IFI-124 Standard
Prevailing-Torques for Nonmetallic Resistant Element Screws – Unified Coarse and Fine Thread Series
| Nom Size of Screw and Threads per Inch | Clamp Load (1) lbs. | First on Prevaling-Torque in. lbs. | First Removal Prevailing-Torque in. lbs. | Fifth Removal Prevailing-Torque in. lbs. | ||
| Strength Grade of Screw | ||||||
| SAE Grade 5 or ASTM A449 | SAE Grade 8 or ASTM A354 | ASTM A574 | Max | Min | Min | |
| #0-80 | 115 | 160 | 190 | 0.75 | 1.5* | 0.5* |
| #2-56 | 234 | 330 | 390 | 2 | 3* | 1.5* |
| #2-64 | 250 | 355 | 410 | 2 | 3* | 1.5* |
| #4-40 | 385 | 540 | 635 | 5 | 1 | 0.5 |
| #4-48 | 420 | 595 | 690 | 5 | 1 | 0.5 |
| #6-32 | 580 | 820 | 950 | 8 | 2 | 1 |
| #6-40 | 650 | 910 | 1060 | 8 | 2 | 1 |
| #8-32 | 900 | 1260 | 1470 | 12 | 2.5 | 1.5 |
| #8-36 | 940 | 1330 | 1540 | 12 | 2.5 | 1.5 |
| #10 -24 | 1120 | 1580 | 1840 | 18 | 3 | 2 |
| #10 -32 | 1280 | 1800 | 2100 | 18 | 3 | 2 |
| 1/4-20 | 2020 | 2850 | 3220 | 40 | 5 | 3 |
| 1/4-28 | 2320 | 3260 | 3680 | 40 | 5 | 3 |
| 5/16-18 | 3340 | 4720 | 5300 | 85 | 8 | 5 |
| 5/16-24 | 3680 | 5210 | 5870 | 85 | 8 | 5 |
| 3/8-16 | 4950 | 6980 | 7880 | 110 | 14 | 9 |
| 3/8-24 | 5590 | 7880 | 8900 | 110 | 14 | 9 |
| 7/16-14 | 6790 | 9600 | 10800 | 150 | 20 | 12 |
| 7/16-20 | 7580 | 10600 | 12000 | 150 | 20 | 12 |
| 1/2-13 | 9080 | 12800 | 14400 | 220 | 26 | 16 |
| 1/2-20 | 10200 | 14400 | 16200 | 220 | 26 | 16 |
| 9/16-12 | 11600 | 16400 | 18400 | 270 | 35 | 22 |
| 9/16-18 | 13000 | 18300 | 20600 | 270 | 35 | 22 |
| 5/8-11 | 14400 | 20300 | 22900 | 350 | 45 | 30 |
| 5/8-18 | 16400 | 23000 | 26000 | 350 | 45 | 30 |
| 3/4-10 | 21300 | 30100 | 33800 | 460 | 60 | 45 |
| 3/4-16 | 23800 | 33600 | 37800 | 460 | 60 | 45 |
| 7/8-9 | 29500 | 41600 | 46800 | 700 | 95 | 65 |
| 7/8-14 | 32500 | 45800 | 51500 | 700 | 95 | 65 |
| 1-8 | 38600 | 54500 | 61400 | 900 | 130 | 85 |
| 1-12 | 42300 | 59700 | 67100 | 900 | 130 | 85 |
| 1-1/8-7 | 42400 | 68700 | 77200 | 1050 | 150 | 110 |
| 1-1/8-12 | 47500 | 77000 | 87000 | 1050 | 150 | 110 |
| 1-1/4-7 | 53800 | 87200 | 98200 | 1150 | 200 | 140 |
| 1-1/4-12 | 59600 | 96600 | 109000 | 1150 | 200 | 140 |
| 1-3/8-6 | 64400 | 104000 | 117000 | 1300 | 240 | 150 |
| 1-3/8-12 | 73000 | 118000 | 134000 | 1300 | 240 | 150 |
| 1-1/2-6 | 78000 | 126000 | 142000 | 1500 | 280 | 185 |
| 1-1/2-12 | 87800 | 142000 | 160000 | 1500 | 280 | 185 |
*Torque values are in inch ounce.
(1) Clamp loads equal 75 percent of the proof loads specified for the respective strength grade of screw material.
IFI Standard is a registered trademark of the Industrial Fasteners Institute of Cleveland, OH.
All standards and specifications are advisory only. Their use by anyone is entirely voluntary. Reliance thereon for any purpose by anyone is at the sole risk of that person or the user of the product, and the IFI is not responsible for any loss, claim, or damage arising therefrom. ln formulating and approving standards and specifications, the IFI has not investigated and will not investigate patents which may apply to the subject matter. Prospective users of the standards and specifications are responsible for advising themselves of and protecting themselves against any patent infringement liability which may arise out of such use. © INDUSTRIAL FASTENERS INSTITUTE 2002