UNS N06022 (Alloy 22) Nickel-Based Super Alloy Coil Tube
1. Product Overview
UNS N06022, commercially designated as Alloy 22 (originally developed by Haynes International), is a high-performance nickel-chromium-molybdenum-tungsten alloy supplied by Wenzhou Jixing Metal Materials Co., Ltd. in coil tube (Coiltube) configuration. This product is engineered to deliver exceptional resistance to aggressive chemical environments, particularly reducing acids and mixed-acid conditions where conventional austenitic stainless steels (e.g., 316L, 904L) exhibit unacceptable corrosion rates. The coil tube form factor provides significant advantages in downstream fabrication, including continuous processing, reduced waste, and enhanced dimensional consistency.
Wenzhou Jixing Metal Materials Co., Ltd. specializes in the supply of high-grade nickel alloy tubing products, with UNS N06022 coil tube representing a flagship offering for critical applications in chemical processing, environmental remediation, and pulp/paper manufacturing. The company's commitment to metallurgical integrity and traceability ensures that each coil tube lot meets or exceeds industry-standard specifications.
2. Material & Properties
2.1 Chemical Composition (Wt%)
| Element | Minimum | Maximum |
|---|---|---|
| Nickel (Ni) | Balance (≥67%) | — |
| Chromium (Cr) | 13.0% | 17.0% |
| Molybdenum (Mo) | 2.5% | 4.5% |
| Tungsten (W) | 2.5% | 4.5% |
| Iron (Fe) | — | 2.0% |
| Silicon (Si) | — | 0.35% |
| Manganese (Mn) | — | 1.0% |
| Carbon (C) | — | 0.03% |
| Copper (Cu) | — | 0.30% |
| Niobium (Nb) | — | 0.35% |
2.2 Mechanical Properties
| Property | Specification (Annealed Condition) |
|---|---|
| Tensile Strength (UTS) | ≥ 550 MPa (80 ksi) |
| Yield Strength (0.2% Offset) | ≥ 240 MPa (35 ksi) |
| Elongation | ≥ 40% |
| Density | 8.82 g/cm³ (0.319 lb/in³) |
| Thermal Conductivity (20°C) | 11.4 W/m·K |
| Specific Heat (20°C) | 440 J/kg·K |
| Thermal Expansion (20–800°C) | 13.3 × 10⁻⁶ /°C |
| Magnetic Permeability | Non-magnetic (relative permeability ≈ 1.00) |
2.3 Corrosion Resistance Characteristics
- Sulfuric Acid (H₂SO₄): Excellent resistance across a wide range of concentrations and temperatures; significantly outperforms Alloy 6 (C-276) in dilute and boiling sulfuric acid solutions.
- Hydrochloric Acid (HCl): Superior resistance compared to most nickel alloys; suitable for moderate concentrations at elevated temperatures.
- Phosphoric Acid (H₃PO₄): Outstanding resistance even at high concentrations and temperatures.
- Mixed Acid Environments: Exceptional performance in combinations of sulfuric, hydrochloric, and phosphoric acids.
- Oxidizing Acids: Good resistance to nitric acid (HNO₃) at moderate concentrations; unsuitable for hot, concentrated oxidizing environments.
- Chloride-Containing Solutions: Excellent resistance to pitting and crevice corrosion (PREN > 130).
3. Specifications
| Parameter | Specification |
|---|---|
| Product Designation | UNS N06022 / Alloy 22 Coil Tube |
| Applicable Standards | ASTM B733 / ASTM B730 / ASME SB733 / EN 12450 |
| Outer Diameter (OD) | 3.0 mm – 50.8 mm (custom sizes available upon request) |
| Wall Thickness | 0.3 mm – 6.0 mm |
| Coil Inner Diameter (ID) | 300 mm – 600 mm (standard); adjustable per customer requirement |
| Length per Coil | Customizable; typical range 50 m – 500 m |
| Surface Finish | Pickled & Passivated (P&P); optional polished finish |
| Temperature Range | Cryogenic to 650°C (continuous); up to 800°C (intermittent) |
| Heat Treatment Condition | Solution Annealed (1150–1200°C, water quenched) |
| Weldability | Excellent; suitable for TIG, MIG, and resistance welding without preheat |
| Packaging | Wooden drum or steel frame with moisture-proof wrapping |
4. Manufacturing Process
The production of UNS N06022 coil tube at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous, multi-stage manufacturing sequence designed to ensure metallurgical homogeneity, dimensional precision, and corrosion resistance:
- Raw Material Procurement & Verification: Virgin nickel, chromium, molybdenum, and tungsten ingots are sourced from certified suppliers. Each batch undergoes spectrographic analysis (OES) to confirm composition compliance with ASTM B733 requirements.
- Vacuum Arc Remelting (VAR) or Electron Beam Melting (EBM): Primary alloys are melted under controlled vacuum conditions to minimize oxygen and nitrogen pickup, ensuring a clean, uniform melt.
- Hot Rolling & Annealing: Billets are hot-rolled into seamless tube blanks. Intermediate annealing cycles at 1100–1150°C relieve residual stresses and restore ductility.
- Piercing & Cross-Rolling: The solid billets are pierced and cross-rolled to produce seamless tubes of the target outer diameter and wall thickness.
- Heat Treatment (Solution Annealing): Tubes are solution-annealed at 1150–1200°C followed by rapid water quenching to dissolve carbides and precipitate a uniform solid-solution microstructure free of deleterious intermetallic phases.
- Pickling & Passivation: A final acid pickling cycle (typically HNO₃/HF blend) removes oxide scales, followed by passivation to establish a protective chromium oxide film on the surface.
- Coiling & Dimensional Inspection: Tubes are precisely coiled to specified inner diameters using automated coiling equipment. Each coil undergoes dimensional verification (OD, wall thickness, straightness) via ultrasonic thickness gauging and optical measurement systems.
- Non-Destructive Testing (NDT): 100% eddy current testing and/or hydrostatic testing is performed to detect internal and external defects. Radiographic testing (RT) may be applied per customer specification.
- Final Certification & Packaging: Each coil is accompanied by a Mill Test Certificate (MTC) conforming to EN 10204 Type 3.1, documenting chemical composition, mechanical properties, and heat treatment records.
5. Applications
UNS N06022 coil tube is deployed in demanding industrial environments where corrosion resistance, mechanical integrity, and long-term reliability are paramount:
- Chemical Processing: Heat exchangers, reactor coils, condensers, and piping systems handling sulfuric acid, phosphoric acid, hydrochloric acid, and mixed-acid environments in the production of fertilizers, polymers, and specialty chemicals.
- Pulp & Paper Industry: Bleach digesters, pulp washing systems, and acid recovery units where exposure to chlorinated organics and acidic pulping liquors is prevalent.
- Environmental & Waste Treatment: Flue gas desulfurization (FGD) systems, landfill gas treatment, and wastewater treatment systems involving aggressive acid mixtures and chlorinated compounds.
- Petrochemical & Refining: Catalytic reforming units, hydroprocessing systems, and acid gas treating circuits where chloride-induced stress corrosion cracking (SCC) is a concern.
- Pharmaceutical & Food Processing: Sanitary-grade tubing and heat exchanger coils requiring biocompatibility, non-magnetic properties, and resistance to caustic cleaning agents (CIP systems).
- Power Generation: Flue gas desulfurization scrubbers and electrostatic precipitators in coal-fired and gas-fired power plants.
- Marine & Offshore: Seawater cooling systems, desalination plant heat exchangers, and offshore platform piping exposed to chloride-rich marine environments.
6. Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework to ensure every UNS N06022 coil tube product meets international standards and customer expectations:
- ISO 9001:2015 — Quality Management System certification, demonstrating systematic commitment to consistent quality and continuous improvement.
- ISO 14001:2015 — Environmental Management System certification, reflecting responsible environmental practices throughout the manufacturing lifecycle.
- ISO 45001:2018 — Occupational Health and Safety Management System certification.
- ASTM B733 / B730 Compliance — All products are manufactured and tested in accordance with ASTM standards for wrought nickel and nickel alloy seamless and welded tubing and pipe.
- ASME SB733 / SB730 — Certification for use in pressure-containing applications under ASME Boiler and Pressure Vessel Code.
- EN 12450 (DIN 2478) — European standard compliance for nickel and nickel alloy tubing.
- Mill Test Certificate (MTC) per EN 10204 Type 3.1 — Independent third-party inspection reports available upon request.
- NADCAP / TAF — Specialized process certifications for aerospace and defense-grade manufacturing (where applicable).
7. Unique Selling Points
Exceptional Mixed-Acid Corrosion Resistance: UNS N06022 offers the highest corrosion resistance among commercial nickel alloys in reducing acid environments, including dilute sulfuric acid, hydrochloric acid, and phosphoric acid — outperforming Alloy 6 (C-276) and Alloy 825 in many service conditions.
- Coil Tube Form Factor: Continuous coil configuration eliminates butt-weld joints, reduces material waste by up to 30%, and enables automated downstream processing (bending, cutting, forming) with minimal labor intervention.
- Low Carbon Content (≤0.03% C): Minimizes carbide precipitation at grain boundaries, ensuring excellent resistance to intergranular corrosion (IGC) and weld decay even in sensitizing temperature ranges (450–850°C).
- Non-Magnetic & Biocompatible: Suitable for MRI-compatible medical devices, pharmaceutical processing, and food-grade applications where magnetic permeability and surface bio-compatibility are critical.
- Full Traceability: Every coil is heat-number tracked from raw material receipt through final dispatch, with complete documentation of chemical analysis, mechanical testing, and heat treatment parameters.
- Custom Fabrication Capability: Wenzhou Jixing offers value-added services including custom coil sizing, precision cutting, end-finishing