Stainless Steel Coil Tube — Industrial & HVAC Applications
Product Code: 927 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Overview
The Stainless Steel Coil Tube (盘管, Coiltube) is a precision-engineered cold-drawn and cold-rolled seamless tube supplied in coiled form, designed for high-flexibility routing in complex piping systems. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product combines the inherent corrosion resistance and hygienic properties of austenitic stainless steel with the installation efficiency afforded by pre-coiled geometry. The coiled configuration eliminates the need for field bending and welding in many applications, significantly reducing installation time, labor costs, and potential leak points.
This product is particularly well-suited for fan coil unit (FCU) air conditioning systems, where time-based billing and precise thermal regulation are critical. The coil tube serves as the heat exchange medium in both supply and return circuits, enabling efficient transfer of thermal energy between refrigerant/water and ambient air within commercial and residential HVAC environments.
Material & Properties
Base Alloy Grades
- ASTM A269 / AMS 5643 (304 / 06Cr19Ni10): General-purpose austenitic stainless steel with excellent corrosion resistance, weldability, and formability. Carbon content ≤ 0.08%.
- ASTM A269 / AMS 5644 (316 / 06Cr17Ni12Mo2): Molybdenum-enhanced grade offering superior resistance to pitting and crevice corrosion in chloride-containing environments.
- ASTM A270 (304L / 316L): Low-carbon variants (C ≤ 0.03%) optimized for post-fabrication welding without sensitization risk.
- 321 / 347 (Stabilized Grades): Titanium- or niobium-stabilized austenitic steels for high-temperature service (up to 870 °C) without intergranular corrosion.
Mechanical Properties (Annealed Condition)
| Property | ASTM A269 (304) | ASTM A269 (316) |
|---|---|---|
| Tensile Strength (Rm) | ≥ 515 MPa (75 ksi) | ≥ 515 MPa (75 ksi) |
| Yield Strength (Rp0.2) | ≥ 205 MPa (30 ksi) | ≥ 205 MPa (30 ksi) |
| Elongation (A50) | ≥ 40% | ≥ 40% |
| Hardness (HBW) | ≤ 217 | ≤ 217 |
| Density (ρ) | 7.93 g/cm³ | 8.00 g/cm³ |
| Thermal Conductivity (λ, 20 °C) | 16.3 W/(m·K) | 16.3 W/(m·K) |
| Specific Heat (cp, 20 °C) | 0.500 J/(g·K) | 0.500 J/(g·K) |
Surface Finish Options
- 2B Finish: Cold-rolled and annealed, bright, non-directional surface. Suitable for general industrial and HVAC applications.
- No. 4 Brushed Finish: Directional satin finish with Ra ≤ 1.6 μm. Aesthetic applications and moderate corrosion environments.
- Electropolished (EP) Finish: Electrochemical dissolution achieving Ra ≤ 0.4 μm. Critical for pharmaceutical, food-grade, and sanitary applications.
- Mirror / 8K Finish: Polished surface with Ra ≤ 0.1 μm. Decorative and high-purity process applications.
Specifications
| Parameter | Specification Range |
|---|---|
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (¼" – 2") |
| Wall Thickness (WT) | 0.5 mm – 3.0 mm (0.020" – 0.118") |
| OD Tolerance | ±0.1 mm (±0.004") |
| Wall Thickness Tolerance | ±10% of nominal |
| Coil Length per Spool | 50 m – 500 m (configurable) |
| Minimum Bend Radius | 3D (D = outer diameter) |
| Maximum Working Pressure (PN) | PN 16 – PN 40 (grade-dependent) |
| Operating Temperature Range | −196 °C to +870 °C (321/347 grades) |
| End Form | Plain, Beveled, Threaded (NPT/BSP), or Flanged |
| Coil Packaging | Wooden reel / steel drum, moisture-proof wrapped |
| Applicable Standards | ASTM A269, ASTM A270, EN 10217-7, GB/T 12771, JIS G3446 |
Manufacturing Process
- Raw Material Selection: Ingot or wire rod sourced from certified mills (e.g., Outokumpu, POSCO, Taigang) with full chemical composition traceability via mill test certificates (MTC).
- Piercing & Reduction: Hot-pierced billet reduced to seamless tube坯 (semi-finished tube) via rotary piercing mill, achieving initial OD and wall dimensions within ±5% tolerance.
- Cold Drawing: Semi-finished tube drawn through precision tungsten carbide dies on hydraulic draw benches to achieve final OD and wall thickness within specified tolerances. This process imparts work hardening, improving mechanical properties by 30–50% over hot-finished equivalents.
- Intermediate Annealing: Multi-pass drawing schedules include intermediate annealing at 1050 °C – 1150 °C followed by controlled cooling to restore ductility and prevent cracking.
- Final Annealing & Pickling: Solution annealing in inert atmosphere (N₂ or vacuum) at 1050 °C, followed by acid pickling (HNO₃ + HF blend) to remove scale and restore passive chromium oxide layer.
- Surface Treatment: Mechanical or electrochemical polishing to achieve specified surface roughness (Ra value).
- Coiling: Finished tube wound onto precision-machined steel reels at controlled tension to prevent deformation. Coil diameter, layer count, and end-overlap geometry are optimized for downstream handling.
- Quality Inspection: 100% inline inspection including eddy current testing (ECT) for wall thickness uniformity, ultrasonic testing (UT) for internal defects, hydrostatic pressure testing at 1.5× PN, and dimensional verification via laser gauging.
Applications
HVAC & Fan Coil Unit Systems
- Heat exchange coils in fan coil units (FCUs) for commercial buildings, hotels, hospitals, and residential complexes
- Time-based air conditioning billing systems where precise thermal regulation and metering are required
- Chilled water and hot water distribution piping in multi-zone HVAC systems
- Condensate drain lines requiring corrosion resistance and hygienic drainage
Industrial & Process Applications
- Chemical processing and pharmaceutical piping systems (316L grade)
- Food and beverage processing lines (electropolished 304L/316L)
- Automotive fuel and hydraulic lines
- Oil and gas instrumentation tubing (stabilized grades)
- Solar thermal collector systems
Specialty Applications
- Cryogenic service (LN₂, LNG) with 304L/316L grades
- Medical gas distribution systems
- Semi-conductor cleanroom fluid delivery
Quality Certifications
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| ISO 14001:2015 | Environmental Management System |
| ISO 45001:2018 | Occupational Health & Safety Management |
| EN 10204 3.1 | Material Test Certificate (MTC) — Third-Party Inspection |
| CE Marking (PED 2014/68/EU) | Pressure Equipment Directive compliance for PN ≥ 0.5 bar |
| 3-A Sanitary Standards | Food-grade surface and design requirements |
| NSF/ANSI 61 | Drinking water system components |
| TÜV / SGS Inspection | Independent third-party verification |
Unique Selling Points
1. Pre-Coiled Geometry — Installation Efficiency: The coil tube format eliminates on-site bending, welding, and alignment labor. Field installation time is reduced by 40–60% compared to straight-length pipe with field fittings, directly lowering project cost and schedule risk.
2. Superior Thermal Performance: The austenitic stainless steel matrix provides thermal conductivity sufficient for efficient heat exchange while maintaining structural integrity across extreme temperature differentials (ΔT up to 1000 °C).
3. Zero-Maintenance Corrosion Resistance: Self-passivating chromium oxide film (Cr₂O₃) provides indefinite service life in aggressive environments without cathodic protection or linings — critical for HVAC condensate circuits and coastal installations.
4. Full Traceability: Every coil is serialized with batch-level chemical and mechanical test data, enabling complete supply chain traceability from raw ingot to installed system.
5. Custom Configuration: Wenzhou Jixing Metal Materials Co., Ltd. offers fully customizable OD, WT, coil length, end-form, and surface finish to meet project-specific requirements, supported by rapid prototyping and sampling within 7 working days.
Technical Notes for HVAC Billing System Integration
In time-based fan coil unit air conditioning billing systems (时间型风机盘管空调计费系统), the stainless steel coil tube serves as the primary heat transfer element. System design considerations include:
- Hydraulic Balance: Coil tube internal diameter and wall thickness must be optimized to maintain uniform flow velocity (recommended: 1.0–2.5 m/s) across all connected FCU terminals, ensuring accurate thermal energy metering.
- Pressure Drop Calculation: Darcy-Weisbach equation applied with stainless steel roughness coefficient (ε = 0.0015 mm) to determine system pump sizing and energy consumption.
- Thermal Expansion Compensation: Linear expansion coefficient α = 17.3 × 10⁻⁶ /K for 304 stainless steel must be accommodated in coil layout design to prevent mechanical stress at connection points during thermal cycling.
- Anti-Scale Performance: The smooth surface finish (Ra ≤ 0.4 μm for EP finish) minimizes scale adhesion, maintaining heat transfer efficiency over extended service intervals and ensuring billing accuracy.
For detailed engineering calculations, material certifications, or custom quotation requests, contact Wenzhou Jixing Metal Materials Co., Ltd. technical sales department.