Stainless Steel Coil Tube (盘管 / Coil Tube) — Technical Product Specification
1. Product Overview
The Stainless Steel Coil Tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product formed into a continuous helical or spiral coil configuration. These coil tubes are designed for use in thermal management systems, heat exchangers, HVAC (Heating, Ventilation, and Air Conditioning) applications, and industrial fluid transport systems. The product is particularly suited for dry fan coil unit (干式风机盘管) applications combined with independent fresh air systems, where efficient heat transfer, corrosion resistance, and long service life are critical performance parameters.
Coil tubes offer significant advantages over straight-length tubing in applications requiring compact heat exchange surfaces, such as condensing units, evaporating coils, refrigeration circuits, and hydronic heating loops. The coiled geometry maximizes surface area within a confined volume, facilitating superior thermal performance while minimizing installation space.
2. Material & Properties
2.1 Base Material Composition
The coil tubes are fabricated from high-grade austenitic stainless steel conforming to international standards including ASTM A213, ASTM A269, GB/T 14976, and EN 10216-5. Commonly specified grades include:
- AISI 304 / SUS 304 (1.4301): 18% Chromium, 8% Nickel — General-purpose corrosion resistance
- AISI 316 / SUS 316 (1.4401): 18% Chromium, 10% Nickel, 2% Molybdenum — Enhanced pitting and crevice corrosion resistance
- AISI 316L / SUS 316L (1.4404): Low-carbon variant of 316 for welding applications
- AISI 321 / SUS 321 (1.4541): Titanium-stabilized for high-temperature service
- AISI 310S / SUS 310S (1.4845): High-temperature oxidation resistance up to 1150°C
2.2 Mechanical Properties (Typical Values)
| Property | ASTM A213 TP304 | ASTM A213 TP316 | ASTM A213 TP316L |
|---|---|---|---|
| Tensile Strength (MPa) | ≥ 515 | ≥ 515 | ≥ 485 |
| Yield Strength (0.2% offset, MPa) | ≥ 205 | ≥ 205 | ≥ 170 |
| Elongation (% in 50 mm) | ≥ 35 | ≥ 35 | ≥ 40 |
| Density (g/cm³) | 8.0 | 8.0 | 8.0 |
| Thermal Conductivity (W/m·K, 100°C) | 16.3 | 14.6 | 14.6 |
| Maximum Service Temperature (°C) | 870 | 870 | 870 |
2.3 Surface Finish Options
- 2B Finish: Cold-rolled and annealed for general industrial use
- No. 4 Brushed Finish: Uniform directional grain pattern for decorative and architectural applications
- Mirror Finish (8K): Highly polished for food-grade and pharmaceutical applications
- Electropolished: Surface roughness Ra ≤ 0.4 μm for hygienic and sanitary applications
- Pickled & Passivated: Removal of mill scale and formation of protective chromium oxide layer
3. Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (盘管) |
| Product Code / Serial No. | 852 |
| Manufacturing Standard | ASTM A213, ASTM A269, GB/T 14976, EN 10216-5 |
| Available Grades | 304, 304L, 316, 316L, 321, 310S, 904L, 2205 (Duplex) |
| Outer Diameter (OD) | Φ6.0 mm – Φ114.3 mm (customizable) |
| Wall Thickness | 0.3 mm – 6.0 mm |
| Coil Diameter (Bundling) | Φ100 mm – Φ600 mm (standard); custom available |
| Coil Length per Bundle | Up to 500 m per coil (standard); up to 1000 m on request |
| Pressure Rating | Up to 16.0 MPa (depending on grade and dimensions) |
| Temperature Range | −196°C to +870°C (grade-dependent) |
| Surface Treatment | 2B, No.4 Brushed, Mirror, Electropolished, Pickled & Passivated |
| End Condition | Plain end, Beveled end, Flanged, Threaded, or Custom |
| Packing | Export-grade wooden crate or steel drum with moisture-proof inner lining |
| Traceability | Full heat number traceability with mill test certificate (MTC) |
4. Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing process:
- Raw Material Procurement: Cold-rolled stainless steel strip (coil) sourced from certified mills, verified for chemical composition and mechanical properties via spectroscopic analysis (OES/PES) and tensile testing.
- Slitting: The master coil is slit to the required strip width using precision slitting lines with edge-quality control to prevent burrs and dimensional deviations.
- Forming: The strip is fed through a multi-station roll-forming machine to produce the desired tube cross-section (round, oval, rectangular, or square). Forming forces are monitored to prevent work-hardening and dimensional drift.
- Welding: Seamless tube is available for small diameters (≤ Φ22 mm) via cold-drawn seamless process. For larger diameters, high-frequency induction welding (HFW) or orbital TIG (Tungsten Inert Gas) welding is employed with real-time weld seam monitoring.
- Heat Treatment / Solution Annealing: Tubes are solution-annealed at 1050–1150°C followed by rapid quenching to restore full austenitic microstructure and eliminate residual stresses from forming and welding.
- Pickling & Passivation: Chemical treatment to remove oxide scale and form a uniform, protective chromium-rich passive film (Cr₂O₃) on the surface.
- Coiling / Spooling: The finished tube is coiled onto a spool or bundling frame at the specified coil diameter using automated coiling equipment to ensure uniform winding tension and prevent deformation.
- Quality Inspection: Non-destructive testing (NDT) including eddy current inspection (ECI) for wall thickness and seam integrity, hydrostatic pressure testing (typically 5.0 MPa minimum), dimensional verification, and visual inspection.
- Packing & Dispatch: Coils are wrapped in protective film, placed in moisture-proof bags, and secured in export-grade wooden crates or steel drums for safe international shipment.
5. Applications
Stainless steel coil tubes find extensive application across multiple industries due to their combination of corrosion resistance, mechanical strength, and thermal performance:
5.1 HVAC & Refrigeration Systems
- Dry fan coil units (干式风机盘管) for commercial and residential air conditioning
- Independent fresh air handling systems with heat recovery
- Chilled water coil assemblies for large-scale HVAC installations
- Condensing and evaporating coils in refrigeration circuits
5.2 Heat Exchangers & Thermal Management
- Shell-and-tube heat exchangers for industrial process cooling/heating
- Plate-fin heat exchangers in cryogenic applications
- Waste heat recovery systems
- Solar thermal collector systems
5.3 Chemical & Petrochemical Industry
- Corrosive fluid transport and circulation loops
- Reactor cooling jackets and internal coils
- Distillation column internals
- Acid and alkali handling systems
5.4 Food & Pharmaceutical Industry
- Sterilization (CIP/SIP) heating coils
- Dairy and beverage processing heat exchangers
- Pharmaceutical formulation equipment
- Hygienic-grade fluid transfer systems
5.5 Marine & Offshore
- Seawater cooling systems
- Ballast water treatment equipment
- Offshore platform heat exchanger assemblies
6. Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring full traceability and compliance with international standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health and Safety Management
- EN 10204 Type 3.1 — Inspection Certificate (Mill Test Certificate) with third-party inspection
- ASTM International — Conformance to ASTM A213, A269, A778 standards
- GB/T National Standards (China) — GB/T 14976, GB/T 12771, GB/T 21832
- CE Marking — European Conformity for pressure equipment (PED 2014/68/EU)
- NACE MR0175 / ISO 15156 — For sour service applications (H₂S resistance)
- PED 2014/68/EU — Pressure Equipment Directive compliance
Each production batch is accompanied by a detailed Mill Test Certificate (MTC) documenting chemical composition, mechanical test results, dimensional verification, and heat treatment parameters. Third-party inspection (TPI) by organizations such as SGS, Bureau Veritas, or TÜV is available upon request.
7. Unique Selling Points
- Custom Coiling Configuration: Ability to produce coil tubes in virtually any coil diameter and length, optimized for specific heat exchanger geometries and installation constraints.
- Multi-Grade Availability: Comprehensive range from standard austenitic grades (304, 316) to specialty alloys (904L, 2205 Duplex, Hastelloy) for the most demanding corrosion environments.
- Precision Dimensional Control: ±0.05 mm tolerance on outer diameter and wall thickness through automated forming and continuous online measurement.
- Seamless Option: Cold-drawn seamless coil tubes available for applications requiring zero weld seam integrity concerns.
- Full Traceability: Each coil is individually identified with heat number, production date, and inspection data, enabling complete supply chain traceability.
- Technical Consultation: Dedicated engineering support for material selection, thermal performance optimization, and system integration guidance.
Note: The dry fan coil unit combined with independent fresh air system (干式风机盘管结合独立新风系统) represents a modern approach to building climate control that decouples thermal comfort from ventilation, enabling superior indoor air quality (IAQ) and energy efficiency. Stainless steel coil tubes are integral components in both the cooling/heating coil assembly and the fresh air handling unit heat recovery section, making material quality and dimensional precision critical to system performance and longevity.