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16UN - 60 Degree Unified Threads

with Controlled Root Radius and Increased Minor Diameter

The 16-thread series (16-UN) is a uniform pitch series for large diameters requiring fine-pitch threads. It is suitable for adjusting collars and retaining nuts, and also serves as a continuation of the Extra-fine Thread Series for diameters larger than 1 11⁄16 inches.

7/16" - 1 1/16" 1 1/16" - 1 5/8" 1 11/16" - 2 1/2" 2 5/8" - 3 3/4" 3 7/8" - 6"

16UN Threads

Nominal Size External (b) Internal (b)
Threads per Inch and Series Designation Class Allowance Major Diameter Minor Diameter UNR Minor Dia.,c Max (Ref.) Class Minor Diameter Pitch Diameter Major Diameter
Max (d) Min Min (e) Max (d) Min Min Max Min Max Min
7/16" - 16 UN 2A 0.0014 11.077 10.838 - 10.046 9.929 9.185 2B 9.398 9.754 10.081 10.231 11.113
7/16" - 16 UN 3A 0 11.113 10.874 - 10.081 9.995 9.22 3B 9.398 9.652 10.081 10.196 11.113
1/2" - 16 UN 2A 0.0014 12.664 12.426 - 11.633 11.514 10.772 2B 10.973 11.328 11.669 11.824 12.7
1/2" - 16 UN 3A 0 12.7 12.461 - 11.669 11.58 10.808 3B 10.973 11.224 11.669 11.786 12.7
9/16" - 16 UN 2A 0.0014 14.252 14.013 - 13.221 13.101 12.36 2B 12.573 12.929 13.256 13.411 14.288
9/16" - 16 UN 3A 0 14.288 14.049 - 13.256 13.167 12.395 3B 12.573 12.802 13.256 13.373 14.288
5/8" - 16 UN 2A 0.0014 15.839 15.601 - 14.808 14.686 13.947 2B 14.148 14.503 14.844 15.001 15.875
5/8" - 16 UN 3A 0 15.875 15.636 - 14.844 14.752 13.983 3B 14.148 14.381 14.844 14.961 15.875
11/16" - 16 UN 2A 0.0014 17.427 17.188 - 16.396 16.274 15.535 2B 15.748 16.104 16.431 16.589 17.463
11/16" - 16 UN 3A 0 17.463 17.224 - 16.431 16.34 15.57 3B 15.748 15.961 16.431 16.548 17.463
13/16" - 16 UN 2A 0.0015 20.599 20.361 - 19.568 19.444 18.707 2B 18.923 19.279 19.606 19.766 20.638
13/16" - 16 UN 3A 0 20.638 20.399 - 19.606 19.515 18.745 3B 18.923 19.134 19.606 19.726 20.638
7/8" - 16 UN 2A 0.0015 22.187 21.948 - 21.156 21.031 20.066 2B 20.498 20.853 21.194 21.354 22.225
7/8" - 16 UN 3A 0 22.225 21.986 - 21.194 21.102 20.333 3B 20.498 20.721 21.194 21.313 22.225
15/16" - 16 UN 2A 0.0015 23.774 23.536 - 22.743 22.616 21.882 2B 22.098 22.454 22.781 22.946 23.813
15/16" - 16 UN 3A 0 23.813 23.574 - 22.781 22.687 21.92 3B 22.098 22.309 22.781 22.906 23.813
1" - 16 UN 2A 0.0015 25.362 25.123 - 24.331 24.204 23.47 2B 23.673 24.028 24.369 24.534 25.4
1" - 16 UN 3A 0 25.4 25.161 - 24.369 24.275 23.508 3B 23.673 23.896 24.369 24.493 25.4
1 1/16" - 16 UN 2A 0.0015 26.949 26.711 - 25.918 25.791 25.057 2B 25.273 25.629 25.956 26.121 26.988
1 1/16" - 16 UN 3A 0 26.988 26.749 - 25.956 25.862 25.095 3B 25.273 25.484 25.956 26.081 26.988
1 1/8" - 16 UN 2A 0.0015 28.537 28.298 - 27.506 27.379 26.645 2B 26.848 27.203 27.544 27.709 28.575
1 1/8" - 16 UN 3A 0 28.575 28.336 - 27.544 27.45 26.683 3B 26.848 27.071 27.544 27.668 28.575
1 3/8" - 16 UN 2A 0.0015 30.124 29.886 - 29.093 28.964 28.232 2B 28.448 28.804 29.131 29.299 30.163
1 3/8" - 16 UN 3A 0 30.163 29.924 - 29.131 29.035 28.27 3B 28.448 28.659 29.131 29.258 30.163
1 1/4" - 16 UN 2A 0.0015 31.712 31.473 - 30.681 30.551 29.82 2B 30.023 30.378 30.719 30.886 31.75
1 1/4" - 16 UN 3A 0 31.75 31.511 - 30.719 30.622 29.858 3B 30.023 30.246 30.719 30.846 31.75
1 5/16" - 16 UN 2A 0.0015 33.299 33.061 - 32.268 32.139 31.407 2B 31.623 31.979 32.306 32.474 33.338
1 5/16" - 16 UN 3A 0 33.338 33.099 - 32.306 32.21 31.445 3B 31.623 31.834 32.306 32.433 33.338
1 3/8" - 16 UN 2A 0.0015 34.887 34.648 - 33.856 33.726 32.995 2B 33.198 33.553 33.894 34.061 34.925
1 3/8" - 16 UN 3A 0 34.925 34.686 - 33.894 33.797 33.033 3B 33.198 33.421 33.894 34.021 34.925
1 7/16" - 16 UN 2A 0.0016 36.472 36.233 - 35.441 35.309 34.58 2B 34.798 35.154 35.481 35.654 36.513
1 7/16" - 16 UN 3A 0 36.513 36.274 - 35.481 35.382 34.62 3B 34.798 35.009 35.481 35.611 36.513
1 1/2" - 16 UN 2A 0.0016 38.059 37.821 - 37.028 36.896 36.167 2B 36.373 36.728 37.069 37.241 38.1
1 1/2" - 16 UN 3A 0 38.1 37.861 - 37.069 36.97 36.208 3B 36.373 36.596 37.069 37.198 38.1
1 9/16" - 16 UN 2A 0.0016 39.647 39.408 - 38.616 38.484 37.755 2B 37.973 38.329 38.656 38.829 39.688
1 9/16" - 16 UN 3A 0 39.688 39.449 - 38.656 38.557 37.795 3B 37.973 38.184 38.656 38.786 39.688
1 5/8" - 16 UN 2A 0.0016 41.234 40.996 - 40.203 40.071 39.342 2B 39.548 39.903 40.244 40.416 41.275
1 5/8" - 16 UN 3A 0 41.275 41.036 - 40.244 40.145 39.383 3B 39.548 39.771 40.244 40.373 41.275
1 11/16" - 16 UN 2A 0.0016 42.822 42.583 - 41.791 41.656 40.93 2B 41.148 41.504 41.831 42.007 42.863
1 11/16" - 16 UN 3A 0 42.863 42.624 - 41.831 41.73 40.97 3B 41.148 41.359 41.831 41.963 42.863
1 3/4" - 16 UN 2A 0.0016 44.409 44.171 - 43.378 43.244 42.517 2B 42.723 43.078 43.419 43.594 44.45
1 3/4" - 16 UN 3A 0 44.45 44.211 - 43.419 43.317 42.558 3B 42.723 42.946 43.419 43.551 44.45
1 13/16" - 16 UN 2A 0.0016 45.997 45.758 - 44.966 44.831 44.105 2B 44.323 44.679 45.006 45.182 46.038
1 13/16" - 16 UN 3A 0 46.038 45.799 - 45.006 44.905 44.145 3B 44.323 44.534 45.006 45.138 46.038
1 7/8" - 16 UN 2A 0.0016 47.584 47.346 - 46.553 46.419 45.692 2B 45.898 46.253 46.594 46.769 47.625
1 7/8" - 16 UN 3A 0 47.625 47.386 - 46.594 46.492 45.733 3B 45.898 46.121 46.594 46.726 47.625
1 15/16" - 16 UN 2A 0.0016 49.172 48.933 - 48.141 48.003 47.28 2B 47.498 47.854 48.181 48.359 49.213
1 15/16" - 16 UN 3A 0 49.213 48.974 - 48.181 48.08 47.32 3B 47.498 47.709 48.181 48.313 49.213
2" - 16 UN 2A 0.0016 50.759 50.521 - 49.728 49.591 48.867 2B 49.073 49.428 49.769 49.947 50.8
2" - 16 UN 3A 0 50.8 50.561 - 49.769 49.667 48.908 3B 49.073 49.296 49.769 49.901 50.8
2 1/8" - 16 UN 2A 0.0016 53.934 53.696 - 52.903 52.766 52.042 2B 52.248 52.603 52.944 53.122 53.975
2 1/8" - 16 UN 3A 0 53.975 53.736 - 52.944 52.84 52.083 3B 52.248 52.471 52.944 53.076 53.975
2 1/4" - 16 UN 2A 0.0016 57.109 56.871 - 56.078 55.941 55.217 2B 55.423 55.778 56.119 56.297 57.15
2 1/4" - 16 UN 3A 0 57.15 56.911 - 56.119 56.015 55.258 3B 55.423 55.778 56.119 56.251 57.15
2 3/8" - 16 UN 2A 0.0017 60.282 60.043 - 59.251 59.111 58.39 2B 58.598 58.953 59.294 59.477 60.325
2 3/8" - 16 UN 3A 0 60.325 60.086 - 59.294 59.19 58.433 3B 58.598 58.821 59.294 59.431 60.325
2 1/2" - 16 UN 2A 0.0017 63.457 63.218 - 62.426 62.286 61.565 2B 61.773 62.128 62.469 62.652 63.5
2 1/2" - 16 UN 3A 0 63.5 63.261 - 62.469 62.365 61.608 3B 61.773 61.996 62.469 62.606 63.5
2 5/8" - 16 UN 2A 0.0017 66.632 66.393 - 65.601 65.461 64.74 2B 64.948 65.303 65.644 65.827 66.675
2 5/8" - 16 UN 3A 0 66.675 66.436 - 65.644 65.54 64.783 3B 64.948 65.171 65.644 65.781 66.675
2 3/4" - 16 UN 2A 0.0017 69.807 69.568 - 68.776 68.636 67.915 2B 68.123 68.478 68.819 69.002 69.85
2 3/4" - 16 UN 3A 0 69.85 69.611 - 68.819 68.715 67.958 3B 68.123 68.346 68.819 68.956 69.85
2 7/8" - 16 UN 2A 0.0017 72.982 72.743 - 71.951 71.808 71.09 2B 71.298 71.653 71.994 72.179 73.025
2 7/8" - 16 UN 3A 0 73.025 72.786 - 71.994 71.887 71.133 3B 71.298 71.521 71.994 72.133 73.025
3" - 16 UN 2A 0.0017 76.157 75.918 - 75.126 74.983 74.265 2B 74.473 74.828 75.169 75.354 76.2
3" - 16 UN 3A 0 76.2 75.961 - 75.169 75.062 74.308 3B 74.473 74.696 75.169 75.308 76.2
3 1/8" - 16 UN 2A 0.0017 79.332 79.093 - 78.301 78.158 77.44 2B 77.648 78.003 78.344 78.529 79.375
3 1/8" - 16 UN 3A 0 79.375 79.136 - 78.344 78.237 77.483 3B 77.648 77.871 78.344 78.483 79.375
3 1/4" - 16 UN 2A 0.0017 82.507 82.268 - 81.476 81.333 80.615 2B 80.823 81.178 81.519 81.704 82.55
3 1/4" - 16 UN 3A 0 82.55 82.311 - 81.519 81.412 80.658 3B 80.823 81.046 81.519 81.658 82.55
3 3/8" - 16 UN 2A 0.0017 85.682 85.443 - 84.651 84.503 83.79 2B 83.998 84.353 84.694 84.884 85.725
3 3/8" - 16 UN 3A 0 85.725 85.486 - 84.694 84.585 83.833 3B 83.998 84.221 84.694 84.836 85.725
3 1/2" - 16 UN 2A 0.0017 88.857 88.618 - 87.826 87.678 86.965 2B 87.173 87.528 87.869 88.059 88.9
3 1/2" - 16 UN 3A 0 88.9 88.661 - 87.869 87.76 87.008 3B 87.173 87.396 87.869 88.011 88.9
3 5/8" - 16 UN 2A 0.0017 92.032 91.793 - 91.001 90.853 90.14 2B 90.348 90.703 91.044 91.234 92.075
3 5/8" - 16 UN 3A 0 92.075 91.836 - 91.044 90.935 90.183 3B 90.348 90.571 91.044 91.186 92.075
3 3/4" - 16 UN 2A 0.0017 95.207 94.968 - 94.176 94.028 93.315 2B 93.523 93.878 94.219 94.409 95.25
3 3/4" - 16 UN 3A 0 95.25 95.011 - 94.219 94.11 93.358 3B 93.523 93.746 94.219 94.361 95.25
3 7/8" - 16 UN 2A 0.0018 98.379 98.141 - 97.348 97.198 96.487 2B 96.698 97.053 97.394 97.587 98.425
3 7/8" - 16 UN 3A 0 98.425 98.186 - 97.394 97.282 96.533 3B 96.698 96.921 97.394 97.539 98.425
4" - 16 UN 2A 0.0018 101.554 101.316 - 100.523 100.373 99.662 2B 99.873 100.228 100.569 100.762 101.6
4" - 16 UN 3A 0 101.6 101.361 - 100.569 100.457 99.708 3B 99.873 100.096 100.569 100.714 101.6
4 1/4" - 16 UN 2A 0.0018 107.904 107.666 - 106.873 106.723 106.012 2B 106.223 106.578 106.919 107.112 107.95
4 1/4" - 16 UN 3A 0 107.95 107.711 - 106.919 106.807 106.058 3B 106.223 106.426 106.919 107.064 107.95
5 3/4" - 16 UN 2A 0.0019 146.002 145.763 - 144.971 144.813 144.109 2B 144.323 144.678 145.019 145.225 146.05
5 3/4" - 16 UN 3A 0 146.05 145.811 - 145.019 144.899 144.158 3B 144.323 144.546 145.019 145.174 146.05
6" - 16 UN 2A 0.0019 152.352 152.113 - 151.321 151.163 150.459 2B 150.673 151.028 151.369 151.575 152.4
6" - 16 UN 3A 0 152.4 152.161 - 151.369 151.249 150.508 3B 150.673 150.896 151.369 151.524 152.4