MIL-N-21337
3.6 Protective coating and treatment. Un-
conforming to Federal Standard No. 66
less otherwise specified in the contract or
Steel No.'s 1005 to 1035 inclusive.
order (see 6.2), nuts shall be plated, coated,
or treated in accordance with 3.6.1, 3.6.2,
3.1.2 Corrosion-resisting steel. `Type I class
3.6.3, or 3.6.4, as applicable.
4 nuts shall be fabricated from corrosion-
resisting steel conforming to Federal Stand-
3.6.1 Zinc plating. Zinc plating shall be in
ard No. 66 Steel No.'s 302, 303, or 304.
accordance with Specification QQ-Z-325,
class 3, type II.
3.1.3 Alloy steel. Type II class 1 nuts shall
be made from alloy steel conforming to Fed-
3.6.2 Cadmium plating. Cadmium plating
eral Standard No. 66 Steel No.'s 8740 or
shall be in accordance with Specification QQ-
8742.
P-416, type H, class C.
3.2 Threads. Threads shall be American
3.6.3 Phosphate coding. Phosphate coat-
National Form class NS3B in accordance
ing shall be in accordance with Specification
with Screw-Thread Standard for Federal
MIL-C-16232, type II without supplemen-
Services, Handbook H28 and 1950 Supple-
tary finish.
ment thereto.
3.6.4 Passivation. Corrosion-resistant steel
3.3 Finish and tolerances.
nuts shall be passivated in acid, subsequent
to the final machining (metal removing) op-
3.3.1 Surface roughness. Surface rough-
eration, in accordance with the following.
ness of types I and II nuts shall not be great-
method:
er than a roughness height rating of 125
except as specified in figure 2. Surface
(a) Solvent-clean (immersion, spray,
roughness shall be interpreted in accordance
or vapor) in accordance with
with the provisions of Standard MILSTD-
grade II, type 3 of Specification
10.
MIL-C-490.
(b) Dip the parts in a 20% aqueous
3.3.2 Tolerances. Tolerances for type I and
solution of nitric acid at ordi-
type II nuts shall be plus or minus .010-inch
nary room temperature for about
for linear dimensions and plus or minus 2
30 minutes, or at approximately
degrees for angular dimensions except as
150°F. for about 10 minutes.
specified on figure 1 and table I or figure
2 and table H, as applicable.
3.6.4.1 Other methods of passivation may
be substituted, in lieu of 3.6.4, only upon
3.4 Sharp edges. Unless otherwise speci-
prior approval of the procuring activity.
fied herein sharp edges shall be rounded,
chamfered, or broken not less than 0.003-
3.7 Hardness.
inch not more than 0.015-inch.
3.7.1 Carbon std. The hardness of carbon
3.5 Designs, sizes. and dimensions. Unless
steel nuts shall be Rockwell B66 minimum
otherwise specified in the contract or order,
to Rockwell B92 maximum.
nuts shall conform to the designs, sizes, and
dimensions specified on figure 1 and table
3.7.2 Corrosion-resisting steel. Corrosion-
I or figure 2 and table II, as applicable.
resisting steel nuts shall be in the annealed
Type I nuts shall have either 4 or 8 slots,
condition and at a hardness of Rockwell B90
at the option of the manufacturer. Type H
maximum.
nuts shall have 8 slots.
3