What Is a Seamless Nickel 201 Tube?
Seamless Nickel 201 Tube — UNS N02201 — is the low-carbon version of commercially pure wrought nickel (99.0% minimum Ni, carbon 0.02% maximum) produced to ASTM B163 from a solid billet with no weld seam.
The single chemistry change — carbon capped at 0.02% — removes the risk of intergranular graphitization that limits Nickel 200 above 315 °C. Nickel 201 therefore carries the same outstanding caustic and reducing-media performance into higher-temperature service, with a lower work-hardening rate that suits deep drawing, spinning and cold forming. Above about 300 °C it loses ferromagnetism, a useful property for instrumentation.
Key Features and Advantages
Seamless UNS N02201 tube extends pure-nickel caustic performance above 315 °C with 0.02% carbon:
Carbon Limited to 0.02%: prevents intergranular graphitization, making Nickel 201 mandatory for hot caustic and high-temperature service above 315 °C.
Hot Caustic Performance: the reference alloy for sodium hydroxide evaporators and molten-caustic equipment at temperatures where Nickel 200 cannot be used.
Superior Cold Formability: lower work-hardening than Nickel 200 suits spinning, deep drawing and multi-pass cold pilgering.
Same Purity and Conductivity: 99.0% minimum nickel with thermal conductivity of 79.3 W/m·K — even higher than Nickel 200.
Ductile at Cryogenic Temperatures: 40% minimum elongation in the annealed condition, retained down to deep-cryogenic service.
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 N02201 seamless tube.
Equivalent Grade
| UNS | Common grade name | EN material number | EN steel name | JIS grade | GB/T grade |
|---|---|---|---|---|---|
| N02201 | Nickel 201 | 2.4068 / 2.4061 | LC-Ni99 | NW2201 | NS5201 / N7 (legacy) |
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 N02201 seamless tube chemistry is tightly controlled so the corrosion and mechanical performance below is repeatable:
| Grade | Ni | Cu | Fe | Mn | C | Si | S |
|---|---|---|---|---|---|---|---|
| UNS N02201 | 99.0 min | ≤0.25 | ≤0.40 | ≤0.35 | ≤0.02 | ≤0.35 | ≤0.01 |
Chemical requirements per ASTM B163-22, Table 1. Single values are maximum content unless a minimum is indicated. Nickel 201 matches the purity of Nickel 200 with carbon limited to 0.02% maximum; nickel is determined arithmetically by difference including cobalt.
Typical Mechanical Properties
Values below are specification minimums for the delivery condition; they define the acceptance basis for UNS N02201 seamless tube.
| Condition | TS, min, ksi (MPa) | YS (0.2% Offset), min, ksi (MPa) | Elongation in 2 in. or 50 mm, min, % | Hardness (or equivalent) for annealed ends |
|---|---|---|---|---|
| Annealed | 50 (345) | 12 (83) | 40 | … |
| Stress-relieved | 60 (414) | 30 (207) | 15 | B62 max |
Mechanical properties per ASTM B163-22, Table 3. Seamless tube is normally supplied in the annealed condition; the stress-relieved condition is available on request and carries a B62 maximum hardness requirement applicable to the annealed ends of the tube. Each tube is hydrostatically or nondestructive electrically tested per the general requirements of ASTM B829.
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 | Curie Temperature |
|---|---|---|---|---|---|---|
| 8.89 g/cm3 | 1435 – 1446 °C | 13.3 μm/m·°C (20–100°C) | 79.3 W/m·K (20°C) | 207 GPa | 0.085 μΩ·m (20°C) | 358 °C |
Size Tolerance Chart (mm)
Permissible variations for seamless nickel alloy tube in accordance with ASTM B163-22, Table 4:
| Nominal Outside Diameter, in. (mm) | Permissible Variation in OD, mm | Average Wall, % | Minimum Wall |
|---|---|---|---|
| 1/2 to 5/8 (12.7 to 15.9), excl | +0.13 / −0 | ±12.5 | +25% / −0 |
| 5/8 to 1-1/2 (15.9 to 38.1), incl | ±0.13 | ±10 | +20% / −0 |
| over 1-1/2 to 3 (38.1 to 76.2), incl | ±0.25 | ±10 | +22% / −0 |
Notes (dimensions per ASTM B163-22, Table 4, UNS N02200/N02201 group): tolerances apply to individual measurements and include out-of-roundness (ovality). For thin-wall tubes with a nominal wall of 3% or less of the outside diameter, the mean OD shall comply with the table and individual measurements are increased by 0.5% of the nominal OD. Note the asymmetric OD variation for the smallest size group (+0.13 mm / −0). Eccentricity: wall variation in any one cross section shall not exceed ±10% of the actual average wall of that section. For small-diameter and light-wall converter sizes, see Appendix X2 (Table X2.2).
Length Tolerance
- When tube is ordered cut-to-length, the length shall not be less than that specified; a variation of +3.2 mm (1/8 in.) is permitted, and for lengths over 30 ft (9.1 m) a variation of +6.4 mm (1/4 in.) is permitted (ASTM B163-22, 7.2).
- Tube is normally supplied in mill lengths or specific cut lengths as agreed in the order.
Disclaimer: Data above are summarized from ASTM B163-22 (Standard Specification for Seamless Nickel and Nickel-Alloy Condenser and Heat-Exchanger Tubes). 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 N02201 seamless tube a preferred choice for:
Hot Caustic Evaporators and Concentrators
NaOH service above 315 °C where graphitization rules out Nickel 200.
Food, Pharmaceutical and Fine Chemicals
High-purity processing lines built from commercially pure nickel.
Fluorine Chemistry and Halogen Service
Reactors and transfer tubing for fluorine generation and halogenated media.
Heat Exchangers at Elevated Temperature
B163 condenser and heat-exchanger tubing in reducing and alkali duty.
Ordering Guide
When specifying UNS N02201 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 Nickel 201 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 Nickel 201 seamless tube?
ASTM B163 / ASME SB163 is the governing specification for Nickel 201 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.
