Stainless Steel Coil Tube (Coiltube) — Model No. 487
Product Overview
The Stainless Steel Coil Tube (Coiltube), designated as Product No. 487, is a precision-engineered tubular component manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is specifically designed for integration into high-efficiency sedimentation systems, particularly the external coil tube lithium precipitation tank (高效沉降外盘管式沉锂釜). The coil tube serves as a critical heat exchange and fluid circulation element within industrial lithium extraction and battery-grade lithium salt production processes.
Engineered with superior corrosion resistance, mechanical integrity, and thermal conductivity, this coil tube product meets the demanding requirements of lithium-ion battery material manufacturing, chemical processing, and high-purity lithium hydroxide/lithium carbonate precipitation operations.
Material & Properties
Base Material
- Primary Alloy: Austenitic Stainless Steel — 316L (UNS S31603) / 304 (UNS S30403)
- Alternative Grades: 321 (UNS S32100), 310S (UNS S31008), 904L (UNS N08904)
- Composition (316L): C ≤ 0.03%, Si ≤ 1.00%, Mn ≤ 2.00%, P ≤ 0.045%, S ≤ 0.030%, Cr 16.00–18.00%, Ni 10.00–14.00%, Mo 2.00–3.00%
Mechanical Properties
- Tensile Strength (UTS): ≥ 515 MPa (75,000 psi)
- Yield Strength (0.2% offset): ≥ 205 MPa (29,700 psi)
- Elongation at Break: ≥ 40%
- Hardness: ≤ 217 HB (Brinell)
- Density: 8.00 g/cm³
Corrosion Resistance
- Pitting Resistance: PREN ≥ 24 (Pitting Resistance Equivalent Number)
- Service Temperature Range: −196°C to +425°C (−321°F to +797°F)
- Chloride Resistance: Excellent resistance to pitting and crevice corrosion in lithium hydroxide (LiOH) and lithium carbonate (Li₂CO₃) solutions
- Acid Resistance: Suitable for dilute sulfuric acid, hydrochloric acid, and phosphoric acid environments
Thermal Properties
- Thermal Conductivity: 14.5–16.5 W/(m·K) at 25°C
- Specific Heat Capacity: 500 J/(kg·K)
- Thermal Expansion Coefficient: 17.3 × 10⁻⁶ /°C
Specifications
| Parameter | Specification | Unit | Standard/Reference |
|---|---|---|---|
| Outer Diameter (OD) | 6.0 / 8.0 / 10.0 / 12.0 / 15.0 / 19.0 / 25.0 | mm | ASTM A269 / GB/T 12771 |
| Wall Thickness | 0.5 – 3.0 (customizable) | mm | ASTM A269 / GB/T 12771 |
| Coil Inner Diameter (ID) | 200 – 2000 (customizable) | mm | Customer Specification |
| Coil Length (per roll) | 50 – 500 | m | — |
| Surface Finish | No. 4 Brushed / Mirror (Ra ≤ 0.4 μm) / Electropolished (Ra ≤ 0.2 μm) | — | ASTM A240 / GB/T 343 |
| Tolerance (OD) | ±0.05 – ±0.10 | mm | ASTM A269 |
| Tolerance (Wall) | ±10% nominal | — | ASTM A269 |
| End Condition | Plain / Beveled / Threaded / Welded Caps | — | Customer Specification |
| Winding Pitch | 1.2 – 2.5 × OD (adjustable) | — | Customer Specification |
| Heat Treatment | Solution Annealed & Water Quenched | — | ASTM A269 |
| Welding Process | TIG (GTAW) — Helium Back Purge | — | ASME Section IX / GB/T 985 |
| Maximum Working Pressure | ≤ 1.6 MPa (16 bar) — depending on dimensions | MPa | ASME B31.3 |
| Hydrostatic Test Pressure | 1.5× Working Pressure | MPa | ASTM A269 |
Manufacturing Process
1. Raw Material Selection & Inspection
High-purity austenitic stainless steel seamless tubes conforming to ASTM A269, ASME SA-213, or GB/T 12771 standards are selected. Each batch undergoes spectroscopic analysis (OES) to verify chemical composition and ensure trace element control, particularly carbon and sulfur content for 316L grade.
2. Precision Cutting & Deburring
Seamless tubes are cut to required lengths using CNC plasma or water-jet cutting systems. Internal and external burrs are removed to ensure smooth fluid flow and prevent stress concentration points.
3. Coil Forming (Cold Bending)
Tubes are cold-formed into the specified coil geometry using CNC-controlled coiling machines. The bending process maintains material integrity without inducing work hardening beyond acceptable limits. Mandrel-assisted bending is employed for tight coil radii to prevent ovality and wrinkling.
4. Welding & Joining
U-bends, return bends, and end connections are fabricated using Gas Tungsten Arc Welding (GTAW/TIG) with helium back-purge to maintain a fully inert atmosphere on the weld root. This ensures corrosion-free weld penetration critical for lithium chemistry service.
5. Solution Annealing & Pickling
After forming and welding, the coil tube assembly undergoes solution annealing at 1050–1150°C followed by rapid water quenching. This process dissolves carbides, restores full austenitic microstructure, and maximizes corrosion resistance. Subsequent pickling and passivation removes surface oxides and establishes a stable chromium oxide passive film.
6. Surface Finishing
Depending on application requirements, the coil tube may undergo:
- Mechanical Polishing: Achieving Ra ≤ 0.4 μm for general chemical service
- Electropolishing: Achieving Ra ≤ 0.2 μm for high-purity lithium hydroxide service, removing surface contaminants and enhancing passivity
- Acid Pickling & Passivation: Final surface treatment for maximum corrosion protection
7. Quality Inspection & Testing
- Dimensional Inspection: OD, wall thickness, coil ID, and pitch verified by laser micrometers
- Hydrostatic Testing: 100% of coils tested at 1.5× working pressure
- Visual Inspection: Weld quality and surface condition examined
- Chemical Analysis: OES verification of material composition
- Corrosion Testing: Salt spray testing (ASTM B117) and immersion testing in lithium chemistry solutions
Applications
Primary Application: Lithium Precipitation Systems
The core application of this coil tube is in high-efficiency sedimentation external coil tube lithium precipitation tanks (高效沉降外盘管式沉锂釜). In this configuration, the coil tube functions as an external heat exchange and agitation enhancement element within the lithium precipitation reactor. The coil facilitates:
- Controlled temperature management during lithium hydroxide (LiOH·H₂O) or lithium carbonate (Li₂CO₃) crystallization
- Improved crystal nucleation and growth uniformity
- Enhanced sedimentation efficiency through optimized fluid dynamics
- Precise thermal regulation during lithium extraction from brine solutions
Additional Applications
- Lithium-Ion Battery Material Processing: Heat exchangers in lithium salt refining lines
- Chemical Processing: Corrosive liquid heating/cooling coils in reactors and mixing vessels
- Pharmaceutical Industry: GMP-compliant heat exchange coils for pharmaceutical solutions
- Food Processing: Sanitary-grade coils for food-grade liquid heating and cooling
- Biotechnology: Fermentation tank jacket coils and internal heat exchange elements
- Petrochemical Industry: Corrosion-resistant heat exchange coils for acid service
- Environmental Engineering: Wastewater treatment reactor heating coils
Quality Certifications
Manufacturing Certifications
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health & Safety Management System
- CE Marking — European Conformity
Product Standards & Compliance
- ASTM A269 / A269M — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing
- ASME SA-213 / SA-213M — Standard Specification for Seamless Austenitic Stainless Steel Tubing for High-temperature Service
- GB/T 12771 — Nonferrous Alloy Seamless Tubes (Chinese National Standard)
- EN 10216-5 — Technical Delivery Conditions for Seamless Steel Tubes for Particular Service
- JIS G3459 — Stainless Steel Seamless Tubes (Japanese Industrial Standard)
Testing & Verification
- Third-party material certification (MTC) per EN 10204 Type 3.1
- Hydrostatic pressure testing per ASTM A269 requirements
- Positive Material Identification (PMI) verification
- Full traceability from mill heat number through final product
Unique Selling Points
1. Purpose-Engineered for Lithium Chemistry: Unlike generic stainless steel coils, this product is specifically designed and validated for the aggressive lithium hydroxide and lithium carbonate environments found in battery-grade lithium salt production, offering superior longevity and performance.
2. Precision Coil Geometry: CNC-controlled coiling ensures uniform pitch, consistent bend radius, and minimal geometric variation, directly contributing to predictable thermal performance and fluid dynamics in precipitation tanks.
3. Helium Back-Purged Welding: All weld joints are fabricated with full helium back-purge protection, eliminating internal oxidation and ensuring weld integrity equivalent to the base material — critical for high-purity lithium processing.
4. Electropolished Surface Option: Available with Ra ≤ 0.2 μm electropolished finish, providing maximum corrosion resistance and minimal product contamination — essential for battery-grade lithium hydroxide applications.
5. Full Customization Capability: Complete flexibility in dimensions, coil geometry, surface finish, end conditions, and alloy grade selection to match specific reactor designs and process requirements.
6. Comprehensive Quality Assurance: End-to-end traceability, 100% hydrostatic testing, and third-party material certification ensure consistent product quality and regulatory compliance.
Technical Data Summary
| Item | Detail |
|---|---|
| Product Code | 487 |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. |
| Product Category | Stainless Steel Coil Tube (Coiltube) |
| Primary Application | High-efficiency sedimentation external coil tube lithium precipitation tank |
| Recommended Grade | 316L (UNS S31603) |
| Design Standard | ASME B31.3 / GB/T 12771 |