MIL-HDBK-1110
coating. Standard forms for manually recording data or equipment
for voice recording are also very useful. A failure analysis
checklist can ensure that no important item is overlooked.
Obviously, all items on the list may not be important at all
times, but to inadvertently skip an important one may be a
serious oversight.
11.3.5
On-Site Inspection Techniques. An overall visual
analysis should first be made to determine the areas where the
deterioration is most extensive and where any apparent deviation
from specification may have occurred. This should then be
followed by a closer examination as to the specific types of
deterioration that may be present.
a) Use of a hand lens may provide information not
otherwise visually apparent. All types of failure, including
color changes and chalking, should be described fully. For
example, does peeling occur between coats or from the substrate?
Are blisters broken or filled with water? This detailed
information may be necessary for finalizing conclusions as to the
type of failure. The terms defined later in this section should
be used to describe failures rather than locally used terms that
may not be clear to other people. Care must be taken not to come
to final conclusions until all the data are analyzed. It is a
good practice to state at the inspection site that the final
conclusions on causes of failure cannot be made until completion
of laboratory testing.
b) Dry film thicknesses should be routinely measured
and recorded, as any significant deviations from recommended
thicknesses can be a factor contributing to coating failure. The
procedure for measurement of these thicknesses required in the
specification should be followed.
c) Other measurements that may be important are
coating adhesion and hardness, since they may provide important
information on application or curing of the coating. Adhesion
can be easily determined with a simple tape test described in
Section 9 or by using more sophisticated instrumentation (refer
to Sections 8 and 9). Hardness can be tested in the field with a
d) It is generally important to verify the identity of
the finish coatings and occasionally the identity of the entire
coating system. If wet samples of the paints used have been
retained, they can be submitted for laboratory analysis for
conformance to specification or manufacturer's data sheet. If
these are not available, a simple solvent rub test may be useful
166
Previous Page
