Hastelloy C22
Hex Bolts
UNS N06022
Why Hastelloy C22 Hex Bolts in Oxidising Chloride Service
In flanged bolted connections exposed to oxidising chloride environments — FGD scrubbers, mixed acid streams, wet chlorine, hypochlorite, and high-Cl⁻ bleaching solutions — Hastelloy C22 (UNS N06022) is specified over Hastelloy C276 because of a fundamental alloy difference. C22 contains 20–22.5% Cr versus C276’s 14.5–16.5%, and adds tungsten (2.5–3.5%). This higher chromium and tungsten content gives C22 a distinctly superior pitting resistance index (PRE ≈ 73) versus C276 (PRE ≈ 66) in oxidising chloride — translating directly to longer service life for hex bolt heads and shanks exposed in bolt hole crevice geometry.
In practical bolt-in-flange geometry, C22 is specified when: (1) the process stream contains oxidising acids alongside chloride, (2) the service is FGD where wet SO₂ plus oxidising chloride creates mixed-acid attack, or (3) the process contains wet chlorine, hypochlorite, or ferric/cupric chloride where C276 may pit. For purely reducing HCl or H₂SO₄ service, our Hastelloy B3 stud bolts and bolts remain the correct specification.
Akbar Fasteners Pvt. Ltd. machines C22 hex bolts from ASTM B574 solution-annealed UNS N06022 bar. Every lot is XRF PMI-verified against the MTC before machining. Matched C22 hex nuts from same certified heat available on request to complete the galvanic-neutral assembly.
| Element | Min % | Max % | Typical |
|---|---|---|---|
| Nickel (Ni) | Balance | — | ~57% |
| Chromium (Cr) | 20.0 | 22.5 | ~22% |
| Molybdenum (Mo) | 12.5 | 14.5 | ~13% |
| Tungsten (W) | 2.5 | 3.5 | ~3% |
| Iron (Fe) | 2.0 | 6.0 | ~4% |
| Cobalt (Co) | — | 2.5 | — |
| Manganese (Mn) | — | 0.5 | — |
| 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 standard C22 hex bolt for flanged connections in FGD scrubber ductwork, chemical process equipment covers, and agitated reactor closures in oxidising chloride service. Full thread allows engagement across the complete bolt length for maximum pullout resistance in tapped hole assemblies. M6–M100.
Compared to C22 stud bolts, full thread hex bolts are preferred when the joint is assembled and disassembled from one side, or when hex head access is available and stud projection is not required.
| Spec | Details |
|---|---|
| Material | UNS N06022 / C22 |
| 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 | ≥ 45% |
| Condition | Solution Annealed |
Partial Thread Hex Bolts — DIN 931
DIN 931 / ISO 4014 — threaded end with a plain unthreaded shank between head and thread start. The shank carries shear load across the joint interface and prevents thread engagement into structural members. Standard for chemical plant structural connections, FGD absorber tower access platform brackets, and equipment skid base connections in wet oxidising chloride environments. M6–M100.
| Spec | Details |
|---|---|
| Material | UNS N06022 / C22 |
| Standard | ASTM B574 · DIN 931 · ISO 4014 |
| Size Range | M6 — M100 |
| Shank | Plain unthreaded per DIN 931 |
| Thread Length | 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 when maximum wrench bearing area and high-torque tightening is required — chemical reactor body bolts, FGD gas outlet duct covers, and large-diameter agitated vessel closures in C22 service. Supply with matched C22 heavy hex nuts from same heat. M12–M100.
| Spec | Details |
|---|---|
| Material | UNS N06022 / C22 |
| 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 C22 socket cap screws (hex socket, cylindrical head) per DIN 912 / ISO 4762. Used in chemical process equipment where hex bolt head clearance is not available — cover plate fastening on reactor internals, agitated vessel baffle attachment, and instrument flange connections in FGD and mixed acid environments. Allen key drive. M4–M48.
| Spec | Details |
|---|---|
| Material | UNS N06022 / C22 |
| 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 C22 hex bolts in UNC (coarse) and UNF (fine) thread per ASME B1.1. Head dimensions per ASME B18.2.1. ¼”–4″. For US process plant, pulp and paper, and pharmaceutical projects specified in imperial dimensions. Same ASTM B574 certified UNS N06022 solution-annealed material. Matched inch-thread C22 nuts from same heat on request.
| Spec | Details |
|---|---|
| Material | UNS N06022 / C22 |
| 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 C22 Hex Bolt Dimensions
Standard dimensions per DIN 931 / 933 and ISO 4014 / 4017. All in mm. Partial thread shank length (b) per DIN 931 grip length formula. Non-standard and fine pitch 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 N06022 · 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, and non-standard lengths on request. sales@akbarfasteners.in
Standards We Manufacture & Test To
Same quality system as our Hastelloy B3 stud bolts and complete exotic alloy range. Full heat traceability from mill certificate to dispatch.
Industry Applications
The oxidising chloride environments, mixed acid streams, and FGD service where C22 is specified over C276 for superior pitting and crevice corrosion resistance in bolted connections.
FGD Scrubbers
wet SO₂ cover fastening
Chemical Processing
mixed acid vessel bolts
Pulp & Paper
hypochlorite cover bolts
Oil & Gas
NACE sour service bolts
Desalination
concentration stage
Pharmaceutical
CIP system cover bolts
Offshore Platforms
seawater oxidising service
Waste Treatment
wet scrubber cover bolts
Complete Documentation Package
Heat & Lot Traceable
Conformance
100% Lots Verified
Tensile · Hardness
TÜV · BV · Lloyds
Complete C22 & Hastelloy Assembly
C22 stud bolts, C22 nuts, and matched alloy alternatives — select the right product and grade for your service environment from one ISO 9001:2015 certified source.
Hastelloy C22 Stud Bolts
Fully threaded and double-end stud bolts, Class 150–2500, M12–M100, lengths to 3,000mm. For pressure flange joints in FGD and oxidising chloride service.
View Page →Hastelloy B3 Stud Bolts
For HCl and reducing acid service where C22 is not the specification. Near-zero corrosion in HCl. Class 150–2500. When C22 is chosen for oxidising, B3 is chosen for reducing.
View Page →ASTM B574 Hastelloy Fasteners
Full Hastelloy range under one ASTM standard. Grade selection matrix across C-series and B-series grades. All product forms including bolts, studs, nuts, washers.
View All →Hastelloy Fasteners India
Complete Hastelloy manufacturer page. Six grades, all product forms, grade selection guidance. Export to 50+ countries from Mumbai. ISO 9001:2015 certified facility.
View Range →Need Hastelloy C22
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