Nuts
In the testing of proof load and hardness values of the hex nuts by manufactories and third
party laboratories, the following standards are commonly used or recognized.

Proof Load Values for Hex Nuts (N)

Thread, d Pitch, P Proof Load as per ISO898‑2 Proof Load as per DIN267‑4 Proof Load as per BS4190
Class 8 Class 10 Class 12 Class 8 Class 10 Class 12 Class 8 Class 10 Class 12
M5 0.8 12,140 14,800 16,300 11,400 14,200 17,000 11,400 14,800 17,000
M6 1.0 17,200 20,900 23,100 16,000 20,000 24,000 16,000 20,000 24,000
M8 1.25 31,800 38,100 42,500 29,000 36,500 43,000 29,000 36,500 43,000
M10 1.5 50,500 60,300 67,300 46,000 58,000 69,500 46,000 58,000 69,500
M12 1.75 74,200 88,500 100,300 67,000 84,000 100,000 67,000 84,000 100,000
M14 2.0 101,200 120,800 136,900 92,000 115,000 138,000 -- -- --
M16 2.0 138,200 164,900 186,800 126,000 157,000 188,000 125,000 157,000 188,000
M18 2.5 176,600 203,500 230,400 154,000 192,000 230,000 -- -- --
M20 2.5 225,400 259,700 294,000 196,000 245,000 294,000 196,000 245,000 294,000
M22 2.5 278,800 321,200 363,600 242,000 303,000 364,000 242,000 303,000 364,000
M24 3.0 324,800 374,200 423,600 282,000 353,000 423,000 282,000 353,000 423,000
M27 3.0 422,300 486,500 550,800 367,000 459,000 550,000 367,000 459,000 550,000
M30 3.5 516,100 594,700 673,200 448,000 561,000 673,000 448,000 561,000 673,000
M33 3.5 638,500 735,600 832,800 555,000 694,000 833,000 555,000 694,000 833,000
M36 4.0 751,600 866,000 980,400 653,000 817,000 980,000 653,000 817,000 980,000
M39 4.0 897,900 1,035,000 1,171,000 780,000 976,000 1,170,000 780,000 976,000 1,170,000
M42 4.5 -- -- -- -- -- -- 896,000 1,120,000 1,340,000
M45 4.5 -- -- -- -- -- -- 1,400,000 1,300,000 1,560,000
M48 5.0 -- -- -- -- -- -- 1,180,000 1,470,000 1,760,000
M52 5.0 -- -- -- -- -- -- 1,410,000 1,760,000 2,110,000
M56 5.5 -- -- -- -- -- -- 1,620,000 2,030,000 2,440,000
M60 5.5 -- -- -- -- -- -- 1,890,000 2,360,000 2,830,000
M64 6.0 -- -- -- -- -- -- 2,140,000 2,680,000 3,220,000
M68 6.0 -- -- -- -- -- -- 2,450,000 3,060,000 3,670,000

Hardness Properties for Hex Nuts - Style 1 (Vickers Hardness, HV)

Thread, d Hardness as per ISO898‑2 Hardness as per DIN267‑4 Hardness as per BS4190
Class 8 Class 10 Class 12 Class 8 Class 10 Class 12 Class 8 Class 10 Class 12
M5 ‑ M16 min. 200 272 272 - - - - - -
max. 302 353 353 302 353 353 310 370 395
M18 ‑ M39 min. 233 272 272 - - - - - -
max. 353 353 353 302 353 353 310 370 395

DIN267-Part 10 specifies the technical delivery conditions for hot-dip galvanized bolts and nuts, diameter size M6 to M36,coarse thread.

Minimum Failure Loads for Hot-Dip Galvanized Bolts and Proof Loads for Hot-dip Galvanized Nuts with oversize thread.

Thread
size		 Pitch, (P) Stress area,
(mm2)		 Property class bolt/nut
8.8/8 10.9/10
Minimum failure load of bolt or
proof load for nut, (N)
M6 1.0 16.4 13,100 17,100
M8 1.25 31.3 25,000 32,600
M10 1.5 50.9 40,700 52,900
M12 1.75 75.1 60,100 78,100
M14 2.0 104 83,200 108,000
M16 2.0 144 115,000 150,000
M18 2.5 177 147,000 184,000
M20 2.5 227 188,000 236,000
M22 2.5 284 236,000 295,000
M24 3.0 329 273,000 342,000
M27 3.0 433 359,000 450,000
M30 3.5 530 440,000 551,000
M33 3.5 659 547,000 685,000
M36 4.0 777 645,000 808,000

Proof Load for Hot-dip Galvanized Nuts

Thread
size		 Pitch, (P) Stress area,
(mm2)		 Class 8 Class 10
Proof load, (N)
M6 1.0 16.4 9,510 13,610
M8 1.25 31.3 18,150 25,980
M10 1.5 50.9 29,500 42,200
M12 1.75 75.1 43,600 62,300
M14 2.0 104 60,300 86,300
M16 2.0 144 83,500 119,000
M18 2.5 177 106,000 147,000
M20 2.5 227 136,000 188,000
M22 2.5 284 170,000 236,000
M24 3.0 329 197,000 273,000
M27 3.0 433 260,000 359,000
M30 3.5 530 318,000 440,000
M33 3.5 659 395,000 547,000
M36 4.0 777 466,000 645,000

For detailed information, please refer to complete governing standards.

SAE J995 specifies the requirements for high tensile and alloy steel inch-series nuts. Sizes covered range from ¼" to 1-½" diameter.


Proof Load for ANSI B18.2.2 Hex Nut

Size Proof Load (lbf) for UNC Hex Nut Size Proof Load (lbf) for UNF Hex
Grade 5 Grade 8 Grade 5 Grade 8
1/4"-20 3,800 4,750 1/4"-28 4,000 5,460
5/16"-18 6,300 7,850 5/16"-24 6,300 8,700
3/8"-16 9,300 11,600 3/8"-24 9,550 13,150
7/16"-14 12,800 15,900 7/16"-20 13,000 17,800
1/2"-13 17,000 21,300 1/2"-20 17,450 24,000
9/16"-12 21,800 27,300 9/16"-18 22,150 30,450
5/8"-11 27,100 33,900 5/8"-18 27,900 38,400
3/4"-10 40,100 50,100 3/4"-16 40,650 55,950
7/8"-9 55,400 69,300 7/8"-14 55,500 76,350
1"-8 72,700 90,900 1"-12 72,300 99,450
1-1/8"-7 80,100 114,000 1-1/8"-12 80,450 128,400
1-1/4"-7 102,000 145,000 1-1/4"-12 100,850 160,950
1-3/8"-6 121,000 173,000 1-3/8"-12 123,800 197,250
1-1/2"-6 148,000 211,000 1-1/2"-12 148,600 237,150

Hardness Requirements for ANSI B18.2.2 Hex Nuts

Nut Grade Size Hardness
5 1/4" to 1-1/2" 32 HRC Max
8 1/4" to 5/8" 24--32 HRC
8 Over 5/8" to 1" 26--34 HRC
8 Over 1" to 1-1/2" 26--36 HRC

For detailed information, please refer to complete governing standards.

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