What Is a Seamless Hastelloy C22 Tube?
Seamless Hastelloy C22 Tube — UNS N06022 — is a nickel–chromium–molybdenum–tungsten alloy (20.0–22.5% Cr, 12.5–14.5% Mo, 2.5–3.5% W) produced to ASTM B622 from a solid billet with no weld seam.
The elevated chromium level makes C22 the best choice of the C family for oxidizing media — wet chlorine, hypochlorite, chlorine dioxide and ferric/ Cupric chlorides — while the molybdenum and tungsten keep strong resistance to reducing acids. It also resists pitting, crevice attack and stress-corrosion cracking in seawater brines, and its heat-affected zone retains full corrosion resistance after welding, which is why it is the standard material for high-purity and waste-treatment systems.
Key Features and Advantages
Seamless UNS N06022 tube maximizes oxidizing-media resistance within the C family:
Best Oxidizing-Media Resistance in the C Family: 20.0–22.5% chromium stands up to wet chlorine, hypochlorite, chlorine dioxide and ferric ions.
Balanced Reducing-Acid Capability: 12.5–14.5% Mo plus 2.5–3.5% W retain strong performance in sulfuric, hydrochloric and organic acids.
Superior Weld-Zone Corrosion Resistance: the Cr-Mo-W balance prevents heat-affected-zone attack, so as-welded tube performs like the parent metal.
Excellent Localized Corrosion Resistance: high resistance to pitting, crevice corrosion and chloride SCC in seawater and brine service.
Tightest Purity Limits: P and S each 0.02% maximum per ASTM B622 suit high-purity pharmaceutical and fine-chemical duty.
Product Specifications and Data
To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for UNS N06022 seamless tube.
Equivalent Grade
| UNS | Common grade name | EN material number | EN steel name | JIS grade | GB/T grade |
|---|---|---|---|---|---|
| N06022 | Hastelloy C-22 | 2.4602 | NiCr21Mo14W | NW6022 | NS3308 |
Grade correspondence does not make ASTM, ASME, EN, JIS and GB delivery requirements interchangeable. Confirm chemistry, heat treatment, mechanical properties, dimensions, testing and certification against the purchase specification. Approximate or unconfirmed correspondences retain their qualification. See the grade designation index.
Chemical Composition
UNS N06022 seamless tube chemistry is tightly controlled so the corrosion and mechanical performance below is repeatable:
| Grade | Ni | Mo | Cr | Fe | W | Co | Mn | V | C | Si | P | S |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UNS N06022 | remainder | 12.5–14.5 | 20.0–22.5 | 2.0–6.0 | 2.5–3.5 | ≤2.50 | ≤0.50 | ≤0.35 | ≤0.015 | ≤0.08 | ≤0.02 | ≤0.02 |
Chemical requirements per ASTM B622-23, Table 1. Single values are maximum content unless a range is indicated. Nickel is determined arithmetically by difference (remainder). C22 carries the highest chromium of the C family (20.0–22.5%) with 12.5–14.5% Mo and 2.5–3.5% W, and the tightest P and S limits (≤0.02% each).
Typical Mechanical Properties
Values below are specification minimums for the delivery condition; they define the acceptance basis for UNS N06022 seamless tube.
| Condition | Tensile Strength, min, ksi (MPa) | Yield Strength (0.2% Offset), min, ksi (MPa) | Elongation in 2 in. or 50 mm, min, % |
|---|---|---|---|
| Solution annealed | 100 (690) | 45 (310) | 45 |
Mechanical properties per ASTM B622-23, Table 2, in the solution annealed and descaled condition (6.2). Each pipe and tube is hydrostatically or nondestructive electrically tested (9.1) per the general requirements of ASTM B829. C22 shows the best weld-zone corrosion performance of the C family thanks to its balanced Cr-Mo-W ratio.
Typical Physical Properties
These physical properties highlight the material’s ability to perform reliably across a range of environments.
| Density | Melting Range | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 8.69 g/cm3 (ASTM B622) | 1350 – 1390 °C | 12.3 μm/m·°C (20–100°C) | 10.5 W/m·K | 205 GPa | 1.20 μΩ·m (20°C) |
Size Tolerance Chart (mm)
Permissible variations for seamless nickel alloy tube in accordance with ASTM B829-24, Table 2:
| Nominal Outside Diameter, mm | Permissible Variation in OD, mm | Average Wall, % | Minimum Wall |
|---|---|---|---|
| 10.0 to 15.9, excl | ±0.13 | ±15 | +30% / −0 |
| 15.9 to 38.1, incl | ±0.19 | ±10 | +22% / −0 |
| over 38.1 to 76.2, incl | ±0.25 | ±10 | +22% / −0 |
| over 76.2 to 88.9, incl | ±0.38 | ±10 | +22% / −0 |
Notes (dimensions per ASTM B829-24, Table 2, referenced by ASTM B622-23): tolerances apply to individual measurements and include ovality. For thin-wall tube (nominal wall 3% or less of the OD), the mean OD shall comply with the table and individual measurements are increased by 0.5% of the nominal OD. Wall variation in any cross section (eccentricity) shall not exceed ±10% of the actual average wall. B622-23 limits seamless tube to 88.9 mm (3.5 in.) outside diameter; larger hollows are covered as pipe under the same general requirements.
Length Tolerance
- When tube is ordered cut-to-length, length variation is +3.2 mm / −0 for OD under 50.8 mm and +4.8 mm / −0 for larger sizes (ASTM B829-24, Table 5); for lengths over 24 ft, an additional +3.2 mm per 10 ft applies, up to a maximum of +12.7 mm.
- Tube is normally supplied in mill lengths or specific cut lengths as agreed in the order.
Disclaimer: Dimensional data above are summarized from ASTM B829-24, Table 2, as referenced by ASTM B622-23. The full and most current specification documents must always be consulted for official design and procurement purposes.
Common Industrial Applications
The combination of corrosion resistance, mechanical strength and manufacturing quality makes UNS N06022 seamless tube a preferred choice for:
Flue Gas Desulfurization
Quench and absorber tubing where wet SO3, chlorides and acidic slurries combine.
Pharmaceutical and Fine Chemicals
High-purity process lines, clean-in-place systems and corrosive solvent circuits.
Waste Treatment and Incineration
Scrubber and quench tubing handling aggressive mixed waste acids.
Pulp and Paper and Chlorine Dioxide Systems
Bleach plant tubing in oxidizing chlorinated environments.
Ordering Guide
When specifying UNS N06022 seamless tube, please include: quantity, outside diameter and wall (nominal or minimum), delivery condition, length, and any third-party inspection or supplementary requirements — our sales team will confirm the production schedule and send a formal quotation.
Frequently Asked Questions
What sizes are available for Hastelloy C22 seamless tube?
The overall range is OD 6–257 mm; WT 0.5–35 mm. Requirements outside this range are reviewed against mill capability on request.
Which specification governs Hastelloy C22 seamless tube?
ASTM B622 / ASME SB622 is the governing specification for Hastelloy C22 seamless tube. The edition in force at order time is stated on the quotation and purchase order; chemistry, mechanical properties, heat treatment, dimensions and testing are reported against the ordered standard and material heat.
What inspection documents are provided?
Each order is documented with a mill test certificate stating heat chemistry and mechanical test results. EN 10204 3.1 certification, hydrostatic testing, eddy-current or ultrasonic inspection and PMI are performed when specified in the purchase order.
Ready to Request a Quotation?
Send the NPS and schedule (or actual OD and wall), quantity, length, end finish and the inspection items you need as acceptance criteria — you will get a written quotation stating the specification and edition, delivery condition, documents included and lead time.
