface Preparation." Record blast nozzle type and size, air pressure at
nozzle and compressor, distance of nozzle from panel, and angle of blast to
establish procedures for blast cleaning. Measure surface profile in
accordance with ASTM D 4417. When the surface standard complies with all
specified requirements, seal with a clearcoat protectant. Use the surface
standard for comparison to abrasive blasted surfaces throughout the course
of work.
3.6.3
Pre-Preparation Testing for Surface Contamination
Perform testing, abrasive blasting, and testing in the prescribed order.
3.6.3.1
Pre-Preparation Testing for Oil and Grease Contamination
**************************************************************************
NOTE: When specifying maintenance painting, use a
water based pH neutral degreaser to avoid damaging
existing coating.
**************************************************************************
Inspect all surfaces for oil and/or grease contamination using two or more
of the following inspection techniques: 1) Visual inspection, 2) WATER
BREAK TEST, 3) CLOTH RUB TEST. Reject oil and/or grease contaminated
surfaces, clean [using a water based pH neutral degreaser ]in accordance
with SSPC SP 1, and recheck for contamination 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.
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.
3.6.3.2
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
SECTION 09971
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