2H Heavy Hex Nut
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2H Heavy Hex Nut

ASTM A194 Grade 2H heavy hex nuts are intended for use in flange bolting applications, as well as structural applications and with other high strength bolting. ASTM A194 covers carbon steel, alloy steel, and stainless steel nuts for bolts in high pressure or high temperature service. They are a common high strength nut used with many different bolting grades, including A193 Grade B7, F3125 Grades A325 and A490, as well as with F1554 Grade 105 anchor bolts and studs. Dimensional specifications are governed by ASME B18.2.2. Heavy hex nuts provide increased bearing surface area over finished nuts such as J995 Grade 5 nuts.

Governing StandardsGrade 2H

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 2H Head Marking
Grade 2H Material Marking

Mechanical PropertiesGrade 2H

Carbon Steel, Quenched & Tempered Per ASTM A194/A194M-16
Diameter Proof Load Stress Core Hardness Tempering Temperature
Min psi Rockwell Min
Min Max
1/4" thru 1 1/2" 175,000 C24 C35 850F
Over 1 1/2" 175,000   C35 850F

Chemical PropertiesGrade 2H

Per ASTM A194/A194M-16
Grade Material Carbon Manganese Phosphorus Sulfur (1) Silicon
% by weight % by weight % by weight % by weight % by weight
2H Carbon Steel 0.40 min 1.00 max 0.040 max 0.050 max 0.04 max
  1. 1. Because of the degree to which sulfur segregates, product analysis for sulfur over 0.060 % max is not technologically appropriate.

Dimensional SpecificationsGrade 2H

Heavy hex nut dimensions
Per ASME B18.2.2-2015
Nominal Diameter UNC UNF UN8 F G H
Width Across Flats Width Across Corners Thickness
Basic Max Min Max Min Basic Max Min
1/4 0.250 20 28   1/2 0.500 0.488 0.577 0.556 15/64 0.250 0.218
5/16 0.313 18 24   9/16 0.562 0.546 0.650 0.220 19/64 0.314 0.280
3/8 0.375 16 24   11/16 0.688 0.669 0.794 0.763 23/64 0.377 0.341
7/16 0.438 14 20   3/4 0.750 0.728 0.866 0.830 27/64 0.441 0.403
1/2 0.500 13 20   7/8 0.875 0.850 1.010 0.990 31/64 0.504 0.464
9/16 0.563 12 18   15/16 0.938 0.909 1.083 1.037 35/64 0.568 0.526
5/8 0.625 11 18   1 1/16 1.062 1.031 1.227 1.175 39/64 0.631 0.587
3/4 0.750 10 16   1 1/4 0.250 1.212 1.443 1.382 47/64 0.758 0.710
7/8 0.875 9 14   1 7/16 1.438 1.394 1.660 1.589 55/64 0.885 0.833
1 1.000 8 14   1 5/8 1.625 1.575 1.876 1.796 63/64 1.012 0.956
1 1/8 1.125 7 12 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 12 8 2 2.000 1.380 2.309 2.209 1 7/32 1.251 1.187
1 3/8 1.375 6 12 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 12 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 12 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 12 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 12 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 12 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 12 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 12 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 12 8 4 1/4 4.250 4.112 4.907 4.688 2 45/64 2.759 2.647
3 3.000 4 12 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 12 8 5 5.000 4.838 5.774 5.515 3 3/16 3.252 3.124
3 1/2 3.500 4 12 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 12 8 5 3/4 5.750 5.562 5.562 6.341 3 11/16 3.670 3.616
4 4.000 4 12 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.
2H Heavy Hex Nut
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Diameter Thread Pitch Width Across Flats Height of Nut Item # Availability Price Quantity UOM
1/4 20 1/2 0.2344 N2HB0250000-I In Stock $0.12577/EA EA
5/16 18 9/16 0.2969 N2HB0310000-I In Stock $0.04534/EA EA
3/8 16 11/16 0.3594 N2HB0370000-I In Stock $0.06113/EA EA
7/16 14 3/4 0.4219 N2HB0430000-I In Stock $0.14935/EA EA
1/2 13 7/8 0.4844 N2HB0500000-I In Stock $0.13817/EA EA
9/16 12 15/16 0.5469 N2HB0560000-I In Stock $0.52275/EA EA
5/8 11 1 1/16 0.6094 N2HB0620000-I In Stock $0.28889/EA EA
3/4 10 1 1/4 0.7344 N2HB0750000-I In Stock $0.43972/EA EA
7/8 9 1 7/16 0.8594 N2HB0870000-I In Stock $0.68476/EA EA
1 8 1 5/8 0.9844 N2HB1000000-I In Stock $0.81669/EA EA
1 1/8 7 1 13/16 1.1094 N2HB112NC00-I In Stock $3.30114/EA EA
1 1/8 8 1 13/16 1.1094 N2HB1120000-I In Stock $1.25892/EA EA
1 1/4 7 2 1.2188 N2HB125NC00-I In Stock $3.31388/EA EA
1 1/4 8 2 1.2188 N2HB1250000-I In Stock $1.52568/EA EA
1 3/8 6 2 3/16 1.3438 N2HB137NC00-I In Stock $3.56519/EA EA
1 3/8 8 2 3/16 1.3438 N2HB1370000-I In Stock $2.00528/EA EA
1 1/2 6 2 3/8 1.4688 N2HB150NC00-I In Stock $4.7115/EA EA
1 1/2 8 2 3/8 1.4688 N2HB1500000-I In Stock $3.47944/EA EA
1 5/8 5.5 2 9/16 1.5938 N2HB162NC00-I In Stock $4.38739/EA EA
1 5/8 8 2 9/16 1.5938 N2HB1620000-I In Stock $3.35682/EA EA
1 3/4 5 2 3/4 1.7188 N2HB175NC00-I In Stock $11.17735/EA EA
1 3/4 8 2 3/4 1.7188 N2HB1750000-I In Stock $4.28831/EA EA
1 7/8 5 2 15/16 1.8438 N2HB187NC00-I In Stock $10.68443/EA EA
1 7/8 8 2 15/16 1.8438 N2HB1870000-I In Stock $5.31591/EA EA
2 4 3 1/8 1.9688 N2HB200NC00-I In Stock $9.94475/EA EA
2 8 3 1/8 1.9688 N2HB2000000-I In Stock $6.24843/EA EA
2 8 4 5/8 2.9531 N2HB3000000-I In Stock $27.64449/EA EA
2 1/4 4.5 3 1/2 2.2031 N2HB225NC00-I In Stock $30.13893/EA EA
2 1/4 8 3 1/2 2.2031 N2HB2250000-I In Stock $9.49311/EA EA
2 1/2 4 3 7/8 2.4531 N2HB250NC00-I In Stock $19.93971/EA EA
2 1/2 8 3 7/8 2.4531 N2HB2500000-I In Stock $16.23737/EA EA
2 3/4 4 4 1/4 2.7031 N2HB275NC00-I In Stock $19.67556/EA EA
2 3/4 8 4 1/4 2.7031 N2HB2750000-I In Stock $17.35408/EA EA