Stainless Steel Coil Tube (Coiltube) — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered cold-drawn or cold-rolled stainless steel tubing product, supplied in continuous coil form for downstream processing and fabrication. Designed for high-performance thermal management applications, this product line is particularly suited for integration into advanced HVAC (Heating, Ventilation, and Air Conditioning) systems, including floor radiation coupled with fan coil unit air conditioning configurations.
The coil tube format enables efficient material utilization, minimizes waste during cutting and forming operations, and supports automated manufacturing workflows. The product adheres to international material standards and is engineered to deliver superior corrosion resistance, mechanical integrity, and thermal transfer efficiency across demanding operating environments.
2. Material & Properties
2.1 Base Material Grades
- AISI 304 / ASTM A269 TP304 — General-purpose austenitic stainless steel offering excellent weldability and corrosion resistance
- AISI 316 / ASTM A269 TP316 — Enhanced chromium-molybdenum austenitic grade with superior resistance to chlorides and acidic environments
- AISI 321 / ASTM A269 TP321 — Titanium-stabilized austenitic grade suitable for elevated-temperature service conditions
2.2 Mechanical Properties
| Property | Specification (AISI 304) | Specification (AISI 316) |
|---|---|---|
| Tensile Strength (UTS) | ≥ 515 MPa | ≥ 515 MPa |
| Yield Strength (0.2% Offset) | ≥ 205 MPa | ≥ 205 MPa |
| Elongation (at Break) | ≥ 40% | ≥ 40% |
| Hardness (Rockwell B) | ≤ 95 HRB | ≤ 95 HRB |
| Thermal Conductivity (at 20°C) | 16.3 W/(m·K) | 14.6 W/(m·K) |
| Operating Temperature Range | −196°C to +870°C | −196°C to +870°C |
2.3 Chemical Composition (Typical, wt%)
| Element | 304 Grade | 316 Grade |
|---|---|---|
| Carbon (C) | ≤ 0.08 | ≤ 0.08 |
| Chromium (Cr) | 18.0 – 20.0 | 16.0 – 18.0 |
| Nickel (Ni) | 8.0 – 10.5 | 10.0 – 14.0 |
| Molybdenum (Mo) | — | 2.0 – 3.0 |
| Iron (Fe) | Balance | Balance |
3. Dimensions & Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (customizable upon request) |
| Wall Thickness | 0.5 mm – 3.0 mm |
| Coil Length (per roll) | Up to 1,000 m (standard); custom lengths available |
| Coil Inner Diameter (ID) | 150 mm – 500 mm |
| Surface Finish | 2B, BA (Bright Annealed), No. 4 Brushed, Mirror (8K) |
| Tolerance on OD | ± 0.1 mm (standard); ± 0.05 mm (precision grade) |
| Tolerance on Wall Thickness | ± 10% of nominal |
| Forming Condition | Annealed (A), Half-Hard (H½), Full-Hard (H) |
| End Treatment | Plain, Beveled, or Threaded (per customer specification) |
4. Manufacturing Process
4.1 Production Workflow
- Raw Material Preparation: High-purity stainless steel strip is sourced from certified mills and subjected to incoming quality inspection, including spectroscopic composition analysis and dimensional verification.
- Forming & Welding: Precision roll-forming or drawing processes convert flat strip into tubular geometry. Where applicable, continuous TIG (Tungsten Inert Gas) or orbital welding produces a seamless inner surface with minimal heat-affected zone.
- Cold Drawing: Tubes undergo multi-stage cold drawing through tungsten carbide dies to achieve precise dimensional tolerances and enhanced mechanical properties.
- Heat Treatment (Annealing): Solution annealing at 1050°C – 1150°C followed by controlled cooling eliminates residual stresses, restores full ductility, and ensures uniform microstructure.
- Surface Treatment: Pickling and passivation remove scale and contaminants; electropolishing or mechanical finishing achieves the specified surface roughness (Ra ≤ 0.4 μm for mirror finish).
- Coiling: Finished tubing is wound onto precision-controlled coil pay-offs with tension regulation to prevent deformation or kinking.
- Quality Inspection & Packaging: Each coil undergoes non-destructive testing (NDT) including eddy current or ultrasonic examination, dimensional gauging, and visual inspection before protective packaging.
4.2 Process Advantages
- Continuous coil production ensures uniformity along the entire tube length, eliminating joint-to-joint variability inherent in straight-length manufacturing
- Minimal material waste (typically < 3%) compared to cut-to-length production methods
- Automation-compatible format enables seamless integration with high-speed downstream fabrication equipment
- Customizable coil parameters accommodate diverse downstream processing requirements
5. Applications
5.1 Primary Application Domains
- HVAC Systems — Floor Radiation Coupled Fan Coil Unit (FCU) Configurations: The coil tube serves as the core heat exchange element in hybrid radiant-floor and fan coil air conditioning systems. In such systems, stainless steel coil tubes embedded in floor panels provide low-temperature radiant heating/cooling, while integrated fan coil units deliver supplementary forced-air conditioning. This coupled approach achieves superior thermal comfort through stratified temperature management, reduced surface condensation risk, and optimized energy consumption profiles.
- Industrial Heat Exchangers: Compact heat exchanger assemblies for chemical processing, pharmaceutical manufacturing, and food-grade fluid handling
- Automotive & Transportation: Radiator cores, intercooler tubes, and exhaust system components requiring high-temperature and corrosion-resistant tubing
- Medical Equipment: Autoclave-compatible fluid lines, sterilization chambers, and diagnostic instrument heat exchangers
- Building Services: Domestic hot water circulation loops, geothermal heat pump systems, and district heating/cooling distribution networks
- Process Engineering: Condensers, evaporators, and reboilers in petrochemical and power generation applications
5.2 Performance in Floor Radiation Coupled FCU Systems
In the context of floor radiation coupled fan coil unit air conditioning systems, the stainless steel coil tube offers the following engineering advantages:
- Thermal Stability: Austenitic stainless steel maintains dimensional and mechanical stability across the wide temperature differential encountered between radiant floor loops (typically 25°C – 45°C) and fan coil supply air (typically 12°C – 18°C for cooling)
- Long-Term Corrosion Resistance: Eliminates iron oxide scale formation that degrades heat transfer efficiency over time, ensuring consistent thermal performance throughout the system's service life
- Hygienic Surface Characteristics: Smooth, non-porous interior surfaces prevent biofilm accumulation, critical for indoor air quality (IAQ) maintenance in occupied spaces
- Design Flexibility: Coil tube format permits custom loop configurations, enabling system designers to optimize flow distribution and pressure drop characteristics for specific architectural geometries
6. Quality Certifications & Compliance
| Certification / Standard | Scope of Applicability |
|---|---|
| ISO 9001:2015 | Quality Management System — Full production process |
| ISO 14001:2015 | Environmental Management System |
| ASTM A269 / A270 | Material specification for seamless and welded austenitic stainless steel tube |
| EN 10216-5 | European specification for stainless steel tubes for pressure purposes |
| GB/T 14976 (Chinese National Standard) | Specifications for seamless stainless steel tubes for general applications |
| CE Marking | Compliance with European Directive requirements for pressure equipment |
| Mill Test Certificates (MTC / EN 10204 3.1) | Material traceability and chemical/mechanical property verification per batch |
6.1 Inspection & Testing Protocols
- 100% dimensional inspection using automated laser gauging systems
- Batch sampling for chemical composition verification via Optical Emission Spectrometry (OES)
- Non-destructive testing (NDT) per ASTM E2489 (eddy current) or ASTM E3097 (magnetic flux leakage) for weld seam integrity
- Pneumatic or hydrostatic pressure testing per customer-specified test pressure (typically 2.0 – 3.0× working pressure)
- Surface quality verification through profilometry and visual inspection under controlled lighting
7. Unique Selling Points
- Integrated Coil Format: Continuous coil supply eliminates butt-weld joints, reducing potential leak points and improving system reliability in critical thermal applications
- Precision Engineering: Tight dimensional tolerances (± 0.05 mm OD) ensure optimal fit within heat exchanger tube sheets and manifold assemblies
- Grade Flexibility: Availability across 304, 316, and 321 grades allows specification matching to specific environmental and thermal requirements
- Surface Finish Options: Multiple finish grades support applications ranging from industrial process piping to hygienic food-contact and medical systems
- Customization Capability: Bespoke coil dimensions, lengths, and forming conditions accommodate project-specific engineering requirements
- Full Traceability: Complete material documentation and batch-level traceability support regulatory compliance in pharmaceutical, food, and aerospace supply chains
8. Packaging & Delivery
Each coil is wound onto a steel or wooden core, wrapped in moisture-proof protective film, and secured with steel strapping. Coils are palletized and shrink-wrapped for containerized shipping. Desiccant packs are included to prevent moisture ingress during transit. Custom packaging configurations are available for export shipments to comply with destination-country import regulations.
Note: All specifications are subject to verification against current production capabilities. Custom orders require prior technical consultation and approval of engineering drawings. Wenzhou Jixing Metal Materials Co., Ltd reserves the right to update specifications based on material availability and process improvements.