UNS N08028|1.4563|Incoloy 028 Seamless Pipe
Our N08028 pipes are specifically designed to outperform standard stainless steels in wet-process phosphoric acid and sulfuric acid services. Due to its high Pitting Resistance Equivalent Number (PREN), this alloy offers outstanding protection against chloride-induced stress corrosion cracking (SCC) and pitting in sour gas (H2S) and marine applications. Through advanced cold-drawing and specialized solution annealing, XinZhe ensures every pipe delivers the mechanical strength and structural stability required for critical chemical processing and oil & gas infrastructure.
"Our N08028 pipes are equivalent to Sanicro 28, providing the same high-level corrosion resistance."
What Is Seamless UNS N08028 Pipe (Alloy 28)?
Seamless UNS N08028 pipes, commonly known as Alloy 28 or Sanicro 28 (W.Nr. 1.4563), are high-alloy austenitic stainless steel pipes specifically designed for extremely corrosive environments involving strong mineral acids and chloride-containing media. Manufactured in accordance with ASTM B668 / ASME SB668, these pipes are produced through hot extrusion and precision cold drawing from a solid billet, resulting in a seamless, weld-free structure with uniform metallurgical grain.
To achieve maximum corrosion resistance, UNS N08028 pipes are supplied in a fully solution-annealed condition, typically heat treated at 1900–2050°F (1040–1120°C) followed by rapid water quenching — ensuring optimal microstructure, corrosion resistance and mechanical properties.
Alloy 28 bridges the performance gap between conventional stainless steels such as 316L or 904L and more expensive nickel-based superalloys.
Technical Performance and Metallurgical Advantages
Exceptional Resistance to Mineral Acids: excellent resistance to phosphoric acid (H₃PO₄), sulfuric acid (H₂SO₄) and various organic and inorganic acids — widely used in fertilizer production and chemical processing plants.
Superior Resistance to Chloride-Induced SCC: the high nickel content (~31%) significantly improves resistance to chloride stress corrosion cracking compared with conventional stainless steels.
High Pitting Resistance (PREN ≈ 38–40): the synergistic combination of chromium (~27%) and molybdenum (~3.5%) provides a high Pitting Resistance Equivalent Number for chloride-rich environments.
Excellent Fabrication and Weldability: excellent ductility, formability and weldability for complex piping in heat exchangers, pressure vessels and process systems.
Product Specifications and Data
Chemical Composition
| Grade | Cr | Ni | Mo | Cu | N | C | Fe |
|---|---|---|---|---|---|---|---|
| N08028 | 26.00–28.00 | 30.00–34.00 | 3.00–4.00 | 0.60–1.40 | ≤ 0.18 | ≤ 0.03 | Balance |
Typical Mechanical Properties
The alloy maintains excellent mechanical stability under corrosive conditions.
| Yield Strength | Tensile Strength | Elongation | Hardness |
|---|---|---|---|
| ≥ 214 MPa | ≥ 500 MPa | ≥ 40% | ≤ 220 HB |
Pipe and Tube Specifications
| Specification | Value |
|---|---|
| Standard | ASTM B668 / ASME SB668 |
| Product Forms | Seamless Pipe, Tube |
| Heat Treatment | Solution Annealed (1900–2050°F / 1040–1120°C, rapid quench) |
| Manufacturing | Cold Drawn / Hot Finished |
Alloy 28 vs 904L vs Inconel 625
| Alloy | PREN | Key Advantage | Typical Use |
|---|---|---|---|
| 904L | ~34 | Good acid resistance | Chemical equipment |
| Alloy 28 (N08028) | 38–40 | Strong phosphoric acid resistance | Fertilizer plants |
| Inconel 625 | >45 | Extreme corrosion resistance | Offshore & aerospace |
Alloy 28 provides an excellent balance between performance and cost, positioned between high-end stainless steels and nickel superalloys.
Typical Applications of UNS N08028 Seamless Pipes
Fertilizer Industry
- Phosphoric acid evaporators
- Fertilizer processing equipment
Oil and Gas (Sour Service)
- Downhole production tubing
- Corrosion-resistant flowlines in HPHT wells containing H₂S and CO₂
Chemical Processing
- Sulfuric acid handling systems
- Reactors and heat exchangers
Marine and Desalination
- High-pressure seawater pipelines
- Brine circulation systems in desalination plants
Environmental Systems
- Flue gas desulfurization (FGD)
- Chemical scrubbers
Quality Assurance and Testing
All Alloy 28 seamless pipes undergo strict quality control
100% PMI (Positive Material Identification), Ultrasonic Testing (UT), Eddy Current Testing (ET), hydrostatic pressure testing and EN 10204 3.1 / 3.2 Material Test Certificates.
Why choose our ASTM B668 Alloy 28 pipes
strict standard compliance, precision solution annealing for optimal microstructure, comprehensive non-destructive testing and full material traceability.
Frequently Asked Questions About Alloy 28 Pipe
What is Alloy 28 (UNS N08028)?
Alloy 28, also known as Sanicro 28 or W.Nr. 1.4563, is a high-alloy austenitic stainless steel (Cr 26–28%, Ni 30–32%, Mo 3–4%, Cu) designed for severe mineral acid and chloride environments.
What standards apply to Alloy 28 seamless pipe?
ASTM B668 / ASME SB668, supplied solution annealed with rapid quenching.
How does Alloy 28 compare with 904L and Inconel 625?
Alloy 28 (PREN 38–40) outperforms 904L (~34) in phosphoric acid service, while Inconel 625 (>45) serves the most extreme environments at higher cost — Alloy 28 is the cost-performance middle ground.
Where is UNS N08028 pipe commonly used?
Wet-process phosphoric acid evaporators in fertilizer plants, sulfuric acid systems, sour service downhole tubing in HPHT wells, desalination brine lines and FGD scrubbers.
What heat treatment is specified for Alloy 28?
Solution annealing at 1900–2050°F (1040–1120°C) followed by rapid water quenching to achieve optimal corrosion resistance and mechanical properties.
Ready to Request a Quotation?
Send your Alloy 28 (UNS N08028) pipe enquiry with grade, ASTM B668 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.
Contact Us
