Prev PostASTM A563
ASTM A563
The ASTM A563 specification covers the chemical and mechanical requirements for carbon and alloy steel nuts used on bolts, studs, and externally threaded fasteners. The charts below address over tapping allowances for hot-dip galvanized nuts, grade marking requirements, and mechanical requirements. For information on suitable nuts for various grades of bolts, visit the Nut Compatibility Chart.
According the A563 specification, ""The requirements for any grade of nut may, at the supplier's option, and with notice to the purchaser, be fulfilled by furnishing nuts of one of the stronger grades specified herein unless such a substitution is barred in the inquiry and purchase order"". This is important because some nut grades are not readily available in certain sizes and finishes. Additionally, the specification allows for the substitution of ASTM A194 grade 2H nuts in lieu of A563 grade DH nuts due to the lack of availability of grade DH nuts in nominal sizes ¾"" and larger.
Hot-dip galvanized nuts must be tapped oversize to allow for the added thickness of the zinc on the threads of the externally threaded fastener. These allowances are addressed in the chart below and a more detailed explanation of this issue can be found in the Frequently Asked Questions section of this site.
Various nut styles exist and to some degree are determined by their grade. These styles include hex, heavy hex, square, jam, coupling, and sleeve.
Scope
Standard specification for carbon and alloy steel nuts.
Grades
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A
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Low carbon steel, hex or heavy hex
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B
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Low carbon steel, hex or heavy hex
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C
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Carbon steel, quenched and tempered, heavy hex
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D
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Carbon steel, quenched and tempered, heavy hex
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DH
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Carbon steel, quenched and tempered, heavy hex
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C3
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Weathering steel, quenched and tempered, heavy hex
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DH3
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Weathering steel, quenched and tempered, heavy hex
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Mechanical Properties
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Grade
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Style
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Size, in.
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Proof Load, ksi
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Hardness, HBN
|
|
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Black
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Galvanized
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A
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Hex
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1/4 - 1-1/2
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90
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68
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116 - 302
|
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Heavy Hex
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1/4 - 4
|
100
|
75
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116 - 302
|
|
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B
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Heavy Hex
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1/4 - 1
|
133
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100
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121 - 302
|
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Heavy Hex
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1-1/8 - 1-1/2
|
116
|
87
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121 - 302
|
|
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C / C3
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Heavy Hex
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1/4 - 4
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144
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144
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143 - 352
|
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D
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Heavy Hex
|
1/4 - 4
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150
|
150
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248 - 352
|
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DH / DH3
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Heavy Hex
|
1/4 - 4
|
175
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150
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248 - 352
|
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For UNC, 8UN, 6UN, and Coarse Pitch Threads
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Grade Identification Markings
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Grade Identification Marking
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Specification
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Material
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Nominal Size, In.
|
Proof Load Stress, ksi
|
Hardness Rockwell
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See Note
|
|
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Min
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Max
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No Mark |
ASTM A563 Grade O
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Carbon Steel
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1/4 - 1-1/2
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69
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B55
|
C32
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2,3
|
|
ASTM A563 Grade A
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Carbon Steel
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1/4 - 1-1/2
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90
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B68
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C32
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2,3
|
|
|
ASTM A563 Grade B
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Carbon Steel
|
1/4 - 1
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120
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B69
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C32
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2,3
|
|
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>1 - 1-1/2
|
105
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ASTM A563 Grade C
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Carbon Steel, may be Quenched and Tempered
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1/4 - 4
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144
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B78
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C38
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4
|
|
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ASTM A563 Grade C3
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Atmospheric Corrosion Resistant Steel, may be Quenched and Tempered
|
1/4 - 4
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144
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B78
|
38
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4,6
|
|
|
ASTM A563 Grade D
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Carbon Steel, may be Quenched and Tempered
|
1/4 - 4
|
150
|
B84
|
C38
|
5
|
|
|
ASTM A563 Grade DH
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Carbon Steel, Quenched and Tempered
|
1/4 - 4
|
175
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C24
|
C38
|
5
|
|
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ASTM A563 Grade DH3
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Atmospheric Corrosion Resistant Steel, Quenched and Tempered
|
1/4 - 4
|
175
|
C24
|
C38
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4,6
|
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NOTES:
Inch Fastener Standards. 7th ed. Cleveland: Industrial Fasteners Institute, 2003. n-80-n-81.
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Thread Dimensions and Oversizing Allowances
for Nuts: Hot Dipped Galvanized per Specification A153, C1.C
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Nominal Nut Size, in. and Pitch
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Diametral Allowance, in.
|
Pitch Diameter
|
|
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Min
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Max
|
||
|
0.250 - 20
|
0.016
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0.2335
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0.2384
|
|
0.312 - 18
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0.017
|
0.2934
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0.2987
|
|
0.375 - 16
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0.017
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0.3514
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0.3571
|
|
0.437 - 14
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0.018
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0.4091
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0.4152
|
|
0.500 - 13
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0.018
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0.4680
|
0.4745
|
|
0.0562 - 12
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0.020
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0.5284
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0.5352
|
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0.625 - 11
|
0.020
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0.5860
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0.5932
|
|
0.750 - 10
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0.020
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0.7050
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0.7127
|
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0.875 - 9
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0.022
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0.8248
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0.8330
|
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1.000 - 8
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0.024
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0.9428
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0.9516
|
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1.125 - 8
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0.024
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1.0678
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1.0768
|
|
1.125 - 7
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0.024
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1.0562
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1.0656
|
|
1.250 - 8
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0.024
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1.1928
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1.2020
|
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1.250 - 7
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0.024
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1.1812
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1.1908
|
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1.375 - 8
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0.027
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1.3208
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1.3301
|
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1.375 - 6
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0.027
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1.2937
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1.3041
|
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1.500 - 8
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0.027
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1.4458
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1.4553
|
|
1.500 - 6
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0.027
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1.4187
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1.4292
|
|
1.750 - 5
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0.050
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1.6701
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1.6817
|
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2.000 - 4.5
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0.050
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1.9057
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1.9181
|
|
2.250 - 4.5
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0.050
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2.1557
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2.1683
|
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2.500 - 4
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0.050
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2.3876
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2.4011
|
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2.750 - 4
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0.050
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2.6376
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2.6513
|
|
3.000 - 4
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0.050
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2.8876
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2.9015
|
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3.250 - 4
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0.050
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3.1376
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3.1517
|
|
3.500 - 4
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0.050
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3.3876
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3.4019
|
|
3.750 - 4
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0.050
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3.6376
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3.6521
|
|
4.000 - 4
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0.050
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3.8876
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3.9023
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Inch Fastener Standards. 7th ed. Cleveland: Industrial Fasteners Institute, 2003. B-173.
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