What is the difference between b407 incoloy 800 tube and b163 nickel alloy tube?

When an engineer is selecting nickel alloy tubing for a heat-transfer or high-temperature service, two ASTM specifications are often mentioned together: ASTM B407 Incoloy 800 tube and ASTM B163 nickel alloy tube. Both cover seamless nickel-iron-chromium products, both list UNS N08800 as a valid material, and both are routinely supplied by the same manufacturers. So it is easy to assume they are interchangeable. In practice they are written for different jobs, and choosing the wrong one can lead to oversized material, unnecessary cost, or even a non-conformance at inspection.

This guide walks through what each specification really covers, where the technical requirements overlap, and where they diverge — so the next time you compare a B407 incoloy 800 tube with a B163 nickel alloy condenser/heat-exchanger tube, you know exactly which one belongs in your project.

What ASTM B407 Covers

ASTM B407 is the standard specification for seamless nickel-iron-chromium alloy pipe in the Incoloy 800 family. The current edition covers three UNS designations:

• UNS N08800 — Incoloy 800, the base composition with 30.0–35.0% Ni, 19.0–23.0% Cr, 0.15–0.60% Al, 0.15–0.60% Ti, carbon ≤ 0.10%, balance Fe.
• UNS N08810 — Incoloy 800H, with carbon restricted to 0.05–0.10% for improved creep strength at elevated temperature.
• UNS N08811 — Incoloy 800HT, with a tighter Al+Ti combination that further stabilises high-temperature service.

B407 is written as a pipe specification. The size envelope reflects that: outside diameter typically ranges from about 10 mm up to 762 mm, with wall thickness between roughly 2.0 mm and 140 mm. The standard defines hot-finished and cold-worked solution-annealed product, with mechanical properties that suit general process piping — minimum tensile strength around 520 MPa and minimum yield strength around 205 MPa for N08800 in the annealed condition.

Typical applications for B407 product include chemical process piping (especially nitric acid service), oil and gas gathering lines, ethylene pyrolysis furnace tubes, superheater and reheater tubing in thermal power, steam generator piping in nuclear stations, and aerospace propulsion components. In short, B407 is the specification you turn to when you need a structural or process pipe in an 800-series alloy.

What ASTM B163 Covers

ASTM B163 is the standard specification for seamless nickel and nickel alloy condenser and heat-exchanger tubes. Unlike B407, B163 is a multi-alloy specification. It covers a broad family of UNS numbers, including:

• Commercially pure nickel: N02200, N02201
• Nickel-copper alloy: N04400 (Monel 400)
• Nickel-chromium-iron alloys: N06600, N06601, N06690, N06025, N06045, N06603
• Nickel-chromium-molybdenum-tungsten: N06686
• Nickel-iron-chromium alloys: N08120, N08800, N08801, N08810, N08811
• Nickel-iron-chromium-molybdenum-copper: N08825 (Incoloy 825)

The fact that N08800, N08810 and N08811 appear in B163 is what causes the confusion. They are listed in B163 because they are valid materials for heat-exchanger service, not because B163 replaces B407. The product form is the key: B163 covers tubes, not pipes, and the size envelope is correspondingly tight.

For B163, the maximum outside diameter is 3 in (76.2 mm) and the maximum average wall thickness is 0.165 in (4.19 mm). The standard also includes supplementary requirements for U-bent tubes, high-yield-strength (HYS) tubes, and coiled or unstraightened tubing — all of which are heat-exchanger-specific geometries. Mechanical properties are tabulated per alloy and condition; for N08800 in the annealed condition the minimum tensile strength is 517 MPa with a minimum yield of 207 MPa and 30% elongation, while the cold-worked condition raises tensile strength to 572 MPa minimum.

Side-by-Side Comparison

The table below summarises the most important differences between the two specifications.

In short: B407 is for pipe, B163 is for heat-exchanger tube. When the same UNS number — say N08800 — is produced to either specification, the chemistry is the same, but the dimensional scope, mechanical-property tables, and supplementary options are written for two very different service environments.

Where the Two Specifications Overlap

Because B163 also lists the 800-family alloys, there is a small practical zone of overlap in the N08800 / N08810 / N08811 range, typically for tube sizes inside the B163 envelope (OD ≤ 76.2 mm, wall ≤ 4.19 mm). In that zone, the chemical composition tables are essentially identical to B407, and the annealed-condition mechanical properties are comparable.

This is why a single Incoloy 800 melt can be produced to either standard. The buyer decides which specification to call out on the purchase order, and the mill runs the product through the corresponding testing and inspection regime. The choice comes down to the service:

• If the tube is going into a shell-and-tube heat exchanger, condenser, or feedwater heater, B163 is the correct call, especially when U-bending or tight eccentricity control is required.
• If the tube is being used as a process pipe or structural line — even at a size that would technically fit B163 — B407 is usually the right choice, because it documents the application more accurately and avoids an auditor challenge later.

Choosing the Right Material for Heat-Exchanger Service

When B163 is selected, the alloy choice is driven by the process fluid and temperature, not by the specification itself. A few common pairings:

• N04400 (Monel 400) — the workhorse for seawater and brackish water coolers, hydrofluoric acid alkylation units, and marine heat exchangers.
• N06600 / N06601 — for high-temperature steam, ethylene furnace quench, and caustic service.
• N08800 / N08810 / N08811 — for nitric acid coolers, reformer outlet piping, and high-temperature petrochemical exchangers where resistance to carburisation and chloride stress-corrosion cracking is required.
• N08825 (Incoloy 825) — for sulphuric and phosphoric acid service, where the addition of Mo and Cu improves resistance to reducing acids.
• N06686 — for the most aggressive multi-acid service, including wet flue gas desulphurisation and high-chloride environments.

If you are still deciding which B163 alloy best fits a particular duty, the broader nickel alloy overview on our B163 nickel alloy tube page gives a side-by-side comparison of the most commonly supplied grades and their typical service envelopes.

Quality, Testing, and Documentation

Both specifications require lot-based inspection, full chemical analysis, mechanical testing, and traceability. The practical differences are:

• B163 includes eccentricity control (≤ 10% of average wall) because concentricity matters in heat-exchanger bundle fabrication, particularly for tube-sheet drilling and rolling.
• B163 lists hardness limits for some alloys and conditions (for example, N02200 stress-relieved ≤ B65, N04400 stress-relieved ≤ B75), which supports field inspection of U-bent regions.
• B407 product is more likely to be ordered with additional NDT such as 100% ultrasonic or eddy-current testing, especially for high-pressure or hydrogen-service piping, even where the standard itself does not mandate it.

For ASME Boiler and Pressure Vessel Code work, the corresponding ASME specifications are SB407 and SB163. The technical content is identical to the ASTM versions, but the SB designation is what an ASME-stamped fabricator will reference on the data report.

Practical Sourcing Tips

A few points that save time and prevent re-orders when you are buying either of these products from a mill or stockist:

1. Specify the standard on the PO, not just the alloy. “N08800, 25.4 mm OD × 2.11 mm wall, annealed” is ambiguous. Add “per ASTM B407/SB407” or “per ASTM B163/SB163” so the mill runs the right test schedule.
2. Call out the condition. B163 in particular has multiple delivery conditions (annealed, stress-relieved, stress-relieved with annealed ends). U-bent tubes are almost always stress-relieved in the bend area, with the straight legs optionally annealed.
3. Watch the dimensional envelope. If your tube exceeds 76.2 mm OD or 4.19 mm average wall, B163 no longer applies and you are in B407 / B423 / B444 territory.
4. Request MTRs with full traceability. Both standards require a mill test certificate, but the depth of information (heat number, condition, NDT results, hardness) varies. For critical service, ask for EN 10204 3.1 or 3.2 certification.
5. Plan for the right U-bend radius if relevant. B163’s supplementary requirements cover U-bent tubing; the minimum bend radius is typically 1.5× to 3× the tube OD, depending on the alloy and customer specification.

Frequently Asked Questions

Can a B407 pipe be used in a heat exchanger? In a narrow sense, yes — if the size and geometry fit the bundle. In practice, B407 product rarely meets the tight eccentricity, hardness, and U-bending requirements that exchanger designers expect. Use B163 for heat-exchanger service.

Is the chemistry of N08800 the same in B407 and B163? Yes. Both standards list the same composition limits for N08800 (30.0–35.0% Ni, 19.0–23.0% Cr, Al and Ti each 0.15–0.60%, C ≤ 0.10%, Fe balance). The difference is in the testing, dimensional envelope, and supplementary options, not the alloy chemistry.

Which one should I specify for a nitric acid cooler? For tube bundles, B163 in N08800 or N08810 is the typical call. For the connecting process piping outside the bundle, B407 in the same alloy is the matching choice.

Do I need ASME SB407 or SB163 for ASME-stamped exchangers? Yes. ASME BPVC Section II Part B references the SB designations. The technical content matches the ASTM versions, but the SB reference is what an R-stamp or U-stamp holder will look for on the data report.

Can the same heat be dual-certified to B407 and B163? In some size ranges, yes. Many mills will dual-certify N08800 product in OD ≤ 76.2 mm and wall ≤ 4.19 mm. Beyond that envelope, only B407 applies.

Closing Thoughts

ASTM B407 and ASTM B163 are complementary, not competing, specifications. B407 Incoloy 800 tube is the right call for process and high-temperature piping in the 800-family alloys. B163 nickel alloy tube is the right call when the same alloys are needed in heat-exchanger and condenser geometries, or when a different nickel alloy from the broader B163 family is required.

If you are still weighing which alloy and specification best fit a specific duty — and you would like to see a side-by-side comparison of the most common B163 grades — take a look at the detailed product pages for our nickel alloy tube and petrochemical facilities product lines, or send your enquiry to our team with the service fluid, temperature, pressure, and preferred geometry. We will work back from there to the right specification, alloy, and size.