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.
3.6.4
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 zinc primer. On
steel that was previously prepared to a deeper depth
and coated, it is not feasible to reduce the deeper
depth to the preferred depth. A depth of 4 mils can
be tolerated with an additional mil of zinc 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 near-white metal in accordance with SSPC
SP 10. 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 brushing,
blowing with oil-free and moisture-free compressed air, or vacuum cleaning.
Time interval between abrasive blasting and application of primer shall
not exceed eight hours.
3.6.5
Disposal of Used Abrasive
Dispose of used abrasive off Government property in accordance with
Federal, State, and Local mandated regulations.
SECTION 09971
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