Grade 8M SS Heavy Hex Nut
Choose Favorites List

Grade 8M SS Heavy Hex Nut

ASTM A194 Grade 8M heavy hex nuts are manufactured from AISI 316 grade stainless steel and tested to meet ASTM A194 Grade 8M. Dimensional specifications are governed by ASME B18.2.2. Grade markings for A194 Grade 8M heavy hex nuts consists of the number/letter combination of 8M. Grade 8M stainless steel heavy hex nuts are intended for use in high-pressure and/or high-temperature service with ASTM A193 and A320 bolting of similar material, such as B8M and B8M Class 2. Heavy hex nuts provide increased bearing surface area over finished nuts.

Governing StandardsGrade 8M Stainless Steel

ASTM A194 This specification covers a variety of carbon, alloy, and martensitic stainless steel nuts in the size range 1⁄4 through 4 in. and metric M6 through M100 nominal. It also covers austenitic stainless steel nuts in the size range 1⁄4 in. and M6 nominal and above. These nuts are intended for high-pressure or high temperature service, or both. Grade substitutions without the purchaser’s permission are not allowed.
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.

Grade 8M Stainless Steel Head Marking
Grade 8M Stainless Steel Material Marking

Mechanical PropertiesGrade 8M Stainless Steel

Stainless AISI 316 Per ASTM A194/A194M-16
Diameter Proof Load Stress Core Hardness
Min psi Rockwell
1/4" thru 4" 80,000 C32 max

Chemical PropertiesGrade 8M Stainless Steel

Per ASTM A194/A194M-16
Grade Material Carbon Manganese Phosphorus Sulfur (1) Silicon Chromium Nickel Molybdenum
% by weight % by weight % by weight % by weight % by weight % by weight % by weight % by weight
8M Type 316 Stainless Steel 0.08 max 2.00 max 0.045 max 0.030 max 1.00 max 16.0-18.0 10.0-14.0 2.00-3.00
  1. 1. Because of the degree to which sulfur segregates, product analysis for sulfur over 0.060 % max is not technologically appropriate.

Dimensional SpecificationsGrade 8M Stainless Steel

Heavy hex nut dimensions
Per ASME B18.2.2-2015
Nominal Diameter UNC UN8 F G H
Width Across Flats Width Across Corners Thickness
Basic Max Min Max Min Basic Max Min
1/4 0.250 20   1/2 0.500 0.488 0.577 0.556 15/64 0.250 0.218
5/16 0.313 18   9/16 0.562 0.546 0.650 0.220 19/64 0.314 0.280
3/8 0.375 16   11/16 0.688 0.669 0.794 0.763 23/64 0.377 0.341
7/16 0.438 14   3/4 0.750 0.728 0.866 0.830 27/64 0.441 0.403
1/2 0.500 13   7/8 0.875 0.850 1.010 0.990 31/64 0.504 0.464
9/16 0.563 12   15/16 0.938 0.909 1.083 1.037 35/64 0.568 0.526
5/8 0.625 11   1 1/16 1.062 1.031 1.227 1.175 39/64 0.631 0.587
3/4 0.750 10   1 1/4 0.250 1.212 1.443 1.382 47/64 0.758 0.710
7/8 0.875 9   1 7/16 1.438 1.394 1.660 1.589 55/64 0.885 0.833
1 1.000 8   1 5/8 1.625 1.575 1.876 1.796 63/64 1.012 0.956
1 1/8 1.125 7 8 1 13/16 1.812 1.756 2.093 2.002 1 7/64 1.139 1.079
1 1/4 1.250 7 8 2 2.000 1.380 2.309 2.209 1 7/32 1.251 1.187
1 3/8 1.375 6 8 2 3/16 2.188 2.119 2.526 2.416 1 11/32 1.378 1.310
1 1/2 1.500 6 8 2 3/8 2.375 2.300 2.742 2.622 1 15/32 1.505 1.433
1 5/8 1.625 5 1/2 8 2 9/16 2.562 2.481 2.959 2.828 1 19/32 1.632 1.556
1 3/4 1.750 5 8 2 3/4 2.750 2.662 3.175 3.035 1 23/32 1.759 1.679
1 7/8 1.875 5 8 2 15/16 2.938 2.844 3.392 3.242 1 27/32 1.886 1.802
2 2.000 4 1/2 8 3 1/8 3.125 3.025 3.608 3.449 1 31/32 2.013 1.925
2 1/4 2.250 4 1/2 8 3 1/2 3.500 3.388 4.041 3.862 2 13/64 2.251 2.155
2 1/2 2.500 4 8 3 7/8 3.875 3.750 4.474 4.275 2 29/64 2.505 2.401
2 3/4 2.750 4 8 4 1/4 4.250 4.112 4.907 4.688 2 45/64 2.759 2.647
3 3.000 4 8 4 5/8 4.625 4.475 5.340 5.102 2 61/64 3.013 2.893
3 1/4 3.250 4 8 5 5.000 4.838 5.774 5.515 3 3/16 3.252 3.124
3 1/2 3.500 4 8 5 3/8 5.375 5.200 6.207 5.928 3 7/16 3.506 3.370
3 3/4 3.750 4 8 5 3/4 5.750 5.562 5.562 6.341 3 11/16 3.670 3.616
4 4.000 4 8 6 1/8 6.125 5.925 5.925 6.755 3 15/16 4.014 3.862
  1. All dimensions are in inches.
Grade 8M SS Heavy Hex Nut
View
Diameter Thread Pitch Width Across Flats Height of Nut Item # Availability Price Quantity UOM
1/4 20 1/2 0.2344 NH8M0250000-I In Stock $0.2066/EA EA
5/16 18 9/16 0.2969 NH8M0310000-I 3-5 Working Days $0.27873/EA EA
3/8 16 11/16 0.3594 NH8M0370000-I In Stock $0.27908/EA EA
7/16 14 3/4 0.4219 NH8M0430000-I In Stock $0.64221/EA EA
1/2 13 7/8 0.4844 NH8M0500000-I In Stock $0.50531/EA EA
9/16 12 15/16 0.5469 NH8M0560000-I In Stock $3.7309/EA EA
5/8 11 1 1/16 0.6094 NH8M0620000-I In Stock $1.30564/EA EA
3/4 10 1 1/4 0.7344 NH8M0750000-I In Stock $1.77608/EA EA
7/8 9 1 7/16 0.8594 NH8M0870000-I In Stock $3.7542/EA EA
1 8 1 5/8 0.9844 NH8M1000000-I In Stock $5.37878/EA EA
1 1/8 7 1 13/16 1.1094 NH8M112NC00-I In Stock $8.53506/EA EA
1 1/8 8 1 13/16 1.1094 NH8M1120000-I In Stock $5.37363/EA EA
1 1/4 7 2 1.2188 NH8M125NC00-I In Stock $11.41011/EA EA
1 1/4 8 2 1.2188 NH8M1250000-I In Stock $6.96747/EA EA
1 3/8 8 2 3/16 1.3438 NH8M1370000-I In Stock $9.7585/EA EA
1 1/2 6 2 3/8 1.4688 NH8M150NC00-I In Stock $10.81081/EA EA
1 1/2 8 2 3/8 1.4688 NH8M1500000-I In Stock $13.79774/EA EA