ASTM A193 GRADE B8R & B8RA BOLTS — DATASHEET, DIMENSIONS & MECHANICAL PROPERTIES

Ananka Fasteners is a premier global manufacturer and supplier of ASTM A193 Grade B8R and B8RA Fasteners. Forged from the elite XM-19 super-austenitic stainless steel (UNS S20910—widely known by its trade name, Nitronic® 50), these fasteners represent a massive leap in metallurgical capability. XM-19 is a highly alloyed, nitrogen-strengthened matrix designed to deliver nearly double the yield strength of standard 316 stainless steel while simultaneously providing vastly superior resistance to localized chloride pitting, crevice corrosion, and severe sour-gas (H2S) degradation.

This exceptional baseline strength is achieved entirely through complex chemistry (Manganese, Molybdenum, and Nitrogen), completely eliminating the need for ductility-destroying cold-working. While Grade B8R undergoes standard carbide solution treatment, the B8RA designation mandates strict post-fabrication annealing. This final thermal cycle eradicates all residual threading stresses, rendering B8RA fasteners flawlessly immune to stress-corrosion cracking (SCC) in the most aggressive offshore and downhole environments. All our B8R/B8RA studs, heavy hex bolts, and threaded rods are strictly supported by EN 10204 Type 3.1 Material Test Certificates (MTC).

For lead marine engineers, sub-sea platform designers, and NACE compliance auditors requiring empirical PREN chloride pitting calculations and high-yield stress models for ASTM A193 B8R/B8RA, the complete technical datasheet must be accessed.

Because the elite performance of B8R/B8RA relies on a highly sophisticated 7-element chemical synergy, the EN 10204 3.1 Mill Test Certificate (MTC) is the absolute proof of component integrity. Ananka Fasteners’ MTCs for B8R explicitly guarantee:

• Super-Austenitic Verification: Empirical spectrography proving the precise balance of high Chromium (20.5%+), Manganese (4.0%+), and Nitrogen (0.20%+) that defines genuine S20910.
• Elevated Mechanical Proof: Destructive test verification proving the batch natively meets the massive 55 ksi minimum yield and 100 ksi minimum tensile requirements without strain-hardening.
• Post-Fabrication Verification (B8RA): An explicit statement confirming that carbide solution treatment was performed after all heavy machining and threading operations.
• Complete Traceability: Heat number documentation strictly linking the finished bolt back to the primary super-alloy melt.

Standard dimensional specifications for ASME B18.2.1 Heavy Hex Bolts. The heavy hex profile provides the expanded bearing footprint necessary to securely distribute the immense compressive preloads generated by high-yield XM-19 fastening systems across marine and chemical flanges.

*Notice the immense baseline strength. Without any cold-working, B8R natively yields at 55,000 psi (compared to standard B8M at 30,000 psi). NACE MR0175 explicitly permits S20910 in the annealed condition to carry a higher maximum hardness limit than standard 300-series stainless due to its superior environmental cracking resistance.

For decades, ASTM A193 B8M (SS 316) was the default standard for marine and chemical fastening. However, as deep-water extraction and high-temperature chemical refining became more extreme, 316 began to fail—either stretching under immense pipeline pressure (due to low yield strength) or suffering chloride stress-corrosion cracking.

ASTM A193 B8R (XM-19) was engineered specifically to solve this. It provides nearly twice the yield strength of 316 at room temperature, allowing engineers to drastically increase flange clamping force without snapping the bolt. Furthermore, its PREN score (Pitting Resistance Equivalent Number) hovers around 35, compared to 316's score of 24. This means B8R can survive boiling saltwater, severe sour-gas (H2S), and highly acidic pulp/paper bleaching chemicals indefinitely, where standard stainless would corrode in weeks.

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 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.
• Exotic Alloy Mastery: Our deep expertise in highly engineered marine superalloys extends far beyond XM-19; we actively forge and machine superalloys including Inconel 718, Hastelloy C276, Monel K500, Super Duplex 2507, and Titanium Grade 5.
• Customization and Capacity: Utilizing a strict 6-step in-house quality check protocol, we possess the agile manufacturing capacity to rapidly prototype, forge, anneal, test, and ship specialized marine fasteners globally.

• 1. Is B8R (Nitronic 50) magnetic like B8 Class 2?
  No, absolutely not. Unlike standard 300-series stainless steels that become magnetic when cold-worked (due to martensite formation), the massive Manganese and Nitrogen content in XM-19 locks the austenite phase in place. Even if severely cold-worked or exposed to sub-zero temperatures, B8R remains perfectly non-magnetic.
• 2. Does B8R suffer from thread galling as much as standard stainless?
  No. While all stainless steels have a tendency to gall (cold-weld), the elevated Manganese and Nitrogen alloying in XM-19 significantly improves its surface wear resistance. It has a noticeably lower galling tendency compared to standard 316, making it safer for high-torque assembly.
• 3. Is ASTM A193 B8RA compliant with NACE MR0175?
  Yes. NACE MR0175/ISO 15156 specifically recognizes the elite environmental resistance of UNS S20910. While standard austenitic stainless is capped at 22 HRC, NACE explicitly permits annealed XM-19 to be utilized at hardness levels up to 35 HRC in severe hydrogen sulfide environments. B8RA (post-fabrication annealed) is the gold standard for sour-gas compliance in this alloy.