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Inconel pipes are nickel-chromium superalloy pipes engineered for service in extreme heat (up to 2,200°F / 1,204°C) and corrosive environments. Four primary grades — 600, 601, 625 and 718. Ideal for aerospace, chemical process industry (CPI), oil & gas, marine, and power generation sectors.
Available in seamless and welded configurations, governed by strict ASTM/ASME standards for material composition, mechanical properties, and dimensional tolerances.
Type | Seamless/Welded/SAW/ERW/EFW Pipe | |
End | BE (Beveled End) | |
Size | OD: 1/2"-48" | |
Manufacturing Technique | Hot rolling / Hot work / Cold rolling / Cold-drawn | |
Producing Standard | ASME B36.10 and ASME B36.19 | |
Inconel Steel Grades | ASTM B474 | UNS N06600/Inconel 600, UNS N06601/ Inconel 601, UNS N06625/Inconel 625 |
ASTM B163 | UNS N06600/Inconel 600, UNS N06601/ Inconel 601 | |
ASTM B444 | UNS N06625/Inconel 625 | |
Seamless Inconel Pipes
Seamless Inconel pipes are manufactured by hot extrusion, rotary piercing, or pilgering from a solid billet. Because they contain no longitudinal weld seam, seamless pipes offer uniformly homogeneous grain structure, superior pressure integrity, and are the preferred choice for high-pressure, high-temperature, and critical-service applications.
Features: No weld seam / uniform wall thickness / higher pressure ratings / ideal for heat exchangers, boiler tubes, and aerospace hydraulic systems.
Welded Inconel Pipes (ERW & EFW)
Welded Inconel pipes are formed from rolled plate or coil and welded using Electric Resistance Welding (ERW) or Electric Fusion Welding (EFW). Welded pipes are more economical for larger diameters (typically NPS 8 and above) and low-to-medium-pressure applications. With proper post-weld heat treatment (PWHT), welded Inconel pipes can approach seamless-grade corrosion resistance in the heat-affected zone.
Features: Cost-effective for large diameters / available in longer lengths than seamless / suitable for structural, exhaust, and moderate-pressure process piping.
Inconel 600 (UNS N06600 / W.Nr. 2.4816)
Chemistry: Nickel 72.0% min, Chromium 14.0–17.0%, Iron 6.0–10.0%. Best for: General-purpose high-temperature oxidation resistance up to 2,000°F (1,093°C). Excellent resistance to chloride-ion stress-corrosion cracking (Cl-SCC). Not age-hardenable; strength is achieved through solid-solution strengthening and cold work.
Primary applications: Chemical and petrochemical processing, furnace components, nuclear steam generator tubing, food processing equipment.
Inconel 601 (UNS N06601 / W.Nr. 2.4851)
Chemistry: Nickel 58.0–63.0%, Chromium 21.0–25.0%, Aluminum 1.0–1.7%. Best for: The addition of aluminum dramatically enhances oxidation resistance up to 2,200°F (1,204°C). Exceptional resistance to carburization and oxidation in cyclic heating/cooling conditions. Not age-hardenable.
Primary applications: Radiant tubes, thermal processing equipment, industrial furnace muffles, petrochemical reformers, combustion chambers.
Inconel 625 (UNS N06625 / W.Nr. 2.4856)
Chemistry: Nickel 58.0% min, Chromium 20.0–23.0%, Molybdenum 8.0–10.0%, Niobium 3.15–4.15%. Best for: The molybdenum and niobium additions provide outstanding resistance to pitting, crevice corrosion, and chloride environments. Non-magnetic. Service temperature up to 1,800°F (982°C). High fatigue strength.
Primary applications: Seawater equipment, chemical process piping, aerospace ducting, subsea oil & gas components, power plant scrubbers, nuclear waste processing.
Inconel 718 (UNS N07718 / W.Nr. 2.4668)
Chemistry: Nickel 50.0–55.0%, Chromium 17.0–21.0%, Niobium 4.75–5.5%, Molybdenum 2.8–3.3%, Titanium 0.65–1.15%, Aluminum 0.2–0.8%. Best for: The strongest Inconel grade — precipitation-hardenable via gamma-double-prime (γ″) phase formation. Exceptional tensile strength (up to 220 ksi / 1,517 MPa in aged condition) up to 1,300°F (704°C).
Primary applications: Aerospace jet engine components (turbine discs, shafts, casings), cryogenic storage vessels, gas turbine hot sections, nuclear reactor structural components.
Every Incoloy® and Inconel® pipe we supply is manufactured and tested to the latest ASTM and ASME specifications. The dual-certification (ASTM + ASME SB) ensures compliance with both general industrial and pressure vessel codes. Below is a comprehensive mapping of each grade to its governing standards.
Grade | Seamless Pipe/Tube | Welded Pipe/Tube | General Requirem. |
600 | ASTM B167 / ASME SB167 | ASTM B517 / ASME SB517 | ASTM B829 (general Ni alloy pipe) |
601 | ASTM B167 / ASME SB167 | ASTM B517 / ASME SB517 | ASTM B829 (general Ni alloy pipe) |
625 | ASTM B444 Gr.1 / SB444 | ASTM B705 / ASME SB705 | ASTM B829, ASTM B880 |
718 | ASTM B983 / AMS 5589 | API 6ACRA (oil & gas) | ASTM B637, AMS 5662/5663 |
The table below presents the nominal chemical composition for each Inconel grade. Values are weight-percent maximum unless a range is specified. All compositions conform to the corresponding ASTM specifications.
Grade | Ni | Cr | Fe | Mo | Nb | Ti | Al | Mn/Si/C |
600 | 72 min | 14-17 | 6-10 | — | — | — | — | Bal. |
601 | 58-63 | 21-25 | Bal. | — | — | — | 1.0-1.7 | Low |
625 | 58 min | 20-23 | 5 max | 8-10 | 3.15-4.15 | 0.4 max | 0.4 max | Low |
718 | 50-55 | 17-21 | Bal. | 2.8-3.3 | 4.75-5.5 | 0.65-1.15 | 0.2-0.8 | Low |
Mechanical properties are reported per the applicable ASTM specification at room temperature (solution-annealed condition, unless noted otherwise). Actual values may exceed minimums. Precipitation-hardenable grades (718 and X-750) offer substantially higher strength in the aged condition.
Grade | Tensile Str. (min) | Yield Str. 0.2% (min) | Elong. (min) | Hardness (max) | Density | MP |
600 | 80 ksi / 550 MPa | 35 ksi / 240 MPa | 30% | HRB 92 | 8.47 g/cm³ | 2,470–2,575°F |
601 | 80 ksi / 550 MPa | 30 ksi / 205 MPa | 30% | HRB 95 | 8.05 g/cm³ | 2,370–2,570°F |
625 | 120 ksi / 827 MPa | 60 ksi / 414 MPa | 30% | HRC 35 | 8.44 g/cm³ | 2,350–2,460°F |
718 | 150–220 ksi* | 120–200 ksi* | 12–20%* | HRC 36–44* | 8.19 g/cm³ | 2,300–2,437°F |
Inconel pipes serve in virtually every major industrial sector that encounters extreme thermal, mechanical, and chemical operating conditions. The following table maps each industry to the most commonly specified Inconel grades.
Industry | Common Grades | Typical Applications |
Aerospace | 718, 625 | Jet engine turbine discs & casings, exhaust ducts, thrust reversers, hydraulic systems, APU components |
Chemical Processing | 600, 601, 625 | Heat exchangers, reactor vessels, distillation columns, acid-handling piping, evaporators, catalyst support grids |
Oil & Gas | 625, 718 | Subsea wellhead components, downhole tubing hangers, sour-service piping, refinery crude distillation units, flare tips |
Nuclear Power | 600, 625, 718 | Steam generator tubes, reactor internals, control rod drive mechanisms, pressurizer heaters, spent fuel storage |
Power Generation | 601, 625 | Gas turbine combustion liners, superheater tubes, boiler reheat tubing, SCR catalyst supports, transition ducts |
Marine | 625 | Seawater cooling pipes, ballast water systems, desalination heat exchangers, exhaust scrubbers, propeller shafts |
Automotive | 601, 625, 718 | Turbocharger turbine housings, EGR cooler tubes, exhaust flex couplings, fuel cell reformer components |
Q: What is the difference between Inconel and Incoloy?
A: Both are nickel-based superalloys from Special Metals Corporation, but they differ in composition: Inconel is nickel-chromium-based (typically Ni 50–72%) with higher high-temperature strength, while Incoloy is nickel-iron-chromium-based (typically Ni 30–45%) with a lower nickel content and better cost-efficiency in moderately corrosive, high-temperature environments. Inconel is specified when extreme heat or corrosion demands the highest nickel content; Incoloy is often chosen for sulfur-bearing or less extreme environments.
Q: What is the difference between seamless and welded Inconel pipes?
A: Seamless Inconel pipes are manufactured from solid billets via hot extrusion or rotary piercing, yielding a homogeneous grain structure without longitudinal welds. They deliver the highest pressure ratings and are the default choice for nuclear, aerospace, and high-pressure chemical service. Welded Inconel pipes (ERW/EFW) are fabricated from rolled plate or coil and joined by welding. They are cost-competitive for large-diameter, lower-pressure piping and are commonly used in structural and process applications.
Q: Which Inconel grade should I choose for seawater service?
A: Inconel 625 is the benchmark for seawater applications. Its high molybdenum content (8–10%) and niobium addition provide unmatched resistance to pitting (PREN ≥ 48) and crevice corrosion in chloride-rich environments, including marine, offshore, and desalination service. Inconel 718 may be used for high-strength seawater fasteners, but 625 is the primary material for pipe and tubing.
Q: What temperature can Inconel pipes withstand?
A: Temperature limits are grade-specific: Inconel 600 handles up to 2,000°F (1,093°C), 601 up to 2,200°F (1,204°C), 625 up to 1,800°F (982°C), 718 up to 1,300°F (704°C) for high-strength applications, and X-750 up to 1,500°F (816°C). These limits assume oxidizing atmospheres; reducing or sulfur-rich environments may lower the service ceiling. Always consult the mill test certificate (MTC) and relevant ASTM specification for your specific operating conditions.
Q: What ASTM standards apply to Inconel pipes?
A: Key standards include ASTM B167 (Inconel 600/601 seamless pipe), ASTM B444 (Inconel 625 seamless), ASTM B517 (Inconel 600/601 welded), ASTM B705 (Inconel 625 welded), ASTM B983 (Inconel 718 seamless), and ASTM B829 (general nickel alloy pipe). ASME SB equivalents (e.g., SB167, SB444) apply for ASME Boiler and Pressure Vessel Code (BPVC) applications. Pipes are dimensioned to ASME B36.10M and B36.19M.
Q: Can Inconel pipes be welded?
A: Yes. All Inconel pipe grades are weldable using standard arc welding processes, including GTAW (TIG), GMAW (MIG), SMAW (stick), and SAW. Matching or over-matching filler metals (e.g., ERNiCrMo-3 for 625, ERNiFeCr-2 for 718) must be used. Post-weld heat treatment (PWHT) is required for precipitation-hardenable grades (718, X-750) to restore full mechanical properties. Pre-weld cleaning to remove surface oxides and contamination is critical to prevent hot cracking.
For technical inquiries, quotation requests, or to discuss custom Inconel pipe specifications, please reach out to our sales team. We supply seamless and welded Inconel pipes in all major grades across a full range of sizes and schedules. Custom lengths, non-standard diameters, and specialty heat treatments are available upon request.
