| Standard | ASTM A193 / ASME B18.31.2 (inch studs) · A193M Grade B8M Class 2 / Metric dimensions to drawing |
|---|---|
| Material | Type 316 austenitic stainless steel |
| Strength Grade | B8M Class 2 |
| Size Range | M12-M64 |
| Surface Treatment | Strain Hardened / Passivated as specified |
Product Description
ASTM A193/A193M Grade B8M is a Type 316 austenitic stainless bolting grade. This product covers Class 2 studs for flange, valve and pressure equipment joints where the design specification permits the selected grade.
Class 2 requires solution treatment followed by strain hardening. Class 1 is solution treated without the Class 2 strain-hardening condition. Mechanical requirements depend on diameter and the applicable standard edition; a final solution anneal must not be assumed to retain Class 2 strength.
ASTM A193 defines material, processing and mechanical requirements. ASME B18.31.2 is an inch stud dimensional reference; metric threads and dimensions follow the agreed drawing or purchase specification. ASME B16.5 is a flange standard, not a substitute for the stud material or dimensional specification.
B8M Class 2 must not be specified as interchangeable with ISO 3506 A4-80 or 316Ti. Nut strength, thread fit, lubrication, service temperature and corrosion exposure are confirmed for the joint.
| Product | ASTM A193/A193M Grade B8M Class 2 stud bolts |
|---|---|
| Material | Type 316 austenitic stainless steel |
| Material condition | Solution treated and strain hardened to Class 2 requirements |
| Dimensions | ASME B18.31.2 for inch studs; metric dimensions to agreed drawing |
| Size range | M12-M64; inch sizes and lengths to quotation or drawing |
| Thread form | Full-thread or double-end geometry; metric / UNC / 8UN as specified |
| Surface | Passivated where specified; preserve the required Class 2 condition |
| Nut selection | ASTM A194 Grade 8M with class and strength confirmed to the joint specification |
| Documents | Material certificate, heat traceability and inspection reports as ordered |
Manufacturing
Selection
B8M Class 2 studs for corrosion-resistant flange and valve joints when accepted by the design code and project specification. Confirm diameter-dependent mechanical requirements, compatible nuts and installation procedure.
Oil and gas fastenersType 316 stainless bolting for specified equipment joints. Suitability for hot service, seawater or splash-zone exposure depends on the temperature, chloride level, crevice conditions and design requirements.
Power generation fastenersAssembly
FAQ
Class 1 is supplied in the solution-treated condition. Class 2 is solution treated and strain hardened, with different mechanical requirements that depend on diameter. Specify the required class on the order.
No. ASTM A193 B8M Class 2 and ISO 3506 A4-80 use different grade definitions, processing and acceptance requirements. Substitution requires review against the joint specification.
B8M is associated with Type 316 chemistry. A generic 316Ti designation does not establish compliance with ASTM A193 B8M; the specified chemistry, processing and certificate govern.
ASTM A194 Grade 8M nuts are commonly specified, but the nut class, strength and thread fit must suit the Class 2 stud and joint requirements. A Grade 8M label alone does not confirm the required proof-load capacity.
Send the diameter, thread series, length, required standard edition, nut class, service conditions, quantity and inspection documents for a quotation.
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