ASTM A194 Specification covers Carbon and Alloy Steel Nuts most popular grade 2H, 2HM, 3, 4, 6, 7, 7M, 8, 8M, 8T, 16, etc., to be used with ASTM A193 Bolts for High Pressure or High Temperature Service, or both.
ASTM A194 specification covers a variety of carbon, alloy, and martensitic stainless steel nuts in the size range 1/4 through 4
in. and metric M6 through M100 nominal. It also covers austenitic stainless steel nuts in the size range 1/4 in. and M6
nominal and above. These nuts are intended for high-pressure or high-temperature service, or both.
Nut Grades
| Grades |
Material |
UNS Number |
| 2H |
Carbon Steel |
- |
| 2HM |
Carbon Steel |
- |
| 3 |
Ferritic Stainless Steel Type 501 |
S50100 |
| 4 |
Carbon, Molybdenum Steel
|
- |
| 6 |
Ferritic Stainless Steel Type 410 |
S41000 |
| 7 |
Chromium Molybdenum Steel Type 4140, 4142, 4145, 4140H, 4142H, 4145H |
- |
| 7M |
Chromium Molybdenum Steel Type 4140, 4142, 4145, 4140H, 4142H, 4145H |
- |
| 8 |
Austenitic Stainless Steel Type 304 |
S30400 |
| 8M |
Austenitic Stainless Steel Type 316 |
S31600 |
| 8T |
Austenitic Stainless Steel Type 321 |
S32100 |
| 16 |
Chromium Molybdenum Vanadium Alloy Steel |
- |
(For all grades, please visit ASTM A194 Grades)
Chemical Composition
| Element |
Grade 2H, 2HM |
Grade 3 |
Grade 4 |
Grade 6 |
Grade 7, 7M |
Grade 8 |
Grade 8M |
Grade 8T |
Grade 16 |
| Carbon |
0.40 min |
0.10 min |
0.4-0.5 |
0.15 |
0.37-0.49 |
0.08 |
0.08 |
0.080 |
0.36 -0.47 |
| Manganese |
1.00 |
1.00 |
0.7-0.9 |
1.000 |
0.65-1.10 |
2.00 |
2.00 |
2.000 |
0.45-0.70 |
| Phosphorus |
0.04 |
0.04 |
0.035 |
0.04 |
0.035 |
0.045 |
0.045 |
0.045 |
0.035 |
| Sulphur |
0.05 |
0.03 |
0.04 |
0.03 |
0.04 |
0.03 |
0.030 |
0.030 |
0.040 |
| Silicon |
0.40 |
1.00 |
0.15-0.35 |
1.00 |
0.15-0.35 |
1.00 |
1.00 |
1.000 |
0.15-0.35 |
| Chromium |
- |
4.0-6.0 |
- |
11.5-13.5 |
0.75-1.2 |
18-20 |
16-18 |
17.0-19.0 |
0.80-1.15 |
| Nickel |
- |
- |
- |
- |
- |
8-11 |
10-14 |
9.0-12.0 |
- |
| Molybdenum |
- |
0.40-0.65 |
0.20-0.30 |
- |
0.15-0.25 |
- |
2.0-3.0 |
- |
0.50-0.65 |
| Titanium |
- |
- |
- |
- |
- |
- |
- |
5 x (C+N),
Min – 0.70 max |
- |
| Nitrogen |
- |
- |
- |
- |
- |
- |
- |
0.100 |
- |
| Others |
- |
- |
- |
- |
- |
- |
- |
- |
Vanadium 0.25-0.35
Aluminum 0.015 max |
Nut Hardness Requirement
| Nut Grade |
Brinell Hardness |
Rockwell Hardness |
| HRC |
HRB |
| 2H |
To 1-1⁄2 in. or M36, incl. |
248 - 327 |
24 - 35 |
- |
| Over 1-1⁄2 in. or M36 |
212 - 327 |
35 max |
95 min |
| 2HM and 7M |
159 - 235 |
- |
84 - 99 |
| 3, 4, 7, 16 |
248 - 327 |
24 - 35 |
- |
| 6 |
225 - 271 |
20 - 28 |
- |
| 8, 8C, 8M, 8T, 8F, 8MLCuN |
126 - 300 |
32 max |
60 min |
Nut Proof Load
| Nominal Size, inch |
Threads per inch |
Proof Load, lbf |
| All Grades of 8 |
Grade 2, 2HM, 6, 6f, 7M |
Grade 2H, 4, 7, 16 |
| Heavy Hex |
Hex |
Heavy Hex |
Hex |
Heavy Hex |
Hex |
| 1/4" |
20 |
2 540 |
2 380 |
4 770 |
4 300 |
5 570 |
4 770 |
| 5/16" |
18 |
4 190 |
3 930 |
7 860 |
7 070 |
9 170 |
7 860 |
| 3/8" |
16 |
6 200 |
5 810 |
11 620 |
10 460 |
13 560 |
11 620 |
| 7/16" |
14 |
8 500 |
7 970 |
15 940 |
14 350 |
18 600 |
15 940 |
| 1/2" |
13 |
11 350 |
10 640 |
21 280 |
19 160 |
24 830 |
21 280 |
| 9/16" |
12 |
14 560 |
13 650 |
27 300 |
24 570 |
31 850 |
27 300 |
| 5/8" |
11 |
18 080 |
16 950 |
33 900 |
30 510 |
39 550 |
33 900 |
| 3/4" |
10 |
26 720 |
25 050 |
50 100 |
45 090 |
58 450 |
50 100 |
| 7/8" |
9 |
36 960 |
34 650 |
69 300 |
62 370 |
80 850 |
69 300 |
| 1" |
8 |
48 480 |
45 450 |
90 900 |
81 810 |
106 000 |
90 900 |
| 1 1/8" |
8 |
63 200 |
59 250 |
118 500 |
106 700 |
138 200 |
118 500 |
| 1 1/4" |
8 |
80 000 |
75 000 |
150 000 |
135 000 |
175 000 |
150 000 |
| 1 3/8" |
8 |
98 640 |
92 450 |
185 000 |
166 500 |
215 800 |
185 000 |
| 1 1/2" |
8 |
119 360 |
111 900 |
223 800 |
201 400 |
261 100 |
223 800 |
Nut Marking
| Nut Grade |
Hot Forged or Cold Punched Nuts |
Nuts Machined from Bar Stock |
| 2H |
2H |
2HB |
| 2HM |
2HM |
2HMB |
| 4 |
4 |
4B |
| 6 |
6 |
6B |
| 7 |
7 |
7B |
| 7M |
7M |
7MB |
| 8 |
8 |
8B |
| 8M |
8M |
8MB |
| 8T |
8T |
8TB |
| 16 |
16 |
16B |