Stainless Steel Coil Tube — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Product No. 609) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled tubular product designed for demanding thermal exchange, fluid conveyance, and structural applications. This product category encompasses seamless and welded stainless steel tubes formed into continuous coil configurations, offering superior corrosion resistance, mechanical integrity, and thermal conductivity. The coil tube is particularly suited for integration into medium-temperature water air-conditioning systems, where it serves as a critical component in fan coil units (FCU) and heat exchanger assemblies.
Coil tubes are distinguished from straight-length tubes by their continuous helical winding geometry, which enables compact heat exchange surface area within constrained installation envelopes. This product line is engineered to meet international quality standards and is widely adopted in HVAC (Heating, Ventilation, and Air Conditioning), refrigeration, chemical processing, and medical equipment manufacturing sectors.
2. Material Composition & Physical Properties
The coil tubes are fabricated from austenitic and duplex stainless steel grades conforming to ASTM (American Society for Testing and Materials) and EN (European Norm) standards. The primary material grades include:
- ASTM A213 TP304 / TP304L — General-purpose austenitic stainless steel with excellent corrosion resistance and formability.
- ASTM A213 TP316 / TP316L — Molybdenum-enhanced austenitic grade offering superior resistance to pitting and crevice corrosion.
- ASTM A213 TP316L (Low Carbon) — Enhanced weldability and resistance to intergranular corrosion in sensitized conditions.
- ASTM A269 TP321 — Titanium-stabilized grade suitable for elevated-temperature service.
- Duplex Grades (2205 / UNS S31803) — High-strength, chloride-resistant duplex stainless steel for aggressive environments.
| Property | Specification |
|---|---|
| Chemical Composition (Grade 304) | C ≤ 0.08%, Si ≤ 1.00%, Mn ≤ 2.00%, Cr 18.00–20.00%, Ni 8.00–10.50%, S ≤ 0.030% |
| Chemical Composition (Grade 316L) | C ≤ 0.030%, Si ≤ 1.00%, Mn ≤ 2.00%, Cr 16.00–18.00%, Ni 10.00–14.00%, Mo 2.00–3.00%, S ≤ 0.030% |
| Tensile Strength | ≥ 515 MPa (Grade 304); ≥ 530 MPa (Grade 316L) |
| Yield Strength (0.2% Offset) | ≥ 205 MPa (Grade 304); ≥ 220 MPa (Grade 316L) |
| Elongation | ≥ 40% (Grade 304); ≥ 35% (Grade 316L) |
| Thermal Conductivity (20°C) | 16.3 W/(m·K) (Grade 304); 16.3 W/(m·K) (Grade 316L) |
| Operating Temperature Range | −196°C to +870°C (vacuum); −196°C to +700°C (air) |
| Surface Finish | Bright Annealed (BA), Pickled & Passivated, 2B, or Custom Polished (Ra ≤ 0.4 μm) |
| Density | 8.00 g/cm³ |
3. Dimensional Specifications
| Parameter | Range / Options |
|---|---|
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (¼" – 2") |
| Wall Thickness (WT) | 0.30 mm – 3.00 mm |
| Coil Inner Diameter (CID) | 100 mm – 1500 mm |
| Coil Length per Spool | 5 m – 500 m (configurable) |
| Tolerance on OD | ±0.05 mm (precision grade); ±0.10 mm (standard grade) |
| Tolerance on Wall Thickness | ±10% of nominal |
| Helix Pitch Tolerance | ±0.5 mm |
| End Treatment | Plain cut, beveled, or threaded per customer specification |
| Standard Reference | ASTM A213, ASTM A269, EN 10217-7, GB/T 14976 |
4. Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing workflow:
- Raw Material Selection: Hot-rolled stainless steel coil stock sourced from certified mills, inspected for chemical composition and mechanical properties via spectroscopic analysis and tensile testing.
- Piercing & Pipe Making: Steel coil is fed through a multi-stand piercing mill or ERW (Electric Resistance Welding) / TIG (Tungsten Inert Gas) welding line to form tubular blanks with precise OD and wall thickness.
- Forming & Coil Winding: Tubular blanks are guided through precision forming rollers and wound onto coil mandrels using CNC-controlled winding equipment to ensure consistent helix geometry and uniform pitch.
- Heat Treatment (Solution Annealing): Tubes are annealed at 1050–1150°C followed by controlled cooling to achieve full austenitic microstructure, relieve residual stresses, and restore corrosion resistance.
- Pickling & Passivation: Surface oxide scale is removed through acid pickling (HNO₃/HF mixture), followed by passivation treatment to establish a protective chromium oxide film (Cr₂O₃) on the surface.
- Hydrostatic Testing: Each coil length is pressure-tested at 1.5× the maximum operating pressure to verify weld integrity and detect porosity or defects.
- Dimensional Inspection: Coordinate Measuring Machine (CMM) and ultrasonic thickness gauging are employed to verify OD, WT, and coil geometry against specified tolerances.
- Packaging & Dispatch: Coils are wrapped in protective VCI (Vapor Corrosion Inhibitor) film, secured on wooden pallets, and labeled with material certificates and traceability codes.
5. Applications
The Stainless Steel Coil Tube (Product No. 609) finds extensive application across multiple industrial sectors:
- HVAC & Air Conditioning Systems: Serves as the core heat transfer element in fan coil units (FCU) for medium-temperature water systems, where the coil tube facilitates efficient thermal exchange between circulating water and air streams. Research on medium-temperature water air-conditioning systems has demonstrated that stainless steel coil tubes outperform traditional copper tubes in terms of longevity, resistance to refrigerant-induced corrosion, and compatibility with environmentally friendly refrigerants.
- Refrigeration & Chilled Water Systems: Used in evaporators, condensers, and heat exchangers where corrosion resistance and thermal efficiency are paramount.
- Medical & Pharmaceutical Equipment: Employed in sterilization systems, medical gas delivery, and pharmaceutical processing lines requiring hygienic-grade surfaces (Ra ≤ 0.4 μm).
- Food & Beverage Industry: Utilized in pasteurization coils, CIP (Clean-in-Place) systems, and beverage dispensing equipment.
- Chemical Processing: Applied in heat exchangers, condensers, and reactor cooling systems handling aggressive chemicals, acids, and chlorides.
- Marine & Offshore Engineering: Deployed in ballast water systems, cooling circuits, and seawater heat exchangers where resistance to marine biofouling and chloride pitting is essential.
- Solar Thermal Systems: Used as absorber tubes and heat collection coils in concentrated solar power (CSP) installations.
- Automotive & Transportation: Integrated into exhaust heat recovery systems, fuel cell cooling loops, and EV battery thermal management.
6. Unique Selling Points
Exceptional Corrosion Resistance: The austenitic and duplex stainless steel grades provide outstanding resistance to oxidation, pitting, and stress-corrosion cracking in aggressive environments, significantly extending service life compared to carbon steel or copper alternatives.
Compact Thermal Performance: The helical coil geometry maximizes heat transfer surface area within minimal spatial footprint, making it ideal for medium-temperature water systems where space constraints are critical.
Hygienic & Food-Grade Compliance: Available in electropolished and passivated finishes meeting FDA, EHEDG (European Hygienic Engineering Design Group), and 3-A Sanitary Standards for food, beverage, and pharmaceutical applications.
Full Traceability & Certifiability: Every coil lot is accompanied by a mill test certificate (MTC) per EN 10204 Type 3.1, with full chemical and mechanical property documentation for audit compliance.
Customizability: Wenzhou Jixing Metal Materials Co., Ltd. offers fully configurable OD, wall thickness, coil diameter, length, and surface finish options to meet project-specific engineering requirements.
7. Quality Certifications & Standards Compliance
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification ensuring consistent product quality and process control. |
| ISO 14001:2015 | Environmental Management System certification demonstrating commitment to sustainable manufacturing. |
| ISO 45001:2018 | Occupational Health & Safety Management System certification. |
| CE Marking | Compliance with European Union directives for market access. |
| ASTM A213 / A269 | Conformance to American standards for seamless and welded stainless steel tubing. |
| EN 10217-7 | European standard for heat exchanger tubes made of non-ferrous metals and alloys (stainless steel). |
| GB/T 14976 | Chinese national standard for seamless stainless steel tubes for fluid transport. |
| EN 10204 Type 3.1 | Mill test certificate providing detailed material verification and inspection data. |
| NSF / ANSI 61 | Drinking water system components certification (for potable water applications). |
| PED 2014/68/EU | Pressure Equipment Directive compliance for pressure-containing applications. |
8. Technical Notes & Recommendations
- Installation Guidance: Coil tubes should be installed with a minimum bend radius of 3× the outer diameter to prevent kinking or ovality. Avoid sharp compression or axial loading during mounting.
- Welding Considerations: When field-welding coil tube connections, use GTAW (Gas Tungsten Arc Welding) or ORBT (Orbital Ring Butt TIG) welding with argon shielding gas. Post-weld passivation is recommended to restore corrosion resistance at weld zones.
- Storage Conditions: Store in a dry, well-ventilated area away from direct contact with carbon steel to prevent galvanic corrosion. Avoid exposure to chlorinated environments during storage.
- Medium-Temperature Water System Integration: For FCU applications, coil tube configurations with 6–12 mm OD and 0.5–1.0 mm wall thickness provide optimal balance between thermal efficiency and pressure drop, as validated by performance studies on medium-temperature water air-conditioning systems.
Wenzhou Jixing Metal Materials Co., Ltd. — Engineering Excellence in Stainless Steel Tubular Solutions