How does b167 ni-cr-fe alloy tube compare to b167 Inconel 600 tube?

When project specifications call for a seamless nickel alloy tube that can handle high temperature, pressure, and corrosive media, B167 Ni-Cr-Fe alloy tube is one of the most common references on a purchaser's drawing. The same specification also covers what most buyers simply call "B167 Inconel 600 tube" because UNS N06600 is by far the most widely ordered grade under that standard. The two descriptions are not interchangeable, however, and the differences matter for material selection, certification, and total cost. This guide explains how ASTM B167 defines the family, where Inconel 600 fits inside it, and what to check when sourcing either tube from a manufacturer or integrated supplier.

What ASTM B167 Actually Covers

ASTM B167 is the standard specification for "Nickel-Chromium-Iron Alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, and N06045) and Nickel-Chromium-Cobalt-Molybdenum Alloy (UNS N06617) Seamless Pipe and Tube." In simple terms, B167 is a family specification rather than a single product. The "Ni-Cr-Fe alloy tube" name on a purchase order is a generic reference to any of these UNS numbers that fall under the B167 scope, and the buyer is expected to add the specific UNS designation to make the order unambiguous. EZ Steel Industrial supplies the full B167 range, with alloy steel tube and complementary nickel grades manufactured to MTR-certified mill standards for project and industrial use.

Where Inconel 600 Sits Inside B167

Inconel 600 is the trade name associated with UNS N06600, which is the first alloy listed in B167's scope and the historical baseline for the entire family. The typical composition is 72% nickel minimum, 14–17% chromium, and 6–10% iron, with tightly controlled limits on carbon, manganese, silicon, sulfur, and copper. Because UNS N06600 was the original alloy in the standard, most drawings that say "B167 Inconel 600 tube" or simply "B167 Ni-Cr-Fe alloy tube" historically meant the same product. Modern specifications, however, should always state the UNS number to avoid confusion with higher-chromium grades like N06690 or aluminum-bearing N06601.

Key specification anchors for Inconel 600 under B167 include:

• UNS designation: N06600 (Werkstoff 2.4816, EN NiCr15Fe)
• Density: 8.42 g/cm³
• Tensile strength (hot-worked or hot-worked annealed, OD ≤ 127 mm): minimum 550 MPa (80 ksi)
• Yield strength (0.2% offset): minimum 205 MPa (30 ksi)
• Elongation: minimum 35%
• Tensile strength (annealed): 550–690 MPa typical, yield 170–345 MPa, elongation 35–55%

Comparing the B167 Ni-Cr-Fe Family Side by Side

The B167 family shares a nickel-chromium-iron backbone, but each grade is tuned for a different service environment. The table below summarizes the most ordered members; full composition limits should always be confirmed against the current revision of ASTM B167 and the project's material requisition.

In short, a generic "B167 Ni-Cr-Fe alloy tube" can be any of these grades. A "B167 Inconel 600 tube" is specifically UNS N06600. The mechanical property envelope for B167 also varies by UNS designation and condition; for example, N06025 in the specified hot-worked condition delivers higher tensile strength than N06600, while N06600 in the annealed condition provides the deepest forming and bending behavior of the group.

When Inconel 600 Is the Right Choice

Inconel 600 remains the workhorse of the B167 family because it balances high-temperature strength with resistance to chloride-ion stress-corrosion cracking and caustic corrosion. It is the default selection for:

• Heat-treatment baskets, trays, and fixtures operating up to about 1150 °C in oxidizing atmospheres
• Furnace muffles, retorts, and radiant tubes
• Chemical process equipment handling alkaline solutions, hot caustic, and organic acids
• Nuclear power plant components such as steam generator tube sheets and support plates, where its low cobalt content is an advantage
• Aerospace and engine components exposed to jet exhaust and combustion gases

When the service temperature is high but the environment is not strongly oxidizing or chloridized, Inconel 600 generally offers the best cost-to-performance ratio of the B167 grades. Many heat efficiency tube and B163 nickel alloy tube specifications actually cross-reference B167 when N06600 is permitted, so confirming the UNS number on the MTR is the cleanest way to verify the alloy.

When to Specify a Higher B167 Grade Instead

There are well-defined cases where another B167 member is the technically correct material rather than N06600:

• Pressurized water reactor steam generator tubing: N06690 (Inconel 690) is the industry standard because its higher chromium content dramatically improves resistance to primary water stress-corrosion cracking.
• Carburizing and cyclic-oxidation service: N06601 (Inconel 601) with its aluminum addition forms a more stable oxide layer and resists spalling during thermal cycling.
• Metal dusting and high-temperature sulfidation: N06693 (Inconel 693) is engineered for syngas, ammonia, and petrochemical environments where carbon deposition would attack N06600.
• Severe creep or load-bearing service above 1100 °C: N06025 (Inconel 602CA) maintains useful strength beyond the limits of annealed N06600.

For high-pressure boiler tubing and heat exchanger tube applications that still call out the Ni-Cr-Fe family, it is common to see B167 cross-referenced with ASTM B163 (seamless nickel and nickel alloy condenser and heat-exchanger tubes) or B516/B517 welded tube. Pairing the right UNS with the right product form is what makes the difference between a routine supply and a project-specific package.

Sourcing and Quality Verification

Procurement of B167 tubes, whether the generic Ni-Cr-Fe family or Inconel 600 specifically, should always be controlled through four checkpoints:

1. UNS designation on the MTR: Confirm that the mill test certificate lists the exact UNS number (N06600, N06601, N06690, etc.) and the heat number that can be traced to the original heat analysis.
2. Heat-treated condition: Specify whether the tube is hot-worked, hot-worked annealed, or annealed, since the mechanical properties change with condition.
3. Dimensional and testing requirements: Reference OD, wall, length, tolerance per ASTM B167, and the required tests — typically hydrostatic or nondestructive electric testing, plus intergranular corrosion testing for nuclear or caustic service.
4. Documentation package: MTR EN 10204 3.1 certificates, PMI verification, and project-specific traceability records for EPC and nuclear applications.

An integrated supplier that produces in multiple locations and holds API 5L, API 5CT, ISO 9001, and PED certifications can bundle B167 tubes with matching pipe fittings, pipe flanges, and gaskets under a single QA plan, simplifying documentation and shortening delivery to site.

Practical Selection Checklist

Before placing a B167 order, run through the following questions:

• Is the design code calling for the generic family or a specific UNS? If the UNS is missing, the mill will default to N06600 unless told otherwise.
• What is the operating temperature, and is the environment oxidizing, reducing, or carburizing?
• Is chloride-induced stress-corrosion cracking a concern, or is primary-water SCC a concern (pointing to N06690)?
• Are there project specifications that require nuclear-grade documentation, RCC-M compliance, or specific NDT scope?
• Are complementary components (fittings, flanges, gaskets) being ordered from the same supplier to keep metallurgy consistent?

Conclusion

A B167 Ni-Cr-Fe alloy tube is the broader category; a B167 Inconel 600 tube is the most common member of that category, identified as UNS N06600. The two terms overlap on historical drawings, but a modern specification should always state the UNS number, the heat-treated condition, and the testing scope. For most high-temperature, mildly corrosive service, Inconel 600 remains the most cost-effective choice, while N06601, N06690, N06693, and N06025 address more aggressive environments that fall within the same B167 framework. Working with a manufacturer that can supply the full B167 family, together with the fittings, flanges, and documentation needed for project execution, keeps the supply chain simple and the metallurgical story consistent from the drawing to the field.