18-8 SS Hex Nut
18-8 SS Hex Nut
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18-8 stainless steel hex nuts are made from one of the following austenitic alloys: 303, 303Se, 304, XM7, all of which are characterized as having a chromium content of 17-19% and nickel content of 8-10%. Dimensional specifications are governed by ASME B18.2.2. There are no grade markings on 18-8 stainless hex nuts. 300 series stainless steel fasteners are commonly used in applications that require general atmospheric corrosion resistance, such as chemical and food processing equipment. Stainless steel has a higher corrosion resistance than carbon steel.
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Governing Standards
| ASME B18.2.2 | Covers the complete general and dimensional data for the various types of inch series square and hex nuts, including machine screw nuts and coupling nuts. |
| ASME B1.1 UNC & UNF Class 2B | Specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads. |
18-8 Stainless Steel requires no material marking
Dimensional Specifications
| Per ASME B18.2.2-2015 | |||||||||||
| Nominal Diameter | UNC | UNF | F | G | H | ||||||
| Width Across Flats | Width Across Corners | Thickness | |||||||||
| Basic | Max | Min | Max | Min | Basic | Max | Min | ||||
| #0 | 0.060 | 80 | 80 | 5/32 | 0.1560 | 0.1500 | 0.2210 | 0.2060 | 5/32 | 0.0500 | 0.0430 |
| #1 | 0.073 | 64 | 72 | 5/32 | 0.1560 | 0.1500 | 0.2210 | 0.2060 | 5/32 | 0.0500 | 0.0430 |
| #2 | 0.086 | 56 | 72 | 3/16 | 0.1880 | 0.1800 | 0.2650 | 0.2050 | 3/16 | 0.0660 | 0.0570 |
| #3 | 0.099 | 48 | 64 | 3/16 | 0.1880 | 0.1800 | 0.2650 | 0.2050 | 3/16 | 0.0660 | 0.0570 |
| #4 | 0.112 | 40 | 48 | 1/4 | 0.2500 | 0.2410 | 0.2890 | 0.2750 | 1/4 | 0.0980 | 0.0870 |
| #5 | 0.125 | 40 | 44 | 5/16 | 0.3120 | 0.3020 | 0.3610 | 0.3440 | 5/16 | 0.1140 | 0.1020 |
| #6 | 0.138 | 32 | 40 | 5/16 | 0.3120 | 0.3020 | 0.3610 | 0.3440 | 5/16 | 0.1140 | 0.1020 |
| #8 | 0.164 | 32 | 36 | 11/32 | 0.3440 | 0.3320 | 0.3970 | 1.2540 | 11/32 | 0.1300 | 0.1170 |
| #10 | 0.190 | 24 | 32 | 3/8 | 0.3750 | 0.3620 | 0.4330 | 1.4650 | 3/8 | 0.1300 | 0.1170 |
| #12 | 0.216 | 24 | 28 | 7/16 | 0.4380 | 0.4380 | 0.5050 | 1.6750 | 7/16 | 0.1610 | 0.1480 |
| 1/4 | 0.2500 | 20 | 28 | 7/16 | 0.4380 | 0.4280 | 0.5050 | 0.4880 | 7/32 | 0.2260 | 0.2120 |
| 5/16 | 0.3125 | 18 | 24 | 1/2 | 0.5000 | 0.4890 | 0.5770 | 0.5570 | 17/64 | 0.2730 | 0.2580 |
| 3/8 | 0.3750 | 16 | 24 | 9/16 | 0.5630 | 0.5510 | 0.6500 | 0.6280 | 21/64 | 0.3370 | 0.3200 |
| 7/16 | 0.4375 | 14 | 20 | 11/16 | 0.6880 | 0.6750 | 0.7940 | 0.7680 | 3/8 | 0.3850 | 0.3650 |
| 1/2 | 0.5000 | 13 | 20 | 3/4 | 0.7500 | 0.7300 | 0.8660 | 0.8400 | 7/16 | 0.4480 | 0.4270 |
| 9/16 | 0.5625 | 12 | 18 | 7/8 | 0.8750 | 0.8610 | 1.0100 | 0.9820 | 31/64 | 0.4960 | 0.4730 |
| 5/8 | 0.6250 | 11 | 18 | 15/16 | 0.9380 | 0.9220 | 1.0830 | 1.0510 | 35/64 | 0.5590 | 0.5350 |
| 3/4 | 0.7500 | 10 | 16 | 1 1/8 | 1.1250 | 1.0880 | 1.2990 | 1.2400 | 41/64 | 0.6650 | 0.6170 |
| 7/8 | 0.8750 | 9 | 14 | 1 5/16 | 1.3120 | 1.2690 | 1.5160 | 1.4470 | 3/4 | 0.7760 | 0.7240 |
| 1 | 1.0000 | 8 | 14 | 1 1/2 | 1.5000 | 1.4500 | 1.7320 | 1.6530 | 55/64 | 0.8870 | 0.8310 |
| 1 1/8 | 1.1250 | 7 | 12 | 1 11/16 | 1.6880 | 1.6310 | 1.9490 | 1.8590 | 31/32 | 0.9990 | 0.9390 |
| 1 1/4 | 1.2500 | 7 | 12 | 1 7/8 | 1.8750 | 1.8120 | 2.1650 | 2.0660 | 1 1/16 | 1.0940 | 1.0300 |
| 1 3/8 | 1.3750 | 6 | 12 | 2 1/16 | 2.0620 | 1.9940 | 2.3820 | 2.2730 | 1 11/16 | 1.2060 | 1.3800 |
| 1 1/2 | 1.5000 | 6 | 12 | 2 1/4 | 2.2500 | 2.1750 | 2.5980 | 2.4800 | 1 9/32 | 1.3170 | 1.2450 |
- All dimensions are in inches.