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 Symbol Material UNSNumber Carbon % Manganese % Phosphorus % SulfurE % Silicon % Chromium % Nickel % Molybdenum % Titanium % Columbium % Nitrogen % OtherElements %
Grade 1 carbon Steel   0.15 min 1.00 0.040 0.050 0.40              
Grade 2, 2HM, and 2H carbon Steel   0.40 min 1.00 0.040 0.050 0.40              
Grade 4 carbon Steel   0.40-0.50 0.70-0.90 0.035 0.040 0.15-0.35     0.20-0.30        
Grade 3 molybdenum Type 501   0.10 min 1.00 0.040 0.030 1.00 4.0-6.0   0.40-0.65        
Grade 6 Type 410 Stainless steel S41000 0.08-0.15 1.00 0.040 0.030 1.00 11.5-13.5            
Grade 6F Type 416 Stainless steel S41600 0.15 1.25 0.060 0.15 min 1.00 12.0-14.0            
6F Type 416 se Stainless steel S41623 0.15 1.25 0.060 0.060 1.00 12.0-14.0           Selenium 0.15 min
Grade 7, Grade 7M Type 4140 / 4142 / 4145, 4140H, 4142H, 4145H   0.38-0.48 0.75-1.0 0.035 0.04 0.15-0.35 0.80-1.10   0.15-0.25        
Grade 8, 8A Type 304 Stainless steel S30400 0.08 2.00 0.045 0.030 1.00 18.0-20.0 8.0-11.0          
Grade 8C, 8CA Type 347 Stainless steel S34700 0.08 2.00 0.045 0.030 1.00 17.0-19.0 9.0-12.0     10 X    
Grade 8CLN,8CLNA Type 347LN Stainless steel S34751 0.005- 2.00 0.045 0.030 1.00 17.0-19.0 9.0-13.0     carbon content, min 1.10 0.20-0.50, 0.06-0.10  
Grade 8M, 8MA Type 316 Stainless steel S31600 0.0200.08 2.00 0.045 0.030 1.00 16.0-18.0 10.0-14.0 2.00-3.00   15 X carbon content, min    
Grade 8T, 8TA Type 321 Stainless steel S32100 0.08 2.00 0.045 0.030 1.00 17.0-19.0 9.0-12.0   5 X   0.10  
8F, 8FA Type 303 Stainless steel S30300 0.15 2.00 0.20 0.15 min 1.00 17.0-19.0 8.0-10.0   (C+N) min -0.70 max      
Grade 8F, 8FA Type 303se Stainless steel S30323 0.15 2.00 0.20 0.06 1.00 17.0-19.0 8.0-10.0         Selenium 0.15 min
Grade 8P, 8PA Type 305 Stainless steel S30500 0.12 2.00 0.045 0.030 1.00 17.0-19.0 11.0-13.0          
Grade 8N, 8NA Type 304N Stainless steel S30451 0.08 2.00 0.045 0.030 1.00 18.0-20.0 8.0-11.0       0.10-0.16  
Grade 8LN,8LNA Type 304LN Stainless steel S30453 0.030 2.00 0.045 0.030 1.00 18.0-20.0 8.0-11.0       0.10-0.16  
Grade 8MN, 8MNA Type 316N Stainless steel S31651 0.08 2.00 0.045 0.030 1.00 16.0-18.0 10.0-13.0 2.00-3.00     0.10-0.16  
Grade 8MLN, MLNA, Type 316LN Stainless steel S31653 0.030 2.00 0.045 0.030 1.00 16.0-18.0 10.0-13.0 2.00-3.00     0.10-0.16  
Grade 8R, 8RAf XM19 Nitronic S20910 0.06 4.0-6.0 0.045 0.030 1.00 20.5-23.5 11.5-13.5 1.50-3.00   0.10-0.30 0.20-0.40 Vanadium 0.10-0.30
Grade 8S, 8SA Grade 8MLCuN, S31254 S21800 S31254 0.100.020 7.0-9.0 1.00 0.0600.030 0.0300.010 3.5^.50.80 16.0-18.019.5-20.5 8.0-9.0 17.5-18.5 6.0-6.5     0.08-0.180.18-0.22 Copper,0.50-1.00
Grade 8MLCUNA, B8ML4CUN S31730 S31730 0.030 2.00 0.040 0.010 1.00 17.0-19.0 15.0-16.5 3.0-4.0     0.045 Copper 4.0-5.0
Grade 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
Grade 16 Chromium Molybdenum Vanadium Steel   0.36-0.47 0.45-0.70 0.035 0.040 0.15-0.35 0.80-1.15   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 Type BrinellHardness Rockwell HardnessC Scale B Scale BrinellHardness,min Rockwell Hardness B 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 1V2 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, 8N,8MN,8LN, 8MLN, 8MLCuN, 8ML4CuN, and 9C 126 to 300 32 max 60 min    
8A, 8CA, 8CLNA, 8MA, 8TA, 8FA, 8PA, 8NA,8MNA, 8LNA, 8MLNA, 8MLCuNA, 8ML4CuNA and 9CA 126 to 192   60 to 90    
8R, 8RA, 8S, and 8SA 183 to 271 25 max 88 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 Inch Stress Area in.2     Proof Load, lbfA    
  Grade 1 Grades 2, 2HM, 6, 6F, 7M Grades 2H, 3, 4, 7, 16
Heavy HexB HexC Heavy HexD HexE Heavy HexF HexG
1/4 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
3/8 16 0.0774 10 080 9 300 11 620 10 460 13 560 11 620
7/16 14 0.1063 13 820 12 760 15 940 14 350 18 600 15 940
1/2 13 0.1419 18 450 17 030 21 280 19 160 24 830 21 280
9/l6 12 0.182 23 660 21 840 27 300 24 570 31 850 27 300
5/8 11 0.226 29 380 27 120 33 900 30 510 39 550 33 900
3/4 10 0.334 43 420 40 080 50 100 45 090 58 450 50 100
7/8 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

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)

Nominal ThreadsPitch Stress Area mm2       Proof Load, kN A    
Size,   Grade 1 Grades 2, 2HM, 6, 6F, 7M Grades 2H, 3, 4, 7, 16
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 Hex’      
        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.

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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