ASTM A193 GRADE B8 CLASS 2 BOLTS — DATASHEET, DIMENSIONS & MECHANICAL PROPERTIES

Ananka Fasteners is a premier global manufacturer and supplier of ASTM A193 Grade B8 Class 2 Fasteners. Manufactured from AISI 304 austenitic stainless steel (UNS S30400), these highly engineered fasteners undergo a rigorous strain-hardening (cold-working) process after initial carbide solution treatment. This mechanical deformation drastically elevates the material's yield strength far beyond standard annealed levels.

By transforming the grain structure physically rather than thermally, Grade B8 Class 2 achieves an immense maximum yield strength of 100,000 psi (100 ksi), making it the definitive choice for high-pressure flanged joints requiring massive, sustained clamping forces in petrochemical refineries, power generation pipelines, and heavy industrial applications. All our B8 Class 2 high-tensile studs, heavy hex bolts, and threaded rods are guaranteed by EN 10204 Type 3.1 Material Test Certificates (MTC).

For lead piping engineers, structural metallurgists, and procurement officers requiring the granular, proprietary technical specifications, thread shear capacities, and full load-bearing yield curves of ASTM A193 B8 Class 2 industrial fasteners, the complete technical datasheet must be accessed.

Because the defining mechanical properties of Class 2 are achieved through a physical manufacturing process rather than baseline chemistry, the EN 10204 3.1 Mill Test Certificate is the only empirical proof of integrity. Ananka Fasteners’ MTCs for B8 Class 2 components explicitly detail:

• Diameter-Specific Mechanical Verification: Lists actual destructive test results proving the batch meets the specific Tensile and Yield strength limits mandated for its exact diameter size bracket.
• Hardness Limit Proof: Verified laboratory results ensuring the strain-hardening did not push the material past the brittle threshold of 35 HRC / 321 HBW.
• Chemical Spectrography: Verification of standard 304 alloy chemistry (UNS S30400).
• Complete Traceability: Heat number documentation linking the finished strain-hardened bolt back to the primary steel casting.

Standard dimensional specifications for ASME B18.2.1 Heavy Hex Bolts. The heavy hex profile provides the expanded bearing footprint absolutely critical for distributing the extreme compressive loads generated by Class 2 strain-hardened fastening systems.

*Crucial Engineering Note: Because strain-hardening requires mechanical force from the outside in, the core of larger diameter bars does not compress as tightly as the exterior. Therefore, the guaranteed yield and tensile strength limits progressively decrease as the fastener diameter increases.

The choice between ASTM A193 B8 Class 1 and Class 2 is one of the most critical structural decisions in pressure piping design. They represent opposite sides of the strength/ductility paradigm.

Class 1 (Fully Annealed): Prioritizes maximum ductility and corrosion resistance. It has a low yield strength (30 ksi), meaning it will stretch easily, but it is highly immune to stress-corrosion cracking (SCC) and is completely non-magnetic.

Class 2 (Strain-Hardened): Prioritizes sheer clamping force. It offers over three times the yield strength of Class 1 (up to 100 ksi), preventing heavy flanges from separating under extreme internal pressure. The trade-off is a massive reduction in ductility (down to 12% elongation), induced magnetism, and a higher susceptibility to SCC in aggressive halogenated environments.

The global industrial fastener market requires manufacturing entities capable of blending hyper-scale production volume with microscopic precision. Ananka Fasteners exemplifies the apex of modern industrial hardware manufacturing, servicing a roster of over 240 high-value corporate clients spanning more than 40 countries.

• Stringent Global Certification: Ananka operates under an integrated management system certified to ISO 9001:2015, ISO 14001:2015, and ISO 45001:2018. We hold the prestigious PED 2014/68/EU certification for explosive, high-pressure environments.
• Strain-Hardening Capabilities: We utilize advanced heavy-duty thread rolling and drawing equipment capable of imparting precise levels of cold-work into thick-diameter bars to strictly hit Class 2 yield windows.
• Customization and Capacity: Utilizing a strict 6-step in-house quality check protocol, we possess the agile manufacturing capacity to rapidly prototype, forge, cold-work, test, and ship specialized fasteners globally.

• 1. Is B8 Class 2 magnetic?
  Yes, it is weakly magnetic. While the base metal (304 stainless) is austenitic and non-magnetic, the intense physical cold-working required to push the yield strength to 100 ksi causes some of the austenite to transform into martensite, creating a distinct magnetic pull.
• 2. Why is galling a major concern with B8 Class 2?
  Thread galling (cold welding) occurs heavily in stainless steels under pressure. Because Class 2 bolts are designed to be torqued to massive clamping loads (up to 100 ksi yield), the friction across the threads is immense. Engineers must specify premium anti-seize compounds or PTFE/Moly coatings on the threads to prevent catastrophic seizure during installation.
• 3. Is ASTM A193 B8 Class 2 compliant with NACE MR0175?
  No. NACE MR0175 regulations strictly limit the maximum hardness of austenitic stainless fasteners to 22 HRC (approx 99 HRB) to prevent sulfide stress cracking in sour gas environments. Because B8 Class 2 relies on strain-hardening and permits hardness up to 35 HRC, it is strictly prohibited for NACE sour service. Engineers must downgrade to B8A or switch to a high-strength exotic alloy like Inconel 718.