Standard Specification for Alloy-Steel and Stainless Steel Bolting for High Temperature or High Pressure Service and Other Special Purpose Applications
ASTM A193 specification covers alloy and stainless steel bolting for pressure vessels, valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications. Several grades are covered, including ferritic steels and austenitic stainless steels designated B5, B6, B7, B8, B8M, etc.
Selection will depend upon design, service conditions, mechanical properties, and high temperature characteristics. This specification is expressed in both inch-pound units
and in SI units; however, unless the purchase order or contract specifies the applicable A193M specification designation (SI units), the inch-pound units shall apply
Bolting Grade B7
| Grade |
Tensile Class |
Raw Material Description |
| B7 |
|
Chromium Molybdenum Alloy Steel, Quenched & Tempered |
ASTM A193 Grade B7 Chemical Composition
| Ferritic Steels |
| Element |
Grade B7 |
| Carbon |
0.37-0.49 |
| Manganese, max |
0.65-1.10 |
| Phosphorus, max |
0.035 |
| Sulfur, max |
0.040 |
| Silicon |
0.15-0.35 |
| Chromium |
0.75-1.20 |
| Molybdenum |
0.15-0.25 |
| Vanadium |
-- |
| Aluminium, max |
-- |
ASTM A193 Grade B7 Mechanical Properties
| Grade |
Diameter |
Tensile Strength |
Yield Strength |
Elongation |
Reduction |
Hardness |
| Grade B7
| M64 and under |
860 |
720 |
16 |
50 |
321 HBW or 35 HRC |
| Grade B7
| Over M64 to M100 |
795 |
655 |
16 |
50 |
321 HBW or 35 HRC |
| Grade B7
| Over M100 to M180 |
690 |
515 |
18 |
50 |
321 HBW or 35 HRC |
Heat Treatment
ASTM A193 Grade B7 Marking Requirements
Recommended Nuts & Washers
| Bolting Grade |
Nut Grade |
Washer Grade |
| ASTM A193 Grade B7 |
ASTM A194 Grade 2H, 2HM |
ASTM F436 |