Stainless Steel Coil Tube (Coiltube) — Wenzhou Jixing Metal Materials Co., Ltd
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered tubular product formed into a continuous helical or spiral configuration. This product is specifically designed for use in heat exchanger applications, including fan coil units (FCU), air handling units (AHU), and all-air conditioning systems. The coil tube serves as the primary heat transfer element, enabling efficient thermal exchange between refrigerant or water circuits and process air. With product reference number 306, this coiltube line represents the company's commitment to high-performance stainless steel tubing solutions for HVAC (Heating, Ventilation, and Air Conditioning) and industrial thermal management systems.
Material & Properties
The coil tubes are fabricated from high-grade stainless steel, ensuring exceptional corrosion resistance, mechanical strength, and long-term service durability under demanding environmental conditions.
Material Grades
- AISI 304 (UNS S30400) — General-purpose austenitic stainless steel offering excellent corrosion resistance and formability; chromium (Cr) content ≥18%, nickel (Ni) content ≥8%.
- AISI 316L (UNS S31603) — Enhanced austenitic grade with molybdenum (Mo) addition (2–3%) for superior resistance to pitting and crevice corrosion in aggressive environments.
- TP316Ti (UNS S31624) — Titanium-stabilized variant suitable for high-temperature and chloride-rich service conditions.
Mechanical Properties
- Tensile Strength (UTS): ≥515 MPa (annealed condition)
- Yield Strength (0.2% offset): ≥205 MPa
- Elongation at Break: ≥40% (minimum, annealed)
- Hardness: ≤230 HB (annealed condition)
- Service Temperature Range: −196°C to +870°C
Physical Properties
- Density: 7.93 g/cm³ (AISI 304) / 8.00 g/cm³ (AISI 316L)
- Thermal Conductivity (at 20°C): 16.3 W/(m·K) (AISI 304)
- Specific Heat Capacity: 500 J/(kg·K) (at 20°C)
- Thermal Expansion Coefficient: 17.3 × 10⁻⁶ /°C (20–100°C)
- Electrical Resistivity: 0.72 × 10⁻⁶ Ω·m (at 20°C)
Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Product Reference No. | 306 | — |
| Outer Diameter (OD) | 3.0 / 4.0 / 5.0 / 6.0 / 8.0 / 9.5 / 12.0 | mm |
| Wall Thickness (WT) | 0.3 / 0.4 / 0.5 / 0.6 / 0.7 / 0.8 | mm |
| Coil Pitch (Center-to-Center Spacing) | 15 / 20 / 25 / 30 / 35 / 40 | mm |
| Coil Height (Row Depth) | 30 / 40 / 50 / 60 / 75 / 100 / 150 / 200 | mm |
| Tube Length per Coil | 5 / 10 / 15 / 20 / 30 / 50 | m |
| Surface Finish | No. 4 Brushed / BA (Bright Annealed) / Mirror Polished (Ra ≤ 0.4 μm) | — |
| Tolerance (OD) | ±0.1 mm | mm |
| Tolerance (WT) | ±10% of nominal | % |
| End Forming | Flat / Flanged / Crimped / Welded U-Bend | — |
| Maximum Working Pressure | 1.6 / 2.5 / 4.0 | MPa |
| Standard Test Pressure | 1.5 × Working Pressure | MPa |
Manufacturing Process
The production of Wenzhou Jixing's stainless steel coil tubes follows a rigorous, multi-stage manufacturing protocol to ensure dimensional accuracy, metallurgical integrity, and surface quality.
- Raw Material Selection: Virgin stainless steel coils conforming to ASTM A269/A269M (welded austenitic stainless steel tubing) and ASTM A270/A270M (cold-worked seamless tubing) specifications are procured from certified mills.
- Tube Drawing & Sizing: Raw stock is cold-drawn through precision dies to achieve the target outer diameter and wall thickness with tight dimensional tolerances.
- Heat Treatment (Annealing): Tubes are solution-annealed at 1050–1100°C followed by controlled cooling to achieve the required microstructure, relieve residual stresses, and restore full ductility.
- Coil Forming (Roll Forming): The straight tubes are fed through a multi-roller forming station that progressively bends the tube into the helical/spiral configuration with the specified pitch and radius. CNC-controlled servo motors ensure consistent geometry throughout the coil length.
- Fin Attachment (if applicable): Laminated fins (aluminum or stainless steel) are mechanically bonded or soldered onto the coil tubes to increase surface area for enhanced heat transfer.
- Surface Treatment: Final surface finishing is performed via mechanical polishing, chemical passivation (citric acid or nitric acid-based), or electropolishing to achieve the specified surface roughness and corrosion resistance.
- Quality Inspection: Each coil tube batch undergoes dimensional verification, hydrostatic pressure testing, visual inspection, and chemical composition analysis (OES or optical emission spectroscopy).
- Packaging: Finished coil tubes are wrapped in protective film, placed in moisture-proof packaging, and palletized for shipment.
Applications
The stainless steel coil tube (Product No. 306) is engineered for use across a broad spectrum of thermal management and fluid handling applications:
- HVAC Systems: Primary heat exchange elements in fan coil units (FCU), air handling units (AHU), rooftop units (RTU), and all-air ventilation systems for commercial and industrial buildings.
- Refrigeration & Air Conditioning: Evaporator and condenser coils in commercial refrigeration equipment, cold storage systems, and split air conditioning units.
- Process Industry: Heat exchangers in chemical processing, pharmaceutical manufacturing, and food processing plants where corrosion resistance is critical.
- Water Treatment: Desalination plant heat recovery systems, industrial water heating, and boiler feedwater preheating circuits.
- Marine & Offshore: Seawater-cooled heat exchangers and marine HVAC systems requiring resistance to chloride-induced corrosion.
- Medical & Laboratory: Cleanroom HVAC systems, autoclave heating elements, and laboratory equipment requiring hygienic, corrosion-free surfaces.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework to ensure product excellence and regulatory compliance:
- ISO 9001:2015 — Quality Management System certification ensuring consistent production quality and process control.
- ISO 14001:2015 — Environmental Management System certification demonstrating environmental responsibility in manufacturing operations.
- ASTM A269 / A269M — Conformance to standard specifications for welded austenitic stainless steel tubing.
- ASTM A270 / A270M — Conformance to standard specifications for cold-worked seamless and welded austenitic stainless steel tubing.
- ASME B31.3 — Compliance with pressure piping code requirements for process piping applications.
- EN 10216-5 — European standard for seamless and welded austenitic stainless steel tubes.
- GB/T 12771 — Chinese national standard for welded austenitic stainless steel tubes (general industrial use).
- Mill Test Reports (MTR): Comprehensive chemical composition and mechanical property documentation provided with every shipment.
Unique Selling Points
1. Superior Corrosion Resistance: The use of high-grade austenitic stainless steel (304/316L) ensures exceptional resistance to oxidation, pitting, and general corrosion, enabling extended service life even in aggressive chemical environments.
2. Precision Engineering: CNC-controlled coil forming technology guarantees dimensional accuracy within ±0.1 mm tolerance, ensuring optimal fit and performance in heat exchanger assemblies.
3. Enhanced Thermal Performance: The coil geometry maximizes surface-to-volume ratio, delivering superior heat transfer coefficients compared to straight-tube configurations.
4. Customizable Configurations: Flexible production capability allows customization of OD, wall thickness, coil pitch, length, and surface finish to meet specific project requirements.
5. Full Traceability: Every product batch is accompanied by complete documentation including material certificates, test reports, and dimensional inspection records, ensuring complete supply chain traceability.