Incoloy 825 Nickel-Base Alloy Coil Tube — Technical Specification
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Category: Materials & Metallurgy — Nickel-Base Alloy (Ni-Fe-Cr-Mo-Ti)
Product Designation: Incoloy 825 Coil Tube (UNS N08825)
1. Product Overview
Incoloy 825 coil tube is a wrought nickel-iron-chromium alloy with molybdenum and titanium stabilization, developed to provide exceptional resistance to a wide range of corrosive environments. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this coil tube product is specifically engineered for demanding industrial applications involving aggressive chemical media, particularly dilute and concentrated sulfuric acid (H₂SO₄) and phosphoric acid (H₃PO₄).
The coil tube format offers significant advantages over straight-length tubing in terms of storage efficiency, transportation logistics, and downstream processing flexibility. The continuous coiled configuration eliminates the need for butt-welding during installation in heat exchanger and process piping systems, thereby reducing potential leak points and enhancing system integrity.
2. Material & Properties
2.1 Chemical Composition (UNS N08825 / Incoloy 825)
| Element | Specification (wt%) |
|---|---|
| Nickel (Ni) | Balance (min. 42%) |
| Chromium (Cr) | 22.0 – 26.0 |
| Iron (Fe) | 25.0 – 30.0 |
| Molybdenum (Mo) | 2.5 – 3.5 |
| Titanium (Ti) | 0.40 – 0.85 |
| Copper (Cu) | 1.0 – 3.0 |
| Carbon (C) | ≤ 0.05 |
| Manganese (Mn) | ≤ 1.0 |
| Silicon (Si) | ≤ 0.50 |
| Sulfur (S) | ≤ 0.015 |
2.2 Mechanical Properties (Solution-Annealed Condition)
| Property | Value |
|---|---|
| Tensile Strength (0.2% Yield) | ≥ 205 MPa (29.7 ksi) |
| Ultimate Tensile Strength (UTS) | ≥ 515 MPa (74.7 ksi) |
| Elongation (in 50 mm / 2 in.) | ≥ 30% |
| Density | 8.14 g/cm³ (0.294 lb/in³) |
| Thermal Conductivity (at 20°C) | 11.4 W/(m·K) |
| Modulus of Elasticity | 203 GPa (29.4 × 10⁶ psi) |
| Maximum Service Temperature | 1100°C (2012°F) |
2.3 Corrosion Resistance Characteristics
- Sulfuric Acid (H₂SO₄): Excellent resistance in dilute solutions up to 25% concentration at temperatures up to 90°C (194°F); moderate resistance in concentrated acid up to 60°C (140°F).
- Phosphoric Acid (H₃PO₄): Outstanding resistance across all concentrations and temperatures up to boiling point; superior to 316L stainless steel and many other nickel alloys.
- Hydrochloric Acid (HCl): Good resistance in dilute solutions at ambient temperatures.
- Oxidizing Acids: Superior resistance to mixed acid environments including nitric acid, chromic acid, and sulfuric-nitric acid mixtures.
- Crevice Corrosion: Excellent resistance due to high chromium and molybdenum content with titanium stabilization.
- Pitting Corrosion: Highly resistant in chloride-containing environments; PREN value exceeds 40.
3. Specifications
| Parameter | Specification |
|---|---|
| Product Form | Coil Tube (Continuous Coil Configuration) |
| Standard Compliance | ASTM B407 / B409; ASME SB407 / SB409; EN 10217-13 |
| Alloy Designation | Incoloy 825 / UNS N08825 / Alloy 825 |
| Outer Diameter (OD) Range | 3.18 mm – 50.8 mm (1/8" – 2") |
| Wall Thickness Range | 0.25 mm – 3.00 mm (0.010" – 0.118") |
| Coil Inner Diameter (ID) | 300 mm – 600 mm (12" – 24") |
| Coil Length | Up to 200 m (656 ft) per coil |
| Surface Finish | Pickle & Passivate / Bright Annealed |
| Tolerance (OD) | ±0.05 mm (±0.002") |
| Tolerance (Wall Thickness) | ±0.03 mm (±0.001") |
| Heat Treatment Condition | Solution Annealed (1040–1150°C, water quenched) |
4. Manufacturing Process
The production of Incoloy 825 coil tube at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing sequence to ensure consistent quality and dimensional accuracy:
- Raw Material Selection: High-purity nickel-iron-chromium master alloy ingots are sourced and verified for chemical composition via Optical Emission Spectroscopy (OES) and Inductively Coupled Plasma (ICP) analysis.
- Hot Rolling & Homogenization: Billets are homogenized at 1150–1250°C to ensure uniform microstructure, followed by hot rolling to achieve initial tube blank dimensions.
- Piercing & Pipe Making: The hot-rolled billet is pierced and reduced to seamless tube blank through multi-stand rolling mills or autogenous piercing techniques.
- Cold Drawing / Cold Expansion: Tubes are cold-worked to achieve precise OD and wall thickness tolerances while improving mechanical properties and surface finish.
- Solution Annealing: Tubes undergo solution heat treatment at 1040–1150°C with rapid water quenching to dissolve carbides, homogenize the solid solution, and achieve optimal corrosion resistance.
- Pickling & Passivation: The oxide scale formed during heat treatment is removed through controlled acid pickling, followed by passivation to restore the protective chromium oxide layer.
- Coiling: The finished tube is wound onto precision-machined coil drums under controlled tension to prevent deformation, kinking, or surface damage.
- Quality Inspection: Final products undergo dimensional verification, hydrostatic pressure testing, chemical analysis, and optional radiographic inspection (RT) or ultrasonic testing (UT).
5. Applications
Incoloy 825 coil tube is uniquely suited for the following industrial sectors:
5.1 Acid Pickling Equipment
Coil tubes fabricated from Incoloy 825 serve as critical heat transfer elements and process piping in acid pickling lines, where they are exposed to hot, concentrated sulfuric acid and hydrofluoric acid mixtures. The alloy's titanium stabilization prevents intergranular corrosion during prolonged exposure to aggressive acid environments.
5.2 Hydrometallurgy
In leaching, solvent extraction, and electrolytic recovery processes within the hydrometallurgical industry, Incoloy 825 coil tubes provide reliable service in strongly oxidizing and reducing acid media. Applications include copper, nickel, and cobalt extraction circuits where mixed acid environments would rapidly degrade conventional stainless steels.
5.3 Condensers & Heat Exchangers
The coil tube format is ideal for shell-and-tube heat exchangers, condensers, and evaporators in chemical processing plants. The continuous coil eliminates weld joints within the heat exchanger bundle, maximizing thermal efficiency and minimizing maintenance requirements. Incoloy 825's thermal stability at elevated temperatures makes it suitable for high-temperature condensation services.
5.4 Additional Applications
- Pharmaceutical processing equipment requiring biocompatible, corrosion-resistant tubing
- Environmental scrubbers and flue gas desulfurization (FGD) systems
- Waste water treatment and effluent handling systems
- Food and beverage processing involving acidic products
- Chemical reactor internals and distillation columns
6. Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains the following quality management and product certifications to ensure compliance with international standards:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- EN 10204 3.1 Certificate — Third-party verified material test certificates for each production lot
- Mill Test Report (MTR) — Comprehensive documentation including chemical analysis, mechanical test results, and heat treatment records
- Material Traceability — Full batch and heat number traceability from raw material to finished product
7. Unique Selling Points
1. Superior Acid Resistance: Incoloy 825 coil tube offers unmatched resistance to sulfuric and phosphoric acids — outperforming 316L stainless steel, Alloy 625, and Alloy 600 in most acid service conditions.
2. Coil Format Advantage: The continuous coil configuration eliminates field welding, reduces installation time by up to 40%, and minimizes potential failure points in process systems.
3. Titanium Stabilization: The addition of titanium (0.40–0.85%) prevents chromium carbide precipitation at grain boundaries, ensuring sustained intergranular corrosion resistance even after prolonged exposure to elevated temperatures.
4. Broad Temperature Range: Maintains mechanical integrity and corrosion resistance from cryogenic temperatures up to 1100°C, enabling versatile deployment across diverse process conditions.
5. Precision Manufacturing: Tight dimensional tolerances (±0.05 mm OD) and uniform wall thickness ensure optimal fit in heat exchanger tube sheets and reliable long-term performance under cyclic thermal stress.
This technical specification is provided for informational purposes. For specific project requirements, please contact Wenzhou Jixing Metal Materials Co., Ltd. for customized engineering support and quotation.