STRUCTURAL NUTS

ASTM A563 GR.DH

ASTM A563 Grade DH and Grade DH3 are essential fastener materials in construction, tailored to specific engineering requirements. Grade DH features a medium carbon and alloy steel composition, striking a balance between strength and ductility. Grade DH3, a weathering steel variant, prioritizes corrosion resistance. These grades play a crucial role in ensuring robust connections for structural integrity in various construction projects, making them indispensable for applications in critical infrastructure such as building and anchoring.

*For Weather resistance, see Gr.DH3 products

A563-DH Specifications

Nominal Size	F			C		H			Weight Per 100 nuts
	Width Across Flats			Width Across Corners		Thickness
	Basic	Max	Min	Max	Min	Basic	Max	Min
1/4	1/2	0.5	0.488	0.577	0.556	15/64	0.25	0.218	1
5//16	9/16	0.562	0.546	0.65	0.622	16/64	0.341	0.28	2
3/8	11/16	0.688	0.669	0.794	0.763	23/64	0.377	0.341	3
1/2	7/8	0.875	0.85	1.01	0.969	31/64	0.504	0.464	7
5/8	1 1/16	1.062	1.031	1.227	1.175	39/64	0.631	0.587	12
3/4	1 1/4	1.25	1.212	1.443	1.382	47/64	0.758	0.71	20
7/8	1 7/16	1.438	1.394	1.66	1.589	54/64	0.885	0.833	30
1	1 5/8	1.625	1.575	1.876	1.796	63/64	1.012	0.956	43
1 1/8	1 13/16	1.812	1.756	2.093	2.002	1 7/64	1.139	1.079	59
1 1/4	2	2	1.938	2.309	2.209	1 7/32	1.251	1.187	79
1 3/8	2 3/16	2.188	2.119	2.526	2.416	1 11/32	1.378	1.31	102
1 1/2	2 3/8	2.375	2.3	2.742	2.622	1 15/32	1.505	1.433	131
1 5/8	2 9/16	2.562	2.481	2.959	2.828	1 19/32	1.632	1.556	162
1 3/4	2 3/4	2.75	2.662	3.175	3.035	1 23/32	1.759	1.679	204
1 7/8	2 15/16	2.938	2.844	3.392	3.242	1 27/32	1.886	1.802	241
2	3 1/8	3.125	3.025	3.608	3.449	1 31/32	2.013	1.925	299
2 1/4	3 1/2	3.5	3.388	4.041	3.862	2 13/64	2.251	2.155	419
2 1/2	3 7/8	3.875	3.75	4.474	4.275	2 29/64	2.505	2.401	564
2 3/4	4 1/4	4.25	4.112	4.907	4.688	2 45/64	2.759	2.647	738
3	4 5/8	4.625	4.475	5.34	5.102	2 61/64	3.013	2.893	950
3 1/4	5	5	4.838	5.774	5.514	3 3/16	3.252	3.124	1,194
3 1/2	5 3/8	5.375	5.2	6.207	5.928	3 7/16	3.506	3.37	1,526
3 3/4	5 3/4	5.75	5.562	6.64	6.341	3 11/16	3.76	3.616	1,812
4	6 1/8	6.125	5.925	7.073	6.755	3 15/16	4.014	3.862	2,180

This table is inspired by Table 3 from ASME B18.2.6 standard

Commonly Applied Coatings (A1.1)
Coating Type	Specification	Grade or Class
Hot-dip zinc	F2329	0.002 in. (50 μm)
Mechanically deposited zinc	B695	Class 55
Zn/Al Coating	F1136	Grade 5
Zn/Al Coating	F2833	Grade 1
Zn/Al Coating	F3019	Grade 4
Zn/Al Coating	F3393	–
Zinc Electroplate	F1941	Fe/Zn 5AN & Fe/Zn 5C

This table is inspired from ASTM A563/A563M-21 Table A1.1

A1.1 This annex provides guidance for the selection of protective coatings for carbon and alloy steel nuts. Table A1.1 is a listing of commonly applied coatings for steel nuts and is not intended to be an all-inclusive list. Other coatings may be used if the purchaser is confident the fastener performance will not be compromised. Overtap requirements for Hot dip and mechanically deposited zinc and Zn/Al coatings are listed in 7.4.

A563 DH/DH3 Chemical Requirements^A
Heat Analysis	DH	DH3
Heat Analysis	Composition %	Composition %	Based On Corrosion Index^C
Carbon	0.20 – 0.55	0.20 – 0.53	0.30 – 0.53
Manganese	0.60 min	0.40 min	0.60 min
Phosphorus, max	0.04	0.035	0.035
Sulfur, max	0.05^E	0.040	0.040
Silicon	^B	^B	^B
Copper	^B	0.20 min	0.20 – 0.60
Nickel	^B	0.20 min	0.20^F min
Chromium	^B	0.45 min	0.45 min
Vanadium	^B	^B	^B
Molybdenum	^B	0.15 min	0.10^F min
Titanium	^B	^B	^B

This table is inspired by ASTM A563/A563M-21A

^A Based on heat analysis. See 5.3 for product analysis requirements.
^B Not specified.
^C See 5.2.
^D For Grades A, B, and 8S a sulfur content of 0.23 % max is acceptable with the purchasers approval.
^EFor Grades D, DH, and 10S a sulfur content of 0.05 – 0.15 % is acceptable provided the manganese is 1.35 % min.
^FEither Nickel or Molybdenum must be present in the amount specified.

5.2:Grades C3, DH3, 8S3, and 10S3 shall be weathering steel and conform to the chemical composition specified in Table 1. Compositions A or B may be used for grades C3 and 8S3. Optionally, a chemical composition based on a corrosion index may be used provided the steel meets the chemical requirements in Table 1 column headed “Based on Corrosion Index”. When certifying based on the corrosion index the steel shall have a corrosion index of 6 or greater, as calculated from the heat analysis, and as described in Guide G101, using the predictive method based on the data of Larabee and Coburn, or the predictive method based on the data of Townsend. See Guide G101 for methods of estimating the atmospheric corrosion resistance of low alloy steels.
5.3: If performed, product analysis made on finished nuts representing each lot shall be within 10 % of the value required of the heat analysis. For example heat analysis C 0.30-0.52 = product analysis C 0.27 0.57.

Mechanical Requirements for Gr.DH & DH3
Grade of Nut	Nom. Nut Size in.	Style of Nut	Proof Load Stress, ksi^A		Hardness
			Non-Zinc-Coated Nuts^B	Zinc-Coated Nuts^B	Brinell		Rockwell
			Non-Zinc-Coated Nuts^B	Zinc-Coated Nuts^B	min	max	min	max
DH^D	1/4 to 4	Heavy Hex	175	150^F†	248	352	C24	C38
DH3	1/4 to 4	Heavy Hex	175	150^F†	248	352	C24	C38

This table is inspired by ASTM A563/A563M-21A

^ATo determine nut proof load in pounds or Newtons, multiply the appropriate nut proof load stress by the tensile stress area of the thread. Stress areas for UNC, UNF, and 8 UN thread series are given in Table 3. Stress areas for metric threads are given in Table 4.
^BNon-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.
^DNuts made in accordance with the requirements of Specification A194/A194M, Grade 2H, and marked with its grade symbol are an acceptable equivalent for Grade DH nuts. When A194/A194M zinc-coated inch series nuts are supplied, the zinc coating, overtapping, and lubrication shall be in accordance with the requirements with this specification. Rotational Capacity test procedures, nut rotations, and acceptance criteria are a function of the bolt with which the nuts will be used. When required, testing for the assembly in which the nut is used shall be in accordance with the applicable bolt specification.
^FOvertapped nuts intended to be used with 150 ksi bolts or equivalent shall be proof load tested at 175 ksi. Metric overtapped nuts intended to be used with 1040 MPa bolts or equivalent shall be proof load tested at 1245 MPa. When overtapped nuts will be used with 150 ksi bolts or equivalent, proof load requirements for overtapped nuts shall be specified by the purchaser in the inquiry and purchase order.
^†Editorially corrected in March 2022.

ASTM A563 GR.C

ASTM A563 Grade C nuts are integral in high-strength applications, forged from carbon steel for exceptional durability. Heat-treated for robustness, they excel in demanding environments. Available with coatings such as plain steel or hot-dip galvanized, in line with ASTM F2329 standards, these nuts provide versatility. Widely applied in industries like construction and machinery, they conform to ASTM A563 Grade C standards, ensuring reliable quality. Ideal for secure fastening in challenging conditions, they stand as a trusted choice for durable projects.

A563-C Specifications

Nominal Size	F			C		H			Weight Per 100 nuts
	Width Across Flats			Width Across Corners		Thickness
	Basic	Max	Min	Max	Min	Basic	Max	Min
1/4	1/2	0.5	0.488	0.577	0.556	15/64	0.25	0.218	1
5//16	9/16	0.562	0.546	0.65	0.622	16/64	0.341	0.28	2
3/8	11/16	0.688	0.669	0.794	0.763	23/64	0.377	0.341	3
1/2	7/8	0.875	0.85	1.01	0.969	31/64	0.504	0.464	7
5/8	1 1/16	1.062	1.031	1.227	1.175	39/64	0.631	0.587	12
3/4	1 1/4	1.25	1.212	1.443	1.382	47/64	0.758	0.71	20
7/8	1 7/16	1.438	1.394	1.66	1.589	54/64	0.885	0.833	30
1	1 5/8	1.625	1.575	1.876	1.796	63/64	1.012	0.956	43
1 1/8	1 13/16	1.812	1.756	2.093	2.002	1 7/64	1.139	1.079	59
1 1/4	2	2	1.938	2.309	2.209	1 7/32	1.251	1.187	79
1 3/8	2 3/16	2.188	2.119	2.526	2.416	1 11/32	1.378	1.31	102
1 1/2	2 3/8	2.375	2.3	2.742	2.622	1 15/32	1.505	1.433	131
1 5/8	2 9/16	2.562	2.481	2.959	2.828	1 19/32	1.632	1.556	162
1 3/4	2 3/4	2.75	2.662	3.175	3.035	1 23/32	1.759	1.679	204
1 7/8	2 15/16	2.938	2.844	3.392	3.242	1 27/32	1.886	1.802	241
2	3 1/8	3.125	3.025	3.608	3.449	1 31/32	2.013	1.925	299
2 1/4	3 1/2	3.5	3.388	4.041	3.862	2 13/64	2.251	2.155	419
2 1/2	3 7/8	3.875	3.75	4.474	4.275	2 29/64	2.505	2.401	564
2 3/4	4 1/4	4.25	4.112	4.907	4.688	2 45/64	2.759	2.647	738
3	4 5/8	4.625	4.475	5.34	5.102	2 61/64	3.013	2.893	950
3 1/4	5	5	4.838	5.774	5.514	3 3/16	3.252	3.124	1,194
3 1/2	5 3/8	5.375	5.2	6.207	5.928	3 7/16	3.506	3.37	1,526
3 3/4	5 3/4	5.75	5.562	6.64	6.341	3 11/16	3.76	3.616	1,812
4	6 1/8	6.125	5.925	7.073	6.755	3 15/16	4.014	3.862	2,180

This table is inspired by Table 3 from ASME B18.2.6 standard

Commonly Applied Coatings (A1.1)
Coating Type	Specification	Grade or Class
Hot-dip zinc	F2329	0.002 in. (50 μm)
Mechanically deposited zinc	B695	Class 55
Zn/Al Coating	F1136	Grade 5
Zn/Al Coating	F2833	Grade 1
Zn/Al Coating	F3019	Grade 4
Zn/Al Coating	F3393	–
Zinc Electroplate	F1941	Fe/Zn 5AN & Fe/Zn 5C

A563 GR.C & C3 Chemical Requirements^A
Heat Analysis	C	C3
Heat Analysis	Composition %	Composition A %	Composition B %	Based On Corrosion Index^C
Carbon	0.55 max	0.33 – 0.40	0.38 – 0.48	0.30 – 0.53
Manganese	–	0.90 – 1.20	0.70 – 0.90	0.60 min
Phosphorus, max	0.12	0.035	0.035	0.035
Sulfur, max	0.15^D	0.040	0.040	0.040
Silicon	^B	0.15 – 0.35	0.30 – 0.50	^B
Copper	^B	0.25 – 0.45	0.20 – 0.40	0.20 – 0.60
Nickel	^B	0.25 – 0.45	0.50 – 0.80	0.20^F
Chromium	^B	0.45 – 0.65	0.50 – 0.75	0.45 min
Vanadium	^B	^B	^B	^B
Molybdenum	^B	^B	0.06 max	0.10^F min
Titanium	^B	^B	^B	^B

This table is inspired by ASTM A563/A563M-21A

^A Based on heat analysis. See 5.3 for product analysis requirements.
^B Not specified.
^C See 5.2.
^D For Grades A, B, and 8S a sulfur content of 0.23 % max is acceptable with the purchasers approval.
^FEither Nickel or Molybdenum must be present in the amount specified.

5.2:Grades C3, DH3, 8S3, and 10S3 shall be weathering steel and conform to the chemical composition specified in Table 1. Compositions A or B may be used for grades C3 and 8S3. Optionally, a chemical composition based on a corrosion index may be used provided the steel meets the chemical requirements in Table 1 column headed “Based on Corrosion Index”. When certifying based on the corrosion index the steel shall have a corrosion index of 6 or greater, as calculated from the heat analysis, and as described in Guide G101, using the predictive method based on the data of Larabee and Coburn, or the predictive method based on the data of Townsend. See Guide G101 for methods of estimating the atmospheric corrosion resistance of low alloy steels.
5.3: If performed, product analysis made on finished nuts representing each lot shall be within 10 % of the value required of the heat analysis. For example heat analysis C 0.30-0.52 = product analysis C 0.27 0.57.

Mechanical Requirements for Gr.C & C3
Grade of Nut	Nom. Nut Size in.	Style of Nut	Proof Load Stress, ksi^A		Hardness
			Non-Zinc-Coated Nuts^B	Zinc-Coated Nuts^B	Brinell		Rockwell
			Non-Zinc-Coated Nuts^B	Zinc-Coated Nuts^B	min	max	min	max
C^C	1/4 to 4	Heavy Hex	144	144	143	352	B78	C38
C3	1/4 to 4	Heavy Hex	144	144	143	352	B78	C38

This table is inspired by ASTM A563/A563M-21A

^ATo determine nut proof load in pounds or Newtons, multiply the appropriate nut proof load stress by the tensile stress area of the thread. Stress areas for UNC, UNF, and 8 UN thread series are given in Table 3. Stress areas for metric threads are given in Table 4.
^BNon-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.
^CNuts made in accordance to the requirements of Specification A194/A194M, Grade 2 or Grade 2H, and marked with their grade symbol are acceptable equivalents for Grades C heavy hex and hex and D nuts. When A194/A194M zinc-coated inch series nuts are supplied, the zinc coating, overtapping, and lubrication shall be in accordance with the requirements of this specification. Rotational Capacity test procedures, nut rotations, and acceptance criteria are a function of the bolt with which the nuts will be used. When required, testing for the assembly in which the nut is used shall be in accordance with the applicable bolt specification.

ASTM A194 GR.2H

ASTM A194 Grade 2H nuts, crucial in high-strength applications, are crafted from robust carbon alloy steel, heat-treated for durability in extreme conditions. Available in plain steel or hot-dip galvanized coatings as per ASTM F2329, these nuts ensure adaptability. Widely employed in demanding industries like shipbuilding and oil and gas, their compliance with ASTM A194 Grade 2H standard, guarantee consistent quality. Ideal for secure fastening in challenging environments, they stand as a reliable choice for durable projects.

A194-2H Specifications

Nominal Size	F			C		H			Weight Per 100 nuts
	Width Across Flats			Width Across Corners		Thickness
	Basic	Max	Min	Max	Min	Basic	Max	Min
1/4	1/2	0.5	0.488	0.577	0.556	15/64	0.25	0.218	1
5//16	9/16	0.562	0.546	0.65	0.622	16/64	0.341	0.28	2
3/8	11/16	0.688	0.669	0.794	0.763	23/64	0.377	0.341	3
1/2	7/8	0.875	0.85	1.01	0.969	31/64	0.504	0.464	7
5/8	1 1/16	1.062	1.031	1.227	1.175	39/64	0.631	0.587	12
3/4	1 1/4	1.25	1.212	1.443	1.382	47/64	0.758	0.71	20
7/8	1 7/16	1.438	1.394	1.66	1.589	54/64	0.885	0.833	30
1	1 5/8	1.625	1.575	1.876	1.796	63/64	1.012	0.956	43
1 1/8	1 13/16	1.812	1.756	2.093	2.002	1 7/64	1.139	1.079	59
1 1/4	2	2	1.938	2.309	2.209	1 7/32	1.251	1.187	79
1 3/8	2 3/16	2.188	2.119	2.526	2.416	1 11/32	1.378	1.31	102
1 1/2	2 3/8	2.375	2.3	2.742	2.622	1 15/32	1.505	1.433	131
1 5/8	2 9/16	2.562	2.481	2.959	2.828	1 19/32	1.632	1.556	162
1 3/4	2 3/4	2.75	2.662	3.175	3.035	1 23/32	1.759	1.679	204
1 7/8	2 15/16	2.938	2.844	3.392	3.242	1 27/32	1.886	1.802	241
2	3 1/8	3.125	3.025	3.608	3.449	1 31/32	2.013	1.925	299
2 1/4	3 1/2	3.5	3.388	4.041	3.862	2 13/64	2.251	2.155	419
2 1/2	3 7/8	3.875	3.75	4.474	4.275	2 29/64	2.505	2.401	564
2 3/4	4 1/4	4.25	4.112	4.907	4.688	2 45/64	2.759	2.647	738
3	4 5/8	4.625	4.475	5.34	5.102	2 61/64	3.013	2.893	950
3 1/4	5	5	4.838	5.774	5.514	3 3/16	3.252	3.124	1,194
3 1/2	5 3/8	5.375	5.2	6.207	5.928	3 7/16	3.506	3.37	1,526
3 3/4	5 3/4	5.75	5.562	6.64	6.341	3 11/16	3.76	3.616	1,812
4	6 1/8	6.125	5.925	7.073	6.755	3 15/16	4.014	3.862	2,180

This table is inspired by Table 3 from ASME B18.2.6 standard

Coatings
Coating Type	Specification
Electrodeposited Zinc Coatings	B633
Mechanically deposited zinc	B695
Mechanically deposited zinc	B696
Electrodeposited Cadmium Coatings	B766
Zinc Electroplating	F1941
Hot-dip zinc	F2329

This table is inspired from section S7 of ASTM A194/A194M-23. There is no actual coating table in this standard at the time of writing. However, section S7.1.2 give some details about coatings.

S7. Coating on Nuts

S7.1 It is the purchaser’s responsibility to specify in the purchase order all information required by the coating facility. Examples of such information may include but are not limited to the following:

S7.1.1 Reference to the appropriate coating specification and type, thickness, location, modification to dimensions, and hydrogen embrittlement relief.

NOTE S7.1 – Modification of thread dimensions may result in loss of load carrying ability.

S7.1.2 Reference to Specifications A153/A153M, B633, B695, B696, B766, F1941/F1941M, F2329/F2329M, or Test Method F1940, or other standards.

S8. Marking Coated Nuts

S8.1 Nuts coated with zinc shall have ZN marked after the grade symbol. Nuts coated with cadmium shall have CD marked after the grade symbol.

NOTE S8.1 As an example, the marking for zinc-coated 2H bolting components will now be 2HZN rather than 2H*

X2. COATINGS AND APPLICATION LIMITS

X2.1 Use of coated bolting components at temperatures above approximately one-half the melting point (Fahrenheit or Celsius) of the coating is not recommended unless consider- ation is given to the potential for liquid and solid metal embrittlement, or both. The melting point of elemental zinc is approximately 780 °F [415 °C]. Therefore, application of zinc coated bolting components should be limited to temperatures less than 390 °F [210 °C]. The melting point of cadmium is approximately 600 °F [320 °C]. Therefore, application of cadmium coated bolting components should be limited to temperatures less than 300 °F [160 °C].

*Please take note that Precision Bolts only stock Plain and HDG coatings. Other coatings may be available upon request

A194 Gr.2H Chemical Requirements^A
Heat Analysis	Composition %
Carbon	0.40 min
Manganese	1.00
Phosphorus	0.040
Sulfur^E	0.050
Silicon	0.40
Chromium	–
Nickel	–
Molybdenum	–
Titanium	–
Niobium^H	–
Nitrogen	–
Copper	–
Selenium	–
Vanadium	–
Aluminium	–

This table is inspired by ASTM 194/194M-23

^A The intentional addition of Bi, Se, Te, and Pb is not permitted except for Grades 6F, 8F, and 8FA, in which Se is specified and required.
^E Because of the degree to which sulfur segregates, product analysis for sulfur over 0.060 % max is not technologically appropriate.
^H Niobium (Nb) and Columbium (Cb) are alternate names for element 41 in the Periodic Table of the Elements.

Hardness Requirements^A
Grade & Types	Completed Nuts			Sample Nuts After Treatment as in 8.1.5
	Brinell Hardness	Rockwell Hardness		Brinell Hardness, min	Rockwell Hardness B Scale, min
	Brinell Hardness	C Scale	B Scale	Brinell Hardness, min	Rockwell Hardness B Scale, min
2H to 1 1/2 in.	248 to 327	24 to 35	—	179	89
2H over 1 1/2 in.	212 to 327	35 max	95 min	147	79

This table is inspired from ASTM A194/A194M-23 Table 2

^A Where ellipses (—) appear in this table there is no requirement.

8.1.5 Test 2:
In addition to the testing required by 8.1.2.1 the manufacturer shall also perform hardness tests on sample nuts after the following test heat treatment. After completion of all production heat treatments heat the specimen nuts to the temperatures indicated below for 24 h, then slow cool. Test at room temperature.

8.1.5.1 Special Requirement, Grades 2HM and 7M:
Preparation of Grades 2HM and 7M nuts for hardness test and the hardness test itself shall be performed with consideration to (1) protect legibility of markings; (2) minimize exterior dimensional changes; and (3) maintain thread fit.