The specification of ASTM A193 includes high tensile fasteners, which are composed of stainless steel or alloy. These are primarily used in the applications of chemical and petroleum construction. The chief use of these bolting solutions
is in services related to high pressure and temperatures like valves, fittings and flanges, and pressure valves.
Let us now check out the grades that fall in the A193 segment.
A193 Grades
| B7 |
Alloy steel, AISI 4140/4142 quenched and tempered |
| B7M |
Alloy steel, AISI 4140/4142 quenched and tempered |
| B8 |
Stainless steel, AISI 304, carbide solution treated. |
| B8 Class 2 |
Stainless steel, AISI 304, carbide solution treated, strain hardened |
| B8M |
Stainless steel, AISI 316, carbide solution treated. |
| B8M Class 2 |
Stainless steel, AISI 316, carbide solution treated, strain hardened |
| B16 |
Alloy steel, AISI 4340 quenched and tempered |
A193 Mechanical properties
| Grade |
Size |
Tensile ksi, min |
Yield ksi, min |
Elong %, min |
RA % min |
HBW |
Rockwell |
| B7 |
Up to 2-1/2 |
125 |
105 |
16 |
50 |
321 Max |
35 HRC max |
| 2-5/8 - 4 |
115 |
95 |
16 |
50 |
| 4-1/8 - 7 |
100 |
75 |
18 |
50 |
| B7M |
Up to 4 |
100 |
80 |
18 |
50 |
235 Max |
- |
| Over 4 - 7 |
100 |
75 |
18 |
50 |
| B8 |
All |
75 |
30 |
30 |
50 |
223 Max |
96 HRB max |
| B8 Class 2 |
Up to 3/4 |
125 |
100 |
12 |
35 |
321 Max |
35 HRC max |
| 7/8 - 1 |
115 |
80 |
15 |
35 |
| 1-1/8 - 1-1/4 |
105 |
65 |
20 |
35 |
| 1-3/8 - 1-1/2 |
100 |
50 |
28 |
45 |
| B8M |
All |
75 |
30 |
30 |
50 |
223 Max |
96 HRB max |
| B8M Class 2 |
Up to 3/4 |
110 |
95 |
15 |
45 |
321 Max |
35 HRC max |
| 7/8 - 1 |
100 |
80 |
20 |
45 |
| 1-1/8 - 1-1/4 |
95 |
65 |
25 |
45 |
| 1-3/8 - 1-1/2 |
90 |
50 |
30 |
45 |
| B16 |
Up to 2-1/2 |
125 |
105 |
18 |
50 |
321 Max |
35 HRC max |
| Over 2-1/2 to 4 |
110 |
95 |
17 |
45 |
| Over 4 to 8 |
100 |
85 |
16 |
45 |
A193 Chemical properties
| Element |
B7 (AISI 4140) |
B8 (AISI 304) |
B8M (AISI 316) |
B16 |
| Carbon |
0.37 - 0.49% |
0.08% max |
0.08% max |
0.36 - 0.47% |
| Manganese |
0.65 - 1.00% |
2.00% max |
2.00% max |
0.45 - 0.70& |
| Phosphorus, max |
0.035% max |
0.045% max |
0.045% max |
0.035% max |
| Sulfur, max |
0.040% max |
0.030% max |
0.030% max |
0.040% max |
| Silicon |
0.15 - 0.35% |
1.00% max |
1.00% max |
0.15 - 0.35% |
| Chromium |
0.80 - 1.10% |
18.0 - 20.0% |
16.0 - 18.0% |
0.80 - 1.15 |
| Nickel |
- |
8.0 - 11.0% |
10.0 - 14.0% |
- |
| Molybdenum |
0.15 - 0.25% |
- |
2.00 - 3.00% |
0.50 - 0.65 |
A193 compatible hardware
| Bolt Grade |
Nut |
Washers |
| B7 |
A194 Grade 2H |
F436 |
| B7M |
A194 Grade 2HM |
F436 |
| B8 |
A194 Grade 8 |
SS304 |
| B8 Class 2 |
A194 Grade 8 |
SS304 |
| B8M |
A194 Grade 8M |
SS316 |
| B8M Class 2 |
A194 Grade 8M |
SS316 |
| B16 |
A194 Grade 16 |
F436 |
