Designation: A194/A194M 15 Endorsed by

Manufacturers Standardization Society

of the Valve and Fittings Industry
Used in USNRC-RDT Standards

Standard Specification for

Carbon Steel, Alloy Steel, and Stainless Steel Nuts for Bolts
for High Pressure or High Temperature Service, or Both1
This standard is issued under the fixed designation A194/A194M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon () indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.

1. Scope* 2. Referenced Documents

1.1 This specification2 covers a variety of carbon, alloy, and 2.1 ASTM Standards:3
martensitic stainless steel nuts in the size range 14 through 4 in. A153/A153M Specification for Zinc Coating (Hot-Dip) on
and metric M6 through M100 nominal. It also covers austenitic Iron and Steel Hardware
stainless steel nuts in the size range 14 in. and M6 nominal and A276 Specification for Stainless Steel Bars and Shapes
above. These nuts are intended for high-pressure or high- A320/A320M Specification for Alloy-Steel and Stainless
temperature service, or both. Grade substitutions without the Steel Bolting for Low-Temperature Service
purchasers permission are not allowed. A370 Test Methods and Definitions for Mechanical Testing
1.2 Bars from which the nuts are made shall be hot-wrought. of Steel Products
The material may be further processed by centerless grinding A962/A962M Specification for Common Requirements for
or by cold drawing. Austenitic stainless steel may be solution Bolting Intended for Use at Any Temperature from Cryo-
annealed or annealed and strain-hardened. When annealed and genic to the Creep Range
strain hardened austenitic stainless steel is ordered in accor- B633 Specification for Electrodeposited Coatings of Zinc on
dance with Supplementary Requirement S1, the purchaser Iron and Steel
should take special care to ensure that 8.2.2, Supplementary B695 Specification for Coatings of Zinc Mechanically De-
Requirement S1, and Appendix X1 are thoroughly understood. posited on Iron and Steel
B696 Specification for Coatings of Cadmium Mechanically
1.3 Supplementary requirements of an optional nature are
Deposited
provided. These shall apply only when specified in the inquiry,
B766 Specification for Electrodeposited Coatings of Cad-
contract, and order.
mium
1.4 This specification is expressed in both inch-pound units E112 Test Methods for Determining Average Grain Size
and in SI units. However, unless the order specifies the E566 Practice for Electromagnetic (Eddy Current) Sorting of
applicable M specification designation (SI units), the mate- Ferrous Metals
rial shall be furnished to inch-pound units. F606 Test Methods for Determining the Mechanical Proper-
1.5 The values stated in either inch-pound units or SI units ties of Externally and Internally Threaded Fasteners,
are to be regarded separately as standard. The values stated in Washers, and Rivets (Metric) F0606_F0606M
each system may not be exact equivalents; therefore, each F1940 Test Method for Process Control Verification to
system shall be used independently of the other. Combining Prevent Hydrogen Embrittlement in Plated or Coated
values from the two systems may result in non-conformance Fasteners
with the standard. Within the text, the SI units are shown in F1941 Specification for Electrodeposited Coatings on
brackets. Threaded Fasteners (Unified Inch Screw Threads (UN/
UNR))
1
This specification is under the jurisdiction of ASTM Committee A01 on Steel, F2329 Specification for Zinc Coating, Hot-Dip, Require-
Stainless Steel and Related Alloysand is the direct responsibility of Subcommittee ments for Application to Carbon and Alloy Steel Bolts,
A01.22 on Steel Forgings and Wrought Fittings for Piping Applications and Bolting
Materials for Piping and Special Purpose Applications.
Current edition approved June 1, 2015. Published June 2015. Originally
3
approved in 1936. Last previous edition approved in 2014 as A194/A194M14a. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
DOI: 10.1520/A0194_A0194M-15. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
2
For ASME Boiler and Pressure Vessel Code applications see related Specifi- Standards volume information, refer to the standards Document Summary page on
cation SA-194 in Section II of that code. the ASTM website.

*A Summary of Changes section appears at the end of this standard

Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

1
 A194/A194M 15
Screws, Washers, Nuts, and Special Threaded Fasteners 4.1.3 Dimensions (see Section 9),
2.2 ASME Standards:4 4.1.4 Options in accordance with 8.2.2.1, 9.1, 9.2, 10.3, and
B 1.1 Unified Screw Threads 12, and
B 1.2 Gages and Gaging for Unified Inch Screw Threads 4.1.5 Supplementary Requirements, if any.
B 1.13M Metric Screw Threads 4.2 CoatingsCoatings are prohibited unless specified by
B 18.2.2 Square and Hex Nuts the purchaser (see Supplementary Requirements S7 and S8).
B 18.2.4.6M Metric Heavy Hex Nuts When coated nuts are ordered, the purchaser should take
2.3 ISO Standards:5 special care to ensure that Appendix X2 is thoroughly under-
4033 Hexagon High Nuts (Style 2) Product A and B stood.
3. Terminology 4.3 See Supplementary Requirement S3 for nuts to be used
3.1 Definitions of Terms Specific to This Standard: in low temperature applications (Specification A320/A320M).
3.1.1 Austenitic GradesAll grades with a prefix of 8 or 4.4 Proof Load TestingSee Supplementary Requirement
9. S9 for proof load testing of nuts manufactured to dimensions
3.1.2 Ferritic GradesGrades 1, 2, 2H, 2HM, 3, 4, 6, 6F, 7, and configurations other than those covered in Tables 3 and 4.
7M, and 16.
5. Common Requirements
3.1.3 LotUnless otherwise specified (see Discussion
below), a lot is the quantity of nuts of a single nominal size and 5.1 Material and fasteners supplied to this specification shall
grade produced by the same manufacturing process. conform to the requirements of Specification A962/A962M.
These requirements include test methods, finish, thread
3.1.3.1 DiscussionWhen Supplementary Requirement S5 dimensions, marking, certification, optional supplementary
is invoked on the purchase order, the following definitions of a requirements, and others. Failure to comply with the require-
lot shall apply: ments of Specification A962/A962M constitutes nonconfor-
3.1.3.2 For Grade 8 NutsThe quantity of all the nuts of a mance with this specification. In case of conflict between the
single nominal diameter and grade made from the same heat of requirements of this specification and Specification A962/
steel and made by the same manufacturing process. A962M, this specification shall prevail.
3.1.3.3 For All Other Grade Nuts(see 8.2 and
8.1.2.1)All the nuts of a single nominal diameter and grade 6. Manufacture (Process)
made from the same heat number and heat treated in the same 6.1 Stainless steels for all types of Grade 6 and 8 nuts shall
batch if batch-type heat treating equipment is used or heat be made by one of the following processes:
treated in the same continuous run of not more than 8 h under 6.1.1 Electric-furnace (with separate degassing and refining
the same conditions if continuous-type heat treating equipment optional),
is used. 6.1.2 Vacuum induction furnace, or
3.1.4 Type: 6.1.3 Either of the above followed by electroslag remelting,
3.1.4.1 For Grade 8 NutsVariations within the grade or consumable-arc remelting.
designated by a letter and differentiated by chemistry and by
6.2 The steel producer shall exercise adequate control to
manufacturing process.
eliminate excessive unhomogeneity, nonmetallics, pipe,
3.1.4.2 For Grade 6 NutsVariations within the grade porosity, and other defects.
designated by the letter F as differentiated by chemical addi-
6.3 Grades 1 and 2 nuts shall be hot or cold forged, or shall
tions made for machineability.
be machined from hot-forged, hot-rolled, or cold-drawn bars.
3.1.5 SeriesThe dimensional relationship and geometry of 6.3.1 All Grade 1 and 2 nuts shall be stress-relief annealed
the nuts as described in ASME B 18.2.2 for inch nuts and ISO at a temperature of at least 1000 F [538 C] after forming or
4033 for metric nuts sizes M6 through M10 and ASME B machining from bar with the following exceptions:
18.2.4.6M for nuts sizes M12 through M100. 6.3.1.1 Nuts made by hot forging.
6.3.1.2 Nuts machined from hot-forged or hot-rolled bar.
4. Ordering Information
6.3.1.3 Nuts machined from hot-forged/hot-rolled and cold-
4.1 The inquiry and order for material under this specifica- finished (max 10 % reduction in area) bar.
tion shall include the following as required to describe the 6.3.1.4 Nuts machined from cold-drawn and annealed (min
material adequately: 1000 F [538 C]) bar.
4.1.1 Specification designation, year date, and grade, issue 6.3.2 Grade 1 and 2 nuts made by hot forging or by
date and revision letter, machining from hot-forged or hot-rolled bars need not be given
4.1.2 Quantity, number of pieces, any stress relief annealing treatment.
6.4 Grades 2H, 2HM, 3, 4, 6, 6F, 7, 7M, and 16 nuts shall
4
Available from American Society of Mechanical Engineers (ASME), ASME be hot- or cold-forged or shall be machined from hot-forged,
International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
hot-rolled, or cold-drawn bars and shall be heat treated to meet
www.asme.org.
5
Available from International Organization for Standardization (ISO), 1, ch. de the required mechanical properties. These grades shall be
la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http://www.iso.org. uniformly reheated to the proper austenitizing temperature (a

2
 TABLE 1 Chemical RequirementsA,B,C,D
Manga- Phospho- Molyb- Tita- Other
Grade UNS Carbon, Sulfur,E Silicon, Chromium, Nickel, Colum- Nitrogen,
Material nese, rus, % denum, nium, Elements,
Symbol Number % % % % bium % %
% % % % %
1 carbon 0.15 min 1.00 0.040 0.050 0.40 ... ... ... ... ... ... ...
2, 2HM, and carbon 0.40 min 1.00 0.040 0.050 0.40 ... ... ... ... ... ... ...
2H
4G carbon, 0.400.50 0.700.90 0.035 0.040 0.150.35 ... ... 0.200.30 ... ... ... ...
molyb-
denum
3 Type 501 0.10 min 1.00 0.040 0.030 1.00 4.06.0 . . . 0.400.65 . . . . . . ... ...
6 Type 410 S41000 0.080.15 1.00 0.040 0.030 1.00 11.513.5 . . . ... . . . . . . ... ...
6F Type 416 S41600 0.15 1.25 0.060 0.15 min 1.00 12.014.0 . . . ... . . . . . . ... ...
6F Type S41623 0.15 1.25 0.060 0.060 1.00 12.014.0 . . . ... . . . . . . Selenium,
416Se 0.15 min
7, 7M Type 0.380.48 0.751.0 0.035 0.04 0.150.35 0.801.10 ... 0.150.25 ... ... ... ...
4140/
4142/
4145,
4140H,
4142H,
4145H
8, 8A Type 304 S30400 0.08 2.00 0.045 0.030 1.00 18.020.0 8.011.0 ... ... ... ... ...
8C, 8CA Type 347 S34700 0.08 2.00 0.045 0.030 1.00 17.019.0 9.012.0 ... ... 10 x ... ...
carbon
content,
min 1.10
8CLN, Type S34751 0.005- 2.00 0.045 0.030 1.00 17.019.0 9.013.0 ... ... 0.200.50, 0.060.10 ...
8CLNA 347LN 0.020 15 x

3
carbon
content,
min
8M, 8MA Type 316 S31600 0.08 2.00 0.045 0.030 1.00 16.018.0 10.014.0 2.003.00 ... ... ... ...
8T, 8TA Type 321 S32100 0.08 2.00 0.045 0.030 1.00 17.019.0 9.012.0 ... 5x ... 0.10 ...
(C+N)
min -
A194/A194M 15

0.70
max
8F, 8FA Type 303 S30300 0.15 2.00 0.20 0.15 min 1.00 17.019.0 8.010.0 ... ... ... ... ...
8F, 8FA Type S30323 0.15 2.00 0.20 0.06 1.00 17.019.0 8.010.0 ... ... ... Selenium,
303Se 0.15 min
8P, 8PA Type 305 S30500 0.12 2.00 0.045 0.030 1.00 17.019.0 11.013.0 ... ... ... ... ...
8N, 8NA Type S30451 0.08 2.00 0.045 0.030 1.00 18.020.0 8.011.0 ... ... ... 0.100.16
304N
8LN, 8LNA Type S30453 0.030 2.00 0.045 0.030 1.00 18.020.0 8.011.0 ... ... ... 0.100.16
304LN
8MN, 8MNA Type S31651 0.08 2.00 0.045 0.030 1.00 16.018.0 10.013.0 2.003.00 ... ... 0.100.16
316N
8MLN, Type S31653 0.030 2.00 0.045 0.030 1.00 16.018.0 10.013.0 2.003.00 ... ... 0.100.16
8MLNA 316LN
8R, 8RAF XM19 S20910 0.06 4.06.0 0.045 0.030 1.00 20.523.5 11.513.5 1.503.00 ... 0.100.30 0.200.40 Vanadium,
0.100.30
8S, 8SA S21800 0.10 7.09.0 0.060 0.030 3.54.5 16.018.0 8.09.0 ... ... ... 0.080.18
8MLCuN, S31254 S31254 0.020 1.00 0.030 0.010 0.80 19.520.5 17.518.5 6.06.5 ... ... 0.180.22 Copper,
8MLCuNA 0.501.00
B8ML4CuN S31730 S31730 0.030 2.00 0.040 0.010 1.00 17.019.0 15.016.5 3.04.0 ... ... 0.045 Copper
4.05.0
9C, 9CA N08367 N08367 0.030 2.00 0.040 0.030 1.00 20.0-22.0 23.5- 25.5 6.0-7.0 0.18-0.25 Copper
0.75
 TABLE 1 Continued
Manga- Phospho- Molyb- Tita- Other
Grade UNS Carbon, Sulfur,E Silicon, Chromium, Nickel, Colum- Nitrogen,
Material nese, rus, % denum, nium, Elements,
Symbol Number % % % % bium % %
% % % % %
16 Chromium 0.360.47 0.450.70 0.035 0.040 0.150.35 0.801.15 ... 0.500.65 ... ... ... Vanadium,
Molyb- 0.250.35
denum AluminumB
Vanadium 0.015

4
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.
B
Total aluminum, soluble and insoluble.
C
Maximum, unless minimum or range is indicated.
D
Where ellipses ({) appear in this table there is no requirement and the element need not be determined or reported.
E
Because of the degree to which sulfur segregates, product analysis for sulfur over 0.060 % max is not technologically appropriate.
F
As described in Specification A276.
A194/A194M 15

G
Grade 4 is expected to be withdrawn within approximately 2 years. Grade 7 is an acceptable substitute for Grade 4. See 7.2.
 A194/A194M 15
TABLE 2 Hardness RequirementsA
Completed Nuts Sample Nut after Treatment as in 8.1.5

Grade and Type Brinell Rockwell Hardness Brinell Rockwell

Hardness Hardness, Hardness B
C Scale B Scale min Scale, min
1 121 min ... 70 min 121 70
2 159 to 352 ... 84 min 159 84
2H to 112 in. or M36, incl 248 to 327 24 to 35 ... 179 89
2H over 112 in. or M36 212 to 327 35 max 95 min 147 79
2HM and 7M 159 to 235 ... 84 to 99 159 84
3, 4, 7, and 16 248 to 327 24 to 35 ... 201 94
6 and 6F 228 to 271 20 to 28 ... ... ...
8, 8C, 8CLN, 8M, 8T, 8F, 8P, 126 to 300 32 max 60 min ... ...
8N,
8MN, 8LN, 8MLN,
8MLCuN, 8ML4CuN,
and 9C
8A, 8CA, 8CLNA, 8MA, 8TA, 126 to 192 ... 60 to 90 ... ...
8FA, 8PA, 8NA, 8MNA,
8LNA, 8MLNA,
8MLCuNA,
8ML4CuNA,
and 9CA
8R, 8RA, 8S, and 8SA 183 to 271 25 max 88 min ... ...
A
Where ellipses ({) appear in this table there is no requirement.

group thus reheated being known as a quenching charge) and 7. Chemical Composition
quenched under substantially uniform conditions for each 7.1 Each alloy shall conform to the chemical composition
quenching charge and tempered as shown below. Grades 2H, requirements prescribed in Table 1.
2HM, 3, 4, 7, and 7M shall be liquid quenched. Grades 6 and
6F shall be quenched in liquid or inert gas. Grade 16 shall be 7.2 Grade 7 may be substituted for Grade 4. When such
heated to a temperature range from 1700 to 1750 F (925 to substitution is made, the nuts shall be marked as Grade 7.
955 C) and oil quenched.
Minimum Tempering Temperature, F
8. Mechanical Requirements
Grade [C] 8.1 Hardness Test:
2H 850 [455]
2HM 1150 [620] 8.1.1 Requirements:
3 1050 [565] 8.1.1.1 All nuts shall meet the hardness requirements speci-
4 1100 [595] fied in Table 2.
6 and 6F 1100 [595]
7 1100 [595] 8.1.1.2 Sample nuts of Grades 1, 2, 2H, 2HM, 3, 4, 7, 7M,
7M 1150 [620] and 16 which have been given the treatment described in 8.1.5
16 1200 [650]
shall meet the minimum hardness specified in Table 2.
Nuts machined from bar heat treated in accordance with this 8.1.2 Number of Tests(Grades 1, 2, 2H, 3, 4, 7, and 16 and
specification need not be reheat-treated. For Grade 2HM and all types of Grade 6):
7M nuts, a final stress relief shall be done at or above the 8.1.2.1 Tests on the number of sample nuts in accordance
minimum tempering temperature after all forming, machining, with the following table shall be performed by the manufac-
and tapping operations. This final stress relief may be the turer following all production heat treatments:
tempering operation.
Lot Size Samples
6.4.1 Grade 6 and 6F nuts shall be tempered for a minimum Up to 800 1
of 1 h at the temperature. 801 to 8000 2
8001 to 22 000 3
6.5 Grades 8, 8C, 8CLN, 8M, 8T, 8F, 8P, 8N, 8MN, 8R, 8S, Over 22 000 5
8LN, 8MLN, 8MLCuN, 8ML4CuN, and 9C nuts shall be hot 8.1.2.2 In addition, a hardness test shall be performed by the
or cold forged, or shall be machined from hot-forged, hot- manufacturer in accordance with 8.1.5 on one sample nut
rolled or cold-drawn bars. selected from each nominal diameter and series from each
6.6 Grades 8A, 8CA, 8CLNA, 8MA, 8TA, 8FA, 8PA, 8NA, grade and heat number following completion of all production
8MNA, 8RA, 8SA, 8LNA, 8MLNA, 8MLCuNA, heat treatments.
8ML4CuNA, and 9CA nuts shall be hot- or cold-forged or shall 8.1.3 Number of Tests, Grades 2HM and 7M:
be machined from hot-forged, hot-rolled, or cold-drawn bars 8.1.3.1 Each nut shall be tested in accordance with either
and the nuts shall subsequently be carbide-solution treated by Specification A962/A962M or with Test Methods F606 to
heating them for a sufficient time at a temperature to dissolve ensure product conformance. The use of 100 % electromag-
chromium carbides followed by cooling at a rate sufficient to netic testing for hardness as an alternative to 100 % indentation
prevent reprecipitation of the carbides. hardness testing is permissible when qualified by sampling

5
 A194/A194M 15
TABLE 3 Proof Load Using Threaded Mandrel Inch Series
NOTE 1Proof loads are not design loads.
Proof Load, lbfA
Nominal Threads Stress Area
Grade 1 Grades 2, 2HM, 6, 6F, 7M Grades 2H, 3, 4, 7, 16
Size, in. per Inch in.2
Heavy HexB HexC Heavy HexD HexE Heavy HexF HexG

14 20 0.0316 4 130 3 820 4 770 4 300 5 570 4 770

5 16 18 0.0524 6 810 6 290 7 860 7 070 9 170 7 860
38 16 0.0774 10 080 9 300 11 620 10 460 13 560 11 620
716 14 0.1063 13 820 12 760 15 940 14 350 18 600 15 940
12 13 0.1419 18 450 17 030 21 280 19 160 24 830 21 280

9 16 12 0.182 23 660 21 840 27 300 24 570 31 850 27 300

58 11 0.226 29 380 27 120 33 900 30 510 39 550 33 900
34 10 0.334 43 420 40 080 50 100 45 090 58 450 50 100
78 9 0.462 60 060 55 440 69 300 62 370 80 850 69 300
1 8 0.606 78 780 72 720 90 900 81 810 106 000 90 900

1 1 8 8 0.790 102 700 94 800 118 500 106 700 138 200 118 500
1 1 4 8 1.000 130 000 120 000 150 000 135 000 175 000 150 000
1 3 8 8 1.233 160 200 148 000 185 000 166 500 215 800 185 000
1 1 2 8 1.492 194 000 170 040 223 800 201 400 261 100 223 800

All Types of Grade 8, Grades 9C and 9CA

Heavy HexH HexI
14 20 0.0316 2 540 2 380

5 16 18 0.0524 4 190 3 930
38 16 0.0774 6 200 5 810

7 16 14 0.1063 8 500 7 970
12 13 0.1419 11 350 10 640

9 16 12 0.182 14 560 13 650
58 11 0.226 18 080 16 950
3 4 10 0.334 26 720 25 050
7 8 9 0.462 36 960 34 650
1 8 0.606 48 480 45 450

1 1 8 8 0.790 63 200 59 250

1 1 4 8 1.000 80 000 75 000
1 3 8 8 1.233 98 640 92 450
1 1 2 8 1.492 119 360 111 900
A
See limit for proof load test in 8.2.2.1. The proof load for jam nuts shall be 46 % of the tabulated load.
B
Based on proof stress of 130 000 psi.
C
Based on proof stress of 120 000 psi.
D
Based on proof stress of 150 000 psi.
E
Based on proof stress of 135 000 psi.
F
Based on proof stress of 175 000 psi.
G
Based on proof stress of 150 000 psi.
H
Based on proof stress of 80 000 psi.
I
Based on proof stress of 75 000 psi.

using indentation hardness testing. Each lot tested for hardness all production heat treatments heat the specimen nuts to the
electromagnetically shall be 100 % examined in accordance temperatures indicated below for 24 h, then slow cool. Test at
with Practice E566. Following electromagnetic testing for room temperature.
hardness, a random sample of a minimum of 100 pieces in each Temperature,
purchase lot (as defined in 3.1.3) shall be tested by indentation GradeA F [C]
hardness methods. All samples must meet hardness require- 1 850 [455]
2, 2H, 2HM 1000 [540]
ments to permit acceptance of the lot. If any one sample is 3, 4, 7, 7M 1100 [590]
outside of the specified maximum or minimum hardness, the 16 1200 [650]
lot shall be rejected and either reprocessed and resampled, or
tested 100 % by indentation hardness methods. A
Nuts intended to be coated with zinc or cadmium (marked in accordance with the
8.1.3.2 In addition, 8.1.2.2 shall be met. requirements of Supplementary Requirement S8) are not subjected to the require-
8.1.4 Number of Tests, All Types of Grade 8Tests on the ments of 8.1.5 (See Appendix X2).
number of sample nuts in accordance with 8.1.2.1 shall be
performed by the manufacturer. 8.1.5.1 Special Requirement, Grades 2HM and 7M
8.1.5 Test 2In addition to the testing required by 8.1.2.1 Preparation of Grades 2HM and 7M nuts for hardness test and
the manufacturer shall also perform hardness tests on sample the hardness test itself shall be performed with consideration to
nuts after the following test heat treatment. After completion of

6
 A194/A194M 15
TABLE 4 Proof Load Using Threaded Mandrel Metric
NOTE 1Proof loads are not design loads.
Nominal Proof Load, kNA
Threads Stress Area
Size, Grade 1 Grades 2, 2HM, 6, 6F, 7M Grades 2H, 3, 4, 7, 16
Pitch mm2
mm Heavy HexB HexC Heavy HexD HexE Heavy HexF HexG
M6 1.0 20.1 18.0 16.6 20.8 18.7 29.2 20.8
M8 1.25 36.6 32.8 30.2 37.9 34.0 44.1 37.9
M10 1.50 58.0 51.9 47.9 60.0 53.9 69.9 60.0
M12 1.75 84.3 75.5 69.5 87.3 78.4 101.6 87.3
M14 2.0 115.0 102.9 94.9 119.0 107.0 138.6 119.0
M16 2.0 157.0 140.5 129.5 162.5 146.0 189.2 162.5
M20 2.5 245.0 219.3 202.1 253.6 227.8 295.2 253.6
M22 2.5 303.0 271.2 249.9 313.6 281.8 365.1 313.6
M24 3.0 353.0 315.9 291.2 365.4 328.3 425.4 365.4
M27 3.0 459.0 411.0 378.7 475.1 426.9 553.4 475.1
M30 3.5 561.0 502.1 462.8 580.6 521.7 676.0 580.6
M36 4.0 817.0 731.2 674.0 845.6 759.8 984.5 845.6

All Types of Grade 8, and

Grades 9C and 9CA
Nominal Size, mm Thread Pitch Stress Heavy HexH HexI
Area,
mm2
M6 1.0 20.1 11.1 10.4
M8 1.25 36.6 20.1 18.8
M10 1.50 58.0 31.9 29.9
M12 1.75 84.3 46.4 43.4
M14 2.0 115.0 63.3 59.2
M16 2.0 157.0 86.4 80.9
M20 2.5 245.0 134.8 126.2
M22 2.5 303.0 166.7 156.0
M24 3.0 353.0 194.2 181.8
M27 3.0 459.0 252.5 236.4
M30 3.5 561.0 308.6 288.9
M36 4.0 817.0 449.4 420.8
A
See limit for proof load test in 8.2.2.1. The proof load for jam nuts shall be 46 % of the tabulated load.
B
Based on proof stress of 895 MPa.
C
Based on proof stress of 825 MPa.
D
Based on proof stress of 1035 MPa.
E
Based on proof stress of 930 MPa.
F
Based on proof stress of 1205 MPa.
G
Based on proof stress of 1035 MPa.
H
Based on proof stress of 550 MPa.
I
Based on proof stress of 515 MPa.

(1) protect legibility of markings; (2) minimize exterior dimen- 8.2.3 Test MethodThe test shall be run using a threaded
sional changes; and (3) maintain thread fit. mandrel or a test bolt in accordance with Specification A962/
8.2 Proof Load Test: A962M.
8.2.1 RequirementsThe nuts listed in Tables 3 and 4 shall 8.3 Cone Proof Load Test:
be capable of withstanding the proof loads specified therein. 8.3.1 RequirementsThis test shall be performed only
Proof load testing of nuts manufactured to dimensions and when visible surface discontinuities become a matter of issue
configurations other than those covered in Table 3 or Table 4 is between the manufacturer and the purchaser. Nuts in the size
only required when S9 is specified in the order or inquiry. range 14 to 112 in. inclusive and M6 to M36 inclusive shall be
8.2.2 Number of Tests: proof load tested. Nuts not in this size range and all types of
8.2.2.1 The manufacturer shall test the number of nuts Grade 8 nuts are not subject to this test. Also, nuts manufac-
specified in 8.1.2.1 following all production heat treatments. tured to dimensions and configurations other than those cov-
Nuts that would require a proof load in excess of 160 000 lb/f ered by Specification A962/A962M, ASME B 1.1, ASME B
or 705 kN shall, unless Supplementary Requirements S1 or S4 1.13M, ASME B 18.2.2, ASME B 18.2.4.6M , and ISO 4033
are invoked in the purchase order or contract, be proof load are not subject to the cone proof load test. The cone proof load
tested per Section 8 or cross sectional hardness tested per applied shall be determined in accordance with the Cone Proof
Annex A3 of Test Methods and Definitions A370. Proof Load Load requirements in Specification A962/A962M (tables or
tests prevail over hardness tests in the event a conflict exists formulae or both) based upon the proof stresses shown in Table
relative to minimum strength. 5 and Table 6 of Specification A194/A194M.

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 A194/A194M 15
TABLE 5 Proof Stress Using 120 Hardened Steel Cone Inch
Proof Stress psi, Minimum
Type Grade 1 Grades 2, Grades 2H
2HM, 6, 3, 4, 7, & 16
6F & 7M
Hex 120 000 135 000 150 000
Heavy Hex 130 000 150 000 175 000

TABLE 6 Proof Stress Using 120 Hardened Steel Cone Metric

Proof Stress MPa, Minimum
Type Grade 1 Grades 2, Grades 2H
2HM, 6, 3, 4, 7, & 16
6F & 7M
Hex 825 930 1035
Heavy Hex 895 1035 1205

8.3.2 Number of TestsThe manufacturer shall sample and 10.2 If visible surface imperfections in size 14 through
test the number of nuts specified in 8.1.2.1. The lot shall be 112 in. and M6 through M36 and in any grade other than Grade
considered acceptable if the sample nut(s) withstand(s) appli- 8 become a matter of issue between the manufacturer and the
cation of the cone proof load without failure. purchaser, the cone proof load test described in 8.3 shall be
employed.
9. Dimensions
10.3 If a scale-free bright finish is required, this shall be
9.1 Nuts shall be hexagonal in shape, and in accordance specified on the purchase order.
with the dimensions for the hex or heavy hex series, as
required, by ASME B 18.2.2, ASME B 18.2.4.6M, and ISO 11. Retests
4033. Unless otherwise specified, the American National 11.1 Provisions for retests by the purchaser and his repre-
Standard Heavy Hex Series shall be used and nuts shall be sentative are specified in Supplementary Requirement S2.
either double chamfered or have a machined or forged washer
face, at the option of the manufacturer, and, conform to the 12. Certification
angularity requirements of ASME B 18.2.2, ASME B 12.1 In addition to the requirements of Specification A962/
18.2.4.6M, and ISO 4033. A962M, the certification shall include the results of the
9.2 Unless otherwise specified, threads shall be in accor- chemical analysis, macroetch examination (Carbon and Alloy
dance with ASME B 1.1 or ASME B 1.13M, and shall be Steels Only), mechanical tests, and the minimum tempering
gauged in accordance with ASME B 1.2 and ASME B 1.13M temperature for nuts of Grades 2H, 2HM, 3, 4, 6, 6F, 7, and
as described in 9.2.1 and 9.2.2. 7M.
9.2.1 Nuts up to and including 1 in. nominal size shall be
UNC Series Class 2B fit. Metric nuts up to and including M24 13. Product Marking
nominal size shall be coarse thread series tolerance 6H. 13.1 In addition to the requirements of Specification A962/
9.2.2 Nuts over 1 in. nominal size shall be either UNC A962M, nuts shall be legibly marked on one face with the
Series Class 2B fit or 8 UN Series Class 2B fit. Unless grade symbol representing the grade, type, and applicable
otherwise specified, the 8 UN series shall be furnished. Metric manufacturing process shown in Table 7. Marking of wrench
nuts over M24 nominal size shall be coarse thread series flats or bearing surfaces is not permitted unless agreed upon
tolerance 6H. between manufacturer and purchaser.
10. Workmanship, Finish, and Appearance 14. Keywords
10.1 Nuts shall be free of defects and shall be good 14.1 bolting; chemical analysis; coated; marking on fasten-
commercial finish. ers; plated

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 A194/A194M 15
TABLE 7 Grade Symbol Marking of NutsA
Nuts Hot- Nuts Machined Nuts Manu-
Grade and Forged or from Bar factured in
Type Cold- Stock Accordance
Punched with 6.6
1 1 1B ...
2 2 2B ...
2HB 2H 2HB ...
2HMB,C 2HM 2HMB ...
3 3 3B ...
4 4 4B ...
4LD 4L 4BL ...
6 6 6B ...
6F 6F 6FB ...
7 7 7B ...
7LD 7L 7BL ...
7MB,C 7M 7MB ...
7MLB,D 7ML 7MLB
8 8 8B 8A
8C 8C 8CB 8CA
8CLN 8CLN 8CLNB 8CLNA
8M 8M 8MB 8MA
8T 8T 8TB 8TA
8F 8F 8FB 8FA
8P 8P 8PB 8PA
8N 8N 8NB 8NA
8MN 8MN 8MNB 8MNA
8R 8R 8RB 8RA
8S 8S 8SB 8SA
8LN 8LN 8LNB 8LNA
8MLN 8MLN 8MLNB 8MLNA
8MLCuN 8MLCuN 8MLCuNB 8MLCuNA
8ML4CuN 8ML4CuN 8ML4CuNB 8ML4CuNA
9C 9C 9CB 9CA
16 16 16B
A
Where ellipses ({) appear in this table there is no requirement.
B
The letters H and M indicate heat-treated nuts (see Section 6).
C
An underline as a marking requirement for grades 2HM and 7M has been
removed but is permitted.
D
See Supplementary Requirement S3.

SUPPLEMENTARY REQUIREMENTS

One or more of the following supplementary requirements shall be applied only when specified by
the purchaser in the inquiry, contract, or order. Details of these supplementary requirements shall be
agreed upon in writing by the manufacturer and purchaser. Supplementary requirements shall in no
way negate any requirement of the specification itself.

S1. Strain-Hardened Austenitic Steel Nuts S2. Retests by Purchasers Representative

S1.1 Strain hardened Grades 8, 8C, 8T, 8M, 8F, 8P, 8N, or S2.1 The purchasers representative may select two nuts per
8MN nuts may be specified. When Supplementary Require- keg (200-lb unit [90-kg]) for sizes 58 in. and M16 and smaller,
ment S1 is invoked in the order, nuts shall be machined from one nut per keg for sizes over 58 in. and M16 up to and
cold drawn bars or shall be cold forged to shape. No subse- including 112 in. and M36, and one nut per every two kegs for
quent heat treatment shall be performed on the nuts. Nuts made sizes larger than 112 in. and M36, which shall be subjected to
in accordance with this requirement shall be proof load tested the tests specified in Section 8.
in accordance with 8.2.2.1 and shall withstand the proof load
specified in Table S1.1 and Table S1.2. Testing nuts requiring S3. Low-Temperature Requirements for Grade 4, Grade 7
proof loads over 160 000 lbf or 705 kN is only required when or Grade 7M Nuts
Supplementary Requirement S4 is invoked. The hardness S3.1 When low-temperature requirements are specified for
limits of Table 2 do not apply to strain hardened nuts. Nuts Grade 4 or Grade 7 nuts, the Charpy test procedures and
made in accordance with this requirement shall be marked with requirements as defined in Specification A320/A320M for
the Grade symbol underlined. Grade L7 shall apply. When low-temperature requirements are

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 A194/A194M 15
TABLE S1.1 Proof Load Testing of Strain Hardened Nuts Using Threaded Mandrel Inch Series
NOTE 1Proof loads are not design loads.
Proof Load, lbfA
All Other Types All Other Types
Nominal Threads Stress Area, Grade 8M Grade 8M
of Grade 8 of Grade 8
Size, in. per in. in.2 (strain hardened) (strain hardened)
(strain hardened) (strain hardened)
Heavy HexB HexC Heavy HexD HexB
14 20 0.0316 3 480 3 160 3 950 3 480

5 16 18 0.0523 5 760 5 240 6 550 5 760
38 16 0.0774 8 510 7 740 9 675 8 510

7 16 14 0.1063 11 690 10 630 13 290 11 690
12 13 0.1419 15 610 14 190 17 740 15 610

9 16 12 0.182 20 020 18 200 22 750 20 020
58 11 0.226 24 860 22 600 28 250 24 860
3 4 10 0.334 36 740 33 400 41 750 36 740
7 8 9 0.462 46 200 41 580 53 130 46 200
1 8 0.606 60 600 54 540 69 690 60 600

1 18 8 0.790 75 050 67 150 82 950 75 050

1 14 8 1.000 95 000 85 000 105 000 95 000
1 38 8 1.233 110 970 98 640 123 300 110 970
1 12 8 1.492 134 280 119 360 149 200 134 280
A
The proof load for jam nuts shall be 46 % of the tabulated value.
B
Based on proof stress of 110 000 psi up to 34 in.; 100 000 psi 78 to 1 in.; 95 000 psi 118 to 114 in.; 90 000 psi 138 to 112 in.
C
Based on proof stress of 100 000 psi up to 34 in.; 90 000 psi 78 to 1 in.; 85 000 psi 118 to 114 in.; 80 000 psi 138 to 112 in.
D
Based on proof stress of 125 000 psi up to 34 in.; 115 000 psi 78 to 1 in.; 105 000 psi 118 to 114 in.; 100 000 psi 138 to 112 in.

TABLE S1.2 Proof Load Testing of Strain Hardened Nuts Using Threaded MandrelMetric
NOTE 1Proof loads are not design loads.
Proof Load, kNA
All Other Types All Other Types
Nominal Thread Stress Area, Grade 8M Grade 8M
of Grade 8 of Grade 8
Size, mm Pitch mm2 (strain hardened) (strain hardened)
(strain hardened) (strain hardened)
Heavy HexB HexC Heavy HexD HexB
M6 1.0 20.1 15.3 13.9 17.3 15.3
M8 1.25 36.6 27.8 25.3 31.3 27.8
M10 1.50 58.0 44.1 40.0 49.9 44.1
M12 1.75 84.3 64.1 58.2 72.5 64.1
M14 2.0 115.0 87.4 79.4 98.9 87.4
M16 2.0 157.0 119.3 108.3 135.0 119.3
M20 2.5 245.0 186.2 169.0 210.9 186.2
M22 2.5 303.0 209.0 187.9 240.9 209.0
M24 3.0 353.0 243.5 218.9 280.6 243.5
M27 3.0 459.0 300.6 268.5 332.7 300.6
M30 3.5 561.0 367.5 328.2 406.7 367.5
M36 4.0 817.0 506.5 449.4 563.7 506.5
A
The proof load for jam nuts shall be 46 % of the tabulated value.
B
Based on proof stress of 760 MPa up to M20 mm; 690 MPa M22 to M24 mm; 655 MPa M27 to M30; and 620 MPa for M36.
C
Based on proof stress of 690 MPa up to M20 mm; 620 MPa M22 to M24 mm; 585 MPa M27 to M30; and 550 MPa for M36.
D
Based on proof stress of 860 MPa up to M20 mm; 795 MPa M22 to M24 mm; 725 MPa M27 to M30 mm; and 690 MPa for M36.

specified for Grade 7M nuts, the Charpy test procedures and with the nuts for which the test is to apply. Impact testing is not
requirements as defined in Specification A320/A320M for required when the bar stock or nut is smaller than 58 in. [16
Grade L7M shall apply. Charpy specimens may be taken from mm] in diameter.
a sample nut, nut blank, or may be taken from separate test S3.2 An L shall be added to the marking, as shown in
samples of the same heat processed through heat treatment Table 7, for nuts so tested.

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 A194/A194M 15
S4. Proof Load Tests of Large Nuts S7.1.1 Reference to the appropriate coating specification
S4.1 Proof load testing of nuts requiring proof loads of over and type, thickness, location, modification to dimensions, and
160 000 lbf or 705 kN is required. Testing shall be performed hydrogen embrittlement relief.
in accordance with 8.2 to the loads required in Table S4.1 and NOTE S7.1Modification of thread dimensions may result in loss of
Table S4.2. The maximum load will be based entirely on the load carrying ability.
equipment available. S7.1.2 Reference to Specifications A153/A153M, B633,
S5. Control of Product by Heat Number B695, B696, B766, F1941, F2329, or Test Method F1940, or
other standards.
S5.1 When control of nuts by actual heat analysis is
required and this supplementary requirement is specified, the
manufacturer shall identify the completed nuts in each ship- S8. Marking Coated Nuts
ment by the actual heat number. When this supplementary S8.1 Nuts coated with zinc shall have ZN marked after the
requirement is specified, a certificate including the results of grade symbol. Nuts coated with cadmium shall have CD
the actual production tests of each test lot together with the heat marked after the grade symbol.
chemical analysis shall be furnished by the manufacturer. NOTE S8.1As an example, the marking for zinc-coated 2H fasteners
S6. Grain Size Requirements for Non H Grade Austenitic will now be 2HZN rather than 2H*.
Steels Used Above 1000 F
S9. Proof Load Testing
S6.1 For design metal temperatures above 1000 F [540
C], the material shall have a grain size of No. 7 or coarser as S9.1 Proof load tests of nuts made to dimensions, thread
determined in accordance with Test Methods E112. The grain pitch, and configurations other than those covered in Table 3 or
size so determined shall be reported on the Certificate of Test. Table 4 shall be made using loads agreed upon between the
S7. Coating on Nuts manufacturer and the purchaser.
S7.1 It is the purchasers responsibility to specify in the S10. 100 % Hardness Testing of Grade 2HM and 7M
purchase order all information required by the coating facility.
Examples of such information may include but are not limited S10.1 Each nut shall be tested for hardness by indentation
to the following: method and shall meet the requirements specified in Table 2.
TABLE S4.1 Proof Load for Large Heavy Hex Nuts InchA
Proof Load, lbfB
Nominal Threads Stress Area,
Grades 2, 2HM, 6, 6F, 7M Grades 2H, 3, 4, 7, 16
Size, in. per in. in. 2 Grade 1 Heavy Hex
Heavy Hex Heavy Hex
158 8 1.78 231 400 267 000 311 500
1 3 4 8 2.08 270 400 312 000 364 000
1 7 8 8 2.41 313 300 361 500 421 800
2 8 2.77 360 100 415 500 484 800
2 1 4 8 3.56 462 800 534 000 623 000
2 1 2 8 4.44 577 200 666 000 777 000
2 3 4 8 5.43 705 900 814 500 950 250
A
ASME B18.2.2 in the size range over 112 in. provides dimensions only for heavy hex nuts. Refer to 8.3.1.
B
Proof loads for nuts of larger dimensions or other thread series may be calculated by multiplying the thread stress area times the proof stress in the notes to Table 3
or Table S1.1. The proof load for jam nuts shall be 46 % of the tabulated load.

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 A194/A194M 15
TABLE S4.2 Proof Load for Large Heavy Hex Nuts MetricA
Nominal Proof Load, kNB
Thread Stress Area,
Size, Grades 2, 2HM, 6, 6F, 7M Grades 2H, 3, 4, 7, 16
Pitch mm 2 Grade 1 Heavy Hex
mm Heavy Hex Heavy Hex
M42 4.5 1120 1002.4 1159.2 1349.6
M48 5 1470 1315.7 1521.4 1771.4
M56 5.5 2030 1816.9 2101.0 2446.2
M64 6 2680 2398.6 2773.8 3229.4
M72 6 3460 3096.7 3581.1 4169.3
A
ASME B 18.2.4.6M in the size range over M36 provides dimensions only for heavy hex nuts. Refer to 7.3.1.
B
Proof loads for nuts of larger dimensions or other thread series may be calculated by multiplying the thread stress area times the proof stress in the notes to Table 4
or Table S1.2. The proof load for jam nuts shall be 46 % of the tabulated load.

APPENDIXES

(Nonmandatory Information)

X1. STRAIN HARDENING OF AUSTENITIC STEELS

X1.1 Strain hardening is the increase in strength and hard- section reduction, die angle and bar size. In large diameter bars,
ness that results from plastic deformation below the recrystal- for example, plastic deformation will occur principally in the
lization temperature (cold work). This effect is produced in outer regions of the bar, so that the increased strength and
austenitic stainless steels by reducing oversized bars to the hardness due to strain hardening is achieved predominantly
desired final size by cold drawing or other process. The degree near the surface of the bar. That is, the smaller the bar, the
of strain hardening achievable in any alloy is limited by its greater the penetration of strain hardening. Thus, the mechani-
strain hardening characteristics. In addition, the amount of cal properties of a given strain hardened fastener are dependent
strain hardening that can be produced is further limited by the not just on the alloy, but also on the size of bar from which it
variables of the process, such as the total amount of cross- is machined.

X2. COATINGS AND APPLICATION LIMITS

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

SUMMARY OF CHANGES

Committee A01 has identified the location of selected changes to this specification since the last issue,
A194/A194M14a, that may impact the use of this specification. (Approved June 1, 2015)

(1) Title of Specification was changed to include Stainless

Steel.

Committee A01 has identified the location of selected changes to this specification since the last issue,
A194/A194M14, that may impact the use of this specification. (Approved November 1, 2014)

(1) Added UNS S31730, Grades 8ML4CuN and 8ML4CuNA, (2) Revised Note D of Table 1 to clarify meaning of ellipses.
to 6.5, 6.6, Table 1, Table 2, and Table 7 (3) ISO 4033 was added as a dimensional reference standard.

Committee A01 has identified the location of selected changes to this specification since the last issue,
A194/A194M13, that may impact the use of this specification. (Approved May 1, 2014)

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 A194/A194M 15
(1) Harmonized chemistry with Specifications A29 and A276 (2) Revised S3.1 to clarify nut Charpy specimens.
as applicable.

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