Stainless Steel Coil Tube — HVAC & Thermal Exchange Series (Model: JX-CT)
1. Product Overview
The Stainless Steel Coil Tube (also referred to as 盘管 / Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product designed for integration into air conditioning, refrigeration, and thermal energy exchange systems. The coil tube is formed by winding seamless or welded stainless steel tubing into a helical or serpentine configuration, enabling compact heat transfer surfaces with high thermal efficiency.
This product line is specifically engineered for applications in single-coil and dual-fan air conditioning systems, as validated through simulation modeling in the EnergyPlus platform. The coil tube serves as the core heat exchange element, facilitating efficient thermal transfer between air streams and refrigerant or water circuits within HVAC (Heating, Ventilation, and Air Conditioning) units.
Key Differentiator: Wenzhou Jixing's coil tubes are optimized for EnergyPlus-compatible thermal performance modeling, ensuring that real-world heat transfer characteristics align closely with simulation predictions — a critical advantage for system designers and engineers working with performance-based HVAC design methodologies.
2. Material & Properties
2.1 Base Material Grades
The coil tubes are fabricated from high-grade austenitic stainless steel conforming to international standards. The primary material specifications are as follows:
- AISI 304 / SUS 304 / EN 1.4301 — General-purpose grade with excellent corrosion resistance and formability; ideal for standard HVAC and refrigeration applications.
- AISI 316 / SUS 316 / EN 1.4401 — Molybdenum-enhanced grade offering superior resistance to chlorides and aggressive chemical environments; suited for coastal or industrial applications.
- AISI 321 / SUS 321 / EN 1.4541 — Titanium-stabilized grade for high-temperature service conditions requiring resistance to intergranular corrosion.
2.2 Mechanical & Physical Properties
| Property | AISI 304 | AISI 316 | AISI 321 |
|---|---|---|---|
| Tensile Strength (MPa) | ≥ 520 | ≥ 520 | ≥ 520 |
| Yield Strength (MPa) | ≥ 205 | ≥ 205 | ≥ 205 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 40 |
| Density (g/cm³) | 7.93 | 8.00 | 7.93 |
| Thermal Conductivity at 20°C (W/m·K) | 16.3 | 14.6 | 16.3 |
| Operating Temperature Range (°C) | −196 to +870 | −196 to +870 | −196 to +900 |
| Surface Finish (Ra) | 0.2 – 1.6 μm (BEP/EP) | 0.2 – 1.6 μm (BEP/EP) | 0.2 – 1.6 μm (BEP/EP) |
BEP = Bright End Polish; EP = Electropolished. The smooth internal surface finish minimizes fluid friction and prevents fouling, directly enhancing heat transfer efficiency in coil applications.
3. Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Tube Outer Diameter (OD) | 6.35 mm, 8.0 mm, 9.53 mm, 12.7 mm, 15.88 mm | ASME B36.19M / GB/T 14976 |
| Wall Thickness | 0.50 mm, 0.80 mm, 1.00 mm, 1.50 mm, 2.00 mm | ASME B36.19M |
| Coil Diameter | 100 mm – 800 mm (customizable) | — |
| Coil Length (Per Coil) | Up to 50 m (standard); longer on request | — |
| OD Tolerance | ±0.05 mm (precision grade) | ASTM A213 |
| Wall Thickness Tolerance | ±10% of nominal | ASTM A213 / EN 10216-5 |
| Coil Pitch (Helical) | 8 mm – 25 mm (adjustable per design) | — |
| Winding Pattern | Spiral, Serpentine, Helical, or Custom | — |
| End Treatment | Beveled, Plain, Flared, or Threaded | ASME B36.19M |
| Maximum Operating Pressure | Up to 2.5 MPa (grade-dependent) | ASME Section VIII |
| Delivery Form | Coiled (on spool), Cut-to-Length, or Pre-Assembled Coil Pack | — |
4. Manufacturing Process
The production of Wenzhou Jixing stainless steel coil tubes follows a rigorous, multi-stage process to ensure dimensional accuracy, mechanical integrity, and surface quality:
- Raw Material Procurement & Inspection: Stainless steel wire rod or pre-formed tubing is sourced from certified mills. Incoming material undergoes spectroscopic analysis (PMI — Positive Material Identification), chemical composition verification, and visual inspection for surface defects.
- Tube Drawing & Forming: For seamless tubes, cold drawing reduces the OD and wall thickness to precise specifications. For welded tubes, high-frequency induction welding (HFW) or orbital welding is employed, followed by cold reduction.
- Heat Treatment & Annealing: Tubes are solution annealed at 1040–1120°C and rapidly quenched to achieve a uniform austenitic microstructure, eliminating residual stresses and ensuring optimal ductility for coiling.
- Surface Finishing: Tubes undergo mechanical polishing followed by electropolishing (EP) to achieve a surface roughness of Ra ≤ 0.2 μm, critical for minimizing thermal boundary layer resistance in heat exchange applications.
- Coil Winding & Forming: Using CNC-controlled coiling machines, the tubing is precisely wound into the specified coil geometry (spiral, serpentine, or helical). The winding process maintains consistent pitch and coil diameter within ±1 mm tolerance.
- Post-Forming Stress Relief: After coiling, the coil tube undergoes stress-relief annealing at 450–600°C to eliminate work-hardening effects introduced during forming, ensuring long-term dimensional stability under thermal cycling.
- Quality Assurance & Testing: Every coil tube batch is subjected to hydrostatic pressure testing (per ASTM A213), dimensional verification, and surface inspection. Batch traceability is maintained through heat-number coding.
5. Applications
5.1 HVAC & Air Conditioning Systems
Coil tubes serve as the primary heat exchange elements in air conditioning units, including:
- Single-Coil Air Conditioning Systems: Where a single coil tube circuit handles both heating and cooling via reversible refrigerant flow.
- Dual-Fan Air Conditioning Systems: As modeled in EnergyPlus simulations, dual-fan configurations with coil tubes enable independent air-side and refrigerant-side flow control, improving part-load efficiency and thermal comfort.
- Heat Pump Units: Integral coil tubes for evaporator and condenser circuits in air-to-air and air-to-water heat pumps.
5.2 Additional Applications
- Refrigeration & Cold Storage: Evaporator and condenser coils for commercial refrigeration, walk-in coolers, and blast freezers.
- Industrial Process Heating & Cooling: Heat exchangers in chemical processing, pharmaceutical manufacturing, and food processing lines.
- Automotive Thermal Management: Intercooler coils, oil coolers, and cabin HVAC heat exchangers.
- Marine & Offshore Systems: Corrosion-resistant coil assemblies for marine air conditioning and cooling systems (AISI 316 grade).
- Building Services: Radiator coils, underfloor heating circuits, and hydronic air handling units (AHUs).
6. Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that all coil tube products meet international standards:
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System certification covering all manufacturing operations |
| ISO 14001:2015 | Environmental Management System |
| ASTM A213 | Standard specification for austenitic stainless steel seamless, cold-drawn tubing |
| ASME B36.19M | Dimensions and tolerances for stainless steel tube |
| EN 10216-5 | European standard for welded austenitic stainless steel tubes for pressure purposes |
| GB/T 14976 | Chinese national standard for cold-rolled stainless steel seamless tubes |
| CE Marking | Conformity to European health, safety, and environmental protection standards |
| RoHS Compliance | Restriction of Hazardous Substances directive compliance |
| Mill Test Report (MTR) | Full chemical and mechanical test documentation provided with each shipment |
7. Unique Selling Points
- EnergyPlus-Validated Thermal Performance: The coil tube's heat transfer characteristics have been characterized and validated through EnergyPlus simulation modeling, providing engineers with reliable performance data for system-level HVAC design and optimization.
- Precision Coiling Tolerance: CNC-controlled winding ensures coil pitch and diameter accuracy of ±1 mm, enabling seamless integration into compact AHU and fan coil unit (FCU) designs.
- Electropolished Interior Surface: Ra ≤ 0.2 μm surface finish reduces thermal boundary layer thickness, improving overall heat exchange efficiency by up to 15% compared to standard mill finish.
- Custom Geometric Configuration: Available in spiral, serpentine, and helical winding patterns with customizable coil diameters, pitches, and end treatments to match specific system design requirements.
- Full Traceability: Every coil tube batch is traceable to its raw material heat number, with complete Mill Test Reports (MTR) and dimensional inspection records provided.
- Multi-Grade Availability: AISI 304, 316, and 321 grades enable selection based on environmental aggressiveness, temperature requirements, and cost optimization.
8. Ordering Information
For custom coil tube configurations, technical consultation, or EnergyPlus-compatible performance data sheets, contact Wenzhou Jixing Metal Materials Co., Ltd. directly. Minimum order quantities and lead times vary based on grade, OD, wall thickness, and coil geometry specifications. Sample coils and full-length prototypes are available for pre-production validation.