TO 35-1-3 - Robins Air Force Base

TO 35-1-3
Figure 3-3. Hollow Member Weld-Nut Configuration
3.12.2.2 Weld nuts should be removed periodically so the
hollow member can be checked for water accumulation and
condition of the corrosion prevention compound. If water has
to be drained, completely dry the area and reapply the appropriate
CPC the entire length of the hollow member. After a
period of two to three years the rubber may compress in the
hole, if this occurs remove the screw, cut the weld-nut flush
with the surface, punch the remainder of the nut inside the
hollow member and install a new weld-nut.
3.13 CORROSION PREVENTIVE COMPOUNDS
(CPC).
Corrosion Preventive Compounds (CPC) are used for temporary
protection of painted and unpainted surfaces and where
coating system has been damaged or removed. CPC's function
by preventing corrosive materials from contacting and corroding
bare metal surfaces. Some of the compounds have the
capability of displacing moisture in seams, joints and faying
surfaces. Some CPC's also provide lubrication as well as corrosion
protection. The thicker CPC's provide the best corrosion
protection, are longer lasting, and more difficult to
remove. The thinner materials provide some lubrication and
do not crack; chip or peel but must be removed and replaced.
The protection provided is temporary, so the compound must
be reapplied periodically and after removal by washing or contact
with solvents or fuel. The recommended maximum frequency
of application is based on the corrosion severity of the
operational environment. The frequency of application can be
set to coincide with wash cycles and periodic inspections, but
should not be extended. These compounds should not be considered
as a long-term alternative for proper painting. The
CPCs should not be applied at temperatures above 95 °F or
below 50 °F. A brief description of authorized CPC's are listed
below.
3.13.1 MIL-PRF-81309.
CPC shall not be used on or adjacent to oxygen lines,
fittings or equipment. The compound shall not be
used on surfaces where temperatures exceed 300
°F. Failure to comply may result in fire hazard.
Corrosion Preventive Compounds (CPC) can be separated
into two major categories: water displacing and
non-water displacing compounds (refer to
TO 1-1-691). Some CPC's have a flash point above
100 °F, but contain flammable solvents. These compounds
should be handled, stored, and applied in accordance
with manufacturer's instructions and the
product Material Safety Data Sheet (MSDS).
MIL-PRF-81309 (CPC Water Displacing Ultra Thin Film) is a
general-purpose corrosion preventive compound that can be
used whenever a CPC or a water-displacing compound is
called for but no specification is referenced. MIL-PRF-81309
materials are excellent water displacing compounds that provide
an ultra thin, soft protective film (0.5-mil or less). The
specification covers two types, both of which can be applied
by dipping, spraying, brushing, or an aerosol container. They
provide temporary protection from corrosion and are easily
removable with a solvent. The two types primarily in used for
SE are Types II and III.
a. Type II. A soft, thin film for general use, particularly on
moving or sliding parts where some lubrication is
needed, such as hinges or bomb racks. It may be washed
away by rain or wash procedures. Type II shall be used
to protect areas which cannot be properly drained or
contain recesses that are particularly difficult to reach.
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