Lock Nuts

Lock nuts come in many different grades, styles, and finishes. As the name signifies, lock nuts are not irremovable once they are fixed. On the contrary, it is possible to remove most of the locknuts and perhaps some can be reused provided they are removed correctly. These nuts are commonly available in ASTM A194 Grade 2H and ASTM A563 Grades A & DH.

Lock nuts are manufactured using a heavy hex or standard hex pattern. Tri-Lok and Anco are the most common style of lock nuts. Anco style happens to be a self-locking nut provided with a ratchet pin made of stainless steel. When the nut is spun right onto the bolt, this pin slides all along the threads and prevents the nut from pulling back. The major benefit of using an Anco style nut is that it is possible to bend the ratchet pin back so that the nut could be removed easily if necessary. Tri-Lok style appears to be a “prevailing-torque” lock nut that is frictionally resistant to rotation owing to the thread distortion found on the nut’s top thread. For more information on the other kinds of lock nuts, contact us today to discuss with our expert estimators!

Finished Hex Dimensions

Click table to show drawingDimensioned Anco Lock Nut
Nominal Size F C H Weight Each (lbs.)
Width Across Flats Width Across Corners Thickness
Basic Max Min Max Min Basic Max Min
12 34 0.750 0.736 0.866 0.840 716 0.448 0.427 0.04
58 1516 0.938 0.922 1.083 1.051 3564 0.559 0.535 0.07
34 118 1.125 1.088 1.299 1.240 4164 0.665 0.617 0.12
78 1516 1.312 1.269 1.516 1.447 34 0.776 0.724 0.19
1 112 1.500 1.450 1.732 1.653 5564 0.887 0.831 0.28
118 11116 1.688 1.631 1.949 1.859 3132 0.999 0.939 0.40
114 178 1.875 1.812 2.165 2.066 1116 1.094 1.030 0.54
138 2116 2.062 1.994 2.382 2.273 11164 1.206 1.138 0.73
112 214 2.250 2.175 2.598 2.480 1932 1.317 1.245 0.94
Dimensions per ASME B18.2.2 1987 (1999)

Heavy Hex Dimensions

Click table to show drawingDimensioned Anco Lock Nut
Nominal Size F C H Weight Each (lbs.)
Width Across Flats Width Across Corners Thickness
Basic Max Min Max Min Basic Max Min
12 78 0.875 0.850 1.010 0.969 3164 0.504 0.464 0.07
58 1116 1.062 1.031 1.227 1.175 3964 0.631 0.587 0.12
34 114 1.250 1.212 1.443 1.382 4764 0.758 0.710 0.20
78 1716 1.438 1.394 1.660 1.589 5564 0.885 0.833 0.30
1 158 1.625 1.575 1.876 1.796 6364 1.012 0.956 0.43
118 11316 1.812 1.756 2.093 2.002 1764 1.139 1.079 0.59
114 2 2.000 1.938 2.309 2.209 1732 1.251 1.187 0.79
138 2316 2.188 2.119 2.526 2.416 11132 1.378 1.310 1.02
112 238 2.375 2.300 2.742 2.622 11532 1.505 1.433 1.31
158 2916 2.562 2.481 2.959 2.828 11932 1.632 1.556 1.62
134 234 2.750 2.662 3.175 3.035 12332 1.759 1.679 2.04
178 21516 2.938 2.844 3.392 3.242 12732 1.886 1.802 2.41
2 318 3.125 3.025 3.608 3.449 13132 2.013 1.925 2.99
214 312 3.500 3.388 4.041 3.862 21364 2.251 2.155 4.19
212 378 3.875 3.750 4.474 4.275 22964 2.505 2.401 5.64
234 414 4.250 4.112 4.907 4.688 24564 2.759 2.647 7.38
3 458 4.625 4.475 5.340 5.102 26164 3.013 2.893 9.50
314 5 5.000 4.838 5.774 5.515 3316 3.252 3.124 11.94
312 538 5.375 5.200 6.207 5.928 3716 3.506 3.370 15.26
334 534 5.750 5.562 6.640 6.341 31116 3.760 3.616 18.12
4 618 6.125 5.925 7.073 6.755 31516 4.014 3.862 21.80
Dimensions per ASME B18.2.2 1987 (1999)