TO 1-1-700 - Robins Air Force Base

TO 1-1-700
CHAPTER 12
SEALANTS
12.1 PURPOSE.
This chapter covers sealing compounds and procedures for
their application. When properly applied, sealants prevent the
intrusion of moisture from condensation, rain, and salt water
as well as dust, dirt, and fluids into joint areas where they can
cause extensive corrosion. Sealants are one of the most important
tools for corrosion prevention and control. To be effective,
it is critical that the correct sealant be chosen for a specific
area/situation and that it be applied correctly. Only qualified
personnel thoroughly familiar with sealants and their application
shall be permitted to handle and apply them.
12.2 APPLICATIONS.
Sealants are used for the following reasons:
• Fuel sealing (fuel tanks and delivery components).
• Weather and fluid sealing (exterior and interior skin
and structural joints and surfaces).
• Electrical sealing (bulkhead wiring, electrical connectors
and components).
• Acid-resistant sealing (battery compartments).
• High temperature sealing
12.3 SEALING COMPOUNDS.
Table 12-1 lists approved sealing compounds, and their available
types, properties, and intended use. Refer to the applicable
maintenance manual and paragraph 12-7 for specific
information concerning selection of the proper sealing compound
and its application. Observe the warnings and cautions
in paragraph 12-6 when using any sealing compound.
NOTE
See the Appendix A in TOs 1-1-691 and 1-1-689-5
for procurement information on sealants (NSNs,
quantities, etc.)
12.3.1.1 Two-Part Kit (KT). The package consists of two
separate containers, usually metal cans; one contains the catalyst
(part A) and the other contains the base compound (part
B), each in pre-measured amounts for mixing together.
12.3.1.2 Cartridge (CA). Cartridges come in two different
types: one for single component sealants and one for two component
sealants.
12.3.1.2.1 Single component sealants are contained in a plastic
cartridge or tube in a ready to use condition requiring no
mixing. If some of a single component sealant remains after a
job, it can be stored and used at a future time as long as the
cartridge/tube is tightly capped at the nozzle opening to prevent
contact with air.
12.3.1.2.2 Two component sealants are packaged in Semkits®
which are complete plastic cartridge assemblies that
store both sealant components (each in separate chambers).
Mixing of sealant materials is accomplished within the assembly,
which is then used for application. Semkits® are convenient
because they eliminate the need to measure and handle
the materials for mixing, and generate less waste as they contain
small quantities for small area applications.
12.3.1.3 Premixed and Frozen (PMF). Two component
sealants can be premeasured, mixed, and frozen at temperatures
of -40 °F (-40 °C) and stored at temperatures of -20 °F
(-29 °C) or lower with the unit of issue being in ounces. The
PMF material in plastic tubes is a convenient package configuration
for low and intermittent usage applications, particularly
in depot level operations. Simply thaw the material and use.
12.3.2 Polysulfide, Polyurethane, and Polythioether
Sealing Compounds. All these materials are two component
with the Part B base containing the prepolymer and the
Part A catalyst containing the curing agent packaged in separate
containers supplied together as a kit. When thoroughly
mixed, the catalyst cures the prepolymer to a rubbery solid.
The rate of cure depend on the type of prepolymer and catalyst,
as well as the temperature and humidity. Full cure of
these materials may require as long as 7 days. Refer to Table
12-1 for a general description of these materials.
12.3.1 Sealant Packaging. Sealants are generally packaged
and available as three different types of packaging or
units of issue (U/I):
12-1