occurrence is water with high-chlorides, even in
potable water, which may leave unacceptable
contamination on cleaned surfaces, and may not be
suitable for water jetting.
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3.8.1
Abrasive Blasting Equipment
Use abrasive blasting equipment of conventional air, force-feed, or
pressure type. Maintain a minimum pressure of 650 kPa 95 psig at nozzle.
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.
3.8.2
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.
3.8.3
Pre-Preparation Testing for Surface Contamination
Perform testing, abrasive blasting, and testing in the prescribed order.
3.8.3.1
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) BLACK LIGHT TEST, and 4) 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.
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 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
SECTION 09972
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