Hastelloy C276 Coil Tube — Ni-Mo-Cr-W Nickel-Based Alloy
1. Product Overview
Hastelloy C276 Coil Tube is a high-performance, nickel-molybdenum-chromium-tungsten (Ni-Mo-Cr-W) alloy coil tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. Engineered for the most demanding corrosion resistance requirements, this product is specifically designed to withstand extreme chemical environments, including wet chlorine gas, strongly oxidizing acids, and a wide range of aggressive chemical media. The coil tube form factor offers superior flexibility in downstream processing, enabling seamless integration into heat exchangers, chemical reactors, and complex piping systems that require tight bending radii and precise dimensional control.
As a member of the renowned Hastelloy superalloy family originally developed by Haynes International, C276 represents the gold standard in nickel-based alloy performance for severe chemical processing applications. Its composition has been carefully optimized to provide outstanding resistance to both reducing and oxidizing environments, making it indispensable in industries where conventional stainless steels and even other nickel alloys fail.
2. Material Composition & Properties
2.1 Chemical Composition (Typical, wt%)
| Element | Specification (wt%) | Role in Alloy |
|---|---|---|
| Nickel (Ni) | Balance (~56–61) | Base matrix element; provides fundamental corrosion resistance |
| Molybdenum (Mo) | 15.0–17.0 | Enhances resistance to reducing acids and pitting corrosion |
| Chromium (Cr) | 14.5–16.5 | Forms protective passive oxide film; improves oxidizing acid resistance |
| Tungsten (W) | 3.0–4.5 | Strengthens resistance to chlorinated environments |
| Iron (Fe) | 4.0–7.0 | Alloying element; aids in solid solution strengthening |
| Cobalt (Co) | 0.5–3.0 | Improves resistance to chloride stress corrosion cracking (Cl-SCC) |
| Carbon (C) | ≤0.01 | Low carbon content minimizes carbide precipitation |
| Manganese (Mn) | ≤1.0 | Residual element from steelmaking |
| Silicon (Si) | ≤1.0 | Residual element from deoxidation |
| Copper (Cu) | ≤0.3 | Residual element |
| Chlorine (Cl) | ≤0.03 | Strictly controlled to prevent intergranular corrosion |
| Sulfur (S) | ≤0.03 | Strictly controlled for hot workability and corrosion resistance |
2.2 Physical Properties
| Property | Value | Unit |
|---|---|---|
| Density (at 20°C) | 8.87 | g/cm³ |
| Melting Range | 1325–1337 | °C |
| Thermal Conductivity (at 100°C) | 10.0 | W/(m·K) |
| Specific Heat Capacity | 450 | J/(kg·K) |
| Modulus of Elasticity | 207 | GPa |
| Thermal Expansion Coefficient (20–100°C) | 13.1 | ×10⁻⁶/K |
| Electrical Resistivity (at 20°C) | 147 | μΩ·cm |
2.3 Mechanical Properties (Annealed Condition)
| Property | Minimum Value | Unit |
|---|---|---|
| Tensile Strength (Rm) | ≥550 | MPa |
| Yield Strength (Rp0.2) | ≥275 | MPa |
| Elongation (A50mm) | ≥40 | % |
| Hardness (HBW) | ≤190 | — |
2.4 Corrosion Resistance Characteristics
- Wet Chlorine Gas Resistance: Exceptional resistance to wet chlorine (Cl₂) and hypochlorite solutions, far exceeding that of 316L stainless steel and most other nickel alloys.
- Strongly Oxidizing Acids: Outstanding performance in concentrated sulfuric acid (H₂SO₄), hydrochloric acid (HCl), and nitric acid (HNO₃) across a broad temperature range.
- Reducing Environments: Superior resistance in reducing acid media due to high molybdenum and tungsten content.
- Chloride Stress Corrosion Cracking (Cl-SCC): Excellent resistance compared to austenitic stainless steels, though not immune at elevated temperatures.
- Intergranular Corrosion: Low carbon content (≤0.01%) provides inherent resistance to sensitization and intergranular attack.
3. Product Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Product Form | Coil Tube (Continuous Length) | — |
| Material Grade | Hastelloy C276 | N06625 (UNS); W.Nr. 2.4610 (EN) |
| Outer Diameter (OD) | Φ6.0 – Φ158.8 mm (customizable) | ASTM B407 / EN 10217-7 |
| Wall Thickness | 0.5 – 12.0 mm (customizable) | ASTM B407 / EN 10217-7 |
| Coil Diameter | Φ500 – Φ1200 mm (configurable) | — |
| Coil Length per Roll | 50 – 500 m (continuous, spool-less) | — |
| Surface Finish | Pickled & Passivated (P&P); Mirror Polished (optional) | — |
| Tolerance (OD) | ±0.05 mm to ±0.15 mm | ASTM B407 |
| Tolerance (Wall Thickness) | ±10% of nominal | ASTM B407 |
| Heat Treatment Condition | Solution Annealed (1150–1200°C, water quench) | — |
| Welding Suitability | Excellent (GTA/WTB/TIG; filler wire: Hastelloy C276 or C22) | ASTM B336 / EN 12534 |
| Operating Temperature Range | −270°C to +600°C (continuous) | — |
| Compliance Standards | ASTM B407, ASME SB407, EN 10217-7, JIS H4701 | — |
4. Manufacturing Process
4.1 Process Flow
- Vacuum Arc Remelting (VAR) or Electro-Slag Remelting (ESR): Primary ingot production ensuring homogeneity and freedom from inclusions. The strict control of carbon (≤0.01%), sulfur (≤0.03%), and chlorine (≤0.03%) is achieved during this stage.
- Hot Rolling: Ingots are homogenized at 1200°C and subsequently hot rolled into semi-finished flat coil stock with controlled grain structure.
- Intermediate Annealing: Solution treatment at 1150–1200°C followed by rapid water quenching to dissolve carbides and restore full corrosion resistance after cold work.
- Slitting & Forming: Flat coil is slit to the required width and formed into tubular geometry using cold-rolling and cold-forming techniques. The coil tube is produced continuously without butt welds, ensuring superior mechanical integrity.
- Seam Welding (if applicable): Where necessary, longitudinal seams are welded using TIG (GTAW) process with inert gas shielding (argon) to maintain metallurgical purity of the weld zone.
- Final Annealing: Solution annealing at 1150–1200°C with water quench to achieve the required mechanical properties and corrosion resistance.
- Pickling & Passivation: Surface treatment to remove scale and contaminants, followed by passivation to form a uniform chromium-rich oxide film.
- Dimensional Inspection & Coiling: Final dimensional verification, surface quality inspection, and coiling onto spools for delivery.
4.2 Quality Control Measures
- Spectroscopic analysis (OES) for chemical composition verification at each production stage
- Hydrogen recombination analysis for sulfur and phosphorus content
- Intergranular corrosion testing per ASTM A262 Practice E (oxalic acid, 6-hour exposure)
- Strut test per ASTM G150 for chloride stress corrosion cracking resistance
- Ultrasonic testing (UT) for internal defects
- Dimensional metrology using laser diameter gauges and wall thickness scanners
- Positive Material Identification (PMI) via XRF or OES for traceability
5. Applications
5.1 Primary Application Domains
- Extreme Chemical Corrosion Environments: Hastelloy C276 coil tubes are deployed in chemical processing plants where exposure to mixed acid solutions, halogenated compounds, and aggressive chemical media renders conventional materials inadequate. The alloy's ability to withstand simultaneous oxidizing and reducing attack makes it uniquely suited for these conditions.
- Waste Acid Regeneration: In the acid regeneration industry, C276 coil tubes serve as heat exchange elements and process piping for recovering spent sulfuric acid, hydrochloric acid, and mixed acid streams. The material's resistance to concentrated, hot acid environments ensures long service life and minimal maintenance downtime.
- Pulp & Paper Bleaching: In the paper and pulp industry, C276 coil tubes are used in chlorine dioxide (ClO₂) generators, chlorine dioxide absorbers, and hot acid circulation systems. The alloy withstands the highly corrosive combination of chlorinated compounds, acidic pH, and elevated temperatures inherent to the bleaching process.
5.2 Additional Applications
- Pharmaceutical and bioprocessing equipment (reactors, heat exchangers, piping)
- Electrochemical and battery manufacturing (chlor-alkali cells, lithium battery electrolyte processing)
- Desalination and water treatment systems (brine handling, chemical injection)
- Oil and gas (sour gas handling, downhole equipment, chemical injection lines)
- Environmental engineering (flue gas desulfurization, wastewater treatment)
- Heat exchangers and condensers in the chemical and petrochemical industries
- Brine coolers and evaporators
6. Quality Certifications & Compliance
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| ISO 14001:2015 | Environmental Management System |
| EN 10204 3.1 | Material Test Report (Third-Party Inspection) |
| ASTM B407 | Standard Specification for Seamless Nickel Alloy Tube |
| ASME SB407 | Boiler and Pressure Vessel Code — Nickel Alloy Tube |
| EN 10217-7 | Heat Exchanger Tubes — Nickel and Nickel Alloys |
| JIS H4701 | Japanese Industrial Standard for Nickel Alloy Tubes |
| NACE MR0175 / ISO 15156 | Materials for Use in H₂S-Containing Environments (where applicable) |
| Mill Test Certificate (MTC) | Full chemical and mechanical property documentation per batch |
| Traceability | Heat number and coil number traceability throughout the production chain |
7. Unique Selling Points
- Unmatched Corrosion Versatility: Hastelloy C276 offers a unique combination of resistance to both oxidizing and reducing environments, making it suitable for mixed-acid and halogenated media where other alloys fail.
- Coil Form Factor Advantage: Continuous-length coil tube eliminates butt welds, reducing potential failure points and enabling direct integration into heat exchanger bundles and complex piping systems without additional fabrication.
- Low Carbon, Low Sulfur Composition: The