Inconel 718 Pipe: Properties, Applications, Sizes and Supplier Guide
When engineering demands leave no room for failure — extreme heat, crushing pressure, and corrosive media all at once — Inconel 718 pipe is the material professionals specify. A precipitation-hardenable nickel-chromium superalloy, Inconel 718 (UNS N07718) delivers extraordinary strength from cryogenic temperatures all the way up to 700°C (1300°F), making it the most widely used high-temperature alloy in the world across aerospace, oil and gas, power generation, and chemical processing.
At Steel Pipe and Tubes, we supply certified Inconel 718 pipe and tube to industries globally, backed by full mill documentation and third-party inspection. This guide covers everything you need — properties, specifications, sizes, applications, and how to choose the right supplier.
What is Inconel 718?
Inconel 718 was developed in the early 1960s to solve a specific engineering problem: the need for a high-strength, weldable superalloy for jet engine components. Its breakthrough lay in the addition of niobium and molybdenum, which enables precipitation hardening — a heat treatment process that creates fine gamma double-prime (γ”) particles within the metal matrix, generating exceptional strength without sacrificing weldability.
This makes Inconel 718 fundamentally different from most other high-temperature alloys. It can be fabricated, welded, and formed in the solution-annealed condition, then aged to achieve maximum strength — a major advantage for pipe fabricators and end users alike.
Explore our full Inconel product range and the Inconel 718 pipe and tube product page for detailed specifications.
Inconel 718 Pipe: Chemical Composition
The performance of Inconel 718 pipe is directly rooted in its precisely controlled chemical makeup.
Element | Content (%) |
|---|---|
Nickel (Ni) | 50.0 – 55.0 |
Chromium (Cr) | 17.0 – 21.0 |
Iron (Fe) | Balance |
Niobium (Nb) + Tantalum (Ta) | 4.75 – 5.50 |
Molybdenum (Mo) | 2.80 – 3.30 |
Titanium (Ti) | 0.65 – 1.15 |
Aluminum (Al) | 0.20 – 0.80 |
Cobalt (Co) | 1.0 max |
Carbon (C) | 0.08 max |
Manganese (Mn) | 0.35 max |
Silicon (Si) | 0.35 max |
Phosphorus (P) | 0.015 max |
Sulfur (S) | 0.015 max |
Boron (B) | 0.006 max |
Copper (Cu) | 0.30 max |
The high niobium content is the defining feature of this alloy — it drives the precipitation hardening mechanism that gives Inconel 718 pipe its remarkable room and elevated temperature strength.
Key Properties of Inconel 718 Pipe
Mechanical Properties (Age-Hardened Condition)
Property | Value |
|---|---|
Ultimate Tensile Strength | Min. 1275 MPa (185 ksi) |
Yield Strength (0.2% offset) | Min. 1034 MPa (150 ksi) |
Elongation | Min. 12% |
Hardness (Rockwell C) | 36–46 HRC |
Density | 8.19 – 8.22 g/cm³ |
Melting Range | 1370°C – 1430°C |
Strength at Temperature
One of the most compelling attributes of Inconel 718 pipe is how well it retains strength at elevated temperatures — a critical factor in pipe applications where operating conditions are far from ambient.
Temperature (°C) | Yield Strength (MPa) | Tensile Strength (MPa) |
|---|---|---|
21 | 1120 | 1345 |
204 | 1060 | 1275 |
427 | 995 | 1205 |
538 | 965 | 1170 |
649 | 925 | 1050 |
705 | 860 | 900 |
Corrosion and Oxidation Resistance
The 17–21% chromium content in Inconel 718 pipe forms a stable, self-renewing passive oxide layer on the surface, providing excellent resistance to:
- Oxidizing and reducing atmospheres up to 980°C
- Pitting and crevice corrosion in chloride-bearing environments
- Stress corrosion cracking in high-purity water and brine solutions
- Hydrogen sulfide (H₂S) and CO₂ in sour gas service
Cryogenic Performance
Unlike most steels, Inconel 718 pipe retains full ductility and impact strength down to cryogenic temperatures (-253°C), making it suitable for LNG processing, liquid hydrogen systems, and aerospace propulsion applications.
Non-Magnetic
Inconel 718 is non-magnetic in all conditions — an important requirement in instrumentation, electronic, and downhole measurement-while-drilling (MWD) applications.
Excellent Weldability
Inconel 718 is one of the most weldable high-strength nickel superalloys. Pipes can be joined using TIG (GTAW), MIG (GMAW), and electron beam welding. Its slow aging response at intermediate temperatures minimizes strain-age cracking during welding — a problem common with other age-hardenable nickel alloys.
Inconel 718 Pipe Specifications and Standards
Steel Pipe and Tubes supplies Inconel 718 pipe and tube conforming to the following internationally recognized standards:
ASTM / ASME Standards
Standard | Description |
|---|---|
ASTM B983 / ASME SB983 | UNS N07718 seamless pipe and tube |
ASTM B704 / ASME SB704 | Welded UNS N07718 pipe and tube |
ASTM B637 | Bar, forgings, and rings (age-hardenable) |
ASTM B670 | Plate, sheet, and strip |
AMS (Aerospace Material Specifications)
Standard | Product Form |
|---|---|
AMS 5589 | Seamless tube (annealed) |
AMS 5590 | Seamless tube (solution treated) |
AMS 5596 | Sheet, strip, plate |
AMS 5662 | Bar, rod, wire (solution treated) |
AMS 5664 | Bar, rod, wire (precipitation hardened) |
Other Designations
- UNS N07718 — Unified Numbering System
- Werkstoff Nr. 2.4668 — European/DIN designation
- W. Nr. 2.4668 — Alternate European designation
- NACE MR0175 / ISO 15156 — Sour service compliance
Available Sizes of Inconel 718 Pipe
Steel Pipe and Tubes supplies Inconel 718 pipe in a wide range of sizes to meet project-specific requirements:
Parameter | Range |
|---|---|
Outer Diameter (OD) | 6.35 mm to 610 mm (1/4″ to 24″) |
Wall Thickness | 0.5 mm to 50 mm |
Schedule | SCH 5S, 10S, 40S, 80S, 160, XXS |
Length | Random, fixed, or cut-to-length |
Form | Seamless, welded (ERW/EFW) |
End Finish | Plain End (PE), Beveled End (BE), Threaded End |
Custom sizes, special lengths, and non-standard wall thicknesses are available on request. Contact us with your project requirements.
Applications of Inconel 718 Pipe
Aerospace and Defense
Aerospace accounts for over 50% of global Inconel 718 consumption. In pipe and tube form, it is used for hydraulic tubing, fuel system lines, combustion chamber liners, exhaust ducts, and instrumentation tubing in jet engines, rocket propulsion systems, and aircraft structures. Its combination of high strength, low weight, and resistance to thermal cycling makes it irreplaceable in this sector.
Oil and Gas — Downhole and Subsea
Inconel 718 pipe is a preferred material for high-pressure, high-temperature (HPHT) downhole tubulars, wellhead components, casing hangers, and subsurface safety valve systems. Its resistance to H₂S and CO₂ in sour gas wells, compliance with NACE MR0175, and outstanding strength-to-weight ratio make it the material of choice for demanding oil and gas environments. For complementary fittings and bar stock, see our Inconel 718 round bar and Inconel 718 plates and sheets.
Need Inconel 718 Pipe for Your Project?Steel Pipe and Tubes supplies certified Inconel 718 seamless and welded pipe to ASTM B983, AMS 5589/5590, and NACE MR0175. Available in all sizes with full documentation. Request a Quote or browse our Inconel 718 pipe and tube product page.
Power Generation and Nuclear
In gas turbines and steam power plants, Inconel 718 pipes and tubes are used for high-temperature steam lines, heat exchanger tubes, and reactor components. Its creep-rupture strength and resistance to stress corrosion cracking in high-purity water environments are critical advantages for long-service power plant components.
Chemical and Petrochemical Processing
Inconel 718 pipe handles aggressive chemical media — including concentrated acids, caustic solutions, and mixed corrosive streams — at elevated temperatures and pressures. Applications include reactor piping, heat exchanger tubes, and transfer lines in refineries and chemical plants. Explore our Inconel pipe and tube category for the full Inconel piping portfolio.
Cryogenic and LNG Applications
The alloy’s exceptional toughness at sub-zero temperatures makes Inconel 718 pipe suitable for LNG transfer lines, liquid hydrogen storage systems, and cryogenic instrumentation tubing where material embrittlement would be catastrophic.
Marine and Naval Engineering
Inconel 718 pipe resists chloride-ion stress corrosion cracking, making it valuable for seawater cooling circuits, marine propulsion shafts, and submarine pressure hull penetrations. See our Nickel Alloy pipes and tubes for related marine-grade alloy piping.
Inconel 718 Pipe vs Other Nickel Alloy Pipes
Alloy | Key Advantage | Best For |
|---|---|---|
Inconel 718 | Highest strength + weldability | Aerospace, HPHT oil & gas, cryogenic |
Superior seawater corrosion resistance | Subsea, marine, offshore | |
High-temperature oxidation resistance | Furnace, chemical, nuclear | |
Widest chemical corrosion resistance | Aggressive acid/chlorine service | |
Hydrofluoric acid and seawater immersion | Chemical, marine |
Quality, Certification, and Supply
Steel Pipe and Tubes supplies Inconel 718 pipe with full traceability and certification:
- Mill Test Reports (MTR) to ASTM B983 / AMS 5589 / 5590
- EN 10204 3.1 and 3.2 certification
- PMI (Positive Material Identification) testing on request
- NACE MR0175 / ISO 15156 compliance certification
- Third-party inspection by SGS, Bureau Veritas, or Lloyd’s Register
- Hardness testing, hydrostatic testing, and NDT on request
Visit our certifications page and export guide for full documentation details. Use our material calculator for weight and quantity estimations.
Ready to Order Certified Inconel 718 Pipe? We maintain stock of Inconel 718 seamless and welded pipe for fast dispatch worldwide. NACE compliant, third-party inspected, and fully documented. Contact our team today or check our pipes and tubes supplier page for more information.
Conclusion
Inconel 718 pipe is the benchmark high-strength nickel alloy pipe for applications where temperature, pressure, and corrosion combine to push ordinary materials beyond their limits. From jet engine hydraulics to HPHT oil wells, its unique precipitation-hardenable microstructure delivers tensile strength exceeding 1275 MPa while remaining fully weldable and fabricable — a combination no other alloy matches at comparable cost.
For certified Inconel 718 pipe and tube in all sizes and standards, explore our Inconel 718 pipe and tube product page, browse our full Pipes and Tubes range, or contact us for a competitive quote and fast delivery.
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