Inconel 625 Nickel-Based Alloy Coil Tube
Product Code: JX-CT-625 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Overview
Inconel 625 Coil Tube (盘管) is a premium nickel-based superalloy coil tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd., specifically engineered for the most demanding high-temperature and highly corrosive industrial environments. Designated as Alloy 625 (UNS N06625, W.Nr. 2.4856), this coil tube product combines exceptional resistance to high-temperature oxidation with outstanding resistance to a wide range of acids, making it the material of choice for aerospace, flue gas desulfurization (FGD), and acidic oil and gas well applications where conventional stainless steels fail.
Inconel 625 Coil Tube is supplied in seamless coil form, enabling efficient downstream processing including cutting, bending, forming, and welding without the need for complex handling procedures. The coil configuration provides continuous-length supply, reducing weld seams and ensuring uniform material properties throughout the entire length of the tube.
Material Composition & Properties
Chemical Composition (Typical)
| Element | Specification (wt%) | Role in Alloy |
|---|---|---|
| Nickel (Ni) | Balance (≥56.0%) | Primary matrix element; provides corrosion resistance and high-temperature strength |
| Chromium (Cr) | 20.0 – 23.0% | Forms protective oxide layer; enhances oxidation and corrosion resistance |
| Molybdenum (Mo) | 8.0 – 10.0% | Improves resistance to reducing acids (e.g., sulfuric, hydrochloric); stabilizes the matrix |
| Niobium (Nb) | 8.0 – 10.0% | Strengthens the alloy via γ″ (Ni₃Nb) precipitate strengthening; enhances creep resistance |
| Iron (Fe) | 2.0 – 3.0% | Trace element; supports solid solution strengthening |
| Tungsten (W) | 1.0 – 3.0% | Further enhances high-temperature strength and creep resistance |
| Copper (Cu) | ≤0.30% | Residual element |
| Carbon (C) | ≤0.10% | Controlled to prevent carbide precipitation and sensitization |
| Silicon (Si) | ≤0.35% | Residual element |
| Manganese (Mn) | ≤0.35% | Residual element |
| Sulfur (S) | ≤0.015% | Tightly controlled to prevent hot cracking during welding |
| Phosphorus (P) | ≤0.015% | Tightly controlled for weldability and ductility |
Key Mechanical Properties
| Property | Value | Test Condition |
|---|---|---|
| Tensile Strength (UTS) | ≥ 690 MPa (100 ksi) | Room Temperature, Annealed |
| 0.2% Proof Stress (Yield) | ≥ 310 MPa (45 ksi) | Room Temperature, Annealed |
| Elongation (% Elongation) | ≥ 30% | Room Temperature, Annealed |
| Young's Modulus (E) | 204 GPa (29.6 × 10⁶ psi) | Room Temperature |
| Thermal Conductivity | 11.4 W/(m·K) at 20°C | Room Temperature |
| Thermal Expansion Coefficient | 13.0 × 10⁻⁶ /°C (20–900°C) | Average over temperature range |
| Density | 8.44 g/cm³ | Room Temperature |
| Maximum Service Temperature | 980°C (1800°F) | Oxidizing Atmospheres |
Corrosion Resistance Profile
- High-Temperature Oxidation Resistance: Inconel 625 maintains an intact, self-healing Cr₂O₃/Nb₂O₅ protective oxide scale at temperatures up to 980°C (1800°F) in oxidizing atmospheres, far exceeding the capabilities of austenitic stainless steels (e.g., 310SS, 321SS).
- Acid Resistance: Demonstrates excellent resistance to sulfuric acid (H₂SO₄), hydrochloric acid (HCl), phosphoric acid (H₃PO₄), nitric acid (HNO₃), and mixed acid environments at moderate temperatures. The combined Ni-Cr-Mo system provides a synergistic defense against both oxidizing and reducing acid media.
- Chloride Stress Corrosion Cracking (SCC) Immunity: Unlike austenitic stainless steels, Inconel 625 is virtually immune to chloride-induced SCC, making it suitable for marine and offshore environments.
- Intergranular Corrosion Resistance: The low carbon content (≤0.10%) and the absence of significant carbide-forming elements prevent intergranular sensitization, even after prolonged exposure to temperatures in the 450–850°C range.
- Creep Resistance: The γ″ (Ni₃Nb) and γ' (Ni₃(Al,Ti)) precipitate phases provide exceptional creep strength at elevated temperatures, sustaining structural integrity under sustained loads.
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Inconel 625 Coil Tube (盘管) |
| Alloy Designation | Inconel 625 / Alloy 625 / UNS N06625 / W.Nr. 2.4856 / CNCS 625 |
| Form | Seamless Coil Tube (continuous coil configuration) |
| Outer Diameter (OD) | 6.35 mm – 168.3 mm (1/4" – 6-11/16") |
| Wall Thickness | 0.50 mm – 12.70 mm (0.020" – 0.500") |
| Coil Length | Customizable; typically 50 m – 500 m per coil |
| Coil Core Diameter | 100 mm – 250 mm (customizable) |
| Surface Finish | Pickled & Passivated, Bright Annealed (BA), or Polished |
| Heat Treatment Condition | Solution Annealed (1093°C / 2000°F, water quench) |
| Standard Compliance | ASTM B407, ASTM B619, ASME SB-407, EN 10217-7, GB/T 2249 |
| Tolerance Class | ASME B7.74 Class 1 or Class 2; ASTM A213 tolerances |
| End Condition | Plain End, Beveled End, or Custom Threaded (upon request) |
| Packaging | Wooden crate or steel banding with moisture-proof wrapping |
Manufacturing Process
The production of Inconel 625 Coil Tube at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing process designed to ensure consistent metallurgical quality, dimensional accuracy, and superior mechanical performance:
- Raw Material Selection & Ingot Casting: High-purity nickel, chromium, molybdenum, niobium, and other alloying elements are precisely weighed and melted in a Vacuum Arc Remelting (VAR) or Electro-Slag Remelting (ESR) furnace. The VAR/ESR process ensures tight control of impurity levels (S ≤ 0.015%, P ≤ 0.015%) and eliminates centerline segregation, producing homogeneous ingots with excellent internal quality.
- Homogenization Heat Treatment: The cast ingots undergo homogenization at 1150–1200°C for extended periods to dissolve any residual segregation and ensure uniform microstructure throughout the ingot cross-section.
- Hot Rolling & Hot Extrusion: The homogenized ingots are reheated to 1100–1200°C and hot-rolled or hot-extruded into seamless tube blanks with the target outer diameter and wall thickness. This step establishes the initial tube geometry and breaks down the cast structure into a fine-grained wrought microstructure.
- Piercing & Mandrel Drawing (for seamless production):st The solid billet is pierced to create a hollow tube, and then drawn over a mandrel to achieve the precise inner diameter and wall thickness specifications. This process ensures uniform wall thickness and tight dimensional tolerances.
- Intermediate Annealing: During the drawing process, intermediate annealing cycles (typically at 1050–1100°C, water quench) are performed to relieve accumulated cold work, restore ductility, and prevent cracking during subsequent deformation steps.
- Coil Winding: The continuous-length seamless tube is wound onto a coil former under controlled tension to produce the final coil tube configuration. The coiling process is carefully managed to avoid kinking, flattening, or residual stress that could compromise downstream formability.
- Solution Annealing & Pickling: The coil tube undergoes a final solution annealing cycle at 1093°C (2000°F) followed by rapid water quenching to achieve the fully solution-treated microstructure with maximum ductility and corrosion resistance. Subsequently, the tube is pickled in a hot mixed acid bath (HNO₃ + H₂SO₄) to remove surface oxide scale, followed by passivation to establish a chromium-rich passive film.
- Non-Destructive Testing (NDT): Every coil tube lot undergoes comprehensive NDT including 100% Eddy Current Testing (ECT) for surface and near-surface defect detection, ultrasonic testing (UT) for internal quality verification, and hydrostatic pressure testing to confirm wall integrity.
- Mechanical Testing & Chemical Analysis: Representative samples from each heat are subjected to tensile testing, hardness testing, and spectrographic chemical analysis to verify compliance with ASTM B407 and ASME SB-407 specifications.
- Final Inspection & Packaging: The inspected and certified coil tubes are wrapped in moisture-proof materials and packaged in wooden crates or secured with steel banding for safe transportation and storage.
Applications
Inconel 625 Coil Tube is the material of choice for critical applications where the combination of high-temperature strength, oxidation resistance, and chemical corrosion resistance is paramount:
Aerospace & Defense
- Jet engine exhaust system components, including turbine nozzle sections, ducting, and heat exchanger tubing
- Afterburner and combustion chamber components operating in extreme thermal gradients
- Aircraft structural components requiring high-temperature creep resistance and fatigue durability
- Missile and rocket engine components, including fuel injection manifolds and thrust chamber liners
- Satellite and space vehicle components exposed to thermal cycling and vacuum environments
Flue Gas Desulfurization (FGD)
- FGD system ducting, absorber internals, and spray nozzles in coal-fired power plants and industrial boilers
- Wet scrubber components exposed to acidic slurry containing sulfuric acid, hydrofluoric acid, and chlorides
- Gas-to-liquid heat exchangers in desulfurization systems
- Condensate handling systems where acidic condensate forms at temperatures below the acid dew point
Acidic Oil & Gas Wells
- Downhole tubing and casing components in sour gas wells containing high concentrations of H₂S and CO₂
- Wellhead equipment and Christmas trees exposed to aggressive produced water and hydrocarbon acids
- Flow lines and manifolds handling acidic crude oil with high chloride and sulfide content
- Subsea production equipment in deepwater environments where chloride-induced SCC is a primary failure mode
- Hydrogen sulfide (H₂S) resistant components in refineries and petrochemical processing units
Additional Applications
- Chemical processing equipment: reactors, distillation columns, heat exchangers, and piping systems handling aggressive chemical media
- Marine and offshore engineering: seawater heat exchangers, propeller shafts, and underwater structural components
- Nuclear energy: primary and secondary circuit components, containment structures, and fuel handling systems
- Power generation: superheater tubes, reheater tubes, and steam generator tubes in ultra-supercritical (USC) boilers
- Waste incineration: heat recovery systems and exhaust ducting exposed to highly corrosive flue gases
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and certifications to ensure that every Inconel 625 Coil Tube product meets or exceeds international standards:
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification ensuring consistent quality across all production stages |
| ISO 14001:2015 | Environmental Management System certification for environmentally responsible manufacturing |
| ASTM B407 | Standard Specification for Nickel-Ch |