Hastelloy C276
Hex Bolts
UNS N10276
Hastelloy C276 Hex Bolts — The Broadest Coverage Choice
Hastelloy C276 (UNS N10276) is the Ni-Cr-Mo alloy with the highest molybdenum content in its class — 15–17% Mo, with 14.5–16.5% Cr and 3–4.5% W. This composition places C276 uniquely in the corrosion-resistance spectrum: it performs excellently across both oxidising and reducing acid environments simultaneously, covering media that would require alloy switches in other material families. For hex bolt applications in multipurpose chemical plant, mixed acid processing, pharmaceutical reactors, and any bolted connection where the process fluid may vary or is not precisely defined — C276 provides the broadest single-alloy protection available.
The selection logic for C276 hex bolts: choose C276 when the service involves mixed or uncertain acid environments, chlorinated solvents, wet chlorine, or combinations of oxidising and reducing media in the same plant. For pure oxidising chloride or FGD service, our Hastelloy C22 provides superior pitting resistance. For purely reducing HCl service, our Hastelloy B3 outperforms C276. When the media covers both, C276 hex bolts are the correct choice.
| Element | Min % | Max % | Typical |
|---|---|---|---|
| Nickel (Ni) | Balance | — | ~57% |
| Molybdenum (Mo) | 15.0 | 17.0 | ~16% |
| Chromium (Cr) | 14.5 | 16.5 | ~15.5% |
| Tungsten (W) | 3.0 | 4.5 | ~4% |
| Iron (Fe) | 4.0 | 7.0 | ~5.5% |
| Cobalt (Co) | — | 2.5 | — |
| Manganese (Mn) | — | 1.0 | — |
| Carbon (C) | — | 0.010 | — |
| Silicon (Si) | — | 0.08 | — |
| Vanadium (V) | — | 0.35 | — |
Full Thread Hex Bolts — DIN 933
Thread runs the complete length — DIN 933 / ISO 4017. The most common C276 hex bolt form for chemical plant equipment covers, reactor body bolts, and multipurpose process equipment connections in mixed or uncertain acid environments. M6–M100. Full thread allows engagement across the complete bolt length for maximum pullout resistance in tapped hole applications.
For flanged pressure joints requiring stud bolts, see our Hastelloy C276 stud bolts page for ASME B16.5 Class 150–2500 configurations.
| Spec | Details |
|---|---|
| Material | UNS N10276 / C276 |
| Standard | ASTM B574 · DIN 933 · ISO 4017 |
| Size Range | M6 — M100 |
| Thread | Metric coarse DIN 13 |
| Head Form | Hex per DIN 933 AF |
| UTS | ≥ 690 MPa |
| 0.2% YS | ≥ 276 MPa |
| Elongation | ≥ 40% |
| Condition | Solution Annealed |
Partial Thread Hex Bolts — DIN 931
DIN 931 / ISO 4014 — unthreaded plain shank between head and thread start. The shank carries shear load across the joint interface — required for chemical plant structural connections, equipment skid base bolting, and reactor body structural connections in mixed acid environments where both shear capacity and C276 corrosion resistance are needed simultaneously. M6–M100.
| Spec | Details |
|---|---|
| Material | UNS N10276 / C276 |
| Standard | ASTM B574 · DIN 931 · ISO 4014 |
| Size Range | M6 — M100 |
| Shank | Plain per DIN 931 grip length |
| UTS | ≥ 690 MPa |
| 0.2% YS | ≥ 276 MPa |
| Condition | Solution Annealed |
Heavy Hex Bolts — ASME B18.2.3.6M
ASME B18.2.3.6M — wider across-flats and greater head height than DIN 933. Specified for large-diameter chemical equipment closures, high-torque reactor access covers, and agitated vessel bodies in mixed acid service where maximum wrench bearing area and high-torque capability are required alongside C276’s broad corrosion resistance. Supply with matched C276 heavy hex nuts from same heat. M12–M100.
| Spec | Details |
|---|---|
| Material | UNS N10276 / C276 |
| Standard | ASTM B574 · ASME B18.2.3.6M |
| Size Range | M12 — M100 |
| Head | Heavy Hex — wider AF, greater height |
| UTS | ≥ 690 MPa |
| Condition | Solution Annealed |
Socket Cap Screws — DIN 912
Hastelloy C276 socket cap screws to DIN 912 / ISO 4762 — cylindrical hex-socket head bolts for confined-space and close-access fastening in chemical process equipment where hex bolt clearance is unavailable. Used in chemical reactor internals, heat exchanger internal baffle attachment, sample port closures, and instrument flange bolting in mixed acid and chlorinated solvent environments. M4–M48.
| Spec | Details |
|---|---|
| Material | UNS N10276 / C276 |
| Standard | ASTM B574 · DIN 912 · ISO 4762 |
| Size Range | M4 — M48 |
| Drive | Hex socket (Allen key) |
| Head Form | Cylindrical cap |
| UTS | ≥ 690 MPa |
| Condition | Solution Annealed |
Inch Thread Hex Bolts — UNC / UNF
Hastelloy C276 hex bolts in UNC (coarse) and UNF (fine) thread per ASME B1.1. Head dimensions per ASME B18.2.1. ¼”–4″ diameter. For US chemical plant, pulp and paper, and pharmaceutical projects specified in imperial dimensions. Same ASTM B574 certified UNS N10276 solution-annealed material — identical broad corrosion immunity. Matched C276 inch-thread nuts from same heat on request.
| Spec | Details |
|---|---|
| Material | UNS N10276 / C276 |
| Standard | ASTM B574 · ASME B18.2.1 |
| Size Range | ¼” — 4″ |
| Thread | UNC · UNF per ASME B1.1 |
| Head | Hex per ASME B18.2.1 AF |
| UTS | ≥ 690 MPa |
| Condition | Solution Annealed |
DIN 931 / DIN 933 C276 Hex Bolt Dimensions
Standard dimensions per DIN 931/933 and ISO 4014/4017. All in mm. Compare with our C276 stud bolt table for flanged pressure joint service. Custom lengths and non-standard on request to sales@akbarfasteners.in.
| Size (M) | Pitch | AF (s) mm | Head Ht (k) mm | Full Thread (DIN 933) | Part Thread b (DIN 931) | Heavy Hex AF mm | Condition |
|---|---|---|---|---|---|---|---|
| METRIC HEX BOLTS — UNS N10276 · ASTM B574 · SOLUTION ANNEALED | |||||||
| M6 | 1.0 mm | 10.0 | 4.0 | 10–100 mm | 18 mm | — | Sol. Ann. |
| M8 | 1.25 mm | 13.0 | 5.3 | 12–200 mm | 22 mm | — | Sol. Ann. |
| M10 | 1.5 mm | 17.0 | 6.4 | 16–200 mm | 26 mm | — | Sol. Ann. |
| M12 | 1.75 mm | 19.0 | 7.5 | 20–300 mm | 30 mm | 21.0 | Sol. Ann. |
| M16 | 2.0 mm | 24.0 | 10.0 | 30–300 mm | 38 mm | 26.9 | Sol. Ann. |
| M20 | 2.5 mm | 30.0 | 12.5 | 40–300 mm | 46 mm | 33.5 | Sol. Ann. |
| M24 | 3.0 mm | 36.0 | 15.0 | 50–300 mm | 54 mm | 40.4 | Sol. Ann. |
| M30 | 3.5 mm | 46.0 | 18.7 | 60–300 mm | 66 mm | 50.8 | Sol. Ann. |
| M36 | 4.0 mm | 55.0 | 22.5 | 70–300 mm | 78 mm | 60.3 | Sol. Ann. |
| M42 | 4.5 mm | 65.0 | 26.0 | On order | On order | 71.0 | Sol. Ann. |
| M48 | 5.0 mm | 75.0 | 30.0 | On order | On order | 82.6 | Sol. Ann. |
| M56 – M100 | 5.5–6.0 mm | Custom | Custom | On order | On order | Custom | Sol. Ann. |
* Fine pitch DIN 13, UNC/UNF inch thread, non-standard lengths on request — sales@akbarfasteners.in
Standards We Manufacture & Test To
Same quality system as our Hastelloy B3 stud bolts and complete ASTM B574 Hastelloy fastener range. Full heat traceability from mill certificate to dispatch.
Industry Applications
Mixed or uncertain acid environments, multipurpose chemical plant, and any application requiring the broadest single-alloy corrosion protection in a hex bolt form.
Chemical Processing
multipurpose plant covers
Oil & Gas
offshore mixed media
FGD Scrubbers
wet SO₂ cover fastening
Pulp & Paper
bleaching plant covers
Desalination
brine system fastening
Pharmaceutical
multipurpose vessel covers
Offshore Platforms
mixed media service
Waste Treatment
chlorinated scrubber bolts
Complete Documentation Package
Heat & Lot Traceable
Conformance
100% Lots Verified
Tensile · Hardness
TÜV · BV · Lloyds
Related C276 & Hastelloy Fasteners
C276 stud bolts, washers, and matched alloy alternatives — everything needed from one ISO 9001:2015 certified source.
Hastelloy C276 Stud Bolts
Fully threaded and double-end stud bolts for ASME B16.5 pressure flanges in mixed acid service. Class 150–2500, M12–M100, lengths to 3,000mm.
View Page →Hastelloy C276 Washers
Plain flat and spring washers in C276 from the same certified heat as these bolts — matched material for zero galvanic risk in the complete assembly.
View Page →Hastelloy C22 Stud Bolts
For FGD and oxidising chloride service where C22’s superior pitting resistance outperforms C276. Class 150–2500, M12–M100.
View Page →Hastelloy B3 Stud Bolts
For reducing HCl and H₂SO₄ service where B3 outperforms C276. Near-zero corrosion in HCl at all concentrations. Class 150–2500, M12–M100.
View Page →Need Hastelloy C276
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