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Grade A Heavy Hex Nut
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Grade A Heavy Hex Nut

Grade A Heavy Hex Nut

ASTM A563 Grade A heavy hex nuts are made from carbon steel. Dimensional specifications are governed by ASME B18.2.2. Grade markings are not required for A563 Grade A heavy hex nuts, though in some cases Grade A nuts may be marked with the letter A. ASTM A563 covers standard specifications for carbon and alloy steel nuts. Heavy hex nuts provide increased bearing surface area over finished nuts.

Governing StandardsGrade A

ASTM A563 Covers the chemical and mechanical requirements for eight grades of carbon and alloy steel nuts for general structural and mechanical uses on bolts, studs, and other externally threaded parts.
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 A Marking
Grade A requires no material marking

Mechanical PropertiesGrade A

Carbon & Alloy Steel Per ASTM A563-2015
Diameter Proof Load Stress (1) Core Hardness
ksi Rockwell
Non-Zinc-Coated   (2) Zinc-Coated (2) Min Max
1/4" thru 4" 100 75 B68 C32
  1. 1. To determine nut proof load in pounds, multiply the appropriate nut proof load stress by the tensile stress area of the thread.
  2. 2. Non-zinc-coated nuts are nuts intended for use with externally threaded fasteners which have a plain (nonplated or noncoated) finish or have a plating or coating of insufficient thickness to necessitate overtapping the nut thread to provide assemblability. Zinc-coated nuts are nuts intended for use with externally threaded fasteners which are hot-dip zinc-coated, mechanically zinc-coated, or have a plating or coating of sufficient thickness to necessitate overtapping the nut thread to provide assemblability.

Chemical PropertiesGrade A

Per ASTM A563-2015
Grade Material Carbon Manganese Phosphorus Sulfur
% by weight % by weight % by weight % by weight
A Carbon & Alloy Steel 0.55 max - 0.12 0.15 (1)
  1. 1. For Grade A a sulfur content of 0.23 % max is acceptable with the purchasers approval.

Dimensional SpecificationsGrade A

Heavy hex nut dimensions
Per ASME B18.2.2-2015
Nominal Diameter UNC 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 1 13/16 1.812 1.756 2.093 2.002 1 7/64 1.139 1.079
1 1/4 1.250 7 2 2.000 1.380 2.309 2.209 1 7/32 1.251 1.187
1 3/8 1.375 6 2 3/16 2.188 2.119 2.526 2.416 1 11/32 1.378 1.310
1 1/2 1.500 6 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 2 9/16 2.562 2.481 2.959 2.828 1 19/32 1.632 1.556
1 3/4 1.750 5 2 3/4 2.750 2.662 3.175 3.035 1 23/32 1.759 1.679
1 7/8 1.875 5 2 15/16 2.938 2.844 3.392 3.242 1 27/32 1.886 1.802
2 2.000 4 1/2 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 3 1/2 3.500 3.388 4.041 3.862 2 13/64 2.251 2.155
2 1/2 2.500 4 3 7/8 3.875 3.750 4.474 4.275 2 29/64 2.505 2.401
2 3/4 2.750 4 4 1/4 4.250 4.112 4.907 4.688 2 45/64 2.759 2.647
3 3.000 4 4 5/8 4.625 4.475 5.340 5.102 2 61/64 3.013 2.893
3 1/4 3.250 4 5 5.000 4.838 5.774 5.515 3 3/16 3.252 3.124
3 1/2 3.500 4 5 3/8 5.375 5.200 6.207 5.928 3 7/16 3.506 3.370
3 3/4 3.750 4 5 3/4 5.750 5.562 5.562 6.341 3 11/16 3.670 3.616
4 4.000 4 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 A 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 NH2B0250000 In Stock $0.04186/EA EA
5/16 18 9/16 0.2969 NH2B0310000 3-5 Working Days $0.04087/EA EA
3/8 16 11/16 0.3594 NH2B0370000 In Stock $0.08496/EA EA
1/2 13 7/8 0.4844 NH2B0500000 In Stock $0.19478/EA EA
9/16 12 15/16 0.5469 NH2B0560000 In Stock $0.19201/EA EA
5/8 11 1 1/16 0.6094 NH2B0620000 In Stock $0.29669/EA EA
3/4 10 1 1/4 0.7344 NH2B0750000 In Stock $0.58325/EA EA
7/8 9 1 7/16 0.8594 NH2B0870000 In Stock $0.69299/EA EA
1 8 1 5/8 0.9844 NH2B1000000 In Stock $1.30334/EA EA
1 1/8 7 1 13/16 1.1094 NH2B1120000 In Stock $1.60729/EA EA
1 1/4 7 2 1.2188 NH2B1250000 In Stock $2.06939/EA EA
1 3/8 6 2 3/16 1.3438 NH2B1370000 In Stock $2.85952/EA EA
1 1/2 6 2 3/8 1.4688 NH2B1500000 In Stock $3.27717/EA EA
1 5/8 5.5 2 9/16 1.5938 NH2B1620000 In Stock $3.75082/EA EA
1 3/4 5 2 3/4 1.7188 NH2B1750000 In Stock $7.23591/EA EA
2 4 3 1/8 1.9688 NH2B2000000 In Stock $8.55134/EA EA
2 1/4 4.5 3 1/2 2.2031 NH2B2250000 In Stock $13.17678/EA EA
2 1/2 4 3 7/8 2.4531 NH2B2500000 In Stock $14.2531/EA EA
2 3/4 4 4 1/4 2.7031 NH2B2750000 In Stock $29.88095/EA EA
3 4 4 5/8 2.9531 NH2B3000000 In Stock $32.72763/EA EA
3 1/4 4 5 3.1875 NH2B3250000 In Stock $45.79005/EA EA
3 1/2 4 5 3/8 3.6875 NH2B3750000 In Stock $81.11908/EA EA
4 4 6 1/8 3.9375 NH2B4000000 30-50 Working Days $109.42596/EA EA
4 1/4 4 6 1/2 4.2681 NH2B425NC In Stock $277.86805/EA EA
4 1/2 4 6 7/8 4.5220 NH2B450NC In Stock $355.90452/EA EA
5 1/2 4 8 3/8 5.5378 NH2B550NC In Stock $579.25577/EA EA
5 3/4 4 8 3/4 5.6248 NH2B575NC In Stock $685.42411/EA EA
6 4 9 1/8 6.0457 NH2B600NC In Stock $787.2453/EA EA