Description
Core high-pressure alloy-steel flange bolting
ASTM A193 B7 Stud Bolts with A194 2H Nuts
Fully threaded ASTM A193 Grade B7 stud bolts supplied to the required diameter, thread, length and finish, with matching ASTM A194 Grade 2H heavy hex nuts when specified.
Quick answer
ASTM A193 Grade B7 is a quenched-and-tempered chromium-molybdenum alloy-steel bolting grade used for high-temperature or high-pressure flange, valve, fitting and pressure-vessel joints. ASTM A194 Grade 2H is a common matching nut grade, but the complete bolting assembly must follow the project specification.
Product at a glance
What are ASTM A193 B7 stud bolts?
ASTM A193 B7 stud bolts are heat-treated alloy-steel fasteners manufactured for bolted pressure joints. A typical flange assembly uses one fully threaded stud and two heavy hex nuts. Diameter, length, thread series and coating are selected from the flange bolting schedule rather than from the material grade alone.
Grade B7 identifies bolting material requirements; it does not define flange dimensions, tightening torque or a universal pressure-temperature rating. Joint design also depends on the flange standard, gasket, nut grade, lubrication, installation method and governing piping or pressure-vessel code.
ASTM A193 B7 stud bolt specifications
| Material | Chromium-molybdenum alloy steel |
|---|---|
| Heat treatment | Quenched and tempered in accordance with ASTM A193/A193M |
| Configuration | Fully threaded stud bolt; double-end options by drawing |
| Threads | UNC, 8UN or project-specified series and class to ASME B1.1 |
| Dimensions | ASME B18.31.2, flange bolting schedule or approved drawing |
| Matching nuts | ASTM A194/A194M Grade 2H when specified |
| Finish options | Plain, black, zinc, hot-dip galvanized or approved fluoropolymer system |
| Documentation | MTC, traceability, dimensions, thread inspection and coating records as ordered |
Final dimensions, tolerances, heat treatment, mechanical properties, impact or hardness requirements, coating and acceptance criteria follow the purchase order and the contractually specified standard edition.
Why specify this grade?
Select B7 when the piping class or equipment specification calls for a widely used chromium-molybdenum bolting grade for high-pressure or elevated-temperature joints. It offers a practical combination of strength, availability and compatibility with common flange-bolting systems.
Critical engineering note
Do not select B7 from temperature alone. The designer must verify allowable stress, flange rating, gasket behaviour, nut compatibility, preload, relaxation, corrosion and any low-temperature toughness requirement. B7 is not automatically interchangeable with B7M, B16 or A320 L7.
Stud, nut and finish options
Typical applications
Quality, inspection and documentation
Each order can be controlled by heat number and production batch. Inspection scope is agreed before manufacture so the certificate package matches the project material requisition and inspection plan.
- EN 10204 3.1 material test certificate when ordered
- Heat-number and manufacturing-batch traceability
- Chemical composition and mechanical-property results
- Hardness testing at the frequency required by the ordered grade
- Charpy impact testing for low-temperature grades as specified
- Dimensional inspection and calibrated thread gauging
- Coating thickness or surface-condition inspection when applicable
- Third-party inspection, marking and export packing by agreement
Information required for quotation
- ASTM standard, grade and contractually required edition
- Stud diameter, overall length, thread series and thread class
- Quantity and whether two nuts per stud are required
- Matching nut specification, grade, style and finish
- Plain, coated or plated finish and the approved coating system
- Design temperature, impact-test temperature and sour-service requirements when relevant
- MTC, PMI, hardness, impact, coating and third-party inspection requirements
- Delivery destination, packing method and required schedule
Frequently asked questions
What is ASTM A193 Grade B7?
B7 is a quenched-and-tempered chromium-molybdenum alloy-steel bolting grade covered by ASTM A193/A193M for high-temperature, high-pressure and other special-purpose applications.
Which nuts are commonly used with B7 stud bolts?
ASTM A194 Grade 2H heavy hex nuts are commonly specified. The nut grade, style, dimensions, coating and quantity must still be confirmed by the project specification.
Are B7 and B7M stud bolts the same?
No. B7M has additional hardness-control and processing requirements. B7 material should not be relabelled or treated as B7M merely because a coating is applied.
Can SASA FLANGE supply coated B7 stud bolts?
Yes, subject to technical review. State the coating specification, colour if relevant, target thickness, friction requirements, test method and service temperature in the inquiry.
Related stud bolt products
Reference standards
Material requirements are controlled by ASTM A193/A193M. Matching heavy hex nut requirements are specified separately under ASTM A194/A194M when applicable. Thread form and stud dimensions may reference ASME B1.1 and ASME B18.31.2, subject to the purchase order. Always state the required edition instead of assuming the latest edition applies to an existing project.
Request a technical quotation
Send your flange bolting schedule, bill of materials, drawing or project specification. SASA FLANGE will review the grade, nuts, threads, dimensions, finish, documentation and delivery requirements before quotation.
