MIL-HDBK-1110
To do this, both the severity of the deterioration and its
distribution must be defined. The level of severity will
indicate whether only the finish coat or other coats are involved
in the deterioration and how it can best be repaired. If the
distribution is limited, spot repairing is likely to be
practical; if it is extensive, it is probably best to remove all
the coating and repaint.
Standard block diagrams for estimating coating
deterioration on ships for "Overall Extent" and "Extent Within
Affected Areas" are generally also appropriate for shore
structures. They are described in ASTM F 1130. First, draw an
imaginary line enclosing all deterioration and select the
standard "Overall Extent" diagram that best matches the imaginary
area. Then, select the standard "Extent Within Affected Area"
diagram that best matches the areas within the imaginary line.
The number and letter of the selected diagrams establish the
extent of deterioration. Whatever system is used to determine
the extent of deterioration, it should utilize a standard format
so that evaluations of different structures can be compared and
priorities can be established.
It is also important in maintenance painting to
determine precisely the amount of loose and peeling paint to
establish the amount of work to be done. This will eliminate any
controversy over a "site variation," i.e., the contractor
claiming that there was much more work necessary than described
in the specification. It is a standard practice to define "loose
and peeling paint" as that paint that is easily removed with a
dull putty knife.
12.2.2.3 Determining the Generic Type of the Finish Coat. Once a
painting program is set up, the identifications of paints being
applied will automatically be entered into the database. If the
generic type of the finish coat is not known, it can be
determined by infrared spectrophotometric analysis as described
in Section 11. The general compatibility of a coating can be
determined by the solvent rub test, also described in Section 11.
12.2.3
Types of Maintenance Painting. In planning maintenance
painting, it is first necessary to determine the general scope of
the work. There are four different approaches to maintaining an
existing coating in an acceptable condition:
a)
Cleaning only to restore to an acceptable
condition. This may be accomplished by pressure washing or
steam cleaning.
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