MIL-DTL-1222J
for coatings outside the threaded area. When a coating is specified for
internally-threaded fasteners or externally threaded fasteners with class 3A
or class 5 threads, the minimum thickness in the threaded area shall be as
specified (see 6.2).
3.6.4 Corrosion-resistant steels. Corrosion-resistant steel fasteners
shall be descaled, cleaned and passivated in accordance with ASTM A 380.
3.6.5 Aluminum alloys. Aluminum alloy fasteners shall be supplied
anodized in accordance with ASTM B 580, type D, unless immersion zinc
flake/chromate dispersion coatingis specified (see 6.2).
3.6.6 Titanium alloys. Externally threaded titanium alloy fasteners
shall be finished by anodizing in accordance with AMS 2488. Unless an
inorganic coating is specified (see 6.2), a solid film lubricant to
3.6.7 MIL-L-46010 shall be applied.
When an inorganic coating is
specified, a solid film lubricant to
3.6.8 MIL-PRF-81329 shall be applied.
The AMS 2488 anodizing procedure
shall be modified as follows:
a) The anodizing bath need not be alkaline.
b) The final anodize coating shall be nonconductive.
c) The final anodize coating shall not cause any measurable
dimensional change using standard fastener measuring
equipment.
d) Coating thickness shall be verified by weight change and shall
not be less than 400 milligrams per square foot.
e) Confirmatory preproduction tests of AMS 2488 are not required.
3.7 Hydrogen embrittlement relief. Externally-threaded fasteners of
grades 410, 416, 416Se and 431 in the I and H conditions and grades 8, 4340,
A574 and 630 in the final heat treated condition, which are electroplated or
exposed to pickling acids or any other process that may introduce hydrogen,
shall be given hydrogen embrittlement relief in accordance with ASTM B 633.
3.8 Magnetic permeability. For the annealed condition of 300 series
austenitic corrosion-resistant steels, the relative magnetic permeability
shall be determined and shall not exceed 2.0 (air = 1.0).
3.9 Dimensions.
3.9.1 Threads. Unless otherwise specified, threads shall be in
accordance with the applicable commercial specification cited in table I and
as modified herein (see 6.2). When specified (see 6.2), threads shall be
rolled and shall not be cut or ground. External threads with rounded roots,
identified as UNR in ASME B1.1, may be used in place of the UN series. When
no coating will be applied, class 3A threads in accordance with ASME B1.1 may
be used in place of class 2A threads (see 3.6.13). Thread dimensions of
fasteners, with a specified minimum coating thickness (see 6.2), shall be
modified in accordance with the requirements of 3.9.7.
3.9.1.1 Thread series on bolts, screws and nuts. Unless otherwise
specified (see 6.2) the thread series shall be coarse for sizes 1 inch and
less and constant 8 thread for sizes over 1 inch.
3.9.1.2 Threads series on studs. The threads on the stud end of type
III fasteners (constant strength body) shall be class 5 (5HF or 5 CSF/ONF) in
accordance with ASME B1.12 or class 3A in accordance with ASME B1.1 as
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