Stainless Steel Coil Tube — Coiltube for Heat-Exchange and Anti-Icing Applications
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Reference No.: 1041
Category: Stainless Steel Coil Tube (Coiltube)
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a continuous-length tubular product wound into a helical coil configuration, designed for applications requiring compact heat-exchange geometry, fluid conveyance, and resistance to external icing (de-icing) in cryogenic and cold-climate environments. The coil tube is produced from austenitic stainless steel grades and is supplied in a cold-drawn, cold-rolled, and cold-formed state to achieve precise dimensional tolerances and superior surface finish.
This product line incorporates advanced mathematical modeling and numerical analysis methodologies — specifically Finite Element Method (FEM) and Computational Fluid Dynamics (CFD) — to predict and mitigate external icing (External Ice Accumulation) on coil surfaces. The mathematical model accounts for convective heat transfer, radiative heat exchange, phase-change thermodynamics of moisture deposition, and the mechanical stress induced by ice load on the tubular geometry. These analyses ensure that the coil tube maintains structural integrity and functional performance under icing conditions.
2. Material & Properties
2.1 Base Material Grades
- SAE 304 / ASTM 304 / UNS S30400: General-purpose austenitic stainless steel; excellent corrosion resistance, weldability, and formability.
- SAE 316 / ASTM 316 / UNS S31600: Molybdenum-bearing austenitic grade; superior resistance to pitting and crevice corrosion in chloride-containing environments.
- SAE 316L / ASTM 316L / UNS S31603: Low-carbon variant of 316; preferred for welding applications to prevent intergranular corrosion.
- SAE 321 / ASTM 321 / UNS S32100: Titanium-stabilized grade; enhanced resistance to sensitization at elevated temperatures.
- SAE 310S / ASTM 310S / UNS S31008: High-temperature austenitic grade; suitable for prolonged service above 800°C.
2.2 Mechanical Properties (Typical, Cold-Drawn Condition)
- Tensile Strength (Ultimate Tensile Strength, UTS): ≥ 520 MPa (304); ≥ 515 MPa (316)
- Yield Strength (0.2% Proof Stress): ≥ 205 MPa (304); ≥ 170 MPa (316)
- Elongation (in 50 mm): ≥ 40%
- Hardness (HB): ≤ 217 (304); ≤ 217 (316)
- Density: 7.93 g/cm³ (304); 8.03 g/cm³ (316)
2.3 Thermal and Physical Properties
- Thermal Conductivity (at 20°C): 16.3 W/(m·K) (304); 16.3 W/(m·K) (316)
- Thermal Expansion Coefficient (20–100°C): 17.3 × 10⁻⁶ /K (304); 17.4 × 10⁻⁶ /K (316)
- Specific Heat Capacity (at 20°C): 500 J/(kg·K)
- Maximum Service Temperature: 870°C (304); 870°C (316); 1150°C (310S)
- Minimum Service Temperature: −196°C (cryogenic applications supported)
2.4 Anti-Icing Performance Characteristics
Based on mathematical modeling and numerical simulation of external icing phenomena:
- Heat Transfer Coefficient (Convective, External): Modeled via Nusselt number correlations for helical coil geometries (Dittus-Boelter and Gnielinski correlations adapted for coiled configurations).
- Ice Adhesion Resistance: Surface finish Ra ≤ 0.8 μm reduces ice adhesion forces; optional electropolishing achieves Ra ≤ 0.4 μm.
- De-Icing Efficiency: Numerical analysis confirms that integrated resistive heating traces (optional) reduce ice accumulation by up to 92% under conditions of −20°C ambient temperature and 100% relative humidity.
- Structural Load Capacity Under Ice Shear: FEM analysis validates that the coil tube withstands ice shear stresses up to 15 MPa without permanent deformation.
3. Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 108.0 mm (custom available) | ASTM A269 / ASME SA-269 |
| Wall Thickness (WT) | 0.3 mm – 6.0 mm | ASTM A269 / ASME SA-269 |
| Coil Winding Diameter | 50 mm – 500 mm (custom configurations) | — |
| Coil Length (Per Spool) | 10 m – 500 m (continuous) | — |
| OD Tolerance | ±0.05 mm (precision grade); ±0.1 mm (standard grade) | ASTM A269 |
| Wall Thickness Tolerance | ±10% (standard); ±5% (precision grade) | ASTM A269 |
| Roundness | ≤ 0.5% of OD | ASTM A269 |
| Surface Finish | Ra 0.8 μm (standard); Ra 0.4 μm (electropolished) | ASTM A269 / ASTM A967 |
| Surface Treatment | Pickled & Passivated (P&P); Electropolished; Mirror Polished | ASTM A967 |
| End Condition | Plain end; Beveled end (45°); Flanged end | — |
| Delivery Form | Coiled (Coiltube); Cut-to-length; Custom formed | — |
| Heat Treatment | Solution Annealed (1050°C – 1150°C, water quench) | ASTM A269 |
| Optional Features | Resistive heating trace; Anti-icing surface coating; Helical corrugation | — |
4. Manufacturing Process
- Raw Material Selection: High-purity austenitic stainless steel billets (e.g., 304, 316, 316L) are procured from certified suppliers. Incoming material undergoes spectroscopic analysis (Optical Emission Spectrometry, OES) to verify chemical composition compliance with ASTM standards.
- Hot Rolling: Billets are heated to 1150°C–1200°C and hot-rolled into seamless tube blanks with controlled wall thickness and outer diameter dimensions.
- Piercing & Elongation: The hot-rolled blanks are pierced to form hollow tubes and elongated to achieve near-final dimensions through rotary piercing mills.
- Solution Annealing: Tubes are solution-annealed at 1050°C–1150°C followed by rapid water quenching to dissolve carbides and achieve a fully austenitic microstructure with maximum corrosion resistance.
- Cold Drawing: Tubes are cold-drawn through precision tungsten carbide dies to achieve tight dimensional tolerances (±0.05 mm OD, ±5% wall thickness) and enhanced mechanical properties.
- Cold Coiling (Helical Winding): The cold-drawn tube is wound into a helical coil configuration using CNC-controlled coiling machines. The winding parameters (pitch, coil diameter, winding speed) are optimized based on FEM stress analysis to prevent residual stress concentration and geometric distortion.
- Pickling & Passivation: The coiled tube undergoes acid pickling (nitric/hydrofluoric acid mixture) to remove oxide scales, followed by passivation treatment (nitric acid immersion) to form a protective chromium oxide layer (Cr₂O₃).
- Surface Finishing (Optional): Electropolishing or mechanical polishing is applied to achieve ultra-smooth surface finishes (Ra ≤ 0.4 μm) that reduce ice adhesion and improve heat transfer efficiency.
- Non-Destructive Testing (NDT): All coils undergo 100% ultrasonic testing (UT) for wall thickness verification, eddy current testing (ECT) for surface defect detection, and helium leak testing (for pressure-containing applications) at 1.5× working pressure.
- Final Inspection & Packaging: Dimensional inspection (OD, wall thickness, roundness, straightness), visual inspection, and certification documentation. Coils are packaged with moisture-absorbing desiccants, protective wraps, and steel banding for transport.
5. Applications
5.1 Heat-Exchange Systems
- Air-cooled heat exchangers and condensers in industrial process plants.
- Cryogenic heat exchangers for liquefied natural gas (LNG) processing and liquid oxygen/nitrogen production.
- Plate-fin and shell-and-coil heat exchangers in chemical and petrochemical industries.
5.2 Anti-Icing and De-Icing Systems
- Aircraft engine anti-icing systems (engine inlet heat exchangers).
- Wind turbine blade de-icing heating elements (embedded coil tubes).
- Power transmission line de-icing systems in cold-climate regions.
- Automotive and railway heating systems for cold-environment operation.
5.3 Fluid Conveyance
- Food and beverage processing pipelines (FDA-compliant 316L grade).
- Pharmaceutical and bioprocessing equipment.
- Semiconductor manufacturing ultra-pure water (UPW) distribution systems.
- Medical device tubing (endoscopic and dialysis applications).
5.4 Structural and Mechanical Applications
- Spring and suspension components in automotive and aerospace industries.
- Gas spring accumulators and hydraulic systems.
- Wire rope and cable production (multi-strand stainless steel wire).
6. Quality Certifications & Standards Compliance
6.1 International Standards
- ASTM A269 / ASME SA-269: Standard Specification for Seamless and Wrought Austenitic Stainless Steel Tubing for Chemical and Similar Severe Service.
- ASTM A312 / ASME SA-312: Standard Specification for Seamless and Welded Austenitic Stainless Steel Pipes for High Temperature and High Pressure Boiler, Heat Exchanger, and Similar Applications.
- ASTM A967: Standard Practice for Chemical Cleaning and Passivation of Stainless Steel Parts.
- EN 10216-5: Steel Tubes for Pressure Purposes — Part 5: Non-heat-resistant Austenitic and Ferritic-Austenitic Stainless Steel Tubes.
- ISO 1143: Stainless Steel Seamless Tubes — Dimensions and Tolerances.
- JIS G3459: Stainless Steel Seamless Tubes (Japanese Industrial Standard).
6.2 Quality Management Certifications
- ISO 9001:2015: Quality Management System certification for manufacturing operations.
- ISO 14001:2015: Environmental Management System certification.
- ISO 45001:2018: Occupational Health and Safety Management System certification.
- PED 2014/68/EU: European Pressure Equipment Directive compliance (for pressure-containing applications).
- NACE MR0175 / ISO 15156: Compliance for sour service (H₂S-containing environments).
6.3 Testing and Certification Documentation
- Mill Test Certificate (MTC) / EN 10204 Type 3.1 for each heat lot.
- Third-party inspection reports (SGS, Bureau Veritas, TÜV) available upon request.
- Material traceability through heat number and coil identification system.
- Full chemical composition analysis (OES + wet chemistry for trace elements).
- Mechanical test report (tensile, hardness, impact) per ASTM E8 / ASTM E18.
- NDT report (UT, ECT, PT) per ASTM E164 / ASTM E309.
7. Unique Selling Points
Mathematical Modeling-Driven Design: The coil tube design is validated through rigorous mathematical modeling of external icing phenomena, incorporating coupled heat transfer, mass transfer (moisture deposition), and structural mechanics