Stainless Steel Coil Tube (Coiltube) — Industrial-Grade Product Specification
1. Product Overview
The Stainless Steel Coil Tube (Coiltube), manufactured by Wenzhou Jixing Metal Materials Co., Ltd., is a precision-engineered continuous-length tubing product supplied in coiled configuration. This product is designed for demanding industrial and commercial applications where corrosion resistance, mechanical integrity, and thermal performance are paramount. The coil tube format enables seamless integration into automated forming, bending, and welding systems, significantly reducing material waste and production cycle times.
Coiltube products are extensively utilized in fan coil units (FCUs) and air induction systems within commercial HVAC (Heating, Ventilation, and Air Conditioning) applications, particularly in hospitality and hotel environments. Their inherent material properties ensure long service life under cyclic thermal loading and exposure to humid or corrosive atmospheres.
2. Material & Properties
Coiltube products are fabricated from high-grade austenitic and duplex stainless steel grades, selected according to application requirements:
- Grade 304 (UNS S30408): General-purpose corrosion resistance; suitable for atmospheric and mild chemical environments.
- Grade 316 (UNS S31608): Enhanced resistance to chlorides and marine atmospheres; preferred for coastal or chemical processing applications.
- Grade 321 (UNS S32108): Stabilized with titanium; suitable for elevated-temperature service up to 870°C.
- Grade 316L (UNS S31603): Low-carbon variant for weldability in thick-wall or sensitization-sensitive applications.
Key Mechanical & Physical Properties (Typical — Grade 304, Annealed Condition)
| Property | Specification |
|---|---|
| Tensile Strength (UTS) | ≥ 515 MPa (75 ksi) |
| Yield Strength (0.2% Offset) | ≥ 205 MPa (30 ksi) |
| Elongation (at Break) | ≥ 40% |
| Thermal Conductivity (20°C) | 16.3 W/(m·K) |
| Thermal Expansion Coefficient (20–100°C) | 17.3 × 10⁻⁶ /K |
| Density | 8.00 g/cm³ |
| Maximum Service Temperature | 870°C (1600°F) |
3. Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Product No. | 615 |
| Supplier | Wenzhou Jixing Metal Materials Co., Ltd. |
| Tube Shape | Round (default); oval, rectangular available on request |
| Outer Diameter (OD) | 3.0 mm – 50.8 mm (1/8" – 2") |
| Wall Thickness | 0.3 mm – 3.0 mm |
| Coil Inner Diameter | 100 mm – 600 mm (customizable) |
| Coil Length | Continuous; typical 50 m – 200 m per coil |
| Surface Finish | Bright annealed, pickled, polished (Ra ≤ 0.8 μm) |
| Standards Compliance | ASTM A213 / A269, EN 10216-5, GB/T 12771 |
| Packaging | Wooden crate with moisture-proof wrapping; export-grade |
| Customization | Special dimensions, alloy grades, and surface treatments available |
4. Manufacturing Process
- Material Selection & Incoming Inspection: Virgin stainless steel strip or hot-rolled coil is sourced from certified mills and subjected to spectrographic analysis (PMI) to verify chemical composition compliance.
- Forming & Seaming: Cold-rolled strip is formed into a tubular geometry via roll-forming or hydraulic pressing, followed by resistance welding of the seam to achieve a continuous tube profile.
- Automatic Welding: High-frequency induction welding or orbital TIG (Tungsten Inert Gas) welding is employed for seam integrity, ensuring uniform weld bead geometry and minimum dilution.
- Heat Treatment (Annealing): Tubes are annealed in a controlled atmosphere furnace at 1050–1150°C to relieve residual stresses, restore full annealed properties, and eliminate sensitization.
- Pickling & Passivation: Post-annealing oxide scale is removed via acid pickling (HNO₃/HF blend), followed by passivation to establish a protective chromium oxide layer.
- Surface Finishing: Mechanical polishing or electropolishing is applied to achieve the required surface roughness (Ra) for fluid-flow or aesthetic applications.
- Dimensional Inspection: Each coil undergoes 100% inline dimensional verification including OD, wall thickness, straightness, and coil diameter using laser and ultrasonic gauging.
- Final Testing & Certification: Hydrostatic pressure testing, spectrometric re-verification, and mechanical testing are performed. Mill test certificates (MTC) per EN 10204 3.1/3.2 are issued.
- Coiling & Packaging: Tubes are coiled to specified inner diameter, wrapped in moisture-barrier material, and packed in export-grade wooden crates for shipment.
5. Applications
Stainless steel coiltube products find extensive application across multiple industries:
- HVAC Systems: Heat exchanger coils in fan coil units (FCUs), air handling units (AHUs), and air induction systems for hotels, commercial buildings, and hospitals. The coil tube format allows efficient serpentine or spiral coil winding for maximum heat transfer surface area.
- Refrigeration & Heat Exchangers: Condenser and evaporator tubing for chillers, heat pumps, and cryogenic systems.
- Chemical Processing: Reactor coils, heat transfer lines, and process piping where corrosion resistance is critical.
- Food & Beverage Industry: Sanitary-grade tubing for pasteurization systems, CIP (Clean-in-Place) loops, and beverage transfer lines (316L grade, electropolished).
- Automotive & Aerospace: Fuel lines, hydraulic lines, and exhaust system components.
- Oil & Gas: Downhole tubing, chemical injection lines, and offshore platform piping.
- Medical Devices: Tubing for dialysis machines, oxygen delivery systems, and surgical instrument manufacturing.
6. Quality Certifications
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| ISO 14001:2015 | Environmental Management System |
| ASTM A213 / A269 | Austenitic stainless steel seamless & welded tubing |
| EN 10216-5 | Stainless steel seamless and welded tubes for general applications |
| GB/T 12771 | Chinese national standard for stainless steel welded tubes |
| EN 10204 3.1 / 3.2 | Mill Test Certificate (MTC) — Inspection certificate / Test report |
| CE Marking | European conformity for construction & pressure equipment |
| NORSOK M-650 | Oil & gas industry material specification (available on request) |
7. Unique Selling Points
- Superior Corrosion Resistance: Austenitic stainless steel composition provides exceptional resistance to oxidation, pitting, and crevice corrosion across a wide range of environments and temperatures.
- Continuous Coiled Format: Eliminates weld joints in the tube body, reducing leak points and improving structural integrity compared to cut-length pipe assemblies.
- Full Customization: Non-standard dimensions, exotic alloy grades, and specialized surface finishes are available through the supplier's flexible manufacturing capability.
- Traceability & Compliance: Full batch traceability from raw material to finished product with certified mill test documentation meeting international standards.
- Optimized for HVAC Heat Exchangers: Tube dimensions and surface treatments are specifically optimized for maximum thermal efficiency in fan coil unit and air induction system applications.
- Long Service Life: Design life exceeding 25–30 years under normal operating conditions, significantly reducing lifecycle maintenance costs.
Note: All specifications are subject to confirmation against the final purchase order and applicable project specifications. Custom requirements should be communicated during the quotation stage to ensure full compliance with end-use application criteria.