Grade 2 Coupling Nut, Galvanized
Choose Favorites List

Grade 2 Coupling Nut, Galvanized

These coupling nuts will either conform to SAE J995 Grade 2 or ASTM A563 Grade A, both of which are manufactured from carbon steel and are equivalent in strength.Dimensional specifications are governed by ASME B18.2.2. Grade markings are not required for either A563 Grade A, or SAE J995 Grade 2 hex coupling nuts. Coupling nuts, also known as extension nuts, are used for joining two male threads, usually threaded rods, in a variety of applications. Available in hot dip galvanized finish, which provides a corrosion resistant zinc coating.

Governing StandardsGrade A & Grade 2

SAE J995 Covers the mechanical and material requirements for inch series fasteners used in automotive and related industries in diameters through 1-1/2″.
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 & Grade 2 Marking
Grade A & Grade 2 require 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 1 1/2 Coarse Thread (UNC) 90 68 B68 C32
1/4 thru 1 1/2 Fine Thread (UNF) 80 60 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.

Mechanical PropertiesGrade 2

Low Carbon Steel Per SAE J995 2017-07
Diameter Proof Load Stress (1) Core Hardness
psi Rockwell
1/4 thru 1 1/2 Coarse Thread (UNC) 90,000 C32 Max
1/4 thru 1 1/2 Fine Thread (UNF) 80,000 C32 Max
  1. 1. The proof load in pounds for nuts is computed by multiplying the proof load stress, in psi (lbf/in2), for the nut grade, size, thread series, and type, as shown in Table 2, and tensile stress area in square inches (in2), for the applicable size and thread series shown in Table 3. (For tabulated values see Appendix A.) To convert the inch based pounds per square inch (psi) values above to metric Megapascal (MPa) units, multiply the above values by .00689.

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.

Chemical PropertiesGrade 2

Per SAE J995 2017-07
Grade Material Carbon Manganese Phosphorus Sulfur
% by weight % by weight % by weight % by weight
2 Low Carbon Steel 0.55 max - 0.12 (1) 0.15 max (2)
  1. 1. Resulfurized and rephosphorized material is not subject to rejection based on check analysis for sulfur.
  2. 2. If agreed between purchaser and producer, sulfur content may be 0.23 maximum.

Dimensional SpecificationsGrade A & Grade 2

Hex coupling nut dimensions
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
#6 0.1380 32 40 5/16 0.312 0.302 0.361 0.344 1/2 0.510 0.470
#8 0.1640 32 38 5/16 0.312 0.302 0.361 0.344 5/8 0.645 0.595
#10 0.1900 24 32 5/16 0.312 0.302 0.361 0.344 3/4 0.760 0.711
1/4 0.2500 20 28 7/16 0.438 0.428 0.505 0.488 1 3/4 1.760 1.690
5/16 0.3125 18 28 1/2 0.500 0.489 0.577 0.557 1 3/4 1.760 1.690
3/8 0.3750 16 24 9/16 0.562 0.551 0.650 0.628 1 3/4 1.760 1.690
7/16 0.4375 14 20 5/8 0.625 0.607 0.722 0.692 1 3/4 1.760 1.690
1/2 0.5000 13 20 11/16 0.688 0.663 0.794 0.756 1 3/4 1.760 1.690
9/16 0.5625 12 18 13/16 0.813 0.782 0.939 0.891 2 1/8 2.135 2.067
5/8 0.6250 11 18 13/16 0.813 0.782 0.939 0.891 2 1/8 2.135 2.067
3/4 0.7500 10 16 1 1.000 0.963 1.155 1.097 2 1/4 2.260 2.190
7/8 0.8750 9 14 1 1/4 1.250 1.212 1.443 1.382 2 1/2 2.510 2.440
1 1.0000 8 12 1 3/8 1.375 1.325 1.588 1.511 2 3/4 2.760 2.690
1 1/8 1.1250 7   1 1/2 1.500 1.450 1.732 1.653 3 3.010 2.940
1 1/4 1.2500 7   1 5/8 1.625 1.575 1.876 1.825 3 3.010 2.940
1 1/2 1.5000 6   2 2.000 1.950 2.309 2.275 3 1/2 3.510 3.440
1 5/8 1.6250 6   2 9/16 2.562 2.481 2.959 2.828 4 7/8 4.910 4.830
1 3/4 1.7500 5   2 3/4 2.750 2.662 3.175 3.035 5 1/4 529.000 5.210
1 7/8 1.8750 5   2 15/16 2.938 2.844 3.392 3.242 5 5/8 5.670 5.580
2 2.0000 4 1/2   3 1/8 3.125 3.025 3.608 3.448 6 6.040 5.950
  1. All dimensions are in inches.
Grade 2 Coupling Nut, Galvanized
View
Diameter Thread Pitch Width Across Flats Length Item # Availability Price Quantity UOM
3/8 16 9/16 1 3/4 NCOU037G In Stock $0.74204/EA EA
1/2 13 11/16 1 3/4 NCOU050G In Stock $0.80353/EA EA
5/8 11 13/16 2 1/8 NCOU062G In Stock $1.10197/EA EA
3/4 10 1 2 1/4 NCOU075G In Stock $2.03933/EA EA
7/8 9 1 1/4 2 1/2 NCOU087G In Stock $3.30344/EA EA
1 8 1 3/8 2 3/4 NCOU100G In Stock $2.97583/EA EA
1 1/8 7 1 1/2 3 NCOU112G In Stock $20.92214/EA EA
1 1/4 7 1 5/8 3 NCOU125G In Stock $20.60232/EA EA
1 1/2 6 2 3 1/2 NCOU150G In Stock $29.77821/EA EA
2 4.5 3 1/8 6 NCOU200G In Stock $78.01696/EA EA