ASTM A194 Nuts

ASTM A194 specification covers a variety of carbon, alloy, and martensitic and austenitic stainless steel nuts. It is the Standard Specification for Carbon Steel, Alloy Steel, and Stainless Steel Nuts for Bolts for High Pressure or High Temperature Service. ASTM A194 nuts are intended for high-pressure or high-temperature service, or both. Bars from which the nuts are made shall be hot-wrought. These Nuts are either cold forged or hot forged or bar stock Machined.

ASTM A194 Nut, Hex Nut Manufacturers and Suppliers

Bolting material and bolting components supplied to ASTM A194 specification shall conform to the requirements of Specification A962/A962M, of which nuts are considered bolting components are bolts, studs, screws, and washers intended for use in special service applications.The requirements include test methods, finish, thread dimensions, marking, certification, optional supplementary requirements, and others. Failure to comply with the requirements of Specification A962/A962M constitutes nonconformance with this specification. In case of conflict between the requirements of this specification and Specification A962/A962M, ASTM A194 specification shall prevail.

Most Common Grades of A194 Nuts

ASTM A194 Grade 2 Nuts – Carbon Steel Heavy Hex Nuts

ASTM A194 Grade 2H Nuts – Quenched and tempered Carbon Steel Heavy Hex Nuts

ASTM A194 Grade 3 Nuts – Quenched and tempered Alloy Steel 501 Heavy Hex Nuts

ASTM A194 Grade 6 Nuts – Martensitic Stainless Steel 410 Heavy Hex Nuts

ASTM A194 Grade 7 Nuts – Quenched and Tempered Alloy Steel 4140 Heavy hex Nuts

ASTM A194 Grade 8 Nuts – Solution Annealed / Strain Hardened Stainless Steel 304 Heavy Hex Nuts

ASTM A194 Grade 8M Nuts – Solution Annealed / Strain Hardened Stainless Steel 316 Heavy Hex Nuts

ASTM A194 Grade 8MLCuNA Nuts – Solution Annealed 6 Moly / SMO254 Stainless Steel Heavy Hex Nuts

Size Range

ASTM A194 stated in either inch-pound units or SI units are to be regarded separately as standard. ASTM A194 nuts are manufactured in imperial size range of 1 / 4 ” through 4 inch and metric M6 through M100.

Thread Specification

Unless otherwise specified, the American National Standard Heavy Hex Series (ANSI B 18.2.2) shall be used. Nuts up to and including 1-inch nominal size shall be UNC Series Class2B fit. Nuts over 1 inch nominal size shall be either UNC Series Class 2B fit or 8 UN Series Class 2B fit.

Raw Material Specification for ASTM A194

According to ASTM A194 the material may be further processed by center less grinding or by cold drawing. Austenitic stainless steel may be solution annealed or annealed and strain-hardened. Each alloy shall conform to the chemical composition requirements prescribed. Hardness tests, proof of load tests, and cone proof load tests shall be made to all nuts to meet the requirements specified.

Download PDF: ASTM A194 at ASTM.org

Testing Requirements

Chemical Composition

ASTM A194 Chemical Composition

Grade SymbolMaterialUNSNumberCarbon %Manganese %Phosphorus %SulfurE %Silicon %Chromium %Nickel %Molybdenum %Titanium %Columbium %Nitrogen %OtherElements %
Grade 1carbon Steel 0.15 min1.000.0400.0500.40       
Grade 2, 2HM, and 2Hcarbon Steel 0.40 min1.000.0400.0500.40       
Grade 4carbon Steel 0.40-0.500.70-0.900.0350.0400.15-0.35  0.20-0.30    
Grade 3molybdenum Type 501 0.10 min1.000.0400.0301.004.0-6.0 0.40-0.65    
Grade 6Type 410 Stainless steelS410000.08-0.151.000.0400.0301.0011.5-13.5      
Grade 6FType 416 Stainless steelS416000.151.250.0600.15 min1.0012.0-14.0      
6FType 416 se Stainless steelS416230.151.250.0600.0601.0012.0-14.0     Selenium 0.15 min
Grade 7, Grade 7MType 4140 / 4142 / 4145, 4140H, 4142H, 4145H 0.38-0.480.75-1.00.0350.040.15-0.350.80-1.10 0.15-0.25    
Grade 8, 8AType 304 Stainless steelS304000.082.000.0450.0301.0018.0-20.08.0-11.0     
Grade 8C, 8CAType 347 Stainless steelS347000.082.000.0450.0301.0017.0-19.09.0-12.0  10 X  
Grade 8CLN,8CLNAType 347LN Stainless steelS347510.005-2.000.0450.0301.0017.0-19.09.0-13.0  carbon content, min 1.10 0.20-0.50,0.06-0.10 
Grade 8M, 8MAType 316 Stainless steelS316000.0200.082.000.0450.0301.0016.0-18.010.0-14.02.00-3.00 15 X carbon content, min  
Grade 8T, 8TAType 321 Stainless steelS321000.082.000.0450.0301.0017.0-19.09.0-12.0 5 X 0.10 
8F, 8FAType 303 Stainless steelS303000.152.000.200.15 min1.0017.0-19.08.0-10.0 (C+N) min -0.70 max   
Grade 8F, 8FAType 303se Stainless steelS303230.152.000.200.061.0017.0-19.08.0-10.0    Selenium 0.15 min
Grade 8P, 8PAType 305 Stainless steelS305000.122.000.0450.0301.0017.0-19.011.0-13.0     
Grade 8N, 8NAType 304N Stainless steelS304510.082.000.0450.0301.0018.0-20.08.0-11.0   0.10-0.16 
Grade 8LN,8LNAType 304LN Stainless steelS304530.0302.000.0450.0301.0018.0-20.08.0-11.0   0.10-0.16 
Grade 8MN, 8MNAType 316N Stainless steelS316510.082.000.0450.0301.0016.0-18.010.0-13.02.00-3.00  0.10-0.16 
Grade 8MLN, MLNA,Type 316LN Stainless steelS316530.0302.000.0450.0301.0016.0-18.010.0-13.02.00-3.00  0.10-0.16 
Grade 8R, 8RAfXM19 NitronicS209100.064.0-6.00.0450.0301.0020.5-23.511.5-13.51.50-3.00 0.10-0.300.20-0.40Vanadium 0.10-0.30
Grade 8S, 8SA Grade 8MLCuN,S31254S21800 S312540.100.0207.0-9.0 1.000.0600.0300.0300.0103.5^.50.8016.0-18.019.5-20.58.0-9.0 17.5-18.56.0-6.5  0.08-0.180.18-0.22Copper,0.50-1.00
Grade 8MLCUNA, B8ML4CUNS31730S317300.0302.000.0400.0101.0017.0-19.015.0-16.53.0-4.0  0.045Copper 4.0-5.0
Grade 9C, 9CAN08367N083670.0302.000.0400.0301.0020.0-22.023.5- 25.56.0-7.0  0.18-0.25Copper 0.75
Grade 16Chromium Molybdenum Vanadium Steel 0.36-0.470.45-0.700.0350.0400.15-0.350.80-1.15 0.50-0.65   Vanadium0.25-0.35, Aluminum6 0.015

‘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.

EBecause of the degree to which sulfur segregates, product analysis for sulfur over 0.060 % max is not technologically appropriate.

fAs described in Specification A276.

GGrade 4 is expected to be withdrawn within approximately 2 years. Grade 7 is an acceptable substitute for Grade 4.

 

Hardness Requirements

ASTM A194 Hardness Requirements

  Completed Nuts Sample Nut after Treatment as in 8.1.5
Grade and TypeBrinellHardnessRockwell HardnessC ScaleB ScaleBrinellHardness,minRockwell Hardness B Scale, min
1121 min 70 min12170
2159 to 352 84 min15984
2H to 112 in. or M36, incl248 to 32724 to 35 17989
2H over 1V2 in. or M36212 to 32735 max95 min14779
2HM and 7M159 to 235 84 to 9915984
3, 4, 7, and 16248 to 32724 to 35 20194
6 and 6F228 to 27120 to 28   
8, 8C, 8CLN, 8M, 8T, 8F, 8P, 8N,8MN,8LN, 8MLN, 8MLCuN, 8ML4CuN, and 9C126 to 30032 max60 min  
8A, 8CA, 8CLNA, 8MA, 8TA, 8FA, 8PA, 8NA,8MNA, 8LNA, 8MLNA, 8MLCuNA, 8ML4CuNA and 9CA126 to 192 60 to 90  
8R, 8RA, 8S, and 8SA183 to 27125 max88 min  

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

These grades shall be uniformly reheated to the proper austenitizing temperature (a group thus reheated being known as a quenching charge) and quenched under substantially uniform conditions for each quenching charge and tempered as shown below. Grades 2H, 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 heated to a temperature range from 1700 to 1750 °F (925 to 955 °C) and oil quenched.

Proof Load Requirements (Inch)

ASTM A194 Proof Load Requirements (Inch)

Nominal Size, in.Threads per InchStress Area in.2  Proof Load, lbfA  
 Grade 1Grades 2, 2HM, 6, 6F, 7MGrades 2H, 3, 4, 7, 16
Heavy HexBHexCHeavy HexDHexEHeavy HexFHexG
1/4200.03164 1303 8204 7704 3005 5704 770
5/16180.05246 8106 2907 8607 0709 1707 860
3/8160.077410 0809 30011 62010 46013 56011 620
7/16140.106313 82012 76015 94014 35018 60015 940
1/2130.141918 45017 03021 28019 16024 83021 280
9/l6120.18223 66021 84027 30024 57031 85027 300
5/8110.22629 38027 12033 90030 51039 55033 900
3/4100.33443 42040 08050 10045 09058 45050 100
7/890.46260 06055 44069 30062 37080 85069 300
180.60678 78072 72090 90081 810106 00090 900
1 1/880.790102 70094 800118 500106 700138 200118 500
1 1/481.000130 000120 000150 000135 000175 000150 000
1 3/881.233160 200148 000185 000166 500215 800185 000
1 1/281.492194 000170 040223 800201 400261 100223 800

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.

EBased on proof stress of 135 000 psi.

FBased 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.

‘ Based on proof stress of 75 000 psi.

Proof Load Requirements (Metric)

ASTM A194 Proof Load Requirements (Metric)

NominalThreadsPitchStress Area mm2   Proof Load, kNA  
Size, Grade 1Grades 2, 2HM, 6, 6F, 7MGrades 2H, 3, 4, 7, 16
mmHeavy HexBHexCHeavy HexDHexEHeavy HexFHexG
M61.020.1 18.016.620.818.729.220.8
M81.2536.6 32.830.237.934.044.137.9
M101.5058.0 51.947.960.053.969.960.0
M121.7584.3 75.569.587.378.4101.687.3
M142.0115.0 102.994.9119.0107.0138.6119.0
M162.0157.0 140.5129.5162.5146.0189.2162.5
M202.5245.0 219.3202.1253.6227.8295.2253.6
M222.5303.0 271.2249.9313.6281.8365.1313.6
M243.0353.0 315.9291.2365.4328.3425.4365.4
M273.0459.0 411.0378.7475.1426.9553.4475.1
M303.5561.0 502.1462.8580.6521.7676.0580.6
M364.0817.0 731.2674.0845.6759.8984.5845.6
    All Types of Grade 8, and    
    Grades 9C and 9CA    
 Nominal Size, mm Thread Pitch StressHeavy HexHHex’   
    Area,     
    mm2     
 M6 1.020.111.110.4   
 M8 1.2536.620.118.8   
 M10 1.5058.031.929.9   
 M12 1.7584.346.443.4   
 M14 2.0115.063.359.2   
 M16 2.0157.086.480.9   
 M20 2.5245.0134.8126.2   
 M22 2.5303.0166.7156.0   
 M24 3.0353.0194.2181.8   
 M27 3.0459.0252.5236.4   
 M30 3.5561.0308.6288.9   
 M36 4.0817.0449.4420.8   

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.

E Based on proof stress of 930 MPa.

G Based on proof stress of 1035 MPa.

H Based on proof stress of 550 MPa.

‘ Based on proof stress of 515 MPa.

Astm A194 Nut Types

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