Stainless Steel Coil Tube (Fan Coil Unit Coil Tube)
Product Overview
The Stainless Steel Coil Tube is a precision-engineered coiled piping product manufactured by Wenzhou Jixing Metal Materials Co., Ltd (Product No. 1147). This product is primarily designed for use in fan coil units (FCU), heat exchangers, HVAC systems, and thermal management applications. The coil tube features a consistent helical winding geometry that maximizes heat transfer surface area within a compact envelope, making it an indispensable component in modern air conditioning and refrigeration systems.
Addressing the well-documented challenges in domestic fan coil unit selection—including mismatched coil dimensions, inadequate heat exchange performance, and poor compatibility with system parameters—this product line offers standardized, high-tolerance coil tubes that ensure reliable integration and optimal thermal performance across a wide range of operating conditions.
Material & Properties
- Base Material: Austenitic stainless steel grades including SUS304 (UNS S30400), SUS316 (UNS S31600), and SUS321 (UNS S32100)
- Chemical Composition (SUS304): Carbon (C) ≤ 0.08%, Chromium (Cr) 18.0–20.0%, Nickel (Ni) 8.0–10.5%, Manganese (Mn) ≤ 2.0%, Silicon (Si) ≤ 0.75%
- Tensile Strength: ≥ 515 MPa (for annealed condition)
- Yield Strength: ≥ 205 MPa
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, chemical media, and high-temperature oxidation
- Temperature Range: −196 °C to +870 °C (continuous service)
- Thermal Conductivity: 14.9 W/(m·K) at 20 °C
- Surface Finish: Pickled and passivated, Ra ≤ 0.8 μm
Specifications
| Parameter | Specification |
|---|---|
| Product No. | 1147 |
| Outer Diameter (OD) | 6.0 mm – 25.4 mm (customizable) |
| Wall Thickness (WT) | 0.5 mm – 1.5 mm |
| Coil Diameter | 150 mm – 600 mm |
| Coil Length | 1,000 mm – 12,000 mm |
| Pitch (Coil Spacing) | ±0.5 mm tolerance |
| Roundness Tolerance | ≤ 0.1 mm |
| Straightness Deviation | ≤ 1.0 mm/m |
| End Condition | Flat cut / Beveled / Formed (per customer drawing) |
| Heat Treatment | Solution annealed (1050 °C – 1150 °C, water quench) |
| Standard | ASTM A269 / ASTM A213 / GB/T 12771 / EN 10216-5 |
| Packaging | Coil wound on wooden pallet, wrapped in moisture-proof film |
Manufacturing Process
- Material Selection & Inspection: Raw stainless steel strip or seamless pipe material is sourced from certified mills and subjected to spectroscopic analysis to verify chemical composition compliance with ASTM/GB standards.
- Cold Forming & Coiling: The tube blank is fed through precision coiling machinery equipped with servo-controlled tension systems to produce a uniform helical coil with tight dimensional tolerances.
- Heat Treatment: The formed coil tube undergoes solution annealing at 1050–1150 °C followed by rapid quenching to eliminate residual stresses and restore full austenitic microstructure, ensuring maximum ductility and corrosion resistance.
- Pickling & Passivation: Surface oxide scale is removed via hydrofluoric acid pickling, followed by nitric acid passivation to establish a stable chromium oxide film for long-term corrosion protection.
- Dimensional Inspection: Each coil is measured for OD, wall thickness, coil diameter, pitch uniformity, and straightness using laser scanning and coordinate measuring machines (CMM).
- Pressure Testing: Hydrostatic pressure testing at 1.5× working pressure confirms integrity and absence of leaks or micro-defects.
- Packaging & Dispatch: Qualified products are wound onto protective wooden spools, wrapped in PE film, and labeled with mill test certificates (MTC) prior to shipment.
Applications
- HVAC Fan Coil Units (FCU): Primary heat exchange coil in air handling units, terminal units, and rooftop systems for commercial and residential buildings.
- Refrigeration & Chiller Systems: Evaporator and condenser coils in industrial refrigeration plants and central air conditioning chillers.
- Heat Exchangers: Compact heat transfer surfaces in plate-fin and shell-and-coil heat exchangers for process industries.
- Automotive Thermal Management: Engine coolant loops, intercoolers, and HVAC evaporator coils in commercial vehicles.
- Food & Pharmaceutical Processing: Sanitary-grade heating and cooling coils in pasteurization, sterilization, and fermentation equipment.
- Solar Water Heating Systems: Absorber tubes and circulation coils in thermosiphon and forced-circulation solar thermal installations.
Quality Certifications
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- ISO 45001:2018 — Occupational Health and Safety Management System certification
- EN 10204 — Type 3.1 Mill Test Certificate (MTC) provided with every shipment
- CE Marking — Compliance with European Machinery Directive for HVAC components
- SGS Testing Report — Third-party material and dimensional verification
- RoHS / REACH Compliance — Restriction of hazardous substances for global market access
Unique Selling Points
Precision Engineering for Optimal Heat Transfer: Our coil tubes are manufactured with ±0.5 mm pitch tolerance, ensuring uniform flow distribution and maximizing the effective heat exchange area—directly addressing the common selection errors in domestic fan coil unit design where mismatched coil geometry leads to reduced efficiency and premature failure.
- Full Traceability: Every coil is linked to a unique heat number with complete chemical and mechanical test data, enabling full supply chain traceability from raw material to finished product.
- Customization Capability: Flexible OD, wall thickness, coil diameter, and pitch configurations allow engineers to tailor the coil tube to specific thermal load requirements and spatial constraints.
- Superior Corrosion Performance: SUS316 grade option with 2.0–3.0% Molybdenum content provides enhanced resistance to chloride-induced pitting, extending service life in aggressive environments.
- Technical Support & Selection Guidance: Based on extensive literature study of fan coil unit selection challenges, our engineering team provides complimentary coil tube selection calculations and thermal performance modeling to eliminate design-stage errors.
- Cost-Effective Alternative: Competitive pricing compared to imported equivalents while maintaining equivalent or superior mechanical and dimensional specifications.
Technical Note on Fan Coil Unit Selection
Based on industry literature analysis, common problems in domestic fan coil unit selection include:
- Incorrect assumption of uniform coil tube pitch leading to airflow maldistribution
- Failure to account for coil tube degradation over service life (fouling factor)
- Inadequate consideration of bend radius effects on pressure drop
- Mismatch between coil tube thermal conductivity and refrigerant/water-side heat transfer coefficients
Wenzhou Jixing Metal Materials Co., Ltd addresses these issues by providing coil tubes with documented thermal performance data, guaranteed pitch uniformity, and comprehensive selection support to ensure system-level compatibility and long-term operational reliability.