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Lock Nuts

Lock Nuts

Lock nuts are used where there is a significant probability that a nut will loosen over time because of vibration or frequent temperature changes. When the danger of corrosion is not too severe and 18-8 or 316 Stainless is adequate for fastening, we would offer nylon insert locknuts. These nuts feature a nylon ring that compresses against the bolt threads as the nut is tightened. In instances where common stainless would not be adequate to withstand corrosion and a locknut would be required, we would recommend a top-lock nut. These nuts are produced by crimping the top thread of a standard hex nut. When top-lock nuts are assembled, they should spin freely until the lead thread of the bolt meets the distorted thread in the nut. The more the nut is torqued from this point, the greater the effort for disassembly becomes.

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Specifications & Technical Data

Standard Lock Nut Dimensions

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Nominal Size or Basic Thread Diameter F H I G
Width Across Flats Thickness Side Height Width Across Corners
Basic Max Min Max Min Ref Ref
2 0.0860 1/4 0.251 0.243 0.153 0.133 0.081 0.268
3 0.0990 1/4 0.251 0.243 0.153 0.133 0.081 0.268
4 0.1120 1/4 0.251 0.243 0.153 0.133 0.081 0.268
5 0.1250 1/4 0.251 0.243 0.153 0.133 0.081 0.268
6 0.138 5/16 0.313 0.305 0.188 0.168 0.103 0.339
8 0.1640 11/32 0.345 0.336 0.239 0.219 0.140 0.374
10 0.1900 3/8 0.376 0.367 0.249 0.229 0.140 0.410
12 0.2160 7/16 0.439 0.430 0.328 0.298 0.225 0.482
1/4 0.2500 7/16 0.439 0.430 0.328 0.298 0.225 0.482
5/16 0.3125 1/2 0.502 0.492 0.359 0.329 0.250 0.552
3/8 0.3750 9/16 0.564 0.553 0.468 0.438 0.335 0.622
7/16 0.4375 5/8 0.627 0.616 0.468 0.438 0.324 0.698
1/2 0.5000 3/4 0.752 0.741 0.609 0.579 0.464 0.837
9/16 0.5625 7/8 0.877 0.865 0.656 0.626 0.469 0.978
5/8 0.6250 15/16 0.940 0.928 0.765 0.735 0.593 1.051
3/4 0.7500 1-1/8 1.064 1.052 0.890 0.860 0.742 1.191
7/8 0.8750 1-5/16 1.252 1.239 0.999 0.969 0.790 1.403
1 1.0000 1-1/2 1.440 1.427 1.078 1.016 0.825 1.615
1-1/8 1.1250 1-11/16 1.627 1.614 1.203 1.141 0.930 1.826
1-1/4 1.2500 1-7/8 1.815 1.801 1.422 1.360 1.125 2.038
1-1/2 1.5000 2-1/4 2.197 2.159 1.640 1.578 1.313 2.444

 

Heavy Lock Nut Dimensions

Nominal Size or Basic Thread Diameter F H I G
Width Across Flats Thickness Side Height Width Across Corners
Max Min Max Min Ref Ref
1/4 0.2500 0.503 0.489 0.390 0.360 0.290 0.556
5/16 0.3125 0.566 0.551 0.453 0.423 0.335 0.624
3/8 0.3750 0.691 0.675 0.562 0.532 0.392 0.763
7/16 0.4375 0.754 0.736 0.609 0.579 0.464 0.829
1/2 0.5000 0.879 0.861 0.718 0.688 0.544 0.969
5/8 0.6250 1.067 1.045 0.874 0.844 0.677 1.175
3/4 0.7500 1.255 1.231 1.015 0.985 0.790 1.382
7/8 0.8750 1.444 1.417 1.140 1.110 0.883 1.589
1 1.000 1.632 1.602 1.312 1.250 1.000 1.796
1-1/4 1.2500 2.008 1.973 1.672 1.610 1.250 2.209
1-1/2 1.5000 2.384 2.344 1.953 1.891 1.413 2.622
1-5/8 1.6250 2.572 2.530 2.172 2.110 1.637 2.886
1-3/4 1.7500 2.762 2.715 2.376 2.250 1.830 3.035
2 2.000 3.137 3.086 2.469 2.343 1.750 3.449
2-1/4 2.2500 3.514 3.457 2.876 2.750 1.063 3.862

 

Heavy Thin Lock Nut Dimensions

Nominal Size or Basic Thread Diameter F H I G
Width Across Flats Thickness Side Height Width Across Corners
Max Min Max Min Ref Ref
1/4 0.2500 0.502 0.492 0.296 0.266 0.194 0.552
5/16 0.3125 0.564 0.553 0.328 0.298 0.212 0.622
3/8 0.3750 0.690 0.679 0.421 0.391 0.251 0.766
7/16 0.4375 0.752 0.741 0.453 0.423 0.316 0.837
1/2 0.5000 0.877 0.865 0.546 0.516 0.360 0.978
5/8 0.6250 1.064 1.052 0.624 0.594 0.428 1.191
3/4 0.7500 1.252 1.239 0.718 0.688 0.488 1.403
7/8 0.8750 1.440 1.427 0.796 0.766 0.535 1.615
1 1.000 1.627 1.614 0.922 0.860 0.600 1.826

Lock Nut Specifications

  • Standard (ASME/ANSI)
  • Metric (IFI)
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Industries We Serve

Nickel Systems provides high quality exotic grade materials that hold up in the toughest, most severe heat and corrosive environments. With our large inventory of specialty fasteners in stock, we are always ready to answer the call to serve the most challenging applications.

Nickel Systems stocks nylon insert locknuts in 18-8 and 316 Stainless. We stock some top-lock nuts in Hastelloy® C (Alloy C276) and Carpenter® 20 (Alloy 20). Within a reasonably short lead-time, we can provide top-lock nuts in Hastelloy® (Alloys C22, B2), Inconel® 600 (Alloy 600), AL6XN®, Duplex 2205, Nitronic® 60 (A194 8S – Finished Pattern) and 317L Stainless, as we stock standard hex nuts in these materials.

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