Hastelloy B3
Nuts
Why Hastelloy B3 for Nuts?
Hastelloy B3 (UNS N10675) is the engineering specification for nuts in reducing acid service. While stainless steel corrodes rapidly in hydrochloric acid above trace concentrations, B3’s 28–32% molybdenum matrix passivates against reducing attack at all concentrations and temperatures up to boiling — without requiring an oxidising agent.
For nuts held under sustained clamping stress, B3 offers a critical advantage over Hastelloy B and B2: eliminated stress-corrosion cracking (SCC) susceptibility. The third-generation alloy’s refined chemistry prevents the ordered intermetallic Ni&sub4;Mo phase responsible for SCC in B2, making B3 nuts far safer in thermally cycled flanged assemblies.
Akbar Fasteners Pvt. Ltd. stocks Hastelloy B3 bar to ASTM B335. All nuts are machined from certified bar, PMI-verified, and supplied with NABL-accredited test reports and heat-specific Mill Test Certificates.
| Element | Min % | Max % | Typical |
|---|---|---|---|
| Nickel (Ni) | Balance | Balance | ~65% |
| Molybdenum (Mo) | 27.0 | 32.0 | ~30% |
| Chromium (Cr) | 1.0 | 3.0 | ~1.5% |
| Iron (Fe) | 1.0 | 3.0 | ~2.0% |
| Tungsten (W) | 2.5 | 4.0 | ~3.0% |
| Cobalt (Co) | — | 3.0 | — |
| Manganese (Mn) | — | 3.0 | — |
| Silicon (Si) | — | 0.10 | <0.1% |
| Carbon (C) | — | 0.01 | <0.01% |
| Sulfur (S) | — | 0.030 | — |
Hastelloy B3 Nut Types
All five types available with full dimensional documentation and material certification.
Hex Nut
Standard hex nut per DIN 934 / ISO 4032. M6–M100. For flanged pressure assemblies, heat exchangers and reactor closures in HCl service.
Heavy Hex Nut
Larger AF and greater height. Matches ASME B16.5 flange stud bolt requirements. For chemical reactor pressure service and pressure vessel closure bolting.
Coupling Nut
Long coupling nuts (DIN 6334) for connecting two threaded rods or extending bolt lengths. Ideal for tall flanged connections in HCl synthesis plant assemblies.
Flange Nut
Integral serrated or smooth flange bearing face. Eliminates need for separate washer. Distributes load over wider area for soft or irregular seating surfaces in chemical vessels.
Lock / Prevailing Torque
All-metal prevailing torque lock nuts with deformed top section. Maintains clamp load under vibration and thermal cycling. DIN 980 equivalent.
Standard Sizes — Hastelloy B3 Hex Nuts
Per DIN 934 (Style 1) and Heavy Hex per ASME B18.2.2. All dimensions in mm.
| Thread (M) | Pitch mm | s — AF mm | e — AC mm | m — Height mm | Weight kg/pc |
|---|---|---|---|---|---|
| M6 | 1.0 | 10.0 | 11.05 | 5.0 | 0.0016 |
| M8 | 1.25 | 13.0 | 14.38 | 6.5 | 0.0037 |
| M10 | 1.5 | 17.0 | 18.90 | 8.0 | 0.0085 |
| M12 | 1.75 | 19.0 | 20.88 | 10.0 | 0.0130 |
| M16 | 2.0 | 24.0 | 26.75 | 13.0 | 0.0290 |
| M20 | 2.5 | 30.0 | 32.95 | 16.0 | 0.0570 |
| M24 | 3.0 | 36.0 | 39.55 | 19.0 | 0.0980 |
| M30 | 3.5 | 46.0 | 50.85 | 24.0 | 0.2050 |
| M36 | 4.0 | 55.0 | 60.79 | 29.0 | 0.3570 |
| M42 | 4.5 | 65.0 | 71.30 | 34.0 | 0.5920 |
| M48 | 5.0 | 75.0 | 82.60 | 38.0 | 0.8840 |
| M56 | 5.5 | 85.0 | 93.56 | 45.0 | 1.3410 |
| M64 | 6.0 | 95.0 | 104.86 | 51.0 | 1.9230 |
| M72 | 6.0 | 105.0 | 116.16 | 58.0 | 2.7450 |
| M80 | 6.0 | 115.0 | 127.46 | 64.0 | 3.7300 |
| M90 | 6.0 | 130.0 | 143.07 | 72.0 | 5.4710 |
| M100 | 6.0 | 145.0 | 160.10 | 80.0 | 7.5230 |
| Thread | TPI / Pitch | s — AF mm | e — AC mm | m — Height mm | Weight kg/pc |
|---|---|---|---|---|---|
| M16 | 2.0mm | 27.0 | 29.56 | 16.0 | 0.0420 |
| M20 | 2.5mm | 34.0 | 37.29 | 20.0 | 0.0860 |
| M24 | 3.0mm | 41.0 | 45.20 | 23.5 | 0.1560 |
| M30 | 3.5mm | 50.0 | 55.37 | 28.6 | 0.2780 |
| M36 | 4.0mm | 60.0 | 66.44 | 34.7 | 0.4820 |
| 1” UNC | 8 TPI | 41.3 | 45.72 | 27.8 | 0.1640 |
| 1¼” UNC | 7 TPI | 50.8 | 56.39 | 34.9 | 0.3010 |
| 1½” UNC | 6 TPI | 57.2 | 63.50 | 39.7 | 0.4350 |
| 2” UNC | 4½ TPI | 79.4 | 88.14 | 52.4 | 1.1230 |
| 2½” UNC | 4 TPI | 98.4 | 109.73 | 65.1 | 2.1540 |
| 3” UNC | 4 TPI | 117.5 | 130.81 | 77.8 | 3.6720 |
AF = Across Flats · AC = Across Corners · Custom sizes on request.
Standards We Manufacture To
Every Hastelloy B3 nut manufactured, tested, and documented to the applicable standard.
Where Hastelloy B3 Nuts Perform
Environments where B3 nuts are the engineering specification — not a substitute.
HCl Synthesis Plants
& nut assemblies
Chemical Reactors
vessel closure bolting
Pharmaceutical
reactor flanges
Pulp & Paper
flange closure nuts
Petrochemical
catalyst systems
Desulfurisation
H&sub2;SO&sub4; absorption
Semiconductor
etch equipment
Fertiliser Plants
fluoride environments
Complete Documentation Package
Heat & Lot Traceable
Conformance
XRF Verified
Tensile · Hardness
TÜV · BV · Lloyds
Also Available in Hastelloy B3
Every fastener for a complete B3 flanged assembly — same alloy, same cert, single source.
Hastelloy B3 Bolts
Hex bolts in UNS N10675 / ASTM B335. M6–M100. Partial and full thread. Full MTC and PMI supplied.
Enquire →Hastelloy B3 Stud Bolts
Fully threaded stud bolts per ASME B16.5 for flanged pressure joints in reducing acid and HCl service.
Enquire →Hastelloy B3 Washers
Plain flat, spring and lock washers in Hastelloy B3. DIN 125 / ISO 7089. M5–M100. Full MTC.
View Page →Hastelloy C276 Nuts
For mixed oxidising/reducing service where B3 may sensitise. Same types and sizes, same documentation.
Enquire →Need Hastelloy B3
Nuts Fast?
Nut type, thread size, quantity, standard, documentation requirements. We respond within 24 hours.