Distributore BUMAX ITALIA
Viti Bulloni Alta Resistenza Meccanica

COPPIA e FORZA di SERRAGGIO

Tightening torque, preload, failure load and yield load

Thread size and class Class M3 M4 M5 M6 M8 M10 M12 M14 M16 M18 M20
Tightening Torque MV in Nm 1), 3) BUMAX 129 2.1 4.9 9.7 17 40 79 136 217 333 463 649
BUMAX 109 1.7 4.1 8.1 14 34 66 115 162 248 344 481
BUMAX 88 1.3 2.9 5.7 10 25 47 82 129 198 275 385
BUMAX Lock 6.6 12 29 54 94 228 442
80 1.2 2.7 5,4 9 22 44 76 121 187 261 364
70 0.9 2 4 7 17 33 57 91 140 195 273
50 0.14 1 2 3 8 15 27 43 65 91 127
Preload applied kN ± 23% 2) BUMAX 129 3.5 6.2 10 14 26 41 59 81 110 135 172
BUMAX 109 2.9 5.2 8.6 12 21 34 49 60 81 100 128
BUMAX 88 2.1 3.6 5.9 8.4 15 24 35 48 65 80 102
BUMAX Lock 8.4 15 24 35 65 102
80 2.0 3.4 5.5 7.8 14 23 33 45 61 76 96
70 1.5 2.6 4.2 5.9 11 17 25 34 47 57 72
50 0.8 1.4 1.9 2.7 5 8 12 16 21 27 33
Failure load kN BUMAX 129 6 10.5 17 24 44 70 101 138 188 230 294
BUMAX 109 5 8.8 14 20 37 58 84 115 157 192 245
BUMAX 88 4 7 11 16 29 46 67 92 126 154 196
BUMAX Lock 11 16 29 46 67 126 196
80 4 7 11 16 29 46 67 92 126 154 196
70 3.5 6.1 9.9 14 26 41 59 81 110 134 172
50 2.5 4.4 7,1 10 18 29 42 58 79 96 123
Yield Load kN BUMAX 129 5.4 9.5 15 21.5 39.5 62.5 91 124 170 207 265
BUMAX 109 4.5 8 13 18 33 52 76 92 125 154 196
BUMAX 88 3.2 6 9 13 23 37 54 74 100 123 157
BUMAX Lock 9 13 23 37 54 100 157
80 3 5 8 12 22 35 51 69 94 115 147
70 2.2 4 6 9 16 26 38 52 71 86 110
50 1.3 2 3 4 8 12 18 24 33 40 51
Nominal stress area mm² 5.03 8.78 14.2 20.1 36.6 58.0 84.3 115 157 192 245
Pitch of thread 0.5 0.7 0.8 1.0 1.25 1.5 1.75 2.0 2.0 2.5 2.5
Thread size and class Class M24 M27 M30 M36
Tightening Torque Mv in Nm 1), 3) BUMAX 88 665 961 1310 2280
BUMAX Lock 765
80 629 909 1240 2160
70 472 682 930 1620
50 220 318 434 755
Preload applied KN ± 23% 2) BUMAX 88 181 235 287 418
BUMAX Lock 181
80 138 179 219 319
70 103 134 164 239
50 48 63 77 112
Failure load KN BUMAX 88 282 367 449 654
BUMAX Lock 282
80 282 367 449 654
70 247 321 393 572
50 177 230 281 409
Yield load KN BUMAX 88 226 294 359 523
BUMAX Lock 226
80 212 275 337 490
70 159 207 253 368
50 74 96 118 172
Nominal stress area mm² 353 459 561 817
Pitch of thread 3.0 3.0 3.5 4.0
Thread size and class Class 1/4-20 UNC 5/16-18 UNC 3/8-16 UNC 1/2-13 UNC 5/8-11 UNC 3/4-10 UNC 7/8-9 UNC 1″-8 UNC
Tightening Torque Mv in Nm 1), 3) BUMAX 88 11.0 22.0 39.0 95.0 188.0 329.0 527.0 789.0
80 10.0 21.0 37.0 89.0 175.0 308.0 493.0 737.0
70 7.7 16.0 28.0 66.0 131.0 231.0 369.0 553.0
50 3.6 7.3 13.0 31.0 61.0 108.0 172.0 258.0
Preload applied KN ± 23% 2) BUMAX 88 8.7 14.3 21.1 38.7 61.7 91.2 125.9 165.2
80 8.0 13.2 19.5 35.7 56.9 84.2 116.2 152.5
70 6.0 9.9 14.6 26.8 42.7 63.2 87.2 114.4
50 2.8 4.6 6.8 12.5 19.9 29.5 40.7 53.4
Failure load KN BUMAX 88 17.0 28.0 41.5 75.9 121.0 179.0 247.0 325.0
80 17.0 28.0 41.5 75.9 121.0 179.0 247.0 325.0
70 14.3 23.6 35.0 64.1 102.2 151.2 208.6 273.7
50 10.2 16.9 25.0 45.7 73.0 108.0 149.0 195.5
Yield load KN BUMAX 88 13.1 22.4 33.2 60.8 96.9 143.4 197.9 259.6
80 12.3 20.3 30.0 54.9 87.6 129.6 178.8 234.6
70 9.2 15.2 22.5 41.2 65.7 97.2 134.1 175.9
50 4.3 7.1 10.5 19.2 30.7 45.4 62.6 82.1
Nominal stress area mm² 20.5 33.8 50.0 91.5 146.0 216.0 298.0 391.0

1) The Mv recommendations refer to burr-free surfaces lubricated with a good quality lubricant.

2) The preload applied is calculated as 65% of Rp 0,2 but in practice the value can be expected to vary between 50-80%

3) The Mv recommendations are calculated assuming a coefficient of friction of 0,16 wwhich requires a good quality lubricant.

 

Hole sizes and torque for Taptite

Description Material thickness Dimensions
M3 M4 M5 M6 M8 M10
Hole size
0.1 – 1.5 2.7 3.65
1.51 – 2.5 2.8 3.65 4.6 5.5
2.51 – 4 2.8 3.7 4.7 5.6 7.5 9.3
4.01 – 6.5 2.85 3.75 4.7 5.6 7.5 9.3
6.51 – 10 3.8 4.75 5.65 7.6 9.4
10.01 – 15 5.7 7.7 9.5
15.01 – 20 7.7 9.6
Breaking Torque in Nm min Property-class
BUMAX Hard 4.5 7.9 13 20 30 52
Standard TT 2.2 3.8 7.8 13 32 45
Tightening Torque Mv in Nm BUMAX Hard 1.3 3 6 12 25 49
Standard TT 1.2 2.7 5.4 9.3 22 40

1) The Mv recommendations refer to burr-free surfaces lubricated with a good quality lubricant.

2) The Mv-recommendations are calculated assuming a coefficient of friction of 0.16 that requires a good-quality lubricant.

Assembling

When assembling Stainless joints, a very low revolution screw-driving machine is required or the screws should be tightened by hand. Punching screw-driving machines should not be used. In very unfavourable assembling conditions MoS2 or suchlike is recommended. If considerable thread galling problems occur when assembling, please contact our technical customer service.