Seamless N08028 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."
High-Performance Seamless UNS N08028 Pipe(Alloy 28 / Sanicro 28) – ASTM B668 Nickel Alloy Pipes for Severe Corrosion Service
Seamless UNS N08028 pipes, commonly known as Alloy 28 or Sanicro 28, 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 standards, these pipes are produced through hot extrusion and precision cold drawing from a solid billet, resulting in a seamless, weld-free structure with a uniform metallurgical grain structure.
The seamless design is particularly important for high-pressure chemical processing systems, where weld seams may become susceptible to localized corrosion or stress concentration.
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. This process ensures optimal microstructure, corrosion resistance, and mechanical properties.
Technical Performance and Metallurgical Advantages
Alloy 28 (UNS N08028) is engineered to bridge the performance gap between conventional stainless steels such as 316L or 904L and more expensive nickel-based superalloys.
Exceptional Resistance to Mineral Acids
UNS N08028 pipes offer excellent resistance to highly corrosive environments including:
- Phosphoric acid (H₃PO₄)
- Sulfuric acid (H₂SO₄)
- Various organic and inorganic acids
This makes Alloy 28 widely used in fertilizer production and chemical processing plants.
Superior Resistance to Chloride-Induced Stress Corrosion Cracking
The high nickel content (~31%) significantly improves resistance to chloride-induced Stress Corrosion Cracking (SCC) compared with many 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 (PREN), ensuring strong resistance to pitting and crevice corrosion in chloride-rich environments.
Excellent Fabrication and Weldability
Despite its high alloy content, Alloy 28 seamless pipes maintain excellent ductility, formability, and weldability, enabling complex piping configurations in heat exchangers, pressure vessels, and industrial process systems.
Typical Industrial Applications of UNS N08028 Pipes
Due to its superior corrosion resistance and mechanical reliability, seamless Alloy 28 pipes are widely used in critical industrial sectors.
Fertilizer and Chemical Processing
- Heat exchangers handling wet-process phosphoric acid
- Equipment exposed to concentrated sulfuric acid (up to ~98%)
Oil & Gas (Sour Service)
- Downhole production tubing
- Corrosion-resistant flowlines in HPHT wells containing H₂S and CO₂
Marine and Desalination Systems
- High-pressure seawater pipelines
- Brine circulation systems in desalination plants
Power Generation and Pulp & Paper
- Condensers and reheaters
- Bleaching plant equipment exposed to aggressive chemicals
- Alloy 28 / UNS N08028 Seamless Tubing & Pipe – Complete Technical Guide
- What is Alloy 28 (UNS N08028)?
- Alloy 28 (UNS N08028), also known as Sanicro 28, is a high-alloy austenitic stainless steel designed for severe corrosion environments involving strong mineral acids and chloride-containing media.
- The alloy contains high levels of:
- Chromium (Cr)
- Nickel (Ni)
- Molybdenum (Mo)
- Copper (Cu)
- This balanced composition provides excellent resistance to:
- phosphoric acid (H₃PO₄)
- sulfuric acid (H₂SO₄)
- stress corrosion cracking (SCC)
- pitting and crevice corrosion
- Because of its superior corrosion resistance, UNS N08028 tubing and pipe is widely used in fertilizer plants, chemical processing systems, and oil & gas sour service applications.
- Chemical Composition of UNS N08028
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- This chemistry gives Alloy 28 a PREN value of approximately 38–40, providing strong resistance to pitting corrosion in chloride environments.
- Mechanical Properties of Alloy 28
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- The alloy maintains excellent mechanical stability under corrosive conditions.
- Corrosion Resistance of Alloy 28
- UNS N08028 is specifically developed for acidic process environments where standard stainless steels fail.
- Mineral Acid Resistance
- Excellent resistance to:
- Phosphoric acid (wet-process fertilizer plants)
- Sulfuric acid
- Nitric acid
- Chloride Environments
- High nickel and molybdenum content provide strong protection against:
- Chloride stress corrosion cracking
- Pitting corrosion
- Crevice corrosion
- Alloy 28 Pipe & Tube Specifications
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- Typical solution annealing temperature:
- 1900–2050°F (1040–1120°C) followed by rapid quenching.
- Alloy 28 vs 904L vs Inconel 625
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- Alloy 28 provides an excellent balance between performance and cost, positioned between high-end stainless steels and nickel superalloys.
- Typical Applications of UNS N08028
- Fertilizer Industry
- phosphoric acid evaporators
- fertilizer processing equipment
- Oil & Gas
- sour service tubing
- HPHT production systems
- Chemical Processing
- sulfuric acid handling systems
- reactors and heat exchangers
- Environmental Systems
- flue gas desulfurization (FGD)
- chemical scrubbers
- Quality Assurance & Testing
- AllAlloy 28 seamless pipes undergo strict quality control:
- 100% PMI (Positive Material Identification)
- Ultrasonic Testing (UT)
- Eddy Current Testing (ET)
- Hydrostatic Pressure Testing
- EN 10204 3.1 / 3.2 Material Test Certificates
- Request a Quote for Alloy 28 Tubing
- Looking for high-quality UNS N08028 seamless tubes or pipes?
- Our technical team can provide:
- custom sizes and wall thickness
- ASTM B668 certified materials
- full traceability documentation
- global shipping support
- Contact us today for a quotation or technical consultation.
Why Choose XinZhe ASTM B668 Alloy 28 Pipes?
AtXinZhe, our seamless UNS N08028 pipes are manufactured under strict quality control procedures to meet global industrial project requirements.
Strict Standard Compliance
All pipes comply with ASTM B668 / ASME SB668 specifications.
Advanced Solution Annealing
Precision heat treatment ensures optimal microstructure and corrosion resistance.
Comprehensive Non-Destructive Testing
Every pipe undergoes 100% Positive Material Identification (PMI), Ultrasonic Testing (UT), and Hydrostatic testing to ensure structural integrity.
Full Material Traceability
Products are supplied with EN 10204 3.1 / 3.2 Material Test Certificates (MTC) for complete documentation and quality assurance.