ASTM A194 is a specification that covers a variety of carbon, alloy, and stainless steel nuts intended for use in high-pressure and high-temperature service. The specification covers both inch and metric nuts. The nuts are intended for use with bolts and other fasteners that conform to ASTM A193, ASTM A320, and other specifications. The specification includes several grades of nuts, each with different chemical and mechanical properties, to suit different applications.
The ASTM A194 specification governs mechanical and material requirements for carbon steel, alloy steel, and stainless steel nuts in the size range of 1/4 to 4 inches and metric M6 through M100 nominal. The specification also covers austensic steel nuts up to ¼ inch and M6 nominal and above.
Marking of NutsA | |||
---|---|---|---|
Grade and Type | Nuts Hot Forged or Cold Punched | Nuts Machined from Bar Stock | Nuts Manufactured in Accordance 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 |
AWhere ellipses (...) appear in this table there is no requirement.
BThe letters H and M indicate heat-treated nuts (see Section 6).
CAn underline as a marking requirement for grades 2HM and 7M has been removed
but is permitted.
DSee Supplementary Requirement S3.
The mechanical properties requirements for nuts with an ASTM A194 specification govern the hardness required for nuts depending on their grade and type. The nuts must also be able to withstand proof loads determined by their nominal sizes.
Proof Load Using Threaded Mandrel - Inch Series | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|
Nominal Size, in | Threads per Inch | Stress Area in2 | Proof Load, IbfA | |||||||
Grade 1 | Grades 2, 2HM, 6, 6F, 7M | Grades 2H, 3, 4, 7, 16 | All Types of Grade 8, Grades 9C and 9CA | |||||||
Heavy HexB | HexC | Heavy HexD | HexE | Heavy HexF | HexG | Heavy HexH | HexI | |||
1/4 | 20 | 0.0316 | 4 130 | 3 820 | 4 770 | 4 300 | 5 570 | 4 770 | 2 540 | 2 380 |
5/16 | 18 | 0.0524 | 6 810 | 6 290 | 7 860 | 7 070 | 9 170 | 7 860 | 4 190 | 3 930 |
3/8 | 16 | 0.0774 | 10 080 | 9 300 | 11 620 | 10 460 | 13 560 | 11 620 | 6 200 | 5 810 |
7/16 | 14 | 0.1063 | 13 820 | 12 760 | 15 940 | 14 350 | 18 600 | 15 940 | 8 500 | 7 970 |
1/2 | 13 | 0.1419 | 18 450 | 17 030 | 21 280 | 19 160 | 24 830 | 21 280 | 11 350 | 10 640 |
9/16 | 12 | 0.182 | 23 660 | 21 840 | 27 300 | 24 570 | 31 850 | 27 300 | 14 560 | 13 650 |
5/8 | 11 | 0.226 | 29 380 | 27 120 | 33 900 | 30 510 | 39 550 | 33 900 | 18 080 | 16 950 |
3/4 | 10 | 0.334 | 43 420 | 40 080 | 50 100 | 45 090 | 58 450 | 50 100 | 26 720 | 25 050 |
7/8 | 9 | 0.462 | 60 060 | 55 440 | 69 300 | 62 370 | 80 850 | 69 300 | 36 960 | 34 650 |
1 | 8 | 0.606 | 78 780 | 72 720 | 90 900 | 81 810 | 106 000 | 90 900 | 48 480 | 45 450 |
1 1/8 | 8 | 0.790 | 102 700 | 94 800 | 118 500 | 106 700 | 138 200 | 118 500 | 63 200 | 59 250 |
1 1/4 | 8 | 1.000 | 130 000 | 120 000 | 150 000 | 135 000 | 175 000 | 150 000 | 80 000 | 75 000 |
1 3/8 | 8 | 1.233 | 160 200 | 148 000 | 185 000 | 166 500 | 215 800 | 185 000 | 98 640 | 92 450 |
1 1/2 | 8 | 1.492 | 194 000 | 170 040 | 223 800 | 201 400 | 261 100 | 223 800 | 119 360 | 111 900 |
Proof Load Using Threaded Mandrel - Metric | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|
Nominal Size, mm | Threads Pitch | Stress Area mm2 | Proof Load, kNA | All Types of Grade 8, and Grades 9C and 9CA | ||||||
Grade 1 | Grades 2, 2HM, 6, 6F, 7M | Grades 2H, 3, 4, 7, 16 | ||||||||
Heavy HexB | HexC | Heavy HexD | HexE | Heavy HexF | HexG | Heavy HexH | HexI | |||
M6 | 1.00 | 20.1 | 18.0 | 16.6 | 20.8 | 18.7 | 29.2 | 20.8 | 11.1 | 10.4 |
M8 | 1.25 | 36.6 | 32.8 | 30.2 | 37.9 | 34.0 | 44.1 | 37.9 | 20.1 | 18.8 |
M10 | 1.50 | 58.0 | 51.9 | 47.9 | 60.0 | 53.9 | 69.9 | 60.0 | 31.9 | 29.9 |
M12 | 1.75 | 84.3 | 75.5 | 69.5 | 87.3 | 78.4 | 101.6 | 87.3 | 46.4 | 43.4 |
M14 | 2.00 | 115.0 | 102.9 | 94.9 | 119.0 | 107.0 | 138.6 | 119.0 | 63.3 | 59.2 |
M16 | 2.00 | 157.0 | 140.5 | 129.5 | 162.5 | 146.0 | 189.2 | 162.5 | 86.4 | 80.9 |
M20 | 2.50 | 245.0 | 219.2 | 202.1 | 253.6 | 227.8 | 295.2 | 253.6 | 134.8 | 126.2 |
M22 | 2.50 | 303.0 | 271.2 | 249.9 | 313.6 | 281.8 | 365.1 | 313.6 | 166.7 | 156.0 |
M24 | 3.00 | 353.0 | 315.9 | 291.2 | 365.4 | 328.3 | 425.4 | 365.4 | 194.2 | 181.8 |
M27 | 3.00 | 459.0 | 411.0 | 378.7 | 475.1 | 426.9 | 553.4 | 475.1 | 252.5 | 236.4 |
M30 | 3.50 | 561.0 | 502.1 | 462.8 | 580.6 | 521.7 | 676.0 | 580.6 | 308.6 | 288.9 |
M36 | 4.00 | 817.0 | 731.2 | 674.0 | 845.6 | 759.8 | 984.5 | 845.6 | 449.4 | 420.8 |
ASee limit for proof load test in 8.2.2.1. The proof load for jam nuts shall be 46 % of the tabulated load.
BBased on proof stress of 895 MPa.
CBased on proof stress of 825 MPa.
DBased
on proof stress of 1035 MPa.
EBased on proof stress of 930 MPa.
FBased on proof stress of 1205 MPa.
GBased on proof stress of 1035 MPa.
HBased on proof stress of 550 MPa.
IBased on proof stress of 515 MPa.
The dimensional requirements for nuts with an ASTM A194 specification determines that the nuts should be hexagonal and conform to the dimensions for hex or heavy hex series dimensions outlined by ASME B 18.2.2, ASME B 18.2.4.6M and ISO
4033.
TABLE 2 Hardness RequirementsA | |||||
---|---|---|---|---|---|
Grade and Type | Completed Nuts | Sample Nut after Treatment as in 8.1.5 | |||
Brinell Hardness | Rockwell Hardness | Brinell Hardness, min | Rockwell Hardness B Scale, min | ||
C Scale | B Scale | ||||
1 | 121 min | ... | 70 min | 121 | 70 |
2 | 159 to 352 | ... | 84 min | 159 | 84 |
2H to 1 1⁄2 in. or M36, incl | 248 to 327 | 24 to 35 | … | 179 | 89 |
2H over 1 1⁄2 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, 8N8MN, 8LN, 8MLN, 8MLCuN, 8ML4CuN, and 9C | 228 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.
The steel used to manufacture nuts that fall into the ASTM A194 specification must conform to chemical composition requirements that specify the permitted percentages of elemental metals within the steel used for the nuts.
Chemical RequirementsA,B,C,D | ||||||||||||||
Grade Symbol | Material | UNS Number | Carbon, % | Manganese, % | Phosphorus, % | SulfurE, % | Silicon, % | Chromium, % | Nickel, % | Molybdenium, % | Titanium, % | Columbium, % | Nitrogen, % | Other Elements, % |
1 | carbon | 0.15 min | 1.0 | 0.04 | 0.05 | 0.4 | ... | ... | ... | ... | ... | ... | ... | |
2, 2HM, and 2H | carbon | 0.40 min | 1.0 | 0.04 | 0.05 | 0.4 | ... | ... | ... | ... | ... | ... | ... | |
4G | carbon, molydenum | 0.40-0.50 | 0.70-0.90 | 0.035 | 0.04 | 0.15-0.35 | ... | ... | 0.20-0.30 | ... | ... | ... | ... | |
3 | Type 501 | 0.10 min | 1.0 | 0.04 | 0.03 | 1.0 | 4.0-6.0 | ... | 0.40-0.65 | ... | ... | ... | ... | |
6 | Type 410 | S41000 | 0.08-0.15 | 1.0 | 0.04 | 0.03 | 1.0 | 11.5-13.5 | ... | ... | ... | ... | ... | ... |
6F | Type 416 | S41600 | 0.15 | 1.2 | 0.06 | 0.15 min | 1.0 | 12.0-14.0 | ... | ... | ... | ... | ... | ... |
6F | Type 416Se | S41623 | 0.15 | 1.2 | 0.06 | 0.06 | 1.0 | 12.0-14.0 | ... | ... | ... | ... | ... | Selenium, 0.15 min |
7, 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 | ... | ... | ... | ... | |
8, 8A | Type 304 | S30400 | 0.08 | 2.0 | 0.045 | 0.03 | 1.0 | 18.0-20.0 | 8.0-11.0 | ... | ... | ... | ... | ... |
8C, 8CA | Type 347 | S34700 | 0.08 | 2.0 | 0.045 | 0.03 | 1.0 | 17.0-19.0 | 9.0-12.0 | ... | ... | 10 x carbon content, min 1.10 | ... | ... |
8CLN, 8CLNA | Type 347LN | S34751 | 0.005-0.02 | 2.0 | 0.045 | 0.03 | 1.0 | 17.0-19.0 | 9.0-13.0 | ... | ... | 0.20-0.50, 15x carbon content, min | 0.06-0.10 | ... |
8M, 8MA | Type 316 | S31600 | 0.08 | 2.0 | 0.045 | 0.03 | 1.0 | 16.0-18.0 | 10.0-14.0 | 2.00-3.00 | ... | ... | ... | ... |
8T, 8TA | Type 321 | S32100 | 0.08 | 2.0 | 0.045 | 0.03 | 1.0 | 17.0-19.0 | 9.0-12.0 | ... | 5 x (C+N) min-0.7 max | ... | 0.10 | ... |
8F, 8FA | Type 303 | S30300 | 0.15 | 2.0 | 0.2 | 0.15 min | 1.0 | 17.0-19.0 | 8.0-10.0 | ... | ... | ... | ... | ... |
8F, 8FA | Type 303Se | S30323 | 0.15 | 2.0 | 0.2 | 0.06 | 1.0 | 17.0-19.0 | 8.0-10.0 | ... | ... | ... | ... | Selenium, 0.15 min |
8P, 8PA | Type 305 | S30500 | 0.12 | 2.0 | 0.045 | 0.03 | 1.0 | 17.0-19.0 | 11.0-13.0 | ... | ... | ... | ... | ... |
8N, 8NA | Type 304N | S30451 | 0.08 | 2.0 | 0.045 | 0.03 | 1.0 | 18.0-20.0 | 8.0-11.0 | ... | ... | ... | 0.10-0.16 | ... |
8LN, 8LNA | Type 304LN | S30453 | 0.03 | 2.0 | 0.045 | 0.03 | 1.0 | 18.0-20.0 | 8.0-11.0 | ... | ... | ... | 0.10-0.16 | ... |
8MN, 8MNA | Type 316N | S31651 | 0.08 | 2.0 | 0.045 | 0.03 | 1.0 | 16.0-18.0 | 10.0-13.0 | 2.00-3.00 | ... | ... | 0.10-0.16 | ... |
8MLN, 8MLNA | Type 316LN | S31653 | 0.03 | 2.0 | 0.045 | 0.03 | 1.0 | 16.0-18.0 | 10.0-13.0 | 2.00-3.00 | ... | ... | 0.10-0.16 | ... |
8R, 8RAF | XM19 | S20910 | 0.06 | 4.0-6.0 | 0.045 | 0.03 | 1.0 | 20.5-23.5 | 11.5-13.5 | 1.50-3.00 | ... | 0.10-0.30 | 0.20-0.40 | Vnadium, 0.10-0.30 |
8S, 8Sa | S21800 | 0.1 | 7.0-9.0 | 0.06 | 0.03 | 3.5-4.5 | 16.0-18.0 | 8.0-9.0 | ... | ... | ... | 0.08-0.18 | ||
8MLCuN, 8MLCuNA | S31254 | S31254 | 0.02 | 1.0 | 0.03 | 0.01 | 0.8 | 19.5-20.5 | 17.5-18.5 | 6.0-6.5 | ... | ... | 0.18-0.22 | Copper, 0.50-1.00 |
B8ML4CuN | S31730 | S31730 | 0.03 | 2.0 | 0.04 | 0.01 | 1.0 | 17.0-19.0 | 15.0-16.5 | 3.0-4.0 | ... | ... | 0.045 | Copper 4.0-5.0 |
9C, 9CA | N08367 | N08367 | 0.03 | 2.0 | 0.04 | 0.03 | 1.0 | 20.0-22.0 | 23.5-25.5 | 6.0-7.0 | 0.18-0.25 | Copper 0.75 | ||
16 | Chromium Molybdenum Vanadium | 0.36-0.47 | 0.45-0.70 | 0.035 | 0.04 | 0.15-0.35 | 0.80-1.15 | ... | 0.50-0.65 | ... | ... | ... | Vanadium, 0.25-0.35 AluminumB |
AThe 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.
BTotal aluminum, soluble and insoluble.
CMaximum, unless minimum or range is indicated.
DWhere 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. See 7.2.