Mechanical Requirements A563
Jun 15,2018
Mechanical Requirements
Nuts with UNC, 8UN, 6UN and Coarser Pitch Threads

Grade of Nut

Nominal Nut Size,In.

Style of Nut

Proof Load Stress, ksi A

Hardness

Non-Zinc Coated NutsB

Zinc Coated Nuts B

Brinell

Rockwell

Min

Max

Min

Max

O

1/4 to 1-1/2

Square

69

52

103

302

B55

C32

A

1/4 to 1-1/2

Square

90

68

116

302

B68

C32

O

1/4 to 1-1/2

Hex

69

52

103

302

B55

C32

A

1/4 to 1-1/2

Hex

90

68

116

302

B68

C32

B

1/4 to 1

Hex

120

90

121

302

B69

C32

B

1/8 to 1-1/2

Hex

105

79

121

302

B69

C32

DC

1/4 to 1-1/2

Hex

135

135

159

352

B84

C38

DHD

1/4 to 1

Hex

150

150

248

352

C24

C38

DH3

1/2 to 1

Hex

150

150

248

352

C24

C38

A

1/4 to 4

heavy hex

100

75

116

302

B68

C32

B

1/4 to 1

heavy hex

133

100

121

302

B69

C32

B

1-1/8 to 1-1/2

heavy hex

116

87

121

302

B69

C32

CC

1/4 to 4

heavy hex

144

144

143

352

B78

C38

C3

1/4 to 4

heavy hex

144

144

143

352

B78

C38

DC

1/4 to 4

heavy hex

150

150

159

352

B84

C38

DHD

1/4 to 4

heavy hex

175

150

248

352

C24

C38

DH3

1/4 to 4

heavy hex

175

150

248

352

C24

C38

A

1/4 to 1-1/2

hex thick

100

75

116

302

B68

C32

B

1/4 to 1

hex thick

133

100

121

302

B69

C32

B

1-1/8 to 1-1/2

hex thick

116

87

121

302

B69

C32

DC

1/4 to 1-1/2

hex thick

150

150

159

352

B84

C38

DHD

1/4 to 1-1/2

hex thick

175

175

248

352

C24

C38

Nuts with UNF, 12UN, 6UN and Finer Pitch Threads

O

1/4 to 1-1/2

Hex

65

49

130

302

B55

C32

A

1/4 to 1-1/2

Hex

80

60

116

302

B68

C32

B

1/4 to 1

Hex

109

82

121

302

B69

C32

B

1-1/8 to 1-1/2

Hex

94

70

121

302

B69

C32

DC

1/4 to 1-1/2

Hex

135

135

159

352

B84

C38

DHD

1/4 to 1-1/2

Hex

150

150

248

352

C24

C38

A

1/4 to 4

heavy hex

90

68

116

302

B68

C32

B

1/4 to 1

heavy hex

120

90

121

302

B69

C32

B

1-1/8 to 1-1/2

heavy hex

105

79

121

302

B69

C32

DC

1/4 to 4

heavy hex

150

150

159

352

B84

C38

DHD

1/4 to 4

heavy hex

175

175

248

352

C24

C38


A To determeine nut proof load in pounds, multiply the appropriate nut proof load stress by the tensile stress area of the thread. Stress areas for UNC, UNF,and 88UN thread series are given in table.

B Non-zinc coated nuts are nuts intended for use with exterally thread fasteners whith have a plain(non-plated or non-coated)finish or have a pating or coating of insufficient thickness to necessitate overtapping the nut thread to provide assemblability. Zinc coated nuts intended for use with externally threaded fasteners which are hot-dip zinc coated, mechanically zinc coated, or have a plating or coating of sufficient thickness to necessitate overtapping the nut thread to provide assemblability.

C Nuts made in accordance to the requirements of Specification ASTM A194/A194M, Grade 2 or Grade 2H, and marked with their grade symbol are acceptable equivalents for Grades C and D nuts. When A194 zinc coated inch series nuts are supplied,the zinc coating, overtapping, lubrication and rotation capacity testing shall be in accordance with Specification ASTM A563.

D Nuts made in accordance with the requirement of Specification A194/A194M, Grade 2H, and marked with its grade symbol are an acceptable equivalent for Grade DH nuts. When ASTM A194 zinc coated inch series nuts are supplied, the zinc coating, overtapping, lubrication and rotational capacity testing shall be in accordance with Specification ASTM A563.
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