Stainless Steel Coil Tube (Model: 1303) — Fan Coil & HVAC Application Series
1. Product Overview
The Stainless Steel Coil Tube (Model 1303) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coil tube product specifically designed for fan coil unit (FCU) systems, fresh air air conditioning systems, and related HVAC (Heating, Ventilation, and Air Conditioning) applications. This product represents the integration of high-grade austenitic stainless steel with advanced coiling technology, delivering superior corrosion resistance, thermal conductivity, and mechanical integrity under demanding environmental conditions.
The coil tube is engineered to serve as a critical heat exchange element within fan coil systems, where it facilitates efficient thermal transfer between working fluids and ambient air. Its spiral geometry maximizes surface area within a compact volume, making it an ideal choice for space-constrained installations in commercial buildings, hospitals, laboratories, and cleanroom environments.
2. Material & Properties
The coil tube is fabricated from high-quality austenitic stainless steel grades, selected for their exceptional combination of corrosion resistance, weldability, and thermal performance. The primary material specifications are as follows:
- Base Material: Austenitic Stainless Steel (e.g., AISI 304 / 316 / 316L conforming to ASTM A213/A269 standards)
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, chlorides, and condensate; the presence of Chromium (Cr ≥ 18%) and Nickel (Ni ≥ 8%) ensures a stable passive oxide layer
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20°C, providing reliable heat transfer performance
- Mechanical Strength: Tensile strength ≥ 515 MPa; Yield strength ≥ 205 MPa; Elongation ≥ 40%
- Temperature Range: Suitable for continuous operation from −196°C to +870°C
- Hygienic Surface: Surface roughness Ra ≤ 0.5 μm available upon request for sanitary and pharmaceutical applications
3. Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Product Model | 1303 | — |
| Outer Diameter (OD) | 9.52 / 12.7 / 15.88 / 19.05 / 25.4 (customizable) | mm |
| Wall Thickness | 0.50 – 1.50 | mm |
| Coil Pitch | 15 – 50 (adjustable per design requirement) | mm |
| Coil Length | 100 – 3000 (customizable) | mm |
| Material Grade | ASTM A213 TP304 / TP316 / TP316L | — |
| Surface Finish | Mirror / Matte / Pickled & Passivated | — |
| End Condition | Plain / Beveled / Threaded / Welded Header | — |
| Pressure Rating | Up to 1.6 MPa (16 bar) at 20°C | MPa |
| Tolerance on OD | ±0.05 | mm |
| Tolerance on Wall Thickness | ±0.02 | mm |
4. Manufacturing Process
The production of the Model 1303 stainless steel coil tube follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection & Inspection: Certified stainless steel round bar or seamless tube stock is procured from approved suppliers and subjected to spectroscopic analysis (PMI — Positive Material Identification) to verify chemical composition.
- Cold Drawing / Forming: Seamless tubes are cold-drawn to precise OD and wall thickness specifications, ensuring tight dimensional tolerances and improved mechanical properties through strain hardening.
- Coil Winding (Coiling): The formed tube is wound into a helical coil using CNC-controlled coiling machinery. The pitch, diameter, and number of turns are programmatically controlled to match engineering drawings. This step is critical for fan coil unit integration, where uniform coil geometry ensures balanced airflow and optimal heat exchange efficiency.
- Welding & Header Assembly: Inlet and outlet headers are TIG (Tungsten Inert Gas) welded to the coil ends under argon shielding to prevent oxidation. Weld beads are ground flush for smooth fluid flow.
- Heat Treatment (if required): Solution annealing at 1050°C followed by water quenching to restore full austenitic microstructure and maximize corrosion resistance.
- Pickling & Passivation: The finished coil is immersed in a nitric-hydrofluoric acid pickling solution to remove mill scale and weld discoloration, followed by passivation to establish a uniform chromium oxide passive film.
- Pressure Testing & Leak Detection: Each unit undergoes hydrostatic pressure testing at 1.5× the design pressure for a minimum of 30 minutes, with visual and electronic leak detection.
- Final Inspection & Packaging: Dimensional verification via calipers and micrometers, surface inspection under magnification, and protective packaging with desiccant for moisture-free storage.
5. Applications
The Model 1303 stainless steel coil tube is specifically engineered for the following application domains:
- Fan Coil Unit (FCU) Systems: Serves as the primary heat exchanger coil in both cooling and heating modes within fan coil systems integrated with fresh air ventilation. The stainless steel construction eliminates corrosion issues commonly encountered with copper or aluminum coils in humid or chemically aggressive environments.
- Commercial HVAC Systems: Suitable for large-scale commercial buildings including office towers, hotels, shopping centers, and educational facilities where long service life and low maintenance are paramount.
- Pharmaceutical & Food Processing: The hygienic-grade surface finish and resistance to chemical cleaning agents make this coil tube ideal for GMP (Good Manufacturing Practice) compliant environments.
- Marine & Coastal Installations: Grade 316/316L variants provide exceptional resistance to chloride-induced pitting and crevice corrosion in marine atmospheres.
- Industrial Process Cooling: Employed in closed-loop chiller systems, condenser units, and evaporator assemblies where fluid compatibility and thermal reliability are critical.
- Renewable Energy Systems: Applicable in solar thermal collectors and heat recovery ventilation (HRV) units.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring that the Model 1303 coil tube meets international standards and industry best practices:
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and process control
- ISO 14001:2015 — Environmental Management System certification reflecting sustainable manufacturing practices
- ASTM A213 / A269 — Compliance with standard specifications for seamless austenitic stainless steel tube
- EN 10217-7 — European standard for stainless steel tubes for pressure purposes
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes
- NSF/ANSI 61 — Drinking water system components certification (available upon request for potable water applications)
- CE Marking — Conformity with European health, safety, and environmental protection standards
- Mill Test Reports (MTR): Full chemical and mechanical test documentation provided with each batch shipment
7. Unique Selling Points
- Superior Corrosion Resistance: Unlike copper-coil alternatives, the stainless steel construction eliminates galvanic corrosion, dezincification, and condensate-induced degradation — extending service life beyond 25 years under normal operating conditions.
- Customizable Geometry: CNC-controlled coiling allows precise tailoring of coil pitch, diameter, and length to match specific fan coil unit designs, optimizing thermal performance and airflow balance.
- Hygienic & Food-Grade Capability: Available with electropolished surfaces (Ra ≤ 0.4 μm) suitable for pharmaceutical, biotechnology, and food processing applications.
- Low Maintenance: The passive oxide film self-heals under oxidizing conditions, minimizing fouling, scaling, and the need for chemical descaling — reducing total cost of ownership (TCO).
- Full Traceability: Every coil tube batch is traceable from raw material mill certificate through final inspection, ensuring complete supply chain transparency.
- Wide Material Grade Selection: Available in 304, 316, 316L, 321, and duplex 2205 grades to address specific environmental and mechanical requirements.
Note: All specifications listed above are representative. Custom dimensions, material grades, and surface treatments are available upon request. Wenzhou Jixing Metal Materials Co., Ltd. welcomes OEM (Original Equipment Manufacturer) and ODM (Original Design Manufacturer) partnerships for project-specific coil tube solutions tailored to fan coil unit and HVAC system design requirements.