UNS N06625|2.4856|Inconel 625 Seamless Pipe
Our Inconel 625 seamless pipes offer outstanding protection against pitting, crevice corrosion, and chloride-ion stress corrosion cracking, making them indispensable for aerospace, marine engineering, and chemical processing. Designed to maintain structural integrity from cryogenic temperatures up to 982°C (1800°F), our products undergo rigorous Non-Destructive Testing (NDT) and third-party inspections. XinZhe provides comprehensive technical data—including chemical composition and mechanical properties—to support precision engineering and high-pressure industrial applications.
What Is Seamless Inconel 625 Pipe?
Seamless Inconel 625 Pipe (UNS N06625 / W.Nr. 2.4856) is a high-performance nickel-chromium-molybdenum superalloy designed for applications requiring exceptional corrosion resistance, high strength and reliability under extreme conditions. Manufactured from a solid billet through hot extrusion and cold drawing, the seamless structure eliminates weld seams, ensuring superior structural integrity and improved resistance to pressure, fatigue and thermal stress.
The alloy’s strength comes from solid-solution strengthening through molybdenum and niobium additions, which significantly enhance mechanical properties without the need for precipitation hardening.
Because of its outstanding performance, Inconel 625 seamless pipes are widely used in aerospace, oil & gas, marine engineering, chemical processing and nuclear powerindustries.
Key Performance Advantages of Inconel 625 Seamless Pipes
Outstanding Corrosion Resistance
exceptional resistance to chloride SCC, pitting, crevice corrosion and oxidizing and reducing acids — highly suitable for marine environments and offshore oil production systems.
High Temperature Strength
maintains excellent mechanical strength at temperatures up to 1000°C.
Excellent Oxidation Resistance
forms a stable protective oxide layer, preventing scaling and degradation in high-temperature oxidizing environments.
Superior Fabricability and Weldability
excellent weldability and formability despite high strength, allowing fabrication of complex piping systems.
International Standards and Specifications
| Product Type | ASTM Standard | ASME Standard |
|---|---|---|
| Seamless Pipe & Tube | ASTM B444, ASTM B829 | ASME SB444 |
| Welded Pipe | ASTM B705, ASTM B775 | ASME SB705 |
| Welded Tube | ASTM B704, ASTM B751 | ASME SB704 |
ASTM B444 grades: Grade 1 (annealed) for general high-temperature applications; Grade 2 (solution annealed) for improved creep rupture and fatigue resistance.
Product Specifications and Data
Chemical Composition
Nickel (Ni) ≥ 58%, Chromium (Cr) 20–23%, Molybdenum (Mo) 8–10% and Niobium + Tantalum (Nb+Ta) 3.15–4.15% provide excellent oxidation resistance, outstanding pitting and crevice corrosion resistance and superior chloride SCC resistance.
| Grade | Ni | Cr | Mo | Nb + Ta | Fe | Co | C | Mn | Si | Al | Ti | P | S |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| N06625 | Balance | 20.00–23.00 | 8.00–10.00 | 3.15–4.15 | ≤ 5.00 | ≤ 1.00 | ≤ 0.100 | ≤ 0.500 | ≤ 0.500 | ≤ 0.400 | ≤ 0.400 | ≤ 0.015 | ≤ 0.015 |
Typical Mechanical Properties
| Tensile Strength | Yield Strength | Elongation | Hardness |
|---|---|---|---|
| ≥ 830 MPa | ≥ 414 MPa | ≥ 30% | ≤ 200 HBW |
Typical Physical Properties
| Density | Melting Point | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 8.44 g/cm³ | 1290–1350 °C approx. | 12.8 µm/m·°C (20-100°C) | 9.8 W/m·K (20°C) | 207 GPa | 1.29 × 10⁻⁶ Ω·m (20°C) |
Size Tolerance Chart
Size tolerance of seamless Alloy 625 pipe and tube per ASTM B444(mm):
| Specification | OD (mm) | OD Tolerance (mm) | Wall Thickness Tolerance | Length Tolerance |
|---|---|---|---|---|
| ASTM B444 — Cold Worked | 10 ≤ D | ±0.13 | ±15% | OD ≥ 50.8: +4.8/−0 (per ASTM B829) |
| 16 ≤ D | ±0.19 | ±15% | ||
| 38 ≤ D | ±0.25 | ±10% | ||
| 76 ≤ D | ±0.38 | ±10% | ||
| 114 ≤ D | ±0.51 | ±12.5% | ||
| 152 ≤ D | ±0.64 | ±12.5% | ||
| 168 ≤ D | ±0.79 | ±12.5% | ||
| 219 ≤ D | +1.57/−0.79 | +15.0%/−12.5% | ||
| 356 ≤ D | +3.18/−0.79 | +15.0%/−12.5% | ||
| ASTM B444 — Hot Finished Tube | 19 ≤ D ≤ 38 | +0.4/−0.8 | ±12.5% | |
| 38.1 ≤ D ≤ 102 | +0.8/−0.8 | ±12.5% | ||
| 102 ≤ D ≤ 235 | +1.6/−0.8 | ±12.5% | ||
| ASTM B444 — Hot Finished Pipe | 25 ≤ D ≤ 48 | ±0.38 | +16%/−12.5% | |
| 48 ≤ D ≤ 114 | ±0.51 | +16%/−12.5% | ||
| 114 ≤ D ≤ 165 | ±0.64 | +16%/−12.5% | ||
| 165 ≤ D ≤ 235 | ±0.79 | +16%/−12.5% |
Industrial Applications of Inconel 625 Seamless Pipes
Oil and Gas Industry
- Sour gas production tubing
- Subsea pipelines
- Flare stacks
- Downhole completion equipment
Aerospace Engineering
- Aircraft engine exhaust systems
- Fuel delivery systems
- High-temperature bellows and ducts
Marine and Offshore Engineering
- Seawater cooling systems
- Submarine propulsion components
- Offshore platforms
Chemical Processing Industry
- Phosphoric acid handling
- Organic acids
- Chloride-containing process fluids
Nuclear Power Systems
- Reactor core components
- Control rod assemblies
- Heat exchanger tubing
Manufacturing Process and Quality Assurance
For sour-service projects, material supplied to NACE MR0175 / ISO 15156 requirements is available when specified; final compliance should be confirmed against the purchaser’s specification.
Manufacturing
premium VIM/VAR melted billets → hot extrusion and piercing → cold pilgering or cold drawing → solution annealing → NDT and final inspection.
Quality Certification
EN 10204 3.1 Material Test Certificates, heat number traceability, chemical composition analysis, mechanical testing reports and third-party inspection (TPI).
Frequently Asked Questions About Inconel 625 Pipe
What is Inconel 625 pipe used for?
High-temperature and corrosive environments including aerospace systems, offshore oil platforms, chemical plants handling aggressive media, and nuclear facilities.
What is the difference between Inconel 625 and stainless steel?
Compared with stainless steel, Alloy 625 offers significantly higher corrosion resistance and better high-temperature strength, especially in aggressive chemical and marine environments.
What standards apply to Inconel 625 seamless pipes?
ASTM B444 with ASTM B829 general requirements and ASME SB444; welded products to B705/B704.
Why choose seamless Inconel 625 pipes instead of welded?
Seamless pipes provide higher pressure resistance, better structural integrity and no risk of weld seam failure — ideal for critical industrial systems.
What do Grades 1 and 2 of ASTM B444 mean?
Grade 1 is annealed for general service; Grade 2 is solution annealed for improved creep rupture and fatigue resistance at elevated temperatures.
Ready to Request a Quotation?
Send your Inconel 625 pipe enquiry with grade, ASTM B444 and edition, OD × wall thickness, length, quantity, end finish, delivery destination and inspection documents — you will get a written quotation stating the specification and edition, delivery condition, documents included and lead time.
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