TO 35-1-3 - Robins Air Force Base

TO 35-1-3
3.3.1.2.1 Complete Repaint Criteria. SE requires complete
repainting when the coating system fails. A coating system is
considered failed when over 75% of the total exterior surface
displays obvious oxidation, bleaching, peeling, cracking, flaking,
etc. When the coating system has failed it will be completely
stripped and repainted by qualified personnel in
accordance with the standard paint system in Table 3-1. The
corrosion control facility performing the SE repaint (ie, Fabrication
Flight, contractors, depot, etc.) will validate the need
for a complete repaint prior to accepting the SE into the corrosion
flow.
3.3.2 Abrasive Blasting. The most effective means of completely
depainting and removing corrosion from SE is by
mechanical means such as abrasive blasting using approved
abrasive blasting dry media, water blasting, or water blasting
with abrasive grit injected into the water stream. Plastic media
blasting is effective in removing coatings and light surface
corrosion from SE but will not effectively remove heavy corrosion
TO 1-1-691, Cleaning and Corrosion Prevention and
Control Aerospace and Non-Aerospace Equipment, and TO
1-1-8, Application and Removal of Organic Coatings, Aerospace
and Non-Aerospace Equipment, provides in depth guidance
on abrasive blasting material selection and processes.
Refer to these TOs for the effective development and execution
of all SE abrasive blasting corrosion and coating removal
programs.
3.3.2.1 Several coating systems require the complete coating
removal and surface preparation to include a white metal or
near white metal surface condition with a minimum of a 2 mil
surface profile. This requirement can only be achieved through
abrasive grit blasting or high pressure water blasting. Several
high-pressure water blasting systems will allow the injection
of abrasive grit into the water stream to achieve the required
surface profile. Consult the equipment manufacturer's data
sheet for additional guidance. Ensure the combination of abrasive
grit and medium/high pressure water will not cause warping
or other structural damage to SE and that this process is
environmentally acceptable prior to the requisition of the abrasive
blasting equipment.
3.3.2.1.1 Dry Media Abrasive Blasting for Iron and
Steel. For complete coating and corrosion removal and surface
preparation to include white metal or near white metal
surface condition of iron and steel substrates (other than stainless
steel), 0.063 (16 gauge, US Standard) or thicker, use one
of the approved products listed below:
STARBLAST XL
DBA Dupont
4641 County Rd 230
Starke, FL 32091
Quickstrip 20-40G
US Technologies Corp
4200 Munson St NW
Canton, OH 44718
Phone: 770-254-9449
www.ustechnology.com
Cage Code: 9Z037
Cage Code: 1AM56
Garnet Galaxy (Garnet)
Opta Minerals Inc
407 Parkside Dr.
P.O. Box 260
Waterdown, Ontario LOR 2HO
Phone: (888) 689-6661
www.optaminerals.com
Cage Code: L4566
3.3.2.1.2 Dry Media Abrasive Blasting for Aluminum,
Magnesium, Stainless Steel and Iron and Steel Less
Than 0.063. For complete coating and corrosion removal and
surface preparation to include white metal or near white metal
surface condition of aluminum, magnesium, stainless steel
alloys and for iron and steel substrates less than 0.063, use
abrasive blasting dry media qualified to MIL-PRF-9954 (reference
Table A-1).
3.3.2.2 Medium Pressure Water Blasting. Medium pressure
water blasting, with operating pressures less than 40,000
PSI is also authorized for coating removal on SE. All requirements
and safety considerations listed in abrasive blasting sections
of TO 1-1-691 and TO 1-1-8 apply. Ensure the SE seams,
and crevices are protected from water intrusion/entrapment to
prevent subsequent corrosion. Remove or protect from the
high pressure water stream, all soft metal/non-metal components
such as data plates, copper parts, hoses, etc. 3.3.2.2.1
The use of the optional variable speed drive for the medium
pressure water blasting units is required if abrasive media will
be introduced into the pressurized water stream.
3.3.2.2.2 Use the lowest effective water pressure when
removing paint or when abrasive media is used in combination
with the medium pressure water to remove corrosion.
• Care should be taken in coating removal preparation
with all pressurize coating/corrosion removal
processes to preclude blasting media intrusion and
warpage of unsupported thin panels.
• Water blasting of equipment that has been primed
with a chromate containing primer may allow
leaching of the chromate into the waste water. Organizations
shall gain approval from the appropriate
environmental management office of primary
responsibility prior to the commencement of water
blasting activities.
3.3.2.3 Scuff Sand and Overcoat. If disassembly and complete
mechanical removal is impractical within the organization,
due to environmental constraints, the requirements of
Table 3-1 for mechanical removal and application of the two
layer zinc-rich primer (MIL-PRF-26915)/intermediate primer
(MIL-DTL-53030), on ferrous alloys waived and replaced
with MIL-DTL-53022, Type II Aluminum, fiberglass, and
stainless steel equipment and parts will not be coated with
zinc-rich primer at any time.
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