Stainless Steel Coil Tube (盘管 Coiltube) — Technical Product Specification
1. Product Overview
The Stainless Steel Coil Tube (盘管 Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product designed for thermal management applications, particularly within Fan Coil Unit (FCU) systems and HVAC (Heating, Ventilation, and Air Conditioning) infrastructure. This product is supplied in continuous coil form, enabling efficient downstream processing, custom cutting, and installation in diverse industrial and commercial settings.
Coil tubes serve as critical heat exchange elements, where working fluids circulate through the tubular channels to facilitate thermal energy transfer between the fluid and the surrounding medium. The stainless steel construction provides exceptional corrosion resistance, structural integrity, and long-term durability under demanding operational conditions.
2. Material & Properties
The coil tube is fabricated from high-grade stainless steel, typically conforming to the following material standards:
- Material Grades: AISI 304 (UNS S30400), AISI 316 (UNS S31600), AISI 321 (UNS S32100), and equivalent Chinese national standard grades (e.g., 06Cr19Ni10, 06Cr17Ni12Mo2).
- Corrosion Resistance: Excellent resistance to atmospheric, chemical, and thermal oxidation environments. The chromium (Cr ≥ 18%) and nickel (Ni ≥ 8%) alloy composition forms a passive oxide layer providing long-term protection.
- Mechanical Properties: Tensile strength (Rm) ranging from 520–750 MPa; yield strength (Rp0.2) ≥ 205 MPa; elongation (A) ≥ 40% (annealed condition).
- Thermal Properties: Thermal conductivity of approximately 16.3 W/(m·K) at 100°C, suitable for efficient heat transfer applications.
- Temperature Range: Operational temperature range from −196°C to +870°C, accommodating cryogenic and high-temperature service conditions.
3. Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (customizable) | GB/T 14976, ASTM A213/A269 |
| Wall Thickness | 0.5 mm – 4.0 mm | GB/T 14976, EN 10217 |
| Coil Length (per roll) | 50 m – 500 m (adjustable per order) | Manufacturer specification |
| Coil Inner Diameter | 150 mm – 300 mm | Manufacturer specification |
| Surface Finish | Mirror polish, matte, hairline, or pickled & passivated | GB/T 13116, ASTM A478 |
| Tolerance (OD) | ±0.1 mm (precision grade) | ISO 1307 |
| Tolerance (Wall Thickness) | ±10% of nominal | GB/T 14976 |
| End Condition | Plain, beveled, or threaded (upon request) | — |
| Delivery Form | Continuous coil on wooden or steel spool | — |
| Product Reference No. | 1287 | Internal catalog |
4. Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing sequence to ensure dimensional accuracy, surface quality, and metallurgical integrity:
- Raw Material Selection: High-purity stainless steel strip or seamless pipe blanks are procured from certified suppliers with full mill test certificates (MTC) in accordance with EN 10204 Type 3.1.
- Forming & Welding: Cold-rolled strip is precisely formed into a circular cross-section and seam-welded using TIG (Tungsten Inert Gas) or automatic orbital welding techniques under inert atmosphere protection to prevent oxidation.
- Heat Treatment (Annealing): The formed tube undergoes solution annealing at 1050–1150°C followed by controlled cooling to relieve residual stresses and restore full austenitic microstructure.
- Pickling & Passivation: Chemical pickling removes the heat treatment oxide scale, followed by passivation treatment to re-establish the protective chromium oxide film.
- Surface Finishing: Optional polishing (electrolytic or mechanical) achieves the required surface roughness (Ra ≤ 0.4 μm for mirror finish).
- Dimensional Inspection: Each coil is inspected for OD, wall thickness, roundness, and straightness using ultrasonic (UT), laser, and optical measurement systems.
- Coiling & Packaging: The finished tube is wound onto precision spools, wrapped in protective film, and secured for transportation.
5. Applications
The stainless steel coil tube from Wenzhou Jixing Metal Materials Co., Ltd. is applicable across a broad spectrum of industries:
- HVAC & Fan Coil Unit Systems: Used as heat exchange coils in fan coil units for winter heating and summer cooling configurations. The coil tube geometry optimizes the air-side and fluid-side heat transfer coefficients, as analyzed through psychrometric (i-d) chart design methodologies for precise thermal performance prediction.
- Refrigeration Systems: Evaporator and condenser coils in commercial refrigeration and cold storage facilities.
- Food & Beverage Industry: Heat exchangers, pasteurization systems, and sanitary fluid transfer lines requiring food-grade (3-A, EHEDG) compliance.
- Chemical Processing: Corrosion-resistant heat transfer coils in aggressive chemical environments.
- Pharmaceutical Manufacturing: CIP (Clean-in-Place) compatible tubing for sterile fluid processing.
- Automotive & Marine: Radiator coils, exhaust heat recovery, and marine HVAC systems.
- Power Generation: Condenser tubes and heat recovery steam generators (HRSG) in combined-cycle power plants.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring adherence to international standards:
- Quality Management: ISO 9001:2015 certified quality management system.
- Product Standards: Conformance to GB/T 14976 (Stainless Steel Seamless Tubes), ASTM A213/A269, EN 10217-7, and JIS G3459.
- Material Certification: Mill Test Certificates (MTC) provided per EN 10204 Type 3.1, with optional 3.2 inspection reports.
- Non-Destructive Testing (NDT): 100% ultrasonic testing (per ASTM E1278), helium leak testing (per ASTM F2154), and visual inspection of weld seams.
- Environmental Compliance: RoHS 2.0 and REACH compliant; ISO 14001 environmental management system.
- Industry-Specific Certifications: PED (Pressure Equipment Directive 2014/68/EU) certification for pressure-containing applications; ASME "S" stamp availability upon request.
7. Unique Selling Points
Thermal Efficiency Optimization: The coil tube geometry, combined with precision-controlled dimensions, maximizes the heat transfer surface area-to-volume ratio, enabling optimal performance in fan coil unit systems—particularly in winter air conditioning conditions where dehumidification and heating must be simultaneously balanced as determined by psychrometric (i-d) chart analysis.
- Superior Corrosion Resistance: The austenitic stainless steel matrix provides unmatched durability in humid, saline, and chemically aggressive environments, extending service life beyond 25 years under normal conditions.
- Customizable Specifications: Full flexibility in OD, wall thickness, coil length, surface finish, and end preparation to meet specific application requirements.
- Precision Manufacturing: Tight dimensional tolerances (±0.1 mm) ensure reliable compatibility with brazing, welding, and mechanical assembly processes.
- Hygienic Design: Mirror-polished interior surfaces minimize biofilm accumulation and facilitate CIP/COP cleaning, meeting FDA and 3-A sanitary standards.
- Cost-Effective Coil Supply: Continuous coil format reduces material waste, minimizes handling labor, and accelerates production throughput compared to cut-length alternatives.
- Comprehensive Technical Support: Engineering consultation for coil design, including thermal performance calculations, flow velocity optimization, and pressure drop analysis.
8. Technical Data Summary
| Property | AISI 304 | AISI 316 | AISI 321 |
|---|---|---|---|
| Chromium (%) | 18–20 | 16–18 | 17–19 |
| Nickel (%) | 8–10.5 | 10–14 | 9–12 |
| Molybdenum (%) | — | 2–3 | — |
| Titanium (%) | — | — | 5×(C−0.02)–0.70 |
| Max. Service Temperature (°C) | 870 | 870 | 900 |
| Resistance to Pitting (PREN) | 18–20 | 24–26 | 18–20 |
| Thermal Conductivity @100°C (W/m·K) | 16.3 | 16.3 | 16.3 |
9. Ordering Information
When placing orders for the Stainless Steel Coil Tube (Product Reference No. 1287), customers should specify:
- Material grade (e.g., AISI 304, 316, 321, or equivalent)
- Outer diameter and wall thickness (nominal dimensions)
- Required coil length and coil inner diameter
- Surface finish requirement (mirror, matte, hairline, or pickled)
- End preparation type (plain, beveled, or threaded)
- Applicable standard and required certifications
- Quantity and delivery timeline
10. Storage & Handling Recommendations
- Store in a dry, ventilated warehouse away from direct sunlight and moisture exposure.
- Maintain the protective wrapping until immediately prior to installation to prevent surface contamination or mechanical damage.
- Use non-marking lifting equipment (e.g., soft slings) when handling coils to avoid surface indentation.
- Avoid contact with carbon steel tools, abrasives, or equipment to prevent iron contamination and subsequent rust staining (ferritic staining).
- Recommended maximum storage duration in original packaging: 12 months.
Document prepared for technical reference. For detailed engineering consultation, thermal performance calculations, or custom product development inquiries, contact Wenzhou Jixing Metal Materials Co., Ltd. directly.