What Is a Seamless Hastelloy B2 Tube?
Seamless Hastelloy B2 Tube — UNS N10665 — is a nickel–molybdenum alloy (26.0–30.0% Mo, chromium capped at 1.0%) produced to ASTM B622 from a solid billet with no weld seam.
With chromium deliberately removed, B2 delivers unmatched resistance to reducing media: it handles hydrochloric acid at all concentrations and temperatures, together with mid-strength sulfuric, acetic and phosphoric acids and wet aluminum chloride. The very high molybdenum content also gives it the highest tensile and yield strength of the Hastelloy tube family — 760 MPa (110 ksi) and 350 MPa (51 ksi) minimum per ASTM B622. The trade-off: it has virtually no resistance to oxidizing media, so iron or copper ions in acid streams must be avoided.
Key Features and Advantages
Seamless UNS N10665 tube is the reference alloy for hot, concentrated reducing acids:
Unmatched Hydrochloric Acid Resistance: 26.0–30.0% molybdenum withstands HCl at every concentration, including boiling streams where other alloys dissolve.
Strong Across Reducing Acids: excellent in mid-strength sulfuric, acetic, phosphoric and wet-process phosphoric acid service.
Highest Strength in the Hastelloy Family: tensile 760 MPa (110 ksi) minimum and yield 350 MPa (51 ksi) minimum in the solution annealed condition.
Chromium Kept Below 1.0%: the fully reducing composition prevents transpassive attack but requires the absence of oxidizing species.
Solid-Solution Simplicity: no aging treatment is needed; strength comes directly from the annealed Ni-Mo matrix.
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 N10665 seamless tube.
Equivalent Grade
| UNS | Common grade name | EN material number | EN steel name | JIS grade | GB/T grade |
|---|---|---|---|---|---|
| N10665 | Hastelloy B-2 | 2.4617 | NiMo28 | NW0665 | NS3202 / NS322 (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 N10665 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 N10665 | remainder | 26.0–30.0 | ≤1.00 | ≤2.00 | – | ≤1.00 | ≤1.00 | – | ≤0.02 | ≤0.10 | ≤0.04 | ≤0.03 |
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). B622 sets no requirement for tungsten or vanadium in UNS N10665 (shown as –); chromium is capped at 1.0% and iron at 2.0% to keep the alloy fully reducing in character.
Typical Mechanical Properties
Values below are specification minimums for the delivery condition; they define the acceptance basis for UNS N10665 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 | 110 (760) | 51 (350) | 40 |
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. Note that B2 can embrittle through intermediate-phase precipitation if held in the 550–900 °C range; tube is therefore rapidly cooled from the annealing temperature and should not be re-heated into this window in service.
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 |
|---|---|---|---|---|---|
| 9.22 g/cm3 (ASTM B622) | 1330 – 1380 °C | 10.3 μm/m·°C (20–100°C) | 11.0 W/m·K | 210 GPa | 1.37 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 N10665 seamless tube a preferred choice for:
Hydrochloric Acid Plants and Circuits
Coolers, heaters and transfer tubing across the full HCl concentration range.
Acetic and Phosphoric Acid Production
Reactors, reboilers and acid circulation lines in reducing duty.
Wet-Process Phosphoric and Aluminum Chloride Service
Evaporator and digester tubing where other nickel alloys corrode rapidly.
Chemical Processing with Pure Reducing Media
Any chloride- or acid-bearing stream free of ferric/cupric ions and oxygen.
Ordering Guide
When specifying UNS N10665 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 B2 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 B2 seamless tube?
ASTM B622 / ASME SB622 is the governing specification for Hastelloy B2 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.
