Hastelloy B2 (UNS N10665 / W.Nr. 2.4617) fasteners represent the pinnacle of chemical bolting metallurgy. Specifically developed to withstand non-oxidizing, pure reducing acids, Alloy B-2 offers unparalleled chemical immunity where conventional austenitic, super duplex, and even chromium-bearing nickel superalloys rapidly succumb to generalized uniform corrosion and stress-corrosion cracking.
Engineered with a solid-solution nickel-molybdenum matrix (comprising ~28% Molybdenum and ~68% Nickel), Hastelloy B2 studs, hex head bolts, nuts, and washers exhibit exceptional resistance to pure hydrochloric acid (HCl) across all concentrations and process temperatures up to atmospheric boiling. At TorqBolt Inc., our engineering facilities in Mumbai and manufacturing works in Rajkot transform vacuum-induction melted (VIM) and electroslag remelted (ESR) billets into mission-critical bolting assemblies adhering to ASTM B335, ASTM B574, DIN 931, and ASME B18.2.1 standards.
TorqBolt engineers precision bolting configurations from authentic UNS N10665 bar stock. Designed specifically for chemical distillation columns, alkylation reactors, reboilers, and chlorination vessels, our fasteners guarantee boundary integrity under mechanical fatigue and severe chemical immersion.
Hot-forged and solution-annealed hex and heavy hex bolts built to handle thermal expansion and acidic process media without yielding or head shear.
Continuously threaded, cut-to-length or rolled-thread studs designed for ASME B16.5 and B16.47 pressure vessel flange connections.
Precision-tapped, galling-resistant nuts heat-treated with differential surface hardness to match mating studs seamlessly under high clamping loads.
Through-hardened washers engineered to distribute preload pressure uniformly, preventing flange micro-pitting and creeping under fluctuating temperatures.
The superior corrosion immunity of Hastelloy B2 stems from its precise nickel-molybdenum ratio coupled with tight restrictions on carbon and silicon. Understand how UNS N10665 delivers critical performance benefits over alternative nickel superalloys in pure reducing environments.
| Element / Metric | ASTM B335 / B574 Limits | TorqBolt Controlled Target | Mechanical Property | Annealed Bar Stock Specification |
|---|---|---|---|---|
| Nickel (Ni) | Remainder (min. 66.0%) | Bal. (~67.5% - 69.0%) | Tensile Strength (Rm) | ≥ 760 MPa (110 ksi) |
| Molybdenum (Mo) | 26.0 - 30.0% | 28.0 - 29.5% | Yield Strength (0.2% Offset) | ≥ 350 MPa (51 ksi) |
| Iron (Fe) | ≤ 2.0% | 1.0 - 1.5% | Elongation in 2 in. (4D) | ≥ 40% |
| Chromium (Cr) | ≤ 1.0% | ≤ 0.6% | Hardness (Rockwell B) | ≤ 100 HRB |
| Cobalt (Co) | ≤ 1.0% | ≤ 0.4% | Density | 9.22 g/cm³ (0.333 lb/in³) |
| Carbon (C) | ≤ 0.01% | ≤ 0.005% (Ultra-Low) | Melting Range | 1330°C - 1380°C (2425°F - 2515°F) |
| Silicon (Si) | ≤ 0.10% | ≤ 0.03% | Poisson's Ratio | 0.32 |
Critical Engineering Note: Hastelloy B2 contains minimal chromium (<1.0%). Consequently, fasteners must never be installed in processes contaminated with ferric chloride, cupric ions, or dissolved oxygen, which act as oxidizing agents causing rapid corrosion. For mixed oxidizing/reducing streams, consider Hastelloy C276.
Procuring exotic nickel-molybdenum fasteners requires foresight. As global refining, fine chemical synthesis, and energy transition projects push equipment boundaries, chemical engineering procurement teams are adopting new paradigms for Hastelloy B2 sourcing.
While Hastelloy B2 revolutionized the industry by virtually eliminating weld heat-affected zone carbide precipitation seen in original Alloy B, it exhibits sensitivity to intermediate embrittlement phases (Ni4Mo and Ni3Mo) during sustained exposure between 550°C and 850°C. Modern engineering specifications are strategically differentiating procurement between Alloy B2 and newer Alloy B3 (UNS N10675), which offers improved thermal stability.
Global procurement teams now specify vacuum-degassed VIM-ESR feedstock with verified grain boundary microstructures, ensuring that fast cooling protocols are strictly maintained during forging and post-weld heat treatment. TorqBolt maintains rigorous metallurgical oversight to guarantee our finished fasteners arrive with pristine microstructure and zero intermetallic embrittlement.
The acceleration of green chemical synthesis—including biological acid extraction, bio-fuel esterification, and advanced plastic pyrolysis—is exponentially increasing demand for high-performance reducing-acid bolting. Procurement departments are facing lengthened mill lead times for primary raw materials like pure nickel and molybdenum.
Forward-thinking EPC contractors are shifting from spot purchasing to programmatic strategic partnerships. At TorqBolt, our deep domestic supply lines in India and pre-positioned inventory of certified bar stock allow global buyers to bypass extended 26-week lead times, achieving rapid dispatch in as little as 3 to 4 weeks with uncompromised EN 10204 3.1 documentation.
Hastelloy B2 work-hardens exceptionally quickly, possesses low thermal conductivity, and exhibits high shear resistance during cutting. Processing this alloy demands precision tooling, optimized feeds, and strictly controlled thermodynamic cycles.
Headed at tightly calibrated induction temperatures (1150°C - 1200°C) with immediate rapid water quenching to ensure carbide and intermetallic grain-boundary dissolution.
Machined using heavy-duty carbide tooling, positive rake geometries, and high-pressure flood coolant to eliminate strain hardening and surface work distortion.
Burnished rolled threads preserve uninterrupted grain flow across root radii, maximizing dynamic fatigue thresholds and suppressing micro-notch initiation.
Every batch undergoes Positive Material Identification (PMI), microstructure grain analysis, and full mechanical stress verification traceable to individual ingot heats.
ASME/DIN code review
VIM-ESR certified bar
Induction forge / CNC
1065°C solution anneal
High-tensile burnishing
PMI, tensile, hardness
Export casing & ship
In operating environments where steel, titanium, or standard grades of stainless fail within hours, TorqBolt Hastelloy B2 fasteners safeguard industrial pressure boundaries from disastrous chemical release.
Handling wet HCl gas, aqueous muriatic acid, and pickling acid lines across full concentration ranges.
Resisting pure sulfuric acid catalysts in petroleum refining and petrochemical alkylation reaction columns.
Operating inside monomer synthesis reactors and reboilers utilizing high concentrations of organic acetic media.
Flange fixings in API batch reactors employing anhydrous acidic catalysts demanding zero metal ion leakage.
Incomplete requests for quotation (RFQs) can introduce significant lead time delays and engineering discrepancies. Utilize this authoritative procurement matrix to submit a fully defined specification package.
Established in 2010, TorqBolt Inc. is a premier global manufacturer dedicated exclusively to complex nickel alloys, super duplex, and refractory fastener engineering. Our integrated manufacturing center in Rajkot, Gujarat, alongside corporate sales and logistics headquarters in Mumbai, ensures your mission-critical project is backed by comprehensive metallurgical competence.
Connect directly with TorqBolt's exotic alloy engineering desk. Receive verified pricing, technical compliance reviews, and certified EN 10204 documentation tailored to your exact piping and pressure vessel schedule.