N06022 (Alloy 22) Stainless Steel Coil Tube
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Reference No.: 257
Classification: Nickel-Chromium-Molybdenum Alloy Coil Tube
1. Product Overview
The N06022 (UNS N06022, also designated as Alloy 22 or Incoloy 22) coil tube is a precipitation-strengthened nickel-chromium-molybdenum alloy developed by Special Metals Corporation (now part of ATI Inc.). This high-performance alloy exhibits exceptional resistance to both reducing and oxidizing environments, making it one of the most corrosion-resistant nickel-based alloys available for industrial applications. Unlike austenitic stainless steels, Alloy 22 demonstrates superior resistance to localized corrosion forms including pitting, crevice corrosion, and stress corrosion cracking (SCC) across a wide range of chemical processing environments.
Wenzhou Jixing Metal Materials Co., Ltd. supplies N06022 coil tubes manufactured to international standards, designed for demanding applications in the chemical, petrochemical, and environmental protection industries where conventional stainless steels (e.g., 316L, 904L) prove insufficient. The coil tube format provides superior formability and material utilization efficiency compared to straight-length tubes, enabling cost-effective fabrication of heat exchangers, reactors, and process piping systems.
2. Material & Properties
2.1 Chemical Composition (wt%)
| Element | Minimum | Maximum | Function |
|---|---|---|---|
| Chromium (Cr) | 19.0 | 23.0 | Corrosion resistance, oxidation resistance |
| Nickel (Ni) | 58.0 | — | Matrix element, ductility |
| Molybdenum (Mo) | 2.5 | 4.5 | Pitting and crevice corrosion resistance |
| Tungsten (W) | 2.5 | 4.5 | Hot corrosion resistance, strength retention |
| Iron (Fe) | — | 4.0 | Cost control, minor strengthening |
| Carbon (C) | — | 0.02 | Low carbon for weldability |
| Manganese (Mn) | — | 1.0 | Deoxidizer |
| Silicon (Si) | — | 0.35 | Deoxidizer |
| Copper (Cu) | — | 0.30 | Trace residual |
| Titanium (Ti) | — | 0.35 | Trace residual |
| Nitrogen (N) | — | 0.02 | Trace residual |
2.2 Mechanical Properties
| Property | Value (Solution Annealed) | Test Standard |
|---|---|---|
| Tensile Strength (UTS) | ≥ 585 MPa (85 ksi) | ASTM A276 / AMS 5600 |
| Yield Strength (0.2% offset) | ≥ 240 MPa (35 ksi) | ASTM A276 |
| Elongation at Break | ≥ 40% | ASTM A276 |
| Density | 8.44 g/cm³ | — |
| Thermal Conductivity (20°C) | 10.8 W/(m·K) | — |
| Thermal Expansion (20–100°C) | 13.0 × 10⁻⁶ /°C | — |
| Electrical Resistivity (20°C) | 1.19 μΩ·m | — |
2.3 Corrosion Resistance Characteristics
- Pitting Corrosion Resistance: PREN (Pitting Resistance Equivalent Number) ≥ 130, significantly exceeding 316L (PREN ~24) and 904L (PREN ~45)
- Crevice Corrosion: Resistant in chloride concentrations exceeding 10,000 ppm at temperatures up to 60°C
- Stress Corrosion Cracking (SCC): Immune to chloride-induced SCC at all practical temperatures
- Acid Resistance: Excellent resistance to sulfuric acid (H₂SO₄), hydrochloric acid (HCl), phosphoric acid (H₃PO₄), and nitric acid (HNO₃)
- Oxidizing Environments: Maintains protective oxide film integrity in concentrated oxidizing acids
3. Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Product Form | Coil Tube (Continuous Coiled Length) | — |
| Applicable Standards | ASTM A276, AMS 5600, EN 10217, GB/T 17745 | — |
| Tube Shape | Round (Circular Cross-Section) | ASTM A276 |
| OD Range | 3.0 mm – 168.0 mm (1/8" – 6.5") | ASTM B366 / ASME B36.19M |
| Wall Thickness Range | 0.4 mm – 12.7 mm (0.016" – 0.5") | ASTM A276 |
| Coil Inner Diameter | 150 mm – 500 mm (adjustable per order) | — |
| Coil Length | 50 m – 500 m per coil (continuous) | — |
| Surface Finish | Pickled & Passivated (P&P), Bright Annealed, or Mill Finish | ASTM A380 |
| Heat Treatment Condition | Solution Annealed at 1050°C – 1150°C, Water Quenched | AMS 5600 |
| Welding Seam | Continuous Welded (ERW) or Seamless (for larger sizes) | ASTM A276 |
| End Condition | Plain End, Beveled, or Threaded (per customer specification) | ASME B36.19M |
| Tolerance (OD) | ±0.05 mm (Precision) / ±0.1 mm (Standard) | ASTM A276 |
| Tolerance (Wall) | ±10% of nominal | ASTM A276 |
| Temperature Range | −196°C (LN₂) to 650°C (continuous service) | — |
| Pressure Rating | Up to 40 MPa (per ASME Section VIII) | ASME BPV Section VIII |
4. Manufacturing Process
4.1 Production Flow
- Vacuum Arc Remelting (VAR) / Electro-Slag Remelting (ESR): Primary ingot production to ensure ultra-low sulfur and phosphorus content (< 0.005% S, < 0.02% P) and exceptional homogeneity.
- Hot Rolling / Forging: Billet production to target dimensions with controlled grain structure.
- Pipe Forming: Tube blanking via hot forming (roll forming) or seamless piercing (Mannesmann process) depending on final OD requirements.
- Heat Treatment: Solution annealing at 1050°C – 1150°C followed by rapid water quenching to dissolve all carbides and precipitates, achieving a fully austenitic single-phase microstructure.
- Cold Drawing / Sizing: Multi-pass cold drawing through tungsten carbide tooling to achieve precise dimensional tolerances and enhanced surface finish.
- Intermediate Annealing: Periodic annealing at 1050°C during cold working to relieve accumulated strain and maintain ductility.
- Pickling & Passivation: Immersion in mixed acid bath (HNO₃/HF) to remove surface scale and contaminants, followed by passivation treatment to establish a stable chromium oxide film.
- Coiling: Continuous winding onto precision mandrels with controlled tension to prevent deformation and surface damage.
- Quality Inspection: Full volumetric and surface inspection prior to packaging.
4.2 Key Process Controls
- Grain boundary stability maintained through strict control of carbon (< 0.02%), sulfur (< 0.005%), and phosphorus (< 0.02%) levels
- Delta ferrite content controlled at < 3% (per ASTM A955) to ensure weldability and cracking resistance
- Non-metallic inclusions limited to Class 1 per ASTM E45
- Coil winding tension controlled to prevent ovality exceeding 0.5% of OD
5. Applications
5.1 Primary Industrial Applications
- Chemical Processing: Reactor vessels, heat exchanger tubes, distillation columns, and piping systems handling mixed acids, halogenated compounds, and chlorinated organics
- Petrochemical & Refining: Crude oil distillation overhead systems, sour water strippers, and hydrogen sulfide (H₂S) service equipment
- Environmental Protection: Flue gas desulfurization (FGD) systems, wastewater treatment equipment, and emissions abatement apparatus
- Pharmaceutical & Food Processing: High-purity processing equipment requiring biocompatible, corrosion-free surfaces
- Power Generation: Boiler feedwater systems, condenser tubes, and waste heat recovery units in sulfur-rich fuel environments
- Marine & Offshore: Seawater cooling systems, desalination plant components, and subsea pipeline connections
5.2 Coil Tube Specific Advantages
- Continuous supply format eliminates butt welds, reducing potential failure points in heat exchanger tube bundles
- Enables automated tube cutting, forming, and assembly, reducing fabrication time by 40–60%
- Minimizes material waste through optimized coil length utilization
- Ideal for U-tube and hairpin configurations in shell-and-tube heat exchangers
6. Quality Certifications & Compliance
6.1 International Standards Compliance
| Certification / Standard | Description |
|---|---|
| ASTM A276 | Standard Specification for Seamless, Welded, and Heavy-Walled Austenitic Stainless Steel Pipes |
| AMS 5600 | Aerospace Material Specification for Alloy 22 bar, forging, and sheet |
| EN 10217-7 | Non-ferrous metallic materials for pressure equipment – Nickel alloys |
| ASME BPV Section VIII | Boiler and Pressure Vessel Code – Division 1 |
| ISO 9001:2015 | Quality Management System Certification |
| ISO 14001:2015 | Environmental Management System Certification |
| PED 2014/68/EU | European Pressure Equipment Directive Compliance |
| NACE MR0175 / ISO 15156 | Materials for use in H₂S-containing environments in oil and gas production |
| 3.1 / 3.2 Material Certificates | Per EN 10204, fully traceable mill test reports |
6.2 Testing & Inspection Protocols
- Chemical Analysis: Spectrometric verification of each heat (OES + Leco combustion for C/S)
- Mechanical Testing: Tensile testing per ASTM A370, hardness verification (≤ 250 HV per AMS 5600)
- Corrosion Testing: Ferric chloride (FeCl₃) immersion test per ASTM A262 Practice A (48-hour minimum); Crevice corrosion testing per ASTM G110
- Non-Destructive Testing (NDT):
- Eddy current testing (ECT) per ASTM E797 for wall thickness and defect detection
- Magnetic particle inspection (MPI) for surface and near-surface defects
- Visual inspection per ASTM E165
- Dimensional Verification: Optical measurement of OD, wall thickness, ovality, and straightness
- Hydrostatic Testing: Per ASTM A530 for pressure integrity (ap