TO 35-1-3 - Robins Air Force Base

TO 35-1-3
removed prior to the final blast operation. If the surface is
chemically contaminated, it may be necessary to wash it or
neutralize it before final blasting.
The MWAS process produces high localized noise
levels and ultraviolet radiation emissions from the arc
region. Prior to commencing initial MWAS operations
consult with the base bioenvironmental engineer
(BEE) for approval. Proper hearing, eye protection,
and respiratory PPE will be designated by the local
BEE.
3.16.5.1.3 The abrasive media used for cleaning heavily contaminated
surfaces should not be reused for the final blast,
even though it is rescreened as the media may contain contaminates
that will be re-embedded in the metal surface causing
corrosion and/or coating adhesion failure.
3.16.5.1.4 Follow the thermal spray equipment manufacturers'
preparation and application instructions. The metal coating
shall be applied to a minimum thickness of 6 mils and maximum
of 8 mils.
3.16.5.1.5 Any surface, which shows visible moisture, rust,
scale or other contamination shall be re-blasted before spraying.
The surface must be completely coated to the specified
thickness within six hours of abrasive blasting.
The correct thickness of thermal spray coating in this
application is critical. A coating that is too thin will
not provide corrosion protection while a coating that
is too thick will chip and flake off.
3.16.5.1.6 The metalized coating shall be inspected for
thickness by using the multi-metal dry film thickness gage to
ensure correct surface thickness is achieved. Any thin or
uncoated areas must be immediately roughened with a
mechanical grinder with a minimum of a 25 grit disc to apply
a “cross-hatch” pattern to the substrate. Immediately apply the
thermal spray coating to reach the proper coating thickness.
3.16.5.1.7 On high temperature components metalized with
aluminum, organization may use METCOSEAL SA silicone
aluminum sealer to prevent any rust staining that may occur.
This sealer is available from:
METCO INC.
1101 Prospect Avenue
Westbury, L.I., N.Y. 11590
3.17 FIELD LEVEL MAINTENANCE PAINTING
REQUIREMENTS.
Field level maintenance-painting requirements for SE with
polyurethane are divided into two types, touch-up painting and
general maintenance painting.
3.17.1 Touch-Up Painting. Touch-up painting is defined as
minor touch-up and/or sectionalized painting of equipment
using authorized coating to prevent corrosion. When spot
painting, the amount of paint used should be enough to cover
the affected area plus a one-inch overlap to seal the area's
edges. Treat scratched areas that are one half inch wide by
three inches long or less, or chips one inch in diameter or less
will be touched-up with CPC (temporary repair), or approved
primers and topcoats preloaded in items such as but not limited
to: SEMPENS, Preval compressed air spray packs, Clip-
Pacs, Brush and Roller, or Akzo Nobel Two-Component
MIL-PRF-85285 Aerosol Can. Single component aerosols,
enamels or laquers are not authorized coatings. Information
about these materials can be viewed on the AFCPCO website
located on the AF Portal. Larger scratches/chips in paint or
damaged areas will be grounds to repaint the complete section
per Paragraph 3.3.
3.18 MAINTENANCE PAINTING.
3.18.1 Maintenance Painting Restrictions. Although it is
not recommended, it is a common field level practice during
maintenance painting to repeatedly overcoat the entire exterior
surface. Under no circumstance should the total number of
layers of paint ever exceed six (6). The number of layers can
be determined during the featheredge sanding of damaged
areas. Count each layer of primer as one and each layer of
topcoat as one, the total of which should never exceed six.
3.18.1.1 Equipment exceeding this maximum number of
paint layers should be scheduled for complete coating removal
and repainting.
Change 4 3-15