What Is a Seamless Incoloy 925 Pipe?
Seamless Incoloy 925 pipe is a high-strength, corrosion-resistant pipe crafted from a single, solid billet of a nickel-iron-chromium alloy that is strengthened by age hardening. It is manufactured without a weld joint, ensuring superior structural integrity and reliability, especially in highly corrosive environments where high strength is also required. The”Incoloy 925″designation refers to a specific grade that is a precipitation-hardenable version of Incoloy 825. Its unique composition, which includes controlled amounts of titanium and aluminum, allows it to be heat-treated to achieve exceptional strength while maintaining the excellent corrosion resistance of Incoloy 825. This makes it a top choice for demanding applications in the oil and gas industry, particularly in sour gas environments.
Size Range: OD 6–457 mm · WT 0.5–45 mm
Key Features and Advantages
Seamless 925 Pipe offer a unique combination of benefits that make them invaluable in the most demanding industries:
High Strength: The age-hardening heat treatment provides significantly higher tensile and yield strength than non-hardenable alloys, allowing for the use of thinner wall thicknesses and reduced material costs in high-pressure applications.
Exceptional Corrosion Resistance: It provides outstanding resistance to chloride-ion stress-corrosion cracking, pitting, and crevice corrosion, particularly in sour gas and saltwater environments.
High Pressure and Temperature Tolerance: The seamless construction and robust material allow the pipe to safely handle high internal pressures and a wide range of operating temperatures.
Good Weldability: The alloy can be welded using standard methods, and subsequent heat treatment can restore the desired mechanical properties.
Versatility: Its combination of high strength and exceptional corrosion resistance makes it a highly versatile material for a wide range of applications.
Product Specifications and Data
To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for Incoloy 925.
Equivalent Grade
| UNS | Common grade name | EN material number | EN steel name | JIS grade | GB/T grade |
|---|---|---|---|---|---|
| N09925 | Incoloy 925 | – | – | – | NS2401 |
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. See the grade designation index.
Chemical Composition
The composition of Incoloy 925 is carefully balanced to achieve its superior strength and corrosion resistance.
| Grade | UNS | C | Mn | P | S | Si | Ni | Cr | Mo | Cu | Fe | Ti | Al | Other |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Incoloy 825 | N08825 | ≤0.05 | ≤1.0 | ≤0.030 | ≤0.030 | ≤0.5 | 38.0-46.0 | 19.5-23.5 | 2.5-3.5 | 1.5-3.0 | Bal ≥22.0 | 0.6-1.2 | ≤0.2 | — |
| Incoloy 925 | N09925 | ≤0.03 | ≤1.0 | – | ≤0.030 | ≤0.5 | 38.0-46.0 | 19.5-23.5 | 2.5-3.5 | 1.5-3.0 | 22.0 min | 1.9-2.4 | 0.1-0.5 | Nb: ≤0.50 |
Typical Mechanical Properties
Incoloy 925 is specifically designed to maintain its strength and shape in high-stress, corrosive environments.
| Tensile Strength | Yield Strength | Elongation | Hardness |
|---|---|---|---|
| ≥ 965 MPa | ≥ 758 MPa | ≥ 18% | ≤ 38 HRC |
Per ASTM B983 Table 3 — Solution Annealed + Precipitation Hardened.
Typical Physical Properties
These physical properties highlight the material’s ability to perform reliably under a wide range of conditions.
| Density | Melting Point | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 8.08 g/cm³ | 1340 – 1400 °C approx. | 13.9 μm/m·°C (20-100°C) | 11.1 W/m·K (20°C) | 195 GPa | 1.15 × 10⁻⁶ Ω·m (20°C) |
Size Tolerance Chart (mm)
Cold-Finished Pipes and Tubes:
| Specified/Calculated Nominal OD (Inches) | Permissible Variation (Inches) | Specified/Calculated Nominal OD (mm) | Permissible Variation (mm) |
| 0.500 to 5⁄8, excl. | ±0.005 | 12.7 to 15.8, excl. | ±0.127 |
| 5⁄8 to 1 1⁄2, incl. | ±0.0075 | 15.8 to 38.1, incl. | ±0.190 |
| Over 1 1⁄2 to 3 1⁄2, incl. | ±0.010 | Over 38.1 to 88.9, incl. | ±0.254 |
| Over 3 1⁄2 to 4 1⁄2, incl. | ±0.015 | Over 88.9 to 114.3, incl. | ±0.381 |
| Over 4 1⁄2 to 6, incl. | ±0.020 | Over 114.3 to 152.4, incl. | ±0.508 |
| Over 6 to 6 5⁄8, incl. | ±0.025 | Over 152.4 to 168.3, incl. | ±0.635 |
| Specified/Calculated Nominal OD (Inches) | Permissible Variation (Inches) | Specified/Calculated Nominal OD (mm) | Permissible Variation (mm) |
| 2 1⁄2 to 5 1⁄2, excl. | ±0.031 | 63.5 to 139.7, excl. | ±0.787 |
| 5 1⁄2 to 9 1⁄4, incl. | ±0.047 | 139.7 to 234.9, incl. | ±1.19 |
| Condition | Specified/Calculated Nominal OD (Inches) | Permissible Variation (Wall Thickness) |
| Cold-Finished | 0.500 to 5⁄8, excl. | ±15.0% |
| 5⁄8 to 4 1⁄2, incl. | ±10.0% | |
| Over 4 1⁄2 to 6 5⁄8, incl. | ±12.5% | |
| Hot-Finished | 2 1⁄2 to 9 1⁄4, incl. | ±12.5% |
Common Industrial Applications
The combination of high strength and exceptional corrosion resistance of seamless Incoloy 925 pipes makes them a preferred choice for:
Oil and Gas Industry
For downhole components, hangers, and wellhead equipment in sour gas service.
Marine Engineering
For components exposed to saltwater environments where high strength is required.
Pumps and Valves
In the chemical and process industries for components requiring both high strength and corrosion resistance.
Aerospace
In high-stress applications where both strength and corrosion resistance are critical.
Frequently Asked Questions
What sizes are available for Incoloy 925 seamless pipe?
Continuous supply covers OD 6–457 mm and WT 0.5–45 mm. Requirements outside this range are reviewed against mill capability on request.
Which specification governs Incoloy 925 seamless pipe?
ASTM B983 is the governing seamless specification for UNS N09925. ASTM B423 covers N08825/N08221 and ASTM B704 covers welded product, so they are not applied to N09925 seamless pipe.
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.
Technical review: page data reviewed by the Xinzhe technical desk on 2026-09-27. Property values are typical reference data compiled from Special Metals Corporation alloy data sheets and the governing ASTM specifications; they are not acceptance guarantees unless stated in the purchase order. "Incoloy" is a trademark of Special Metals Corporation, used here to identify the alloy family only.
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.
