UNS N06022|2.4602|Hastelloy C22 Seamless Tube
Distinguished by its optimized chemistry, Hastelloy C22 provides superior resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC), outperforming Alloy C276 in oxidizing environments containing wet chlorine and nitric acid. These tubes are indispensable for mission-critical applications in chemical reactors, pharmaceutical synthesizers, and flue gas desulfurization (FGD) systems. Through advanced cold-drawing and precise vacuum annealing, XinZhe ensures every tube maintains a uniform microstructure and maximum structural reliability under aggressive industrial conditions.
C22 PREN ≈ 45+
What Is a Seamless Hastelloy C22 Tube?
Hastelloy C22 (UNS N06022 / W.Nr. 2.4602) is a nickel-chromium-molybdenum alloy with tungsten, engineered to resist both oxidising and reducing media. Its higher chromium content than C276 improves resistance to oxidising acids and to pitting in halide-containing environments, while the tungsten addition strengthens resistance to localised corrosion, making C22 a preferred choice where C276 is borderline.
Seamless Hastelloy C22 tube (UNS N06022 / W.Nr. 2.4602) is a high-performance nickel–chromium–molybdenum–tungsten alloy, engineered to deliver exceptional corrosion resistance in both oxidizing and reducing environments.
Manufactured from solid billets through hot piercing and cold finishing, seamless C22 tubes feature a uniform, weld-free microstructure, ensuring superior mechanical strength, pressure resistance, and long-term reliability in critical applications.
Recognized as one of the most versatile corrosion-resistant nickel alloys, Hastelloy C22 is widely used in complex chemical processes where media conditions vary or are highly aggressive.
Key Features and Technical Advantages
Outstanding Universal Corrosion Resistance
Hastelloy C22 resists both oxidising and reducing media, giving it the broadest corrosion envelope of the C-family alloys.
Superior Resistance to Oxidising Acids
A higher chromium content than C276 improves performance in oxidising acids and in media containing ferric or cupric ions.
Excellent Localised Corrosion Resistance
Tungsten and molybdenum combine to resist pitting and crevice corrosion in halide-containing environments.
Resistance to Process Streams with Mixed Chemistry
C22 tolerates chlorides, hypochlorite and oxidising contaminants simultaneously, which makes it the default upgrade where C276 is marginal.
Good Fabricability and Weldability
The alloy is readily formed and welded and retains corrosion resistance in the as-welded condition.
Product Specifications and Data
The addition of Tungsten (W) specifically enhances its resistance to pitting in halide-containing environments.
Table 1: Chemical Composition (UNS N06022)
| Ni | Cr | Mo | W | C | Si | Co | Mn | V | P | S |
| Bal | 20.00-22.50 | 12.50-14.50 | 2.50-3.50 | ≤0.015 | ≤0.080 | ≤2.50 | ≤0.50 | ≤0.35 | ≤0.02 | ≤0.02 |
Hastelloy C22 is specifically designed to maintain its strength and shape in high-stress, corrosive environments.
Table 2: Typical Mechanical Properties (Annealed)
| Tensile Strength | Yield Strength | Elongation | Hardness |
|---|---|---|---|
| ≥ 690 MPa | ≥ 310 MPa | ≥ 45% | ≤ 100 HRB |
These physical properties highlight the material's ability to perform reliably under a wide range of conditions.
| Density | Melting Point | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 8.69 g/cm³ | 1399 °C approx. | 12.4 µm/m·°C (20-100°C) | 11.1 W/m·K (20°C) | 205 GPa | 1.15 x 10⁻⁶ Ω·m (20°C) |
Dimensional Standards and Tolerances
Hastelloy C22 seamless tubes are supplied to the dimensional tolerances of ASTM B622 / B829 unless a tighter project specification applies.
Common Industrial Applications
Chemical Processing
- Reactors, heat exchangers and vessels
- Halide-containing process streams
- Mixed oxidising/reducing acid service
Pharmaceutical and Fine Chemicals
- Reactor vessels and internals
- Purification equipment
- Corrosive media transfer
Pollution Control and Waste Treatment
- Flue-gas desulphurisation scrubbers
- Waste-incineration equipment
- Effluent treatment systems
Pulp and Paper Industry
- Bleach plant equipment
- Digester and liquor lines
- Heat exchangers
Offshore and Marine Engineering
- Seawater and brine systems
- Offshore process pipework
- Cooling equipment
Quality Assurance and Manufacturing Process
Certification
All Hastelloy C22 tubes are supplied to ASTM B622 / ASME SB622 and ASTM B619 / ASME SB619 with EN 10204 3.1 mill test certificates. Third-party inspection (SGS, BV, TUV, Lloyd's), PMI reports and full heat-number traceability can be provided on request.
Non-Destructive Testing (NDT)
Hydrostatic or eddy-current testing is performed on 100% of tubes. Ultrasonic testing (UT) and dye-penetrant inspection (PT) are available for critical service, with records retained for each production lot.
Material Verification
Positive Material Identification (PMI) and spectrometric analysis confirm that the chemical composition matches the ordered grade. Intergranular corrosion (IGC) testing to ASTM A262 Practice E is available for austenitic and nickel-alloy tubes.
Mechanical Testing
Tensile, yield, elongation and hardness tests are carried out per heat. Flattening, flaring and reverse-bend tests verify ductility, while creep-rupture data can be supplied for high-temperature grades.
Dimensional Inspection
Outside diameter, wall thickness, ovality and straightness are measured against ASTM A1016 / A1016M or EN 10216-5 tolerances. Length, square-cut ends and end-finish conditions are verified before packing.
Hastelloy C22 vs C276 / B3 – Technical Comparison
Hastelloy C22 was developed to widen the corrosion envelope of C276, particularly toward oxidising media, while keeping the reducing-acid capability that makes the family useful.
Chemistry
- C22: approximately 22% Cr, 13% Mo, 3% W — higher chromium than C276
- C276: approximately 15.5% Cr, 16% Mo, 4% W — higher molybdenum than C22
- B3: nickel-molybdenum with controlled iron and chromium, for reducing acids only
Oxidising versus Reducing Performance
The extra chromium in C22 improves resistance to oxidising acids and to media containing ferric or cupric ions, while the tungsten and molybdenum retain the reducing-acid performance. C276 remains marginally better in the most aggressive reducing conditions.
Localised Corrosion
Both alloys resist pitting and crevice corrosion in chloride-bearing environments. C22 is usually preferred where the process stream contains both chlorides and oxidising contaminants, since it handles the combination with more margin.
Selection Guide
- Choose Hastelloy C22 where the process combines chlorides with oxidising species, or where oxidising acids dominate
- Choose Hastelloy C276 for the most aggressive reducing conditions and the broadest established service record
- Choose Hastelloy B3 only for pure reducing-acid service without oxidising contaminants
Frequently Asked Questions
What is a Hastelloy C22 seamless tube?
Hastelloy C22 (UNS N06022 / W.Nr. 2.4602) is a nickel-chromium-molybdenum alloy tube with tungsten, produced without a longitudinal weld. It is engineered to resist both oxidising and reducing media, with a higher chromium content than C276.
What is the difference between Hastelloy C22 and C276?
C22 carries approximately 22% chromium against roughly 15.5% in C276, which improves performance in oxidising acids and in media containing ferric or cupric ions. C276 carries more molybdenum, which gives it a slight edge in the most aggressive reducing conditions. Both resist chloride pitting and stress-corrosion cracking.
What is Hastelloy C22 tube used for?
C22 is used in chemical and pharmaceutical reactors and heat exchangers, flue-gas desulphurisation and waste-incineration equipment, pulp and paper bleach plants, and offshore seawater and brine systems — particularly where the process combines chlorides with oxidising species.
What standards cover Hastelloy C22 tube?
Hastelloy C22 seamless tube is supplied to ASTM B622 / ASME SB622, with ASTM B829 covering general requirements and ASTM B619 / ASME SB619 applying to welded pipe.
Ready to Request a Quotation?
Send your Seamless Hastelloy C22 Tube enquiry with grade, application, size (OD and wall thickness or schedule), quantity, length, end finish and inspection requirements. Our technical team will confirm availability, testing scope and lead time.
