Seamless Incoloy N08028 Tube
Renowned for their excellent performance in phosphoric acid (H₃PO₄) and sulfuric acid (H₂SO₄) processing, UNS N08028 tubing significantly outperforms conventional stainless steels such as 316L and 904L in demanding applications including fertilizer production, oil and gas sour service, chemical processing, and hydrometallurgy.
Through advanced cold drawing and precision solution annealing, XinZhe ensures that each seamless Alloy 28 tube achieves a uniform metallurgical structure, excellent surface finish, and precise dimensional tolerances. With a Pitting Resistance Equivalent Number (PREN) of approximately 38–40, Alloy 28 provides superior resistance to pitting and crevice corrosion in chloride-containing environments.
For specialized industrial requirements, our technical team provides custom tube dimensions, various wall thickness options, and full material traceability with EN 10204 3.1 / 3.2 Material Test Certificates (MTC).
Seamless Incoloy N08028 Tube(Alloy 28 / Sanicro 28) – High-Performance Acid-Resistant Nickel Alloy Tubes
Seamless Incoloy N08028 Tube(also called seamless alloy 28 tubes), commonly referred to as Alloy 28 or Sanicro 28, is a high-alloy austenitic stainless steel and nickel alloy tube engineered for extremely corrosive environments involving strong mineral acids and high-chloride media.
Unlike welded pipes, seamless Alloy 28 tubes are produced from a single solid billet using hot extrusion and precision cold drawing, creating a continuous metallurgical structure without weld seams. This seamless construction eliminates the risk of preferential corrosion along weld lines, ensuring superior reliability in critical chemical and petrochemical systems.
With a carefully balanced composition of Chromium (Cr), Nickel (Ni), Molybdenum (Mo), and Copper (Cu),UNS N08028 tubing bridges the performance gap between standard austenitic stainless steels (such as 316L or 904L) and more expensive high-nickel superalloys.
It is widely recognized for its excellent resistance to stress corrosion cracking (SCC), pitting corrosion, and aggressive acid attack.
Technical Advantages of Seamless Alloy 28 Tubing
SeamlessN08028 tubes offer an exceptional combination of corrosion resistance, structural integrity, and mechanical strength.
Outstanding Resistance to Mineral Acids
Alloy 28 provides excellent corrosion resistance in highly aggressive environments including:
- Phosphoric acid (H₃PO₄)
- Sulfuric acid (H₂SO₄)
- Nitric acid processing systems
This makes the alloy particularly suitable for fertilizer production and chemical processing plants.
High Pitting Resistance (PREN ≥ 38)
The elevated Chromium and Molybdenum content significantly increases the Pitting Resistance Equivalent Number (PREN ≥ 38), ensuring reliable protection against pitting and crevice corrosion in chloride-rich environments.
Excellent Resistance to Stress Corrosion Cracking (SCC)
The high nickel content (approximately 31%) provides strong resistance to chloride-induced stress corrosion cracking, outperforming many standard 300-series stainless steels.
Seamless Pressure Integrity
Theweld-free seamless constructionguarantees:
- uniform wall thickness
- improved mechanical reliability
- higher allowable working pressure
incritical fluid handling systems.
Good Fabricability and Weldability
Despite its high alloy content, Alloy 28 tubing maintains excellent ductility and formability, allowing standard fabrication processes such as bending, flaring, and welding.
Product Specifications and Data
To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for Nickel Alloy Steel UNS N08120.
Table 1: Chemical Composition of UNS N08028
The composition of UNS N08120 is carefully balanced to achieve its superior corrosion resistance and high strength.
| C | Si | Mn | P | S | Cr | Ni | Cu | Mo | Fe |
| ≤0.03 | ≤1.00 | ≤2.50 | ≤0.03 | ≤0.03 | 26.00-28.00 | 30.00-34.00 | 0.60-1.40 | 3.00-4.00 | Bal |
Table 2: Typical Mechanical Properties of UNS N08028
UNSN08028is specifically designed to maintain its strength and shape in high-stress, corrosive environments.
| Tensile Strength | Yield Strength | Elongation | Hardness |
| ≥ 580 MPa | ≥ 214 MPa | ≥ 40% | 70-90HRB |
Industrial Applications of UNS N08028 Seamless Tubes
Due to its superior corrosion resistance in acidic and chloride-containing environments, Alloy 28 seamless tubing is widely used in the following industries:
Fertilizer Industry
- Heat exchanger tubes in phosphoric acid evaporation systems
- Handling of phosphate rock slurries
Oil & Gas (Sour Service)
- Downhole tubing and liners for HPHT wells
- Applications involving H₂S and CO₂corrosion
Chemical Processing
- Equipment for sulfuric acid (H₂SO₄) production
- Nitric acid and organic acid processing plants
Hydrometallurgy
- Ore leaching pipelines
- Acid recovery and regeneration systems
Environmental & Pollution Control
- Flue Gas Desulfurization (FGD) systems
- Wet scrubbers and corrosion-resistant piping
Quality Assurance & Testing Standards
To ensure reliability in severe service environments, UNS N08028 seamless tubes undergo comprehensive inspection and certification procedures:
- Manufacturing Standards: ASTM B668, ASTM A213, ASME SB668
- Material Certification: EN 10204 3.1 / 3.2 MTC
- Positive Material Identification (PMI): 100% alloy verification
- Mechanical Testing: Tensile strength, yield strength, hardness, flattening, flaring, and bend tests
- Corrosion Testing: Intergranular corrosion (IGC) and pitting corrosion testing according to ASTM G48
- Non-Destructive Testing: 100% Eddy Current Testing (ET), Ultrasonic Testing (UT), and hydrostatic pressure testing
Alloy 28 (UNS N08028) vs 904L Stainless Steel
Feature | 904L (UNS N08904) | Alloy 28 (UNS N08028) |
Chromium (Cr) | 19 – 23% | 26 – 28% (Higher) |
Nickel (Ni) | 23 – 28% | 30 – 32% (Higher) |
PREN Value | ~34 | ≥38 (Superior pitting resistance) |
Acid Resistance | Good for dilute H₂SO₄ | Excellent for concentrated H₃PO₄ |