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.
Prepared surfaces shall conform to SSPC VIS 1 and SSPC Guide to VIS 1 and
shall match the prepared test-panels. Provide a 50 to 75 micron 2 to 3 mil
surface profile. Reject profile greater than 75 microns 3 mils,
discontinue abrasive blasting, and modify processes and materials to
provide the specified profile. Measure surface profile in accordance with
ASTM D 4417. Measure profile at rate of three tests for the first 100
square meters 1000 square feet plus one test for each additional 100 square
meters 1000 square feet or part thereof. Provide two additional
measurements for each non-compliant measurement. When surfaces are
reblasted for any reason, retest profile as specified. If Method C of ASTM
D 4417 is used to measure profile, attach test tapes to Daily Inspection
Reports. Following abrasive blasting, remove dust and debris by vacuum
cleaning.
3.9.5
Disposal of Used Abrasive
Dispose of used abrasive off Government property in accordance with
Federal, State and Local mandated regulations.
3.9.6
Pre-Application Testing For Surface Contamination
3.9.6.1
Pre-Application Testing for Oil and Grease Contamination
Ensure tank surfaces are free of contamination as described in Article
entitled "Pre-Preparation Testing for Oil and Grease Contamination."
3.9.6.2
Pre-Application Testing for Soluble Salts Contamination
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NOTE: In new tanks, require 30% of tests to be
accomplished at welds. In tanks that have been in
service, corroded areas should be tested for high
chlorides.
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Test surfaces for chloride contamination using the Test Kit described in
article entitled "Test Kit for Measuring Chlorides on Steel Surfaces." Test
all surfaces at rate of three tests for the first 100 square meters 1000
square feet plus one test for each additional 200 square meters 2000 square
feet or part thereof. [Concentrate testing of bare steel at areas of
coating failure to bare steel and areas of corrosion pitting. ][Perform
30% of tests on bare steel at welds, divided equally between horizontal and
vertical welds. ]One or more readings greater than 3 micrograms per square
centimeter of chlorides is evidence of chloride contamination. Reject
contaminated surfaces, wash as discussed in article entitled
"Pre-Preparation Testing for Soluble Salts Contamination," allow to dry,
SECTION 09973
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